U.S. patent number RE30,750 [Application Number 06/148,159] was granted by the patent office on 1981-09-29 for cardiac resuscitator and monitoring apparatus.
This patent grant is currently assigned to Cardiac Resuscitator Corporation. Invention is credited to Archibald W. Diack, Robert G. Rullman, Warren S. Welborn.
United States Patent |
RE30,750 |
Diack , et al. |
September 29, 1981 |
Cardiac resuscitator and monitoring apparatus
Abstract
The disclosed apparatus attaches to the patient for monitoring
the patient's condition and administering the correct electrical
stimulation to a suspected heart attack victim as soon as possible
after the occurrence of the attack and in the absence of medical
personnel. The apparatus preferably includes an oro-pharyngeal
airway provided with electrodes for ascertaining electrical
activity of the heart. A microphone attached to the airway, or a
strain gauge applied elsewhere to the patient's body, detects
bodily motion, for example respiration. If neither substantial
electrical activity nor bodily motion is detected, the patient is
considered to be in a cardiac arrest and a pacing impulse is
applied to the patient via the aforementioned airway electrodes
and/or other electrodes, while if electrical activity is
ascertained in the absence of bodily motion, a defibrillating pulse
is applied to the patient.
Inventors: |
Diack; Archibald W. (Portland,
OR), Welborn; Warren S. (Portland, OR), Rullman; Robert
G. (Beaverton, OR) |
Assignee: |
Cardiac Resuscitator
Corporation (Lake Oswego, OR)
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Family
ID: |
34317644 |
Appl.
No.: |
06/148,159 |
Filed: |
May 7, 1980 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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429745 |
Jan 2, 1974 |
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253507 |
May 15, 1972 |
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Reissue of: |
645074 |
Dec 29, 1975 |
04088138 |
May 9, 1978 |
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Current U.S.
Class: |
607/5; 607/6;
607/134; 600/380; 600/484 |
Current CPC
Class: |
A61N
1/3904 (20170801); A61N 1/36514 (20130101); A61N
1/365 (20130101); A61B 5/6852 (20130101) |
Current International
Class: |
A61N
1/365 (20060101); A61N 1/39 (20060101); A61N
001/36 () |
Field of
Search: |
;128/419D,419PG,423,671,691,639,641,642,644,650,689,693,696,702,705,706,710 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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285036 |
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Oct 1970 |
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AT |
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840567 |
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CA |
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869120 |
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Apr 1971 |
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121090 |
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1067538 |
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Oct 1959 |
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DE |
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6752096 |
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Mar 1969 |
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DE |
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2118719 |
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Nov 1972 |
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DE |
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2020437 |
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Jul 1970 |
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FR |
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2076891 |
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Sep 1971 |
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FR |
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2166812 |
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Jul 1973 |
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FR |
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7100758 |
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Jun 1975 |
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SE |
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826766 |
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Jan 1960 |
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1224904 |
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GB |
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1257114 |
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GB |
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1261446 |
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Jan 1972 |
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GB |
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1290537 |
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Sep 1972 |
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GB |
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1313486 |
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Apr 1973 |
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GB |
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1346495 |
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Feb 1974 |
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GB |
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Other References
Sternlieb et al., "U.S. Armed Forces Medical Journal", vol. 11, No.
6, Jun. 1960, pp. 712-713. .
Copland et al., "The Lancet", vol. 1, No. 7330, Feb. 22, 1964, p.
614. .
Zoll et al., "Circulation", vol. 14, Nov. 1956, pp. 745-756. .
Zoll et al., "Circulation", vol. 25, Apr. 1962, pp. 596-603. .
Kouwenhoven et al., "American Journal of Physiology", vol. 100,
1932, pp. 344-350. .
Stratbucker et al., "Rocky Mountain Engineering Society", 1965, pp.
57-61. .
Stephenson, Jr., CV Mosby Co., 1974 pp. 374-377 & 336-337.
.
Stephenson, Jr., CV Mosby Co., 1971 pp. 336-337. .
Lown et al., "Circulation", vol. 44, Oct. 1972, pp. 637-639. .
Mirowski et al., "Archives of Internal Medicine",vol. 126, Jul.
1970, pp. 158-161. .
News Release "Army", Surgeon General's Offices Scientific
Breakthrough in Heart Device"..
|
Primary Examiner: Kamm; Wiliam E.
Attorney, Agent or Firm: Chernoff & Vilhauer
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATIONS
This .[.application is.]. .Iadd.is an application for reissue of
original patent No. 4,088,138, which, as an application, was
.Iaddend.a continuation of copending U.S. Pat. application, Ser.
No. 429,745, filed Jan. 2, 1974, by Archibald W. Diack, Warren S.
Welborn and Robert G. Rullman, entitled "Cardiac Resuscitator and
Monitoring Apparatus" and now abandoned, which was a
continuation-in-part of copending U.S. Pat. application, Ser. No.
253,507, filed May 15, 1972, by Archibald W. Diack, Warren S.
Welborn and Robert G. Rullman, entitled "Cardiac Resuscitator" and
now abandoned.
Claims
We claim:
1. A cardiac resuscitator apparatus comprising:
an oro-pharyngeal airway for insertion into the pharynx of a
patient, said airway having contact means mounted thereon for
making electrical contact with tissue within the patient,
second electrode means for external placement on the patient in the
chest-abdominal region for making electrical contact with the
patient in said region,
circuit means for generating an electrical defibrillating pulse,
said circuit means having first and second terminals between which
said defibrillating pulse is supplied,
and conductor means respectively coupling said first and second
terminals to said contact means and said second electrode means for
delivering said defibrillating pulse to the patient through a
current pathway in the trunk of the patient between said contact
means mounted on said airway and said second electrode means for
defibrillating the patient's heart.
2. A cardiac resuscitator apparatus comprising:
an oro-pharyngeal airway for insertion into the pharynx of a
patient, said airway having contact means mounted thereon for
making electrical contact with tissue within the patient,
second electrode means for external placement on the patient in the
chest-abdominal region for making electrical contact with the
patient in said region,
first circuit means connected to said contact means on said airway
for deriving an electrical input from the patient's heart for
detecting an abnormal heart condition,
second circuit means for generating a defibrillating pulse, said
second circuit means having first and second terminals between
which said defibrillation pulse is supplied, said second circuit
means being responsive in its operation to detection of an abnormal
heart condition by said first circuit means,
and conductor means for respectively connecting said first and
second terminals to said contact means and said second electrode
means for delivering said defibrillating pulse to the patient
through a current pathway in the trunk of the patient between said
contact means mounted on said airway and said second electrode
means for defibrillating the patient's heart.
3. A cardiac resuscitator apparatus comprising:
an oro-pharyngeal airway for insertion into the pharynx of a
patient, said airway having contact means mounted thereon for
making electrical contact with tissue within the patient,
second electrode means for electrically contacting the patient at
another location remote from said contact means,
electrical detecting means mounted on said airway and responsive to
the patient's respiration by the detection of the flow of air past
said detecting means on said airway,
first circuit means connected at least to contact means on said
airway and to said electrical detecting means for ascertaining the
presence of heart associated electrical activity above a
predetermined level together with the absence of respiration above
a predetermined level for thereupon making a logical determination
of a fibrillation condition,
second circuit means for generating an electrical defibrillating
pulse, said second circuit means being coupled to said first
circuit means and responsive to said first circuit means for
generating said defibrillating pulse in response to said logical
determination of a fibrillation condition,
and conductor means for coupling said second circuit means to
contact means on said airway and to said second electrode means for
delivering said defibrillating pulse to the patient through a
current pathway in the trunk of the patient between said contact
means and said second electrode means for defibrillating the
patient's heart.
4. The resuscitator apparatus according to claim 3 wherein said
electrical detecting means for detecting respiration comprises a
microphone mounted on said airway responsive to the sound caused by
said flow of air.
5. The resuscitator apparatus according to claim 4 wherein said
microphone is mounted proximate the forward end of said airway in
non-obstructive relation to the passage of air along said
airway.
6. The resuscitator apparatus according to claim 4 further
including amplifier means coupled to the said microphone and
responsive to respiration of the patient due to the flow of air
past said microphone, and means for coupling the output of said
amplifier means in driving relation to said first circuit
means.
7. The resuscitator apparatus according to claim 4 wherein said
second electrode means comprises an abdominal electrode for
placement on the patient in the chest-abdominal region for making
electrical contact with the patient in said region.
8. The resuscitator apparatus according to claim 4 further
including pacing means for supplying a regular pacing pulse to the
patient via contact means on said airway and said second electrode
means in the substantial absence of electrical activity and
respiration as detected by said first circuit means.
9. The resuscitator apparatus according to claim 4 further
including means for checking the electrical continuity between said
contact means mounted on said airway and said second electrode
means and the patient.
10. The resuscitator apparatus according to claim 4 wherein said
second circuit means for generating said defibrillating pulse
includes timing means, and means for ascertaining the output of
said first circuit means a predetermined time after the generation
of a defibrillating pulse for initiating a second defibrillating
pulse.
11. The cardiac resuscitator apparatus according to claim 10
wherein said means for generating an electrical defibrillating
pulse further includes timing means for disabling the generation of
a defibrillating pulse after the generation of a predetermined
number of defibrillating pulses.
12. A cardiac resuscitator apparatus comprising:
an oro-pharyngeal airway for insertion into the pharynx of a
patient, said airway having contact means mounted thereon for
making electrical contact with tissue within the patient,
second electrode means for external placement on the patient in the
chest-abdominal region for making electrical contact with the
patient in said region,
a microphone mounted on said airway for detecting the respiration
of the patient by detecting a patient's breath sounds caused by the
flow of air past said microphone on said airway,
first circuit means connected to said contact means on said airway
and to said second electrode means for ascertaining the presence of
heart associated electrical activity above a predetermined
level,
second circuit means connected to said microphone for detecting a
patient's respiration above a predetermined level,
logical circuit means coupled to said first circuit means and said
second circuit means for making a logical determination of the
presence of heart associated electrical activity above a
predetermined level together with the absence of respiration above
a predetermined level for indicating a fibrillation condition,
fourth circuit means for generating an electrical defibrillating
pulse, said fourth circuit means being coupled to said logical
circuit means and responsive to the logical determination thereof
for generating said defibrillating pulse in response to
determination of a defibrillation condition,
and conductor means for coupling said fourth circuit means to said
contact means on said airway and to said second electrode means for
delivering said defibrillating pulse to the patient through a
current pathway in the trunk of the patient between said contact
means and said second electrode means for defibrillating the
patient's heart.
13. The cardiac resuscitator apparatus according to claim 12
further including pacing means for generating a regular pacing
pulse, said pacing means being responsive to said logical circuit
means for generating said pacing pulse in the absence of heart
associated electrical activity of the patient above a predetermined
level together with the absence of respiration above a
predetermined level,
and conductor means for coupling the output of said pacing means to
said contact means on said airway and to said second electrode
means for delivering said pacing pulse to the patient through a
current pathway in the trunk of the patient between said contact
means and said second electrode means for pacing the patient's
heart.
14. A cardiac resuscitator apparatus comprising:
first means for insertion into the region of a patient's mouth,
said insertion means comprising electrical contact means for
contacting the patient's tongue,
external electrode means for placement on the patient in the
chest-abdominal region for making electrical contact with the
patient in said region,
circuit means for generating an electrical defibrillating pulse,
said circuit means having first and second terminals between which
said defibrillation pulse is supplied,
and connection means respectively coupling said first and second
terminals to said contact means and said external electrode means
for delivering said defibrillating pulse to the patient through a
current pathway in the trunk of the patient between said contact
means and said external electrode means for defibrillating the
patient's heart.
15. The resuscitator according to claim 14 further including
detection means connected to said contact means and electrode means
for detecting the level of electrical heart activity of the
patient, said circuit means being responsive in its pulse
generating operation to said detection.
16. The resuscitator according to claim 15 further including means
mounted on said first means for detecting respiration of the
patient, said circuit means for generating an electrical
defibrillating pulse being responsive thereto for inhibiting the
application of a defibrillating pulse to the patient in the
presence of respiration detection.
17. The resuscitator according to claim 16 further including means
for generating a pacing pulse, and means for supplying said pacing
pulse between said contact means and said electrode means.
18. A life sign monitoring system comprising:
a device for at least partial insertion into or onto a body cavity
or passageway of a patient, said device having contact means
mounted thereon for contacting tissue on the interior of said
cavity or passageway,
second electrode means for contacting the patient, said second
electrode means comprising means for securely fastening to the
patient at a substantially external location remote from said
contact means, said second electrode means comprising a ring
adapted to grasp an extremity of the patient and provided with ball
and socket means for holding the ring in an extended no-grasping
condition for initial placement upon an extremity of a patient,
and output means coupled to said contact means and said second
electrode means for providing cardiac information in response to
electrical signals coupled from said contact means and said second
electrode means.
