U.S. patent number 3,831,586 [Application Number 05/307,091] was granted by the patent office on 1974-08-27 for respiration monitor.
Invention is credited to Parker H. Petit.
United States Patent |
3,831,586 |
Petit |
August 27, 1974 |
RESPIRATION MONITOR
Abstract
A respiration monitor comprising a sensing unit which senses the
expansion and contraction of the chest, abdomen, side or back; and
through the electrical system sounds an alarm if this motion
ceases. The respiration motion is changed to an electrical signal
in the transducer. Two points on the skin surface are selected as
reference points and the relative motion of the two points is
monitored by a light modulation method. A small transducer is
mounted on the skin at the first reference point. A thin and
flexible modulation reed which conforms to the curvature of the
body is mounted at the second reference point, and extends through
a slot in the transducer. The relative motion of the modulation
reed with reference to the transducer causes the light intensity
impinging on a sensor to change thereby changing the sensor's
resistance and whenever light modulation stops, the electronic
circuitry produces a visual or audial alarm and the patient is
attended.
Inventors: |
Petit; Parker H. (Marietta,
GA) |
Family
ID: |
23188201 |
Appl.
No.: |
05/307,091 |
Filed: |
November 16, 1972 |
Current U.S.
Class: |
600/534; 338/47;
5/940; 340/573.1; 310/330 |
Current CPC
Class: |
A61B
5/1116 (20130101); A61B 5/113 (20130101); A61B
5/1135 (20130101); Y10S 5/94 (20130101); A61B
5/6823 (20130101); A61B 2503/04 (20130101) |
Current International
Class: |
A61B
5/11 (20060101); A61B 5/113 (20060101); A61b
005/02 () |
Field of
Search: |
;340/279
;128/2R,2S,DIG.17,2.5V,2.5E,2.08 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Other References
IB.M. Technical Disclosure Bulletin page 13, Vol. 6, No. 6,
November 1963..
|
Primary Examiner: Medbery; Aldrich F.
Attorney, Agent or Firm: Henry; Patrick F.
Claims
What is claimed is:
1. In a respiration monitor for use on a person including
application to an infant to monitor breathing:
a. a respiration sensing unit for mounting on the person being
monitored, said unit being mounted on a portion of the person which
normally expands and contracts during breating, whereby said unit
may respond to said motion or lack of motion and the effect
thereof,
b. a source of light and a light sensitive component for receiving
light from said source mounted at one place on said persons
portion,
c. a means for modifying the intensity of said received light
comprising a movable light interrupting member mounted on said
person at a second place on said persons portion spaced from said
one place and extending therefrom to between the light path from
the light source and said light sensitive element so as to be moved
by the normal breathing of the person to establish a normal
movement of the light modifying means with respect to the light
responsive element,
d. a transducer and an electrical circuit including the transducer
and the light responsive element, said circuit being established
electrically as normal in response to the normal movement of the
light modifying means with respect to the light responsive
element,
e. and means for operating an alarm means in said electric circuit
upon change in said normal breating which is sensed by the change
in the received light from said modifying means and the change in
the transducer and electrical circuit to indicate the change in
pattern of normal breathing.
2. The device in claim 1: said light modifying member being a
reed-like member having one end attached to the person and the
other end moving to interrupt the light.
3. The device in claim 1: wherein said circuit includes electrical
means for responding to a change in voltage caused by the change in
light on the light responsive element and means for delaying for a
period of time before actuating the alarm whereby temporary pauses
with resumption of normal breathing do not actuate the alarm.
4. The device in claim 1 wherein said light sensitive component is
a photo-resistor.
5. The device in claim 1, wherein: said light is a light emitting
diode.
6. The device is claim 1 wherein said light sensitive component as
a photo-transistor.
7. The device in claim 1 wherein said light sensitive component is
a photo-darlington unit.
8. The device in claim 1 wherein said light is a minature
incandescent lamp.