19. A life sign monitoring system comprising:
an airway adapted to be passed into the pharynx of a patient,
contact means mounted on said airway,
first means connected to said contact means for responding to
electrical activity associated with the patient's heart,
second means for sensing bodily movement of said patient, said
second means comprising a sensor applied elsewhere to the body of
the patient and responsive to chest expansion of the patient with
respiration, said sensor comprising a strain gauge mounted upon
means extending at least part way around the patient's chest
comprising hinged tongs adapted to carry said strain gauge wherein
said strain gauge is pressure-responsive and is disposed between
said tongs and the patient's body,
and logical means responsive to said first and said second means
for indicating the presence of substantial electrical activity and
whether bodily movement substantially accompanies said electrical
activity.
20. A life sign monitoring system comprising:
an airway adapted to be passed into the pharynx of a patient,
contact means mounted on said airway,
first means connected to said contact means for responding to
electrical activity associated with the patient's heart,
second means for sensing bodily movement of said patient, said
second means comprising means for detecting the flow of blood in
the patient, the last mentioned means including sound-sensing
means, amplifier means, and filtering means responsive to blood
flow sounds indicative of a sign of life, and multivibrator means
responsive to blood flow indicating input from said amplifier means
for standardizing the input therefrom, and integrating means for
receiving the output of said multivibrator means,
and logical means responsive to said first and second means for
indicating the presence of substantial electrical activity and
whether bodily movement substantially accompanies said electrical
activity. .Iadd.
21. The resuscitator apparatus according to claim 14 wherein said
first means for insertion further comprises an intratracheal tube,
said electrical contact means being mounted on said intratracheal
tube. .Iaddend..Iadd. 22. A cardiac resuscitator apparatus
comprising:
(a) an oro-pharyngeal airway for insertion into the pharynx of a
patient, said airway having contact means mounted thereon for
making electrical contact with tissue within the patient;
(b) second electrode means for external placement on the patient in
the chest-abdominal region for making electrical contact with the
patient in said region;
(c) circuit means for generating an electrical pacing pulse, said
circuit means having first and second terminals between which said
pacing pulse is supplied; and
(d) conductor means respectively coupling said first and second
terminals to said contact means and said second electrode means for
delivering said pacing pulse to the patient through a current
pathway in the trunk of the patient between said contact means
mounted on said airway and said second electrode means for pacing
the patient's heart. .Iaddend. .Iadd. 23. The resuscitator
apparatus according to claim 22 wherein said circuit means further
includes means for repetitively generating said pacing pulse at a
predetermined rate. .Iaddend..Iadd. 24. A cardiac resuscitator
apparatus comprising:
(a) an oro-pharyngeal airway for insertion into the pharynx of a
patient, said airway having contact means mounted thereon for
making electrical contact with tissue within the patient;
(b) second electrode means for external placement on the patient in
the chest-abdominal region for making electrical contact with the
patient in said region;
(c) first circuit means connected to said contact means on said
airway for deriving an electrical input from the patient's heart
for detecting an abnormal heart condition;
(d) second circuit means for generating a pacing pulse, said second
circuit means having first and second terminals between which said
pacing pulse is supplied, said second circuit means being
responsive in its operation to detection of an abnormal heart
condition by said first circuit means; and
(e) conductor means for respectively connecting said first and
second terminals to said contact means and said second electrode
means for delivering said pacing pulse to the patient through a
current pathway in the trunk of the patient between said contact
means mounted on said airway and said second electrode means for
pacing the patient's heart. .Iaddend..Iadd. 25. A cardiac
resuscitator apparatus comprising:
(a) an oro-pharyngeal airway for insertion into the pharynx of a
patient, said airway having contact means mounted thereon for
making electrical contact with tissue within the patient;
(b) second electrode means for electrically contacting the patient
at another location remote from said contact means;
(c) electrical detecting means mounted on said airway and
responsive to the patient's respiration by the detection of the
flow of air past said detecting means on said airway;
(d) first circuit means connected at least to contact means on said
airway and to said electrical detecting means for ascertaining the
substantial absence of heart associated electrical activity
together with the absence of respiration above a predetermined
level for thereupon making a logical determination of a cardiac
arrest condition;
(e) second circuit means for generating an electrical pacing pulse,
said second circuit means being coupled to said first circuit means
and responsive to said first circuit means for generating said
pacing pulse in response to said logical determination of a cardiac
arrest condition; and
(f) conductor means for coupling said second circuit means to
contact means on said airway and to said second electrode means for
delivering said pacing pulse to the patient through a current
pathway in the trunk of the patient between said contact means and
said second electrode means for
pacing the patient's heart. .Iaddend..Iadd. 26. The resuscitator
apparatus according to claim 25 wherein said electrical detecting
means for detecting respiration comprises a microphone mounted on
said airway responsive to the sound caused by said flow of air.
.Iaddend..Iadd. 27. The resuscitator apparatus according to claim
26 wherein said microphone is mounted proximate the forward end of
said airway in non-obstructive relation to the passage of air along
said airway. .Iaddend.g 28. The resuscitator apparatus according to
claim 26 further including amplifier means coupled to said
microphone and responsive to respiration of the patient due to the
flow of air past said microphone, and means for coupling the output
of said amplifier means in driving relation to said first circuit
means. .Iadd. 29. The resuscitator apparatus according to claim 25
wherein said second electrode means comprises an abdominal
electrode for placement on the patient in the chest-abdominal
region for making electrical contact with the patient in said
region. .Iaddend..Iadd. 30. The resuscitator apparatus according to
claim 25 further including means for checking the electrical
continuity between said contact means mounted on said airway and
said second electrode means and the patient. .Iaddend..Iadd. 31.
The resuscitator apparatus according to claim 25 wherein said
second circuit means includes means for repetitively generating
said pacing pulse at a predetermined rate. .Iaddend..Iadd. 32. A
cardiac resuscitator apparatus comprising:
(a) an oro-pharyngeal airway for insertion into the pharynx of a
patient, said airway having contact means mounted thereon for
making electrical contact with tissue within the patient;
(b) second electrode means for external placement on the patient in
the chest-abdominal region for making electrical contact with the
patient in said region;
(c) a microphone mounted on said airway for detecting the
respiration of the patient by detecting a patient's breath sounds
caused by the flow of air past said microphone on said airway;
(d) first circuit means connected to said contact means on said
airway and to said second electrode means for ascertaining the
absence of heart associated electrical activity of the patient
above a predetermined level;
(e) second circuit means connected to said microphone for detecting
a patient's respiration above a predetermined level;
(f) logical circuit means coupled to said first circuit means and
said second circuit means for making a logical determination of the
absence of heart associated electrical activity above a
predetermined level together with the absence of respiration above
a predetermined level for indicating a cardiac arrest
condition;
(g) fourth circuit means for generating an electrical pacing pulse,
said fourth circuit means being coupled to said logical circuit
means and responsive to the logical determination thereof for
generating said pacing pulse in response to determination of a
cardiac arrest condition; and
(h) conductor means for coupling said fourth circuit means to said
contact means on said airway and to said second electrode means for
delivering said pacing pulse to the patient through a current
pathway in the trunk of the patient between said contact means and
said second electrode means for
pacing the patient's heart. .Iaddend..Iadd. 33. A cardiac
resuscitator apparatus comprising:
(a) first means for insertion into the region of a patient's mouth,
said first means comprising electrical contact means for contacting
the patient's tongue;
(b) external electrode means for placement on the patient in the
chest-abdominal region for making electrical contact with the
patient in said region;
(c) circuit means for generating an electrical pacing pulse, said
circuit means having first and second terminals between which said
pacing pulse is supplied; and
(d) connection means respectively coupling said first and second
terminals to said contact means and said external electrode means
for delivering said pacing pulse to the patient through a current
pathway in the trunk of the patient between said contact means and
said external electrode means for pacing the patient's heart.
.Iaddend..Iadd. 34. The resuscitator according to claim 33 further
including detection means connected to said contact means and
electrode means for detecting the level of electrical heart
activity of the patient, said circuit means being responsive in its
pulse generating operation to said detection. .Iaddend. .Iadd. 35.
The resuscitator apparatus according to claim 33 wherein said
circuit means includes means for repetitively generating said
pacing pulse at a predetermined rate. .Iaddend..Iadd. 36. The
resuscitator apparatus according to claim 33 further including
means for detecting a heart beat, said circuit means for generating
a pacing pulse being responsive thereto for inhibiting the
generation of said pacing pulse in the presence of a patient heart
beat of acceptable rate. .Iaddend..Iadd. 37. The resuscitator
apparatus according to claim 33 wherein said first means for
insertion further comprises an intratracheal tube, said electrical
contact means being mounted on said intratracheal tube.
.Iaddend..Iadd. 38. A life sign monitoring system comprising:
(a) a tube adapted to be passed at least into the pharynx of a
patient;
(b) contact means mounted on said tube;
(c) first means connected to said contact means for responding to
electrical activity associated with the patient's heart;
(d) second means for sensing bodily movement of said patient, said
second means comprising a sensor applied elsewhere to the body of
the patient and responsive to chest expansion of the patient with
respiration, said sensor comprising a strain gauge mounted upon
means extending at least part way around the patient's chest
comprising hinged tongs adapted to carry said strain gauge wherein
said strain gauge is pressure-responsive and is disposed between
said tongs and the patient's body; and
(e) logical means responsive to said first and said second means
for indicating the presence of substantial electrical activity and
whether bodily movement substantially accompanies said electrical
activity. .Iaddend..Iadd. 39. The life sign monitoring system
according to claim 38, wherein said tube is adapted to be passed
into the trachea of a patient. .Iaddend..Iadd. 40. A life sign
monitoring system comprising:
(a) a tube adapted to be passed at least into the pharynx of a
patient;
(b) contact means mounted on said tube;
(c) first means connected to said contact means for responding to
electrical activity associated with the patient's heart;
(d) second means for sensing bodily movement of said patient, said
second means comprising means for detecting the flow of blood in
the patient, the last mentioned means including sound-sensing
means, amplifier means, and filtering means responsive to blood
flow sounds indicative of a sign of life, and multivibrator means
responsive to blood flow indicating input from said amplifier means
for standardizing the input therefrom, and integrating means for
receiving the output of said multivibrator means; and
(e) logical means responsive to said first and second means for
indicating the presence of substantial electrical activity and
whether bodily movement substantially accompanies said electrical
activity. .Iaddend..Iadd. 41. The life sign monitoring system
according to claim 40, wherein said tube is adapted to be passed
into the trachea of a patient. .Iaddend.
Description
BACKGROUND OF THE INVENTION
The present invention relates to cardiac resuscitator and
monitoring apparatus and particularly to such apparatus which is
securely attachable to a patient for rapidly ascertaining his
cardiac condition for the purpose of bringing about corrective
treatment.
An unusually large number of heart attack victims die each year as
a result of delays in providing the intensive care required. A
suspected heart attack victim must typically be hospitalized before
receiving adequate medical attention. However, a great many
patients suffering from coronary attack never reach the hospital.
Cardiac arrests and arrythmias such as ventricular fibrillation
frequently develop within a short time after the onset of the
attack, e.g., within the first hour, with fatal results unless
remedial steps are taken within minutes. Unless the normal rhythm
can be restored to a heart in ventricular fibrillation within
minutes, serious brain damage or death will result.
SUMMARY OF THE INVENTION
In accordance with the present invention, a cardiac resuscitator is
provided which is compact enough for attachment to a suspected
heart attack victim at nearly any location, and which may be
operated by comparatively unskilled personnel. The resuscitator may
be carried in an ambulance, for example, or may be conveniently
stored in an industrial plant, office building, hotel, or the like,
for immediate application to the suspected victim of a heart
attack. In accordance with an embodiment of the present invention,
a resuscitator includes first means for responding to electrical
activity associated with the patient's heart, and second means for
sensing bodily movement of the patient. Logical means respond to
the first and second means for indicating the presence of
electrical activity and whether bodily movement substantially
accompanies such electrical activity. In the absence of either
mechanical or electrical activity, a regular pacing impulse is
applied to the patient. In the presence of detected electrical
activity in the absence of bodily motion, a defibrillating pulse is
applied. If both electrical activity and bodily motion are present,
no corrective action is taken, although the equipment is suitably
left attached to or near by the patient in case one of the
aforementioned conditions develops before the patient is adequately
hospitalized or under the care of adequately trained medical
personnel.
In accordance with one embodiment of the present invention, a life
sign monitoring system comprises an airway device adapted to be
passed in or through the mouth and preferably into the pharynx of
the patient, the airway having contact means mounted thereupon. In
this case, first means connected to the contact means responds to
electrical activity and second means senses bodily motion of the
patient. Logical means responds to the indications for suitably
supplying an output or for initiating appropriate operation of
pacing or defibrillating means. Other external electrode means are
suitably provided for attachment to the patient and cooperating to
provide electrical input and output relative to the patient.
In the instance of a particular embodiment, the second means for
sensing bodily movement advantageously comprises a sound detecting
means or microphone mounted upon the aforementioned airway.
Alternatively, the second means may comprise a sensor applied
elsewhere to the body, and may comprise a strain gauge or the like
applied to a belt or other appliance attached to the patient's
chest. In either case, the mechanical motion output is indicative
of a patient's respiration as a bodily motion life sign.
Alternatively, bodily motion can be detected through detection of
blood flow, phonocardiography, change in bodily impedance with a
patient's pulse, or sensing temperature changes due to
respiration.
When use of an airway is no longer possible, as when the patient
becomes conscious, a mouth contacting clip or clamp is substituted
therefor for monitoring purposes.
It is an object of the present invention to provide an improved
cardiac resuscitator apparatus which may be applied to a suspected
heart attack victim in nearly any location.
It is a further object of the present invention to provide an
improved cardiac resuscitator apparatus which is securely
attachable to a patient suffering from a suspected heart attack for
the purpose of ascertaining electrical heart activity and bodily
motion.
It is another object of the present invention to provide an
improved life sign monitoring system applicable to a patient
suffering from a suspected heart attack wherein required electrical
connection to the patient can be rapidly and correctly
initiated.
It is another object of the present invention to provide an
improved life sign monitoring system for continued connection to a
conscious patient.
It is a further object of the present invention to provide improved
apparatus for ascertaining a plurality of life signs from a victim
suffering a possible heart attack.
The subject matter which we regard as our invention is particularly
pointed out and distinctly claimed in the concluding portion of
this specification. The invention, however, both as to organization
and method of operation, together with further advantages and
objects thereof, may best be understood by reference to the
following description taken in connection with the accompanying
drawings wherein like reference characters refer to like
elements.
DRAWINGS
FIG. 1 is a view of a life sign monitoring and resuscitator system
according to the present invention;
FIG. 2 is a bottom view of an oro-pharyngeal airway, 10, of FIG.
1;
FIG. 3 is a cross section of such airway taken at 3--3 in FIG.
1;
FIG. 4 is a side view of further apparatus for providing life sign
monitoring signals and/or for applying corrective impulses to a
patient;
FIG. 5 is a side view of modified apparatus for ascertaining
patient life signs and/or providing corrective electrical
stimulation to the patient;
FIG. 6 is a schematic diagram of a circuit connectable to
patient-contacting electrodes for providing output signals
indicative of patient electrical heart activity, and including a
Table I indicating corrective electrical stimulation applicable for
different combinations of electrical activity and bodily motion
conditions;
FIG. 7 is a logical diagram of circuitry according to the present
invention for implementing the logical determination according to
the Table I;
FIG. 8 is a schematic and block diagram representation of apparatus
for determining bodily motion by means of impedance changes in the
body according to a patient's pulse;
FIG. 9 is a schematic diagram of a circuit responsive to a
mechanical transducer for indicating bodily movement in the case,
for example, of respiration;
FIG. 10 is a schematic diagram illustrating circuitry responsive to
bodily movement as indicated by respiration and/or pulse
sounds;
FIG. 11 is a schematic diagram of a circuit responsive to bodily
movement in the form of blood flow sounds;
FIG. 12 is a schematic diagram of a circuit for generating pacing
pulses for application to a patient;
FIG. 13 is a schematic diagram of a circuit for generating
defibrillating pulses for application to a patient;
FIG. 14 is a schematic and block diagram of a circuit connectable
to patient-contacting electrodes for providing output signals
indicative of patient electrical heart activity, said circuit
further including apparatus for providing signals indicative of
patient respiration and for making a logical determination of the
patient's condition;
FIGS. 15 and 16 are schematic and block diagrams further
illustrating logical circuitry for providing an indication of the
patient's condition;
FIG. 17 is a schematic diagram of a shaper circuit as employed in
the FIG. 14 apparatus;
FIG. 18 is a schematic and block diagram of an alternative form of
a portion of the FIG. 14 apparatus;
FIG. 19 is a schematic diagram of another alternative form of a
portion of the FIG. 14 apparatus;
FIG. 20 is a block diagram of numerical readout circuitry which may
be employed in conjunction with the FIG. 14 apparatus;
FIG. 21 is a side view of an intratracheal tube employed as a
sensing device according to the present invention;
FIG. 22 is a view of a nasal tube employed as a sensing device
according to the present invention;
FIG. 23 is a side view of a catheter employed as a sensing device
according to the present invention;
FIG. 24 is a perspective view of a clip device according to the
present invention for insertion in the mouth of a patient in place
of an airway;
FIG. 25 is a perspective view of a clamp device according to the
present invention which may be attached either to the mouth of the
patient, or elsewhere on the patient's body as an external
electrode;
FIG. 26 is a perspective view of another clamping device according
to the present invention for connection to the patient's body at an
external location;
FIGS. 27 and 28 are top views of a ring device according to the
present invention for connecting to a patient's extremity;
FIG. 29 is an end view of a ring or bracelet device according to
the present invention also employed for connection to an extremity
of a patient;
FIG. 30 is a cross sectional view taken at 30--30 in FIG. 29;
and
FIG. 31 is a perspective view of an "IV" needle employed as an
external electrode according to the present invention.
DETAILED DESCRIPTION
Referring to FIGS. 1 through 3, apparatus according to the present
invention preferably includes an oropharyngeal airway 10 including
a straight portion 11 and a curved, forward portion 13. The airway
is formed of plastic and comprises a central, vertical web 16,
extending substantially the full length of the airway, supporting
an upper transverse flange 14 and the lower transverse flange 15
defining therebetween open-sided air passages 18 and 20 which are
also open at the respective ends of the device to provide for
communication of air from flanged end 12, exterior to the patient,
to forward end 14. An airway as thus far described is frequently
employed during administration of anesthesia and the like for
maintaining a clear passageway into the patient's throat, the
device being initially inserted through the patient's mouth and
into the patient's pharynx. Such device is also frequently employed
by a physician in providing mouth-to-mouth resuscitation.
In accordance with an embodiment of the present invention, the
aforementioned airway 10 is further provided with first and second,
or positive and negative, electrodes 1 and 2 positioned opposite
one another on the outside flanges 15 and 14, respectively, near
the forward end of the airway, and a neutral electrode 3 positioned
on the curved part of flange 15 near straight portion 11 of the
airway. These electrodes, formed of conductive material, are
suitably round and partially embedded in the plastic from which the
airway is made. An additional electrode plate 4 is disposed on the
underside of the airway, i.e. on flange 15, substantially between
the aforementioned electrodes 1 and 3. Electrode 4 is also formed
of conductive material and is partially embedded in flange 15 while
being completely insulated from the aforementioned electrodes 1 and
3. In one embodiment, the plate electrode 4 partially surrounds
electrode 1 at the forward underside of the airway in spaced
relation to electrode 1.
The airway is further supplied with a small microphone 22 mounted
at the forward end 14 of the airway and secured upon the end of
central web 16 in such a manner that the microphone does not block
the passage of air on either side thereof. Substantially any type
of small microphone may be employed which is substantially
water-resistant, an encapsulated crystal microphone being
suitable.
The various electrodes, as well as the microphone leads, are
connected to logical circuitry and pulse generators 24 in a manner
hereinafter more fully described. Also connected to the latter
circuitry is additional or external electrode means 5 suitably
comprising a relatively large circular electrode 7 mounted upon an
insulating base 9 and further provided with a central, slightly
raised electrode 6. The electrode means 5 is adapted for attachment
to the patient elsewhere upon the patient's body, e.g. on the chest
over the area of the heart or to an extremity. The electrode can be
simply positioned or held against the patient, or may be attached
to the patient by a belt 8 or other suitable clamping means. As
will hereinafter be more fully described, electrode means 5 may be
employed as an external input electrode for use in conjunction with
input electrodes on the airway for ascertaining electrical activity
of the heart, and may be employed in conjunction with electrode
plate 4 for delivering a corrective stimulating pulse to the
patient.
Briefly, an airway is inserted through the mouth of a patient who
has undergone a suspected heart attack, and who is in an
unconscious state. Electrode means 5 is positioned elsewhere on his
body, preferably in the vicinity of the heart. The electrodes 1, 2
and 3 are adapted to provide, in conjunction with circuitry 24, an
indication of electrical heart activity of the type suitable for
providing an electrocardiogram. Circuitry 24 may, indeed, include
conventional EKG equipment, but it is not always necessary, in
accordance with the present invention, to develop the full EKG
waveform of a patient's heart, but rather electrical activity alone
can be detected by circuitry 24 and may be indicative of a normal
heart waveform, or may be indicative of the erratic electrical
heart output symptomatic of ventricular fibrillation. A second
input is applied to circuitry 24 from microphone 22 and is
indicative of sounds associated with bodily motion, i.e., sounds
detected within the region of the patient's pharynx. In particular,
the sound of any respiration or passage of air in the patient's
throat will be detected by microphone 22. Secondarily, sounds
associated with blood flow and/or the patient's heart beat or
phonocardiogram can also be supplied by microphone 22. These
sounds, indicative of bodily movement as a sign of life, are
supplied to circuitry 24 in conjunction with the electrical signal
hereinbefore mentioned, and the circuitry 24 is adapted to provide
corrective electrical stimulation in accordance with the logical
truth table, Table I in the drawings. If the electrical signal,
indicated by the designation "EKG Sensor" in Table I, is present,
and bodily motion according to the designation "Respiration Sensor"
is also present, no corrective stimulating pulsation is delivered
to the patient. If an electrical signal is present, and bodily
motion is absent, a defibrillating pulsation may be delivered to
the patient. However, if neither electrical nor bodily motion
signal is present, cardiac arrest is indicated and a pacing pulse
is delivered to the patient. The difference between a pacing pulse
and a defibrillating pulse is well understood by those skilled in
the art, a pacing pulse being adapted to restore heart action,
e.g., in the case of a patient in the condition of cardiac arrest.
A defibrillating pulse is adapted to inhibit erratic heart action
in a patient wherein ventricular fibrillation is ascertained as
evidenced by electrical output from the heart and no mechanical
motion, e.g., respiration or pulse. The defibrillating pulse is
normally at least an order of magnitude greater in current than the
pacing pulse and is adapted temporarily to interrupt the
functioning of the heart, after which a normal pulse frequently
follows. Either the defibrillating or pacing pulse, as the case may
be, is suitably applied between electrode plate 4, or one of the
other electrodes on the airway 10, and electrode means 5 applied
elsewhere to the patient's body.
Airway 10 is adapted to make relatively certain and immediate
contact with the patient in respect to ascertaining an electrical
signal as well as ascertaining an audible sound indicative of
respiration or the like. It has been found that the EKG signal can
be derived from electrodes mounted on an airway, and mounting the
same in this location provides the advantage of rapid and certain
electrical connection of these electrodes to the patient in an area
where conduction is advantageously enhanced. Thus, the danger of
failing to derive an electrical signal because of improper
connection of electrodes to the patient is minimized.
According to one embodiment of the present invention, external
electrode means 5, located elsewhere on the patient, is employed in
combination with the airway electrodes for delivering the
corrective electrical stimulation to the patient in response to the
logical determination. The corrective pulsation is suitably applied
across or between electrode means 5 and electrode plate 4. The
utilization of the external electrode means 5 is adapted to supply
corrective stimulation closer to the region of the patient's heart.
Furthermore, although an oro-pharyngeal airway is illustrated and
described, similar airway devices may be alternatively employed
such as a nasal-pharyngeal airway or an intratracheal tube or
devices coming under the general heading of catheters or
catheter-like devices may be employed.
Further means for ascertaining physical motion of the patient as a
life sign are illustrated in FIGS. 4 and 5. In FIG. 4, a belt 26,
which may be partially elastic in nature, is strapped to the
patient's chest, such belt being provided with strain gauge means
28 for connecting the ends of the belt. The strain gauge means may
be of any suitable type such as a variable resistance strain gauge
or semiconductor strain gauge. The electrical terminals of such
strain gauge are connected to circuitry 24 providing a substitute
or additional indication of the patient's bodily motion. For
example, with the belt 26 strapped to the patient's chest, the
expansion and contraction associated with respiration will vary the
resistance across the strain gauge means and supply an appropriate
input to circuitry 24. In the event a belt 26 is utilized, EKG
electrodes 30 and 32 are suitably also connected to circuitry 24 to
provide a substitute or additional EKG electrical input to
circuitry 24. Electrodes 30 and 32 can also be used as one or both
of the electrodes for supplying stimulating pulses to the patient.