9. The device in claim 1 wherein said light is a fiber optic light
source.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
Medical monitoring methods and devices and especially respiration
monitoring apparatus. U.S. Class 128 Subclass 2.05 or International
Class A61b5/02. Transducer montioring devices for sensing
physiological changes: Class 310 subclass 8.5; Class 338 Subclass
47.
2. Description of the Prior Art
The following patents are noted:
3,268,845 2,829,637 2,854,968 3,508,235 3,258,009 2,699,465
3,325,799 3,082,414 3,154,066 3,387,149 1,619,005 3,483,861
3,097,639 3,348,535 1,282,908 2,848,992 3,090,377 3,513,832
2,452,799 3,442,263 3,313,803 2,828,734 2,368,207 3,474,526
3,163,856 2,702,354 1,619,886
As disclosed by the above noted prior art there are many
respiration monitors published and some of which are currently
available. These include respiration and movement transducers
disclosed in U.S. Pat. No. 3,268,845. The ones that are at all
suitable for premature infants and the like are primarily designed
for use on premature infants who are subject to sudden inexplicable
cessation of respiration (apnea attack). These attacks generally
occur without any warning. Others of these respiration monitors are
designed for use in the intensive care units of hospitals and most
of these require the bonding of electrodes to the body which is a
source of numerous problems because the conductive jelly irritates
the skin and those that do not utilize conductive jelly are bulky
and taped in place or are not sensitive enough to monitor small
prematures and slight changes. All of these devices are very
complex electronically and consequently the costs are
correspondingly high. Also, many of these include problems of AC
current grounding and leakage and electromotive force dropping
across the patient. To summarize the situation, the currently
available monitors are so complex that the expense precludes their
use in many instances where they are required and needed. Most
hospitals can only afford a few units whereas the need for these
monitors is many times this number. The present invention solves
the problems of cost by means of an inexpensive respiratory monitor
which is simple to operate but at the same time is rugged, reliable
and more sensitive than previous models thereby solving the problem
of sensitivity but without the use of conductive jellies and
bulkiness. The present unit is so inexpensive and simple to operate
that it can be used by non-medically trained personnel thereby
solving the problem of complex electronics and the use of
electronically trained technicians. The electronics in the present
system is so simple and dependable as to provide a very low current
drain feasible for use with a dry or wet cell battery for power,
eliminating the possibility of electrical shocks and the failure of
the unit from loss of outside power and the more complex
arrangement of standby battery power to take over in the case of AC
failure. The problem of patient contact is solved by the present
invention through the use of a universal transducer which does not
have to come in direct contact with the subject in order to measure
respiration or movement. The transducer can be attached to the
patient in a variety of ways and placed in a variety of positions
on the body. Therefore, the present invention unlike the prior art
devices provides a novel means of attaching a transducer to the
patient so as to minimize discomfort, false signals, ease of
application and reliability.
SUMMARY OF THE INVENTION
The present unit comprises the respiratory movement sensing
apparatus, which comprises a light modulation transducer and
modulation reed and the means of attaching said transducer and reed
to the patient via a small rubber belt or adhesive pad, and an
electronic unit which monitors the transducer signal and gives a
light and audible alarm when respiration ceases for an adjustable
time ranging from 6 to 30 =l seconds.
Other and further objects and advantages of this invention will be
apparent from reading the description of the preferred embodiment
in conjunction with the drawings as follows:
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of an infant with the reed and
transducer unit mounted across the chest and abdomen and with a
portion of a typical incubator shown in dotted lines. The
electronics unit is also shown.
FIG. 2 is a cross-sectional view taken on line 2--2 of FIG. 8 of
the direct modulation method of sensing respiratory movement
whereby the light source shines through the modulation reed onto
the sensor.
FIG. 3 is an alternate indirect modulation method whereby light is
reflected from a surface behind the reed onto the sensor.
FIG. 4 is a perspective view of a portion of the belt.
FIG. 5 is a top plan view of the belt shown in FIG. 4 with the
transducer and modulation reed mounted thereon.