For instance, electrode 30 suitably functions as electrode means 5.
Sound sensing devices or microphones may be located at positions of
electrodes 30 and 32 on the belt for providing a phonocardiogram
input for ascertaining physical motion in a patient, i.e., the
heart beat sound, and in the instance of a pair of microphone
transducers, the blood flow can be ascertained indicative of
patient movement by Doppler effect as understood by those skilled
in the art.
A further apparatus advantageously employed for ascertaining bodily
motion of the patient is illustrated in FIG. 5 at 34. This
apparatus comprises a pair of flexible plastic tongs 36 and 38
formed in the arcuate manner as illustrated, and joined by means of
hinge 46. Tongs 36 and 38 carry electrodes 50 and 52 at their
remote ends, wherein these electrodes are suitably formed of a
conducting sponge material. The tongs function in a spring-like
manner for making firm contact with the patient, while a third
electrode 48 supported from hinge 46 is adapted to rest upon the
patient's chest. Electrodes 50 and 52 contact the lower right and
left sides of the patient. Electrode 48 is also formed of a
conductive sponge material of a known type wherein the resistance
between the front and back face of the sponge is reduced as the
same becomes compressed. In the present instance, sponge electrode
48 can function as a strain gauge the resistance of which changes
with the patient's respiration. It is adapted to provide an input
to circuitry 24 in the same manner as strain gauge 28 described in
connection with FIG. 4.
Apparatus 34 is further supplied with brackets 42 and 44 attached
to the back of tongs 36 and 38, respectively, wherein the remote
ends of brackets 42 and 44 are pivotally connected to a hinge
mechanism 40 adapted to lock and not rotate beyond the position
shown. The hinge mechanism 40 thus functions as an over-center
locking mechanism when the hinge mechanism 40 is depressed towards
the patient's chest and into the position illustrated in FIG. 5.
For removal of the apparatus from the patient, hinge mechanism 40
is upraised, for rotating brackets 42 and 44 toward one another,
whereby tongs 36 and 38 are rotated away from the patient. As can
be easily seen, initial attachment of this apparatus to the patient
is accomplished by reversing the above procedure. Electrodes 50 and
52 can be used together or in combination with electrode 48 for
making electrical contact with the patient and deriving the
electrical EKG signal produced by the patient's heart. Furthermore,
such electrodes can be employed for delivering the corrective heart
stimulus to the patient, i.e., either a pacing or defibrillating
pulse. Thus, the apparatus of FIG. 5 may be applied alone, or in
conjunction with the airway apparatus illustrated in FIG. 1 for
ascertaining electrical activity of a patient's heart as well as
physical movement of the patient, and can then be employed either
alone or in conjunction with the airway of FIG. 1 in applying
corrective stimulating electrical impulses to the patient. The
apparatus of FIG. 5 substantially substitutes for the FIG. 4 belt
and electrode construction and has the advantage of not requiring
the extension of a belt or the like completely around the patient.
It is thus adapted for easier and quicker patient application.
FIG. 6 illustrates circuitry for ascertaining the electrical
activity of a patient's heart and represents a portion of the
circuitry to be found within the means indicated at 24 in FIG. 1.
The input is thus provided at terminals 1, 2 and 3 which may
correspond to similarly numbered electrodes 1, 2 and 3 mounted upon
the airway 10 in FIG. 1 especially when an airway alone is used,
although it is clear other electrode combinations placed elsewhere
on the body as herein described may be employed. Terminal 3 in FIG.
6 represents a ground, neutral, or indifferent electrode and may be
connected elsewhere on a patient's body such as to an extremity or
may be coupled to electrode 3 in FIG. 1. Terminals 1 and 2,
respectively, represent the positive and negative input electrodes.
A differential circuit is herein described, although it is clear in
certain instances that a single-ended circuit may be used.
Although the various electrode combinations may be employed for
ascertaining the electrical activity of a patient's heart such as
electrodes located solely upon the airway 10, it is preferred to
employ an electrode or electrodes mounted on airway 10 in
conjunction with the external electrode means such as illustrated
at 5 positioned elsewhere on the body for example in the region of
the chest, abdomen, or one of the extremities of the patient, such
as a limb. Specifically, one of the input terminals, e.g. terminal
1, in FIG. 6 is suitably connected to one or more of the electrodes
on airway 10 in FIG. 1, for example to electrodes 1 and 2, or 1, 2
and 3, while the input terminal designated by the numeral 2 in FIG.
6 is connected to the electrode means 5 and specifically to
electrodes 6 and 7 thereof. The neutral or indifferent input
terminal 3 in FIG. 6 may be connected to another point or extremity
on the human body, or to a metal examining table or the like in the
case where the patient resides on a metal support of this type. In
the case of a "single ended" input, the neutral or indifferent
terminal 3 in FIG. 6 is left unconnected, or the electrode means 5
is connected to terminal 3 in FIG. 6 rather than to terminal 2 in
FIG. 6. In general, then, for the derivation of the strongest EKG
signals, an airway is preferably employed in conjunction with an
external electrode means such as illustrated at 5. Other external
electrode means, for making a quick and easy connection to the
patient for supplying requisite circuit continuity without delay
are described in respect to the devices of FIGS. 25 through 31.
Terminal 1 is here coupled to a first input of a unity gain
isolation amplifier U20 through the series combination of resistor
R27 and capacitor C24. The junction between the resistor and
capacitor is returned to ground via oppositely poled diodes D23 and
D24 as well as capacitor C26, while the resistor R28 returns the
positive or non-inverting input of amplifier U20 to ground.
Resistor R27 and capacitor C26 form a low pass filter for filtering
high frequency artifacts from the electrical input, and the
combination of capacitor C24 and R28 provides sufficient
differentiation to block low frequency level shifting disturbances
from interfering with measurements. A similar combination of
components function in substantially the identical manner in
combination with unity gain isolation amplifier U21, wherein
resistor R26 and capacitor C23 in series couple electrode 2 to the
amplifier, with the center tap between those two components being
returned to ground via diodes D25, D26, and capacitor C25. Diodes
D23, D24, D25 and D26 protect the circuit from pacing and
defibrillating pulses as may be applied to the patient via
electrodes 1, 2 and 3 or other electrodes. A resistor R30 returns
the noninverting input of amplifier U21 to ground.
The outputs of amplifiers U20 and U21 are coupled to inverting and
noninverting inputs of differential amplifier U22 via resistors R24
and R25, the noninverting input being returned to ground by
resistor R25A. Amplifier U22 also receives another input, 70,
employed for clamping or disabling the amplifier as hereinafter
mentioned. The feedback resistor R23 in shunt with capacitor C22
couples the output of amplifier U22 to the inverting input.
Capacitor C22 is employed in removing residual high frequency
components.
The output of amplifier U22 may be either a positive or
negative-going pulse. Amplifier U23 and diode D21, coupled in
cascade with the output of the amplifier, together with diode D22,
form a push-pull, positive-going detector. The gain of amplifier
U23 is arranged to be substantially unity, wherein resistor R29
connected in series with the inverting input of the amplifier, and
resistor R28, in feedback relation to the amplifier, are of equal
value.
A coupling capacitor C27 couples the output of amplifier U22 to the
junction of resistor R29 and the anode of diode D22, wherein the
cathode of diode D22 is connected in common with the cathode of
diode D21, the latter having its anode driven from amplifier U23.
The common outputs of diodes D21 and D22 are coupled to an
integrating circuit comprising resistor R22 in series between the
common diode-cathode connection and the ungrounded terminal of
capacitor C21. A further resistor R22 returns the ungrounded
capacitor terminal to a negative voltage. The integrating circuit
provides further protection in the presence of high frequency
artifacts and moreover requires several electrical input pulses
from the input electrodes for providing an output of predetermined
level at the emitter of output emitter-follower transistor Q20.
Circuit time constants are adjusted such that a pulse rate of no
less than approximately 20 to 30 per minute is required to achieve
an output level sufficient to be acceptable in energizing the logic
circuitry to which the emitter of transistor Q20 is connected. The
emitter of transistor Q20 is connected to terminal 54 of the FIG. 7
logic circuit.
Referring to FIG. 10, a first circuit is illustrated for
ascertaining bodily movement or physical activity in a patient. In
particular, the FIG. 10 circuit involves a microphone 22 which is
responsive to breath sounds and pulse sounds in establishing the
presence or absence of physical motion in the patient. As
hereinafter mentioned, the microphone 22 is suitably attached at
the forward end of airway 10 in FIG. 1. Microphone 22 is coupled to
the inverting input of amplifier U65 via resistor R68 in series
with capacitor C65, and the amplifier is shunted by the parallel
combination of resistor R67 and capacitor C64. Diodes D62 and D63
are reversely poled, connecting the junction beween resistor R68
and capacitor C65 to ground for signals greater than diode drop.
High frequency breath sounds are filtered and passed by a bandpass
filter comprising the combination of resistor R67 and capacitor C65
as well as the combination of components R68 and C64. These sound
packets, indicated by the waveform at the output of amplifier U65,
are detected by diode D66 having its anode connected to the output
of amplifier U65 and its cathode connected to the ungrounded
terminal of capacitor C63. A resistor R66 further returns the
junction of the diode and capacitor to a negative voltage. The
combination of elements D66, R66 and C63 form an integrating
circuit adapted to provide an output sufficient for operating
or-gate U64 in the event of respiration packets or signals having
greater than a designated repetition rate. The time constant of the
circuit is such that the or-gate U64 will cease to be energized if
30 seconds pass without a respiration-indicating input being
received at the microphone. The output of or-gate U64 is supplied
to terminal 56 of the FIG. 7 logic circuit.
Although the lower part of the FIG. 10 circuit may be used alone,
the same microphone may also be connected to detect bodily motion
in the form of pulse or heart beat sounds. As indicated, microphone
22 can also be coupled via resistor R65 in series with resistor R64
to the inverting input of amplifier U61 shunted by means of
resistor R63 in parallel with capacitor C62. Diodes D60 and D61 are
oppositely poled and disposed between the junction of resistors R64
and R65 and ground, while a capacitor C67 is similarly disposed
between the same junction and ground. The low frequency pulse
sounds are passed by a filter comprising the resistors R64, R65 and
capacitor C62. These pulse signals are amplified by amplifier U61
and are normalized with respect to width and amplitude by a
flip-flop comprising nor-gates U62 and U63 cross-coupled in
conventional feedback fashion to provide a one-shot multivibrator.
The feedback input of nor-gate U63 is returned to a positive
voltage by the parallel combination of clamping diode D64 and
resistor R80, while the remaining input of U63 receives a gating
input pulse as hereinafter described. A pulse sound input as
derived from microphone 22 will cause a positive-going output of
predetermined amplitude and duration at the output of nor-gate U63,
assuming the lower or gating input of nor-gate U63 is not up. The
positive-going output pulse is supplied via the series combination
of resistor R62 and diode D65 to the ungrounded terminal of
capacitor C61. A resistor R61 returns the junction of the diode and
the capacitor to a negative voltage point. The circuit has a charge
time constant that attenuates spurious artifact signals and also
determines a minimum acceptable pulse rate, for example, a pulse
rate of 20 to 30 per minute. A pulse rate as determined by this
time constant circuit will then supply an energizing input to
or-gate U64. It is noted that any input to or-gate U64 provides
sufficient indication of bodily motion for the purpose of providing
such indication to the logic circuit. Other inputs to or-gate U64
indicated at 58 may be derived from other circuitry, hereinafter
described, which provides indication of bodily motion, and any of
the inputs may be employed alone or in combination.
Considering now the logic circuit of FIG. 7, this circuit is
designed to fulfill the logic requirements indicated in Table I.
The input lead 54 is connected as an input to nand-gate U4 and to
and-gate U3. Input lead 54 is also connected as an input to
nand-gate U6 via inverter U5. Input 54 is indicative of electrical
activity or EKG activity associated with the patient's heart. As
hereinbefore indicated, a prescribed level of input on terminal 54
is necessary for operating any of the components to which terminal
54 is connected in FIG. 7.
Input lead 56 is connected as an input to and-gate U3, as well as
an input to nand-gate U4 via inverter U7 and an input to nand-gate
U6 via inverter U7. An input at 56 of predetermined level is
indicative of a further life sign indication in the form of bodily
movement sensed through sound detection of respiration, through
phonocardiography, or through one of the other indications of
bodily motion as hereinbefore and hereinafter described. It will be
observed that if both an electrical activity indicating signal is
present at terminal 54 and a bodily motion signal is present at
terminal 56, a high output is supplied from the output terminal of
nand-gate U4, a high output is provided at the output terminal of
and-gate U3, and a high output is provided at the output terminal
of nand-gate U6. Both nor-gates U8 and U9 are then supplied with
inputs such that their outputs are low i.e., neither the positive
level output "DF" or the positive output "P" will be present. Now
if electrical activity is present, indicated by an input at
terminal 54, and bodily movement is absent as indicated by an
absence of an output at terminal 56, nand-gate U4 will be energized
at both its terminals to provide a low output. Since only one input
of and-gate U3 is energized, the output of U3 will be low.
Consequently, the output of nor-gate U8 will be high providing a
"DF" level indicative of a defibrillation condition or electrical
activity in the absence of bodily motion. If, on the other hand,
neither electrical activity nor bodily movement are present, the
output of nand-gate U4 will be high and the output of and-gate U3
will be low. Since one high input is provided nor-gate U8, the
output thereof will be low. However, since the inputs of nand-gate
U6 are supplied via inverters U5 and U7 from terminals 54 and 56,
both inputs of nand-gate U6 are up and consequently this output is
low. Inasmuch as both the inputs of nor-gate U9 are low, the high
level "P" output of U9 is present, indicating the desirability of
providing a pacing pulse to the patient's heart since neither
substantial electrical activity or bodily motion are present.
The circuitry for generating the pacing and defibrillating pulses
for application to the patient in response to these logical outputs
is illustrated in FIGS. 12 and 13, showing pacing and
defibrillating circuitry respectively.
Referring first to FIG. 12, illustrating pacing circuitry, and-gate
U80 receives an input at the input lead shown in full line from
nor-gate U9 shown in FIG. 7. The remaining input to and-gate U80 is
normally up and consequently the input signal level from gate U9 is
applied as an input to nor-gate U10. Nor-gates U10 and U11 are
cross-connected as a flip-flop, with the input from and-gate U80
causing the output of nor-gate U10 to go low and the output from
nor-gate U11 to go high. When the output of nor-gate U10 goes low,
capacitor C703, theretofore substantially shunted by transistor
Q702, will start to charge toward a positive voltage. The pacer
timer comprises a unijunction transistor Q703 having the capacitor
C703 coupled between its emitter terminal and lower base. This
circuit is a relaxation oscillator wherein the period thereof is
suitably approximately 0.85 seconds. The unijunction transistor
periodically discharges capacitor C703 to supply a pulse output at
the lower base of the unijunction transistor. If the input at the
base of transistor Q702 should later go high, transistor Q702 would
be rendered conducting, and short capacitor C703 causing
substantially immediate discharge thereof, and operation of the
unijunction oscillator would be stopped. However, when the input of
transistor Q702 goes low again, the oscillator will be restarted.
The output of the timer is supplied to one-shot multivibrator 7-C,
including transistors Q704 and Q705. The output at the collector of
transistor Q705 is a series of positive pulses, each pulse suitably
having a duration of about 100 milliseconds. This output may be
connected as the right-hand input of or-gate 3-J in FIG. 13 via
lead 76 for disabling or gating off certain circuitry when a pacing
pulse is being generated.
The output of one-shot multivibrator 7-C is also applied as a
resetting input to nor-gate U11 causing the output of nor-gate U11
to go low. If the input provided to gate U80 from the nor-gate U9
in FIG. 7 has gone low, the flip-flop comprising U10 and U11 will
change states. This resetting option gives the circuitry the
opportunity to completely reset and turn off should normal heart
functioning or at least the absence of the need of a pacing pulse
be detected by the presence of a normal beat between pacing
pulsations. Should the input provided gate U80 from the FIG. 7
circuit still be up, the resetting option will have no effect. A
counter U78 may be employed for counting the outputs of
multivibrator 7-C and for locking out the circuit by providing a
step-wave negative-going lower input to and-gate U80 after a
predetermined large number of pacing pulses. The counter U78 may be
reset manually as hereinafter more fully described or automatically
from the output of gate U3 in FIG. 7 when normal heart activity is
restored.
The output of the one-shot multivibrator 7-C is further applied via
transistor Q706 as the input of pulse transformer T701, the
secondary of which is coupled to provide the input of thyristor
Q701. AC voltage from a power supply is normally applied across a
bridge circuit comprising diodes D701, D702, D703 and D704
connected in DC charging relationship to capacitors C701 and C702,
with thyristor Q701 being interposed between the positive end of
capacitor C702 and connections 74 coupled for applying the impulse
output to the patient. Thus, when transistor Q706 turns on, current
flow rapidly increases through the primary winding of pulse
transformer T701, and a resultant secondary pulse triggers
thyristor Q701 into a conducting state. When thyristor Q701 is
turned on, capacitor C702 discharges through the diodes 1-F and
through the patient's body. As capacitor C702 discharges, the
current through thyristor Q701 decreases until the minimum holding
current is reached. At this point, thyristor Q701 turns off, and
capacitor C702 begins recharging. Another pacing pulse will occur
after 0.85 seconds unless spontaneous heart beat takes place. The
diodes 1-F are employed for decoupling the pacer when no output
pulse is provided therefrom. Also, inasmuch as the pacer output
will generally be applied in parallel with defibrillator output
terminals, the diodes prevent application of a defibrillator pulse
to the pacer. The terminals 74 may be connected respectively to the
electrodes 4 and 5 in FIG. 1 in the instance where the separate
stimulating pulse electrodes are used, or alternatively to
electrodes 1 and 3 in FIG. 1 when the same electrodes are being
utilized for both deriving the electrical input from the patient
and applying electrical stimulation to the patient. The pacer
circuit is substantially similar to the pacer circuit described in
the application of Warren S. Welborn and Melvin A. Holznagel, Ser.
No. 66,189 filed Aug. 24, 1970, entitled "Cardiac Resuscitator",
now U.S. Pat. No. 3,716,059.
Referring to FIG. 13, illustrating a defibrillator circuit, the
output from nor-gate U8 in FIG. 7 is applied as the lower input of
nor-gate U13 which, together with nor-gate U12, forms a flip-flop.
When the output from gate U8 in FIG. 7 is thus applied, indicating
the need for a defibrillating pulse, the output of gate U13 goes
down and the output of gate U12 goes up. The output from nor-gate
U12 is applied via inverter U82 for supplying a negative-going
input to one-shot multivibrator 8-A which is substantially similar
in construction and operation to one-shot multivibrator 7-C in FIG.
12. The resulting output pulse is applied to transistor Q801 for
initiating a defibrillating output as hereinafter more fully
described. A timing circuit including unijunction transistor Q803
is adapted for reverting the flip-flop U12, U13 after a
predetermined period of time, i.e., several seconds, as set by
potentiometer R803. Since the output of nor-gate U12 is normally
low, capacitor C803 is normally substantially discharged, and
unijunction transistor Q803 is inoperative. When the output of
nor-gate U12 goes high, diode D805 becomes nonconductive and
capacitor C803 starts charging. When the capacitor charges to a
predetermined voltage, unijunction transistor Q803 discharges the
same and provides a pulse output at the lower base of the
unijunction transistor for application to the noninverting input of
amplifier U17. The output of amplifier U17 is applied as input to
nor-gate U12 for causing the output thereof to go low, and the
flip-flop will be reset if the input of gate U13 from gate U8 in
FIG. 7 has dropped. If such input from FIG. 7 has not disappeared,
whereby another defibrillating pulse is apparently needed, the
output of U12 will go high again when the output of amplifier U17
concludes. As a consequence, one-shot multivibrator 8-A will be
triggered once more. As mentioned, the timing between outputs from
one-shot multivibrator 8-A is determined by the setting of
potentiometer R803. The output of one-shot multivibrator 8-A is
further supplied as an input to counter U84 which functions to lock
out the defibrillating circuit by supplying a positive level output
to nor-gate U12 after a predetermined number of defibrillating
pulses. Thus defibrillating pulses are not applied indefinitely if
the patient is nonresponsive thereto. Counter U84 can be manually
reset if desired by means of a circuit comprising switch S801,
capacitor C803, capacitor C807 and diode D806. Capacitor C805 is
normally charged toward a positive voltage, and upon depression of
switch S801, this capacitor discharges through the switch and
through capacitor C807, developing a positive input at inverter
U86. Diode D806 prevents the input to U86 from dropping
substantially below ground level. Inverter U86 inverts the positive
input provided and resets the counter. A similar manual resetting
circuit can be employed to reset counter U78 in FIG. 12 if
desired.
In addition, the output of one-shot multivibrator 8-A is inverted
and supplied as an input to or-gate 3-J used for clamping or gating
off various detecting circuits during a defibrillating or pacing
pulse. For example, the output of gate 3-J is suitably applied at
70 in FIG. 6. It further supplies the gating pulse at the lower
input of nor-gate U63 in FIG. 10, and the lower input of nor-gate
U73 in FIG. 11 as well as the upper gating input to or-gate U43 in
FIG. 9. In the case of the lower gating input to gate U63 in FIG.
10, for example, the gating signal prevents the one-shot
multivibrator U62, U63 from being triggered at this time.
Transistor Q801 in FIG. 13 has the operating coil of a relay K801
serially connected in its collector circuit. The contacts of relay
K801 normally connect capacitor C801 to the output of a bridge
circuit comprising diodes D801, D802, D803 and D804, receiving a
high voltage alternating current input, for example from a high
voltage power supply built into the means 24. However when
transistor Q801 conducts, relay K801 connects capacitor C801,
theretofore charged through the aforementioned bridge circuit, to
terminals 72 via inductance L801, and diodes 1-E. Terminals 72 are
suitably connected to the same terminals to which the
aforementioned terminals 74 are connected for application of a
defibrillating pulse to the patient. Capacitor C801, initially
charged to the high voltage from the power supply, supplies this
high voltage across the circuit comprising inductance L801, the
switching diodes 1-E, and the body resistance of the patient.
Inductance L801 controls the resulting current. Another
defibrillating pulse cannot be applied to the patient until the
circuit including elements R803, C803 and Q803 times out, and
another defibrillating pulse is called for.
The diodes 1-E have the same purpose as the diodes 1-F hereinbefore
mentioned. That is, the diodes 1-E and 1-F essentially decouple the
pulse generators when either provides an output pulse. Application
of a defibrillator pulse to the pacer or a pacer pulse to the
fibrillator is prevented, as well as loading of the input
circuitry, should the same electrodes be employed for the EKG input
signal as for application of the stimulating output pulses. The
defibrillator circuitry described above is similar to that
described in the aforementioned U.S. Pat. No. 3,716,059.
In general, with the airway and electrode arrangement as
illustrated in FIGS. 1 through 3, and with the electrical activity
detecting circuits of FIG. 6, with the means of sensing bodily
movement by audible indication of FIG. 10, with the logic circuit
of FIG. 7, and with the pacer and defibrillator circuits of FIGS.
12 and 13 intercoupled as described, an electrical input detected
at terminals 1, 2 and 3 in FIG. 6 for a requisite period of time
will provide one logical input at terminal 54 in FIG. 7. Assuming
an audible indication is also present for registering bodily
movement, e.g., as indicating respiration, a second input to the
FIG. 7 circuit will be provided at terminal 56. Consequently,
neither the output of gate U8 nor the output of gate U9 will be up.
(Also, neither would be up if respiration were detected in any
case.) For other input combinations set forth in Table I, either
the defibrillating pulse or the pacing pulse will be supplied. If a
regular pacing pulse is supplied and heart action resumes between
pacing pulses, the pacer of FIG. 12 will be disabled. If a
defibrillating pulse is applied, a time period of several seconds
elapses before the logical output of gate U8 is ascertained again,
and if the need of a defibrillation pulse is again indicated, a
further defibrillating pulse is applied. However, a limited number
of defibrillating pulses, as counted by counter U84, will be
applied to a patient before the counter shuts off the defibrillator
circuit. As mentioned, the same electrodes may be used for both
input of electrical activity information and output of stimulating
pacing and defibrillating pulses, or separate electrodes may be
utilized. The electrodes separately indicated in FIGS. 4 and 5 may
be employed instead of or in conjunction with the electrodes on the
airway. However, an electrode or electrodes on an airway together
with an external electrode means such as electrode means 5 have
been found in practice to provide the most satisfactory input in
reelectrical activity information. Other indications of bodily
movement may be inputted to or-gate U64, as indicated at reference
numerals 58 in FIG. 10, so that a defibrillating pulse will not be
applied to the patient in the presence of some other
life-sign-indicating bodily motion. For instance, the strain gauge
means 28 or 48 of FIGS. 4 or 5 may be connected as hereinafter
described to provide such additional life sign indication.