FIG. 6 is a perspective view of a detail of the adhesive disposable
used as an alternative means of mounting the transducer and
reed.
FIG. 7 is a top plan view of the transducer and reed attached with
the adhesive disposable pads.
FIG. 8 is a side elevation view of the transducer and light sensing
housing with the belt shown in dotted lines.
FIG. 9 is a cross-sectional view of another modulation reed.
FIG. 10 is a schematic circuit diagram of the sensing electronics
system.
FIG. 11 is a diagrammatic view of the sensing unit mounted
longitudinally on the upper abdomen and chest.
FIG. 12 is a diagrammatic view with the sensing unit mounted
transversely on the abdomen.
BRIEF DESCRIPTION OF THE PREFERRED EMBODIMENT
The motion sensing unit is mounted on the back, front or side of
the patient as shown in FIGS. 11 and 12 and is comprised of the
modulation reed 46 and grid 60 and the transducer 14. The internal
details of the transducer are shown in FIGS. 2 and 3. The
transducer housing 16 to which is attached an electrical wire 18
leading to the transducer is shown in FIG. 8. The housing 16
contains the light sensor 20 which converts light energy to
electrical energy, which is well known in the art, and is activated
by means of a small focused light source 22, which is also mounted
in the housing 16. The relative motion of two points on the skin
surface is monitored by a unique light modulation technique. The
relative motion of the grid 60 on the modulation reed 46 in the
transducer slot 28 causes the light intensity impinging on the
sensor to change thus changing the sensors resistance (resistor) or
turning it on and off (transistor). This can be accomplished either
by a direct modulation technique whereby the light is shined
through the reed onto the sensor (FIG. 2) or by an indirect
modulation technique whereby light is reflected from a surface
behind the reed (FIG. 3). The sensitivity of the transducer can be
adjusted by changing the width of the modulation bars (grid) on the
reed and the width of the sensor aperature and by changing the
intensity and type of light source and the type of sensor.
As shown in FIGS. 4 and 5, the mounting belt 30 comprises a pair of
pockets 40 in which are mounted the transducer 14 and modulation
reed 46. The transducer is mounted by means of a tongue formed by
the bottom portion 26 of the housing 16, and the reed is mounted by
means of a slotted tongue 44 on the reed arrangement 46. The reed
46 includes an elongated connection member 48 which contains the
modulation medium or grid 60. The motion sensing unit can also be
mounted by adhesive mounting pads 52 which have pockets 40' for
mounting the transducer or reed.
The grid 60 of the modulation reed can either be perforated to
allow the passage of light, or be a clear plastic with an opaque
set of bars or circular discs. The reed material must be thin and
flexible to allow it to conform to the curvature of the body
between the transducer and the reed mounting point without causing
excess friction in the slot 28 on the transducer.
The transducer housing 16 and the reed 46 are attached to the
patient by the belt 30 but they also may be attached by means of
disposable adhesive (FIG. 6) or any other suitable method which
allows the reed 46 to move relative to the slot in the transducer
as respiration occurs. The transducer housing 16 and reed 46 are
preferably placed in the position where the relative motion between
the two attachment points is at least 0.5 mm so that the transducer
will translate the signal. If the transducer housing 16 and reed 46
are attached with the disposable adhesive, there are many positions
and alignments of the body which will provide for satisfactory
monitoring even on the smallest premature infant with very shallow
breathing pattern. Some infants have most respiratory motion
occurring between the upper abdomen 54 and the lower rib cage 56.
In this case, the transducer housing 16 and reed 46 can best be
mounted so that the reed 46 is aligned with the length of the body
(See FIG. 11). The transducer housing 16 is mounted on the upper
abdomen 54 above the navel 58 and the reed is attached to the chest
56 above the transducer. Other infants have more motion occurring
from the expansion of the diameter of the abdomen 54 and in this
case the transducer housing 16 and reed 46 should be mounted from
left to right and perpendicular to the actions of the body on the
upper abdomen 54 as shown in FIG. 12. If the rubber belt 30 is
used, it can be placed around the abdomen 54 either above or below
the navel 58. The transducer housing 16 and reed 46 can be placed
either on the abdomen or back of the patient.