Referring to FIG. 9, a variable resistance 60 may, for example,
comprise such strain gauge 28 of FIG. 4 or 48 of FIG. 5. The
variable resistance may alternatively comprise a thermistor element
or thermocouple element responsive to the cooling and/or heating
effects of the patient's breath. Such element is suitably
substituted for the microphone at the end of the airway, having
substantially the same appearance as illustrated at 22 in FIG. 1. A
current is supplied to element 60 via resistor R46 from a source of
voltage. The junction between elements 60 and R46 is coupled via
capacitor C43 and resistor R43 in series to the inverting input of
amplifier U40, the latter being shunted in feedback relation by the
parallel combination of capacitor C42 and resistor R42. A pair of
reverse connected diodes D40 and D41 are disposed between the
inverting input of amplifier U40 and ground for protection
purposes. The noninverting input of amplifier U40 is connected to
the midpoint of a voltage divider comprising resistors R44 and R45
disposed between a positive terminal and ground, while the output
of amplifier U40 is applied as a first input to or-gate U43, the
remaining or gating input therefor being derived from gate 3-J in
FIG. 13 such that the output of gate U43 will be high during the
defibrillator or pacing pulse application when there is likely to
be patient movement caused by such impulse.
During motion of the chest, for example, during respiration, a
negative-going output will periodically appear from amplifier U40
causing the output of gate U43 to drop. The output of gate U43 is
applied to a monostable multivibrator comprising nor-gate U41 and
inverting amplifier U42 connected in a conventional feedback
manner. Diode D43, connected to the input, prevents that input from
dropping substantially below ground level. When the negative going
input is applied to gate U41, the output thereof goes positive for
a predetermined period of time, and the positive pulses
representing, for example, normal respiration are applied through
detecting diode D42 to the ungrounded end of capacitor C41. The
junction of the diode and the capacitor is returned to a negative
voltage with the resistor R41. The time constant of the circuit is
such that chest motion or the like must occur at least once every
30 seconds for the output as integrated by capacitor C41 to cause a
continued high level output from transistor Q40. The emitter output
of transistor Q40 is suitably applied as one of the inputs 58 of
or-gate U64 in FIG. 10, thus providing this additional input
indicative of bodily motion. The FIG. 8 circuit, connected to a
strain gauge such as indicated at 28 or 48, may alternatively be
substituted for the remainder of the FIG. 10 circuit if desired,
thus indicating the presence of bodily motion to the logic circuit
of FIG. 7 via gate U64. While a strain gauge indicative of chest
movement associated with respiration has been discussed, such
strain gauge or other similar device may be employed to detect
other bodily motion in order to prevent application of the
defibrillating pulse in the presence of such motion.
Referring to FIG. 11, an additional circuit is illustrated for
detecting the sound of blood flow, e.g., near a constricted or
bifurcated blood vessel, as a form of bodily motion sensing. A
microphone or sound transducer positioned exteriorly of the blood
vessel to detect such motion is coupled at 62 through the series
combination of resistor R74 and capacitor C74 to the inverting
input of amplifier U70, while the junction between elements R74 and
C74 is returned to ground via capacitor C73 and the combination of
reversely poled diodes D70 and D71. A resistor R75 returns the
positive input of the amplifier to ground, and a feedback circuit
comprising the parallel combination of capacitor C71 and resistor
R72 is disposed between the amplifier output and the negative or
inverting input of amplifier U70, the latter being returned to
ground through resistor R73. The microphone connected at terminal
62 may comprise the same microphone 22, illustrated in FIG. 10,
mounted on the end of the airway 10 in FIG. 1, but preferably
comprises a microphone more suitably mounted, e.g., on the neck of
the patient in such a manner as to detect the sound of turbulence
of blood flow in the carotid system. Elements R74, C73, C74, R72
and C71 comprise a bandpass filter adapted to detect the
characteristic sound of blood flow with each heart beat, as opposed
to the actual heart beat sound itself, thus providing an additional
or alternative parameter or means for sensing motion within the
body as a life sign.
The output of amplifier U70 is applied to the non-inverting input
of amplifier U71, the latter comprising a limiting and detecting
amplifier operating as a zero crossing detector. The output of
amplifier U71 is applied through diode D72 to an input terminal of
nor-gate U72 and shunted to ground by means of capacitor C72. The
same terminal is coupled through resistor R76 to a potentiometer
R71. Components D72, C72, R76 and R71 operate as a threshold
detector wherein a threshold level is established by the setting of
potentiometer R71. Short duration artifact signals and the like
will not charge detector capacitor C72 sufficiently for providing
an operating input to nor-gate U72. Nor-gates U72 and U73 form a
monostable multivibrator, cross-connected in the usual manner,
employed to normalize the pulse duration. The feedback input of
nor-gate U73 is returned to a positive voltage via the parallel
combination of resistor R77 and clamping diode D73 which prevents
the said input from rising materially above such voltage. The lower
input of nor-gate U73 is supplied the gating signal output of
or-gate 3-J in FIG. 13 for inhibiting operation upon the occurrence
of a pacing pulse or defibrillating pulse.
Upon the occurrence of an input exceeding the threshold established
for operating gate U72, indicative of the detected blood flow
signals, the output of nor-gate U72 will go down and the output of
nor-gate U73 will go up, a plurality of such positive-going pulses
being generated at the output of nor-gate U73 indicative of the
patient's pulse. The pulse output of nor-gate U73 is applied
through detecting diode D74 to the ungrounded end of integrating
capacitor C70, with the junction between these two components being
returned to the negative voltage via resistor R70. Such junction is
also connected to the base of transistor Q70, the emitter of which
is suitably coupled to one of the inputs 58 of or-gate U64 in FIG.
10. Resistor R70 and capacitor C70 form a minimum acceptable pulse
rate circuit wherein a pulse rate of 20 to 30 pulses per minute is
required to provide a sufficient output for supplying an operative
input to or-gate U64.
FIG. 8 illustrates further apparatus for detecting bodily motion,
and in this case, for detecting mechanical movement in the
patient's body indicative of the patient's heart beat. The
apparatus includes a belt 80 of elastic material suitably disposed
about the chest of the patient and provided with electrodes 82, 84
and 86. According to the FIG. 8 apparatus, a means comprising a
current generator 3-A is employed for applying a signal to the
patient, i.e., between electrodes 82 and 86, and further means is
supplied for detecting a change in voltage drop at electrode 84
with respect to ground in response to changes in body impedance
caused by mechanical heart activity or heart beat. The current
generator 3-A may comprise a direct current generator for providing
a D.C. current to the body, but preferably a fairly high frequency
alternating current is utilized. Thus, current generator 3-A may
supply an alternating current of constant amplitude at a frequency
of approximately 100 kilohertz to the patient electrode 82 with
respect to ground.
Changes in the electrical impedance of the body caused by the
beating of the heart are detected by detecting changes in the high
frequency component of the signal at electrode 84 as amplified by
amplifier 1-B. The output of this amplifier is applied to high
frequency bandpass filter 3-B which suitably rejects signals except
those near 100 kilohertz. The output of filter 3-B is amplified by
a further high frequency amplifier 3-D which has provision for
automatic gain control. The output of circuit 3-C is applied to an
A.M. detector (and A.G.C. unit) 3-D which provides a low frequency
output to amplifier and filter unit 3-E, proportional to the
changes in electrical impedance appearing in the patient's body.
The amplifier and filter 3-E amplifies the desired signal component
while attenuating unwanted components. In particular, low frequency
signals, due in this case to patient respiration, may be
attenuated. The output of circuit 3-E is applied to rectifier 3-F
which produces output pulses of a single polarity. Disable clamp
3-H operates to inhibit transmission of the signal during delivery
of electrical stimulation to the patient, this additional input
being provided from gate 3-J in FIG. 13. The pulses from circuit
3-H are applied to comparator 3-K which supplies an output when
such pulses exceed a voltage reference 3-L. Thus, a pulse occurs at
the output of compare circuit 3-K whenever a rapid change in the
patient's body impedance occurs. These pulses are then applied to
integrator 3-M which in turn supplies an output when the pulse rate
thus derived is in excess of a predetermined value between 20 and
30 pulses per minute. The integrator circuit may be constructed in
a substantially similar manner to the integrating circuits
hereinbefore disclosed, and the remainder of the circuit is
substantially similar to the "I.C.G." circuit as set forth and
claimed in the hereinbefore mentioned U.S. Pat. No. 3,716,059. The
output of integrator 3-M is suitably coupled as an additional
input, 58, to or-gate U64 in FIG. 10.
The apparatus according to the FIG. 8 circuit is described above in
connection with measuring the patient's pulse by means of measuring
impedance changes substantially across the patient's chest,
detected at a rate generally associated with a normal pulse range.
In accordance with the present invention, the circuit constants of
amplifier and filter 3-E are readily altered so that the FIG. 8
apparatus is specifically responsive to the patient's respiration
as a life sign, instead of or in combination with the above
described response relative to the patient's pulse. In any case,
the output of the circuit is applicable as an additional input to
or-gate U64 as mentioned.
Apparatus according to the present invention may also include a
continuity checker which determines if the patient electrodes are
in proper electrical contact with the patient's body, with
particular reference to the electrodes employed in deriving the EKG
signal, i.e., electrodes 1, 2 and 3. If poor contact is made,
defibrillator and pacer output is inhibited. A current is suitably
applied to electrodes 1 and 2 with respect to electrode 3 and the
resulting voltage at electrodes 1 and 2 with respect to 3 is
measured. If an electrode is in poor contact with the patient, a
comparatively high voltage will occur at that electrode and such
voltage will be sensed for inhibiting operation of the apparatus. A
type of continuity interface unit is set forth in the
aforementioned U.S. Pat. No. 3,716,059. However, rather than a DC
source, an AC source having an operating frequency of approximately
100 KHz is preferred in the case of equipment according to the
present invention, whereby an AC voltage drop at that frequency is
sensed for checking continuity. As hereinbefore indicated, when
airway mounted EKG electrodes are employed, the danger of lack of
continuity is minimized. However, the continuity circuit may be
added.
It is not implied that each of the bodily motion detecting means
hereinbefore disclosed will necessarily be utilized in a single
apparatus, but these circuits and devices are disclosed as suitable
alternatives in the detection of bodily motion as a life sign
parameter. In a given instance, the airway of FIGS. 1 through 3 may
alone be employed for deriving both the electrical and respiratory
sound motion inputs, and for providing stimulating pulse outputs on
electrodes thereof in conjunction with the attendant circuitry
apparatus of means 24 as hereinbefore described. The additional
electrode means 5, as an electrical input electrode and as a
stimulating pulse application return, is also suitably employed as
illustrated in FIG. 1. In the case of such apparatus, additional
means comprising a belt or similar attachment as illustrated in
FIGS. 4, 5 and 8 may be applied to the patient, especially if these
attachments can be connected to the patient without undue delay. In
the latter instance, then, additional inputs are supplied via
or-gate U62. Alternatively, a belt, tongs, or similar means can be
employed in a manner hereinbefore described either in conjunction
with the airway or alone for ascertaining both electrical activity
and bodily movement, and for supplying a stimulating output to the
patient in accordance with Table I.
In general, the apparatus is applied to the suspected heart attack
adult patient, with a power supply appropriately energized, for
making the input measurements and supplying outputs, e.g. in
accordance with Table I. If substantial cardiac arrest has
occurred, indicated by a very slow or nonexistent pulse, a pacing
stimulation is applied to the patient. If, on the other hand,
substantial electrical activity is present, while one of the forms
of bodily motion such as respiration is absent, ventricular
fibrillation is indicated, and a defibrillating pulse is applied to
the patient. The defibrillating pulses are well separated by a
period of several seconds, with the condition of the patient being
re-ascertained before another defibrillating pulse is applied.
Since corrective action may be taken by the resuscitator as soon as
or even before an ambulance team of first aid personnel has reached
the patient, the chances for survival are materially increased as
compared with the chances of survival when treatment must await
transport of a heart patient to a hospital.
FIG. 14 illustrates alternative monitoring circuitry suitably
employed for providing a life sign monitoring output, indicative of
normal heart action, cardiac arrest or fibrillation. The input is
provided on terminals 101, 102 and 103 which may correspond to
terminals 1, 2 and 3 in the FIG. 6 circuit, and which may be
similarly connected to patient contacting electrodes such as those
mounted on airway 10 and electrode means 5. The input portions of
the circuit of FIG. 14 are also suitably similar to those
illustrated in FIG. 6. However, protective elements for preventing
damage to the circuit from pacing and defibrillating pulses need
not be employed if a pacer or defibrillator is not connected at the
same time to the patient or to the same patient contacting
electrodes. The FIG. 14 circuit is shown in simplified form, it
being understood that various coupling components, feedback
elements, etc., may be included which are substantially similar to
those as illustrated in the FIG. 6 embodiment. The FIG. 14
embodiment has the advantage of more closely measuring the
patient's pulse rate, and respiration rate, to determine if they
are within predetermined limits. A numerical output may be
provided.
Terminals 101 and 102 are respectively connected to inputs of
isolation amplifiers 104 and 105 through coaxial cables 106 and
107, the exterior conductors of which are grounded and connected to
electrode 103. The outputs of amplifiers 104 and 105 are coupled to
inverting and noninverting inputs of differential amplifier 108 the
output of which drives band pass filter 110 employed to reduce the
effects of muscle potentials and external interference. The low
frequency band limit of filter 110 is suitably 3 Hertz, while the
high frequency cutoff is suitably set to approximately 50 Hertz.
The output of the filter may be presented on lead 112 for
application to means for providing an electrocardiogram as
hereinafter described. Lead 112 is also connected to the input of
automatic gain control circuit 114 which applies feedback to
amplifier 103 for the purpose of presenting electrocardiogram
outputs within predetermined limits.
The output of filter 110 is also applied to shaper 116 which is
illustrated more fully in FIG. 17 and which may be defined as a
threshold detector and regenerator providing a standard output
pulse for each valid input signal.
Referring to FIG. 17, an input signal 118 is presented on lead 120
connected to the base of a first NPN transistor 123 having its
emitter coupled in common with the emitter of NPN transistor 124 to
a negative voltage terminal through resistor 126. The base of
transistor 124 is coupled to the movable tap of a potentiometer 130
the end terminals of which are connected to a positive voltage and
ground. The collector of transistor 122 is connected to a B+
voltage, and the collector of transistor 124 is returned to B+
through load resistor 132 as well as being connected to output lead
134 where square wave output 136 is supplied. The circuit is
characterized by input hysteresis limits 138 and 140 which are
relatively close in voltage value such that the circuit turns on
and produces a positive-going output on lead 134 when the input
crosses level 138 in a positive-going direction, while providing a
negative-going output on lead 134 when the input crosses level 140
in a negative-going direction. The input levels ae substantially
selected by potentiometer 130 such that square wave output 136 is
indicative of a valid heart beat. This pulse is provided as a first
input to counters 142 in FIG. 14.
The FIG. 14 circuit also suitably receives an input from microphone
122 which may be mounted upon an airway or the like, corresponding
to microphone 22 in FIG. 10. One terminal of the microphone is
grounded and the remaining terminal is coupled through band pass
filter 144 to amplifier 146. The microphone is employed for
ascertaining bodily movement or physical activity, and in
particular for ascertaining respiration sound, whereby the filter
144 is suitably arranged to have an upper band limit of
approximately 700 Hertz and a lower band limit of approximately 100
Hertz appropriate for passing breath sound frequencies.
Amplifier 146 is further provided with an automatic gain control
circuit 148 and also drives a shaper 150 which may have the same
circuit configuration as described in connection with FIG. 17. The
output of shaper 150 is coupled to counters 142.
Counter circuitry 142 is further illustrated in FIG. 15 wherein the
output from shaper 116 in FIG. 14 is received on lead 152 and
comprises a plurality of pulses 136, one for each heart beat of the
patient. This input is applied to first counter flip-flop FF.sub.1,
as well as to one-shot multivibrator 154 the output of which is
delayed by delay line 156 and appears as a series of "stretched"
pulses 158 each having a duration T. A given pulse 136 changes the
state of one-shot multivibrator 154 from its stable condition to
its unstable condition for producing the output pulse having a
duration, T, corresponding to the normal total period of several
input pulses 136 as will hereinafter be appreciated. The same pulse
which triggered one-shot multivibrator 154 will also trigger
flip-flop FF.sub.1 from a first state to a second state while the
next input pulse 136 in order will trigger flip-flop FF.sub.1 from
the second state back to the first state. Coincident with the last
transition, flip-flop FF.sub.1 will trigger flip-flop FF.sub.2 from
its first state to a second state. Flip-flop FF.sub.3 is triggered
from FF.sub.2, while flip-flop FF.sub.4 is triggered from flip-flop
FF.sub.3, and so on in binary counter fashion. Flip-flop FF.sub.k
is selected to provide an output indicative of the minimum
acceptable heart rate by providing an output on lead 160 during a
period, T, before the flip-flop is reset. Also, a flip-flop
FF.sub.n provides an output on lead 162 indicative of an
excessively high heart rate when flip-flop FF.sub.n is triggered
within the period, T, before being reset. All the flip-flops,
FF.sub.1 . . . FF.sub.n, are reset at the trailing edge of each
pulse 158. As will be appreciated by those skilled in the art, the
length of the period, T, and the number of flip-flops, FF.sub.1 . .
. FF.sub.n, are chosen such that the number of pulses k divided by
time, T, is descriptive of a minimum acceptable heart rate, while
the number of pulses n divided by time T is indicative of an
excessively high heart rate, wherein k and n are the number of
pulses 136 required to operate flip-flops FF.sub.k and FF.sub.n
respectively. The dashed lines in FIG. 15 indicate additional
flip-flops as may be employed to satisfy those criteria.
When flip-flop FF.sub.k changes states, the output on lead 160
triggers memory flip-flop FF.sub.ME whereby the same provides one
input to nor-gate 164. The other input for nor-gate 164 is provided
from delay line 156, so that at the end of a time T, i.e. during
the lock out period between pulses 158, nor-gate 164 will provide a
positive output on lead 166 if memory flip-flop FF.sub.ME has not
been triggered from flip-flop FF.sub.k in the meantime. The output
on lead 166 is suitably applied for operating low rate alarm 168 in
FIG. 14 and is also connected to logic circuitry 170. The low rate
alarm is suitably a warning light, an audible tone emitting device,
or the like.
Memory flip-flop FF.sub.ME is subsequently reset, at the beginning
of the next pulse 158, via a differentiating circuit comprising
capacitor 172 interposed between delay line 156 and the reset
terminal of flip-flop FF.sub.ME, such differentiating circuit also
including a resistor 174 disposed between such terminal and ground.
The resistor is shunted by a diode 176 having its cathode grounded
such that flip-flop FF.sub.ME is receptive only to a positive-going
reset input provided at the beginning of each pulse 158. If the
counter chain FF.sub.1 . . . FF.sub.n counts out and provides an
output on lead 162, indicating an excessively high heart rate, high
rate alarm 178 in FIG. 14 will be actuated, the same constituting a
warning light, audible tone emitting device, or the like. The
output on lead 162 is also applied to logic circuitry 170.
The remaining input to the FIG. 15 circuit is provided on lead 180
and is derived from shaper 150 in FIG. 14. The input on lead 180
comprises a series of pulses each indicative of a respiration
sound, the pulses being coupled to a first flip-flop FF.sub.a which
in turn is coupled to trigger flip-flop FF.sub.b. Although two such
flip-flops are shown for purposes of illustration, it will be
understood the number of such flip-flops will be chosen such that
flip-flop FF.sub.b will be triggered and provide an output if the
pulse input on lead 180 indicates a minimum standard of respiration
during a period, T. If such minimum standard is attained, memory
flip-flop FF.sub.MB will be triggered and provide a first output to
nor-gate 182. The remaining input to gate 182 is supplied from
delay line 156. Nor-gate 182 will provide a positive-going output
on lead 184 only if flip-flop FF.sub.MB has not been triggered by
the end of a pulse 158. Flip-flops FF.sub.a and FF.sub.b are reset
at the lock out period between pulses 158. However, flip-flop
FF.sub.MB will be reset at the beginning of the next pulse 158
coincidently with the resetting of flip-flop FF.sub.ME. The output
on lead 184 is applied to breath alarm 186 in FIG. 14 which may
comprise a warning light, audible tone emitting device, or the
like, as well as to logic circuitry 170. The lock out period
between pulses 158 is brought about in response to the end of the
unstable period of one-shot multivibrator 154. The next pulse 158
will be initiated in response to another input pulse 136 triggering
one-shot multivibrator 154, thereby initiating another counting
period.
Logic circuitry 170 is more fully illustrated in FIG. 16 wherein
inputs on lead 162 and 166 and 186 are variously applied to gates
188, 190 and 192. A positive-going input on lead 162 indicative of
an abnormally high heart rate, together with a positive-going input
on lead 184, indicative of an abnormally low breath rate, will
operate and-gate 188 for triggering flip-flop 194. The latter then
provides an operating output for defibrillation alarm 196 which may
comprise a warning light, sound emitting device or the like.
A positive input on lead 166 indicative of an abnormally low heart
rate together with a positive input on lead 186 indicative of an
abnormally low breath rate will operate and-gate 190 for triggering
flip-flop 198, the latter providing an input for operating arrest
alarm 200 which may also comprise a warning light, sound emitting
device or the like.
If the indications on all the input leads, 162, 166 and 186, are
negative indicating normal behavior of the patient within set
limits, nor-gate 192 will provide a positive output for setting
flip-flop 202 which operates normal indicator 204 suitably
comprising an indicating light. The flip-flops 194, 198 and 202 are
reset each time one-shot multivibrator 154 resets itself, via
one-shot multivibrator output lead 206. It will be observed that
the flip-flops 194, 198 and 202 are reset slightly before the end
of each pulse 158 provided at the output of delay line 156. Then,
the outputs from the memory flip-flops of counter circuitry 142
will be supplied during the lock out interval between pulses 158
such that flip-flops 194, 198 or 202 will be set and this condition
retained until slightly before the beginning of the next lock out
interval. The delay of delay line 156 is arranged to be a fraction
of the time period T. Although the circuitry of FIGS. 14, 15 and 16
is primarily described in connection with providing monitoring
outputs, it will be appreciated that indications of defibrillation
and arrest can alternatively be employed for operating a
defibrillator or pacer of the general type hereinbefore
described.
Returning to FIG. 14, apparatus may be employed for visually
portraying the electrocardiogram and/or breath sounds or other
indications of bodily movement. Such apparatus may comprise a
cathode ray tube 208 having an electron gun 210, horizontal
deflection plates 212, and vertical deflection plates 214. The
vertical deflection plates are connected to receive push-pull
outputs from vertical amplifier 216 which receives its input from
electronic switch 218. Electronic switch 218 alternatively receives
the output on lead 112 from filter 110, comprising the
electrocardiogram signal, or a breath sound signal on lead 220
comprising the output of amplifier 146. The electrocardiogram and
breath sound viewed by this means may be viewed in a superimposed
manner, or adjacent one another on adjacent cathode ray tube traces
under the control of switch 218 wherein amplifier 216 is a DC
amplifier and electronic switch 218 adds different DC voltage
levels to the respective signals as applied to the amplifier 216. A
triggering signal level is also detected in amplifier 216 and
applied to trigger shaper 222 which may be of the general type
hereinbefore described in connection with FIG. 17 and employed for
initiating operation of ramp generator 224. The latter provides a
saw tooth signal to push-pull amplifier 226 driving the horizontal
deflection plates 212 of cathode ray tube 208. The trigger
circuitry operates for initiating periodic traces in response to
ones of the electrocardiogram or breath signals, or the ramp
generator may be operated at a relatively low and substantially
independent frequency. In any case, the cathode ray tube traces are
conventionally slow and cathode ray tube 208 is chosen for fairly
high trace retention characteristics by selection of a phosphor
having high image persistence.
Alternatively, apparatus may be employed including a cathode ray
storage tube for retaining one or more electrocardiogram traces or
breath sound traces. This circuitry is illustrated in FIG. 18
wherein similar elements are referred to by means of primed
reference numerals and only substantial differences from FIG. 14
apparatus will be described. The cathode ray tube 208' is further
provided with flood guns each having an anode 228 and a cathode 230
for providing a flood of electrons directed toward a target
comprising a transparent target electrode 232 disposed on the
inside of the tube's face plate and covered by light emitting
phosphor material 234. A storage mesh electrode 236 comprises a
conductive mesh and a storage dielectric which has the faculty of
storing a charge image written thereupon by the electron beam from
electron gun 210', the charge image being written and held through
the medium of secondary emission as well understood by those
skilled in the art. Moreover, flood electrons from the flood guns
are passed to the phosphor layer and target electrode in accordance
with the stored image. As a result, an electrocardiogram or the
like received via electronic switch 218' may be displaced and held
as written, but may be erased at the end of each horizontal sweep
when a signal indicating the end of such sweep is provided on lead
240 coupled from ramp generator 224' to storage control circuitry
238 from which the appropriate voltages for the flood gun elements,
mesh and target electrode are normally applied. At the end of a
horizontal sweep, the normal storage enabling voltages are altered
whereby the stored image fades and a new electrocardiogram image is
provided beginning with the next sweep. Alternatively, the
electrocardiogram may be continuously stored on the same horizontal
trace or several spaced horizontal traces until erased by means of
push button 242. For spaced horizontal traces, switch 216' may be
adapted to add a separate DC level to the input each time a new
trace begins. Ramp generator 224' is then connected to electronic
switch 218' by means not shown.
FIG. 19 illustrates schematically a mechanical electrocardiograph
which may alternatively be employed in providing a permanent record
of the signal supplied on lead 112 from filter 110 in FIG. 14. The
signal is coupled to an amplifier 244 driving an electromagnetic
device 248 which controls a linkage connected to stylus 250. Stylus
250 is controlled in a conventional manner for providing a written
record of the signal on moving roll chart 252.