The alignment of the reed 46 and the transducer housing 16 is not
so critical due to the shape of the reed slot 44 shown in FIG. 9.
The "hourglass" shape allows misalignments of up to 30.degree.
before the reed 46 binds in the slot. The reed 46 is only wide
enough to cover the sensor aperture while in contact with one wall
of the aperture. The sensor aperture 24 is square to increase
sensitivity.
DESCRIPTION OF THE ELECTRONIC CIRCUIT FIG. 10 (Example)
Basically the circuit disclosed in FIG. 10 detects modulated light
from the transducer to the circuit and includes resistors R1
through R 17; transistors Q1 thru Q7; capacitors C1 and C2; switch
S1. When light modulation ceases for a period of 6 to 30 seconds
(adjustment is made by changing the value of R11) an alarm B is
sounded. Changes in light intensity are detected by the
photoresistor PR as shown or by any other suitable device such as a
photo-transistor or photo-darlington. These light changes result in
a voltage change across resistor R2. The FET (abbreviation for
unipoler field effect transistor) Q1 provides the needed impedance
conversion between R2 and the input Q2. However, the signal from R2
is not amplified by Q1. The capacitor C1 isolates the D.C. voltage
bias to the input of Q2. R5 serves as a sensitivity adjustment. The
transistors Q2 and Q3 operate as a unit to provide high
amplification. In fact, in this application transistors Q2 and Q3
saturate at approximately 4.5 volts in the presence of the input
signal across R5. Therefore, the voltage from the input side of R10
to ground is either 0 volts in the absence of light modulation or
4.5 volts when light is being modulated. Q4 operates as a switch,
which is on when the voltage across R10 is high. When Q4 is turned
on, a charging current is supplied to the capacitor C2. The voltage
across C2 increases turning on transistor Q6, this lowers the
voltage at the input of R15 and turns off Q7. In this state the
audio alarm B is silent. However, when light modulation stops, the
voltage across C2 decreases slowly providing a time delay
controlled by R11. When C2 is discharged the voltage at the input
of Q7 is high and Q7 conducts thereby turning on the audio alarm
B.
The indicator light L provides a visual indication as to the state
of the system. This light L is controlled by a darlington
transistor pair Q5. When switch S1 is placed in the test position
the indicator light L burns intermittently or constantly depending
on the respiration rate when the transducer T is being modulated,
i.e., a normal condition exists. However, when the switch S1 is
switched in the ON, the light L is turned off and only burns when
the audio alarm is sounding, i.e., respiration ceases.
The L.E.D. (light emitting diode) CRI is located remotely in the
transducer T, and provides the light source for the photo-resistor
PR which is also remotely located in the transducer T.
This device is inherently fail-safe to the discharge of the
battery. As the supply voltage decreases, the system sensitivity
decreases. When the sensitivity has decreased sufficiently the
system will react, as if a patient respiration failure had occurred
and the audio alarm B will be sounded. Low battery voltage may then
be verified by observing the battery level indicator also.
SUMMARY OF OPERATION OF DEVICE
The rhythmic breathing of the patient causes the static or passive
condition of the system, that is, as long as the light from the
light emitting diode L.E.D. is broken regularly and rhymically by
the "shutter" 32 of the reed 46, the voltage changes occur across
the photo-resistor and these changes are amplified and utlilized to
keep the alarm clock deactivated. When breathing stops for a period
of time (e.g. 6 to 30 seconds) the change in the intensity light
impinging on PR ceases and the Alarm B is sounded after the preset
time delay.
While I have shown and described a preferred embodiment of my
invention with suggested modifications, this is by way of
illustration only and does not constitute any sort of restriction
thereon, since there are various alterations, changes, deviations,
departures, omissions, additions, and variations which may be made
in the disclosed invention without departing therefrom as
determined only by reference to a proper construction of the
appended claims.
* * * * *