FIG. 20 illustrates alternative apparatus employed in conjunction
with the apparatus of FIG. 14 for providing a numerical output
indicative of the actual pulse rate or breath rate derived by means
of the FIG. 14 apparatus and in particular utilizing the
information from the counter circuitry 142 as illustrated in FIG.
15. An input lead 256 is coupled alternatively to lead 152 or 180.
Counter and memory circuit 254 counts and remembers the number of
heart beats or respiration signals received during a given
interval, which interval is set by clock interval generator 258.
The output of counter memory circuit 254 is suitably provided in
binary coded decimal form to a decoder 260 for converting the
binary coded decimal output to a seven segment output on leads 262,
lettered A through G, coupled to display unit 266. Display unit 266
successively displays numerical representations in the style
indicated at 268, i.e. composed of segments A through G
corresponding to the ones of leads 262 energized from decoder 260
at a given time. Each numerical display is suitably a
light-emitting display providing seven horizontal and vertical
light-emitter segments which, if all energized, would provide a
visible representation of the FIG. 8 in block style. The other
numerals are formed from a lesser number of such segments.
Since more than one binary coded decimal digit will ordinarily be
required for expressing the rate to be displayed, especially in the
case of pulse rate, the individual digits thereof are successively
selected by decoder 260 while at the same time energizing an
appropriate one of the digit lines 264 for bringing about the
gating on of one of three numerical displays in display unit 266.
The numerical displays representative of the respective digits are
repeatedly energized in order that a substantially constant output
number is continuously displayed, unless, of course, the heart rate
or breath rate being measured changes. A circuit as illustrated in
FIG. 20 is suitably employed for providing a numerical pulse rate
output, while another such circuit is suitably employed for
supplying the numerical output indication of respiration rate.
The circuitry herein described either for monitoring heart rate,
providing EKG information, or supplying resuscitating impulses to
the patient has been described in conjunction with the
advantageously employed airway 10 of the type illustrated in FIG. 1
and the external electrode means of FIG. 1, or in conjunction with
one of the chest-applied means as illustrated in FIGS. 4, 5 and 8.
Alternatively, a plastic intratracheal tube 270 as illustrated in
FIG. 21 is suitably provided with a conducting wire or ribbon 272
extending from an upper contact 274 down the length of the
intratracheal tube. The wire or ribbon 272 may connect to electrode
271 mounted near the lower end of the tube and electrodes 273
mounted on expandable portion 275, as well as to end tip electrode
277, for making good electrical contact with the interior of the
moist passage. The conducting wire or ribbon is desirably embedded
in the surface of the intratracheal tube so that the upper
conducting surface of such wire or ribbon is flush with the
exterior of the tube to prevent damage when the tube is inserted or
removed. The wire or ribbon 272 is in many cases advantageously
helically disposed about the tube as illustrated for making contact
with the body all the way along the tube, especially in the absence
of contacts 271, 273 and 277. However, when contacts 271, 273
and/or 277 are employed, wire or ribbon 272 can be completely
embedded within the plastic wall of the tube, and it is not
necessary for the conducting wire or ribbon to be helically wound
about the tube. The electrodes 271, 273 and 277 may then be
positioned for obtaining an EKG input at a specified location or
region within the body.
The contact 274 will be connected to terminal 1 in the FIG. 6
circuit or terminal 101 in the FIG. 14 circuit, while an external
electrode means 5 including electrode 6 may be employed as an
outside electrode for connection to terminals 2 or 102 in the FIGS.
6 and 14 circuits. The remaining or ground electrode may be
attached elsewhere to the patient or to a conductive table upon
which the patient rests. A microphone 276 is suitably carried by
the intratracheal tube 270 and connects to the FIG. 10 and FIG. 14
apparatus via leads 278 in the manner hereinbefore described in the
case of microphones 22 and 122. The microphone then provides
audible input of breath sounds and the like. The intratracheal tube
would not ordinarily be utilized in making initial contact with a
patient having a suspected heart attack, but is a desirable input
means to be employed in the case of a patient already requiring
such intratracheal tube. The electrode connection and sound
reproducing means provided can then be conveniently connected at
will to the monitoring devices for ascertaining the patient's
condition as hereinbefore described, and for providing emergency
resuscitating impulses. In the latter case, the contact 274 may
also be employed together with external electrode means such as
electrode means 5 including electrode 6 for coupling pacing or
defibrillating impulses to the patient.
FIG. 22 illustrates another airway type of device 280 comprising
tubes 282 and 284 attached to connector 288 for supplying oxygen to
the tubes. These tubes mount plastic nasal tubes 290 and 292
utilized for supplying oxygen to a patient and about which
conducting wires or ribbons 294 are wound for making electrical
contact with a patient. The conducting wire or ribbon is embedded
such that the top surface thereof is substantially flush with the
exterior of the tube, and such wire or ribbon is in each case
connected to a conducting wire 296 employed for coupling to the
circuits of FIGS. 6 or 14 for use in substantially the same manner
as described for the FIG. 21 device, as well as to other previously
described circuitry for providing pacing or defibrillating
impulses.
FIG. 23 illustrates a catheter 302 for insertion into a bodily
opening in substitution for an airway or the like in the case of a
patient already requiring a catheter. The catheter is provided with
a helically wound wire or ribbon conductor 304 embedded in the
surface thereof, wherein the exterior of the conductor is flush
with the surface of the plastic catheter tube. Connection to
external circuitry is made via conductor 304 in the manner
hereinbefore described for an airway electrode for deriving
electrical signals from the heart and providing resuscitating
impulses.
In many cases, a monitoring system according to the present
invention will be connected under emergency conditions to the
patient by means including the airway 10 in FIG. 1, and the airway
will be ejected by the patient when he regains consciousness, for
example after resuscitation. However, it is then desired to
substitute other connecting means to the patient for continuously
monitoring his heart condition. When the airway is ejected, the
device 306 illustrated in FIG. 24 may be substituted therefor. Such
device is designed for at least partial insertion into or onto the
body or passageway of a patient, e.g. the lip or mouth of the
patient. The device comprises a bifurcated metal spring clip
adapted for sliding onto the lip or cheek of the patient and
includes opposed member portions 308 and 310 which are spring
biased toward one another. The member portion 308, adapted for
insertion within the mouth or cheek, suitably supports a microphone
314 employed for detecting breath sounds and suitably connected in
the manner of microphones 22 or 122 in FIGS. 10 and 14. The device
306 is connected to the previously described circuitry by means of
connecting lead 312 to the aforementioned terminals 1 or 101, and
may also be utilized in the case of further emergency for applying
pacing and defibrillating pulses if necessary.
Another device for attachment to the patient, after ejection of the
airway, is illustrated in FIG. 25, the device being numbered 316.
This device takes the form of a clamp including forward opposed
member portions 318 which are normally spring biased toward one
another by spring 320, the device further including levers 322
rearward of the spring and integral with member portions 318 by
means of which the member portions 318 are forced apart for
separating the same whereby the device may be inserted onto the lip
or mouth. The member portions 318 are spaced apart rearward of
their forward or contacting areas so that a relatively firm contact
may be made with the moist tissue inside the lip or cheek. The
device is suitably formed of conducting metal and is provided with
a connecting lead 324 for coupling the device to the hereinbefore
described apparatus for use in the same manner as indicated for the
device of FIG. 24. The FIG. 25 device may also support a microphone
for insertion within the mouth of the patient as previously
mentioned in respect to the FIG. 24 device.
Utilization of a connection external to the patient has been
hereinbefore described, for example, in particular regard to the
electrode means 5 provided with electrodes 6 and 7. This electrode
means, as illustrated in FIG. 1, is suitably employed in
conjunction with means substituted for an airway as in the case of
a conscious patient, as well as in conjunction with the airway
itself, the electrode means 5 being placed elsewhere on the patient
for example on the chest or abdomen area to provide an opposite
polarity input signal electrode means or reference electrode means,
as well as forming possible output electrode means. While suitable
connection can be made with the patient by holding or strapping
such electrode means 5 on the patient, alternative external
electrode contacts as contemplated according to the present
invention are preferred for providing a quicker and more certain
electrical circuit connection. One such device, suitable for
external connection, has already been described in connection with
FIG. 25 and comprises a spring biased clamp. Such spring biased
clamp may alternatively be attached to the patient at a location
remote from the mouth, for example clamped on an extremity such as
a finger, or clamped to a "flap" of skin which may be gathered
between opposed member portions 318 or a "web" of skin as between
the thumb and fingers or the like. The FIG. 25 clamp, employed in
this way, is ordinarily utilized as the external connection in
combination with an airway or similar device for providing the
opposite polarity EKG terminal. Of course, in the event that the
airway is ejected by the patient as hereinbefore mentioned, devices
of the type illustrated in FIG. 25 may be employed both at the
patient's mouth and at a location remote therefrom, such as in the
chest or abdomen area, extremity, or the like.
Another similar device 326 is illustrated in FIG. 26 and comprises
opposed metal clamping members 328 and 332, each respectively
integral with one of a pair of rearward metal handle portions 334
and hingedly connected to one another. Spring 336 biases member 328
toward member 332, member 328 being slightly wider than member 332
and carrying a pair of relatively sharp contacts 330 at the forward
end thereof which adjoin either side of member 332 when the members
are closed toward one another. The device is designed for clamping
to an extremity, flap of skin, or the like wherein the sharp
contact means 330 are adapted to penetrate the patient's skin and
reach the subcutaneous layer whereby a more certain electrical
connection is made. An electrical lead 333 is supplied for
connecting the device 326 to the hereinbefore described circuitry
of FIGS. 6 or 14 in place of electrode means 5.
A further device which may be utilized for making external contact
with the patient in place of the electrode means 5 is illustrated
in FIGS. 27 and 28. The device, numbered 338, comprises a stainless
spring steel ring shaped rod 340 having a relaxed condition
illustrated in FIG. 28. The rod 340 is severed rather than forming
a complete ring, and one end thereof carries a ball 342 while the
other end thereof carries a mating socket 344 adapted for receiving
the ball when the rod is extended to full ring diameter as
illustrated in FIG. 27. A connecting lead 346 is employed for
coupling the ring as an external connection in place of the
hereinbefore mentioned electrode means 5.
The ring device 338 is normally carried in the distended condition
illustrated in FIG. 27 and may be slipped onto the patient's finger
after which the ball 342 is sprung out of the socket 344 causing
the ring device to grasp tightly the finger of the patient and
provide a desired external electrical connection.
Another device for making external connection to a patient's
extremity is illustrated in FIGS. 29 and 30. This device, numbered
348, comprises a malleable metal ring or bracelet band 350
internally carrying a metal socket 352 to which there is secured
sponge material 354 or other absorbent means adapted to be
moistened with a penetrant and/or electrolyte such as silver
chloride, DMSO, a saline solution or the like. The wire lead 356 is
utilized for connecting the device to the hereinbefore described
circuitry in place of electrode means 5. The penetrant contacts the
patient.
FIG. 31 illustrates another "external" electrode means and
comprises a needle 358 such as an "IV" needle, hypodermic needle or
the like which the patient's condition may necessitate. Such
needle, connected to the hereinbefore described circuitry by lead
360, may be utilized as the second apparatus connection in place of
the electrode means 5 in FIG. 1.
Other types of external terminals or electrodes are possible such
as well known adhesive materials and terminals which are
electrically conducting.
The external electrode means of the type illustrated for example in
FIGS. 25-31 are advantageously employed for relatively rapid and
certain connection of the patient to the system according to the
present invention, in combination with the airway 10 as illustrated
in FIG. 1. Thus, in the case of an unconscious patient suffering
from a possible heart attack, the airway 10 is very readily and
rapidly inserted in the person's throat in the same manner as an
airway is frequently inserted in a patient's throat by a physician
for the purpose of delivering mouth-to-mouth resuscitation. The
external electrode, for example the clamping devices of FIGS. 25 or
26, are also rapidly connected to an extremity, flap of skin or the
like for certainly connecting the patient to the system in the
shortest possible period of time. If, as a matter of fact, the
patient is not unconscious, he will eject the airway, but a device
of the FIG. 24 or FIG. 25 type may be attached to the patient's
mouth whereby continual monitoring of the patient's condition is
possible.
In the following claims, the term "non-cardiac", when applied to
measurement, refers to measurement of other than the heart beat
itself.
While we have shown and described several embodiments of our
invention, it will be apparent to those skilled in the art that
many changes and modifications may be made without departing from
our invention in its broader aspects. We, therefore, intend the
appended claims to cover all such changes and modifications as fall
within the true spirit and scope of our invention.
* * * * *