U.S. patent number 3,639,907 [Application Number 04/854,582] was granted by the patent office on 1972-02-01 for interrogated telemetry alarm system for physiological monitoring.
This patent grant is currently assigned to Mennen-Greatbatch Electronic, Inc.. Invention is credited to Wilson Greatbatch.
United States Patent |
3,639,907 |
Greatbatch |
February 1, 1972 |
INTERROGATED TELEMETRY ALARM SYSTEM FOR PHYSIOLOGICAL
MONITORING
Abstract
Apparatus for monitoring from a single station a physiological
condition of each of a plurality of remotely located patients. A
radio transmitter at the station generates sequentially a plurality
of tone signals, one for each patient and each of a different
frequency, on a common carrier. A radio receiver with each patient
has a band pass corresponding to a particular one of the tone
signals. Each receiver when addressed activates a radio transmitter
with the patient for transmitting to a single receiver at the
station a coded signal indicative of the physiological state of the
patient, derived from signal generating means operatively connected
to the patient. The signals received at the station are
sequentially routed, decoded, and applied to suitable
indicators.
Inventors: |
Greatbatch; Wilson (Clarence,
NY) |
Assignee: |
Mennen-Greatbatch Electronic,
Inc. (Clarence, NY)
|
Family
ID: |
25319088 |
Appl.
No.: |
04/854,582 |
Filed: |
September 2, 1969 |
Current U.S.
Class: |
340/870.09;
128/903; 340/518; 340/870.22; 340/573.1; 340/539.12; 340/505;
340/524; 340/870.12; 340/870.28; 346/33ME; 340/539.1 |
Current CPC
Class: |
H04Q
9/10 (20130101); A61B 5/0006 (20130101); A61B
5/363 (20210101); G06K 17/0022 (20130101); G07C
9/28 (20200101); Y10S 128/903 (20130101) |
Current International
Class: |
A61B
5/00 (20060101); A61B 5/0464 (20060101); A61B
5/0452 (20060101); G06K 17/00 (20060101); H04Q
9/08 (20060101); G07C 9/00 (20060101); H04Q
9/10 (20060101); H04q 009/00 () |
Field of
Search: |
;340/150,311,183
;346/33ME ;128/2.1A,2.5R |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Yusko; Donald J.
Claims
I claim:
1. Apparatus for monitoring from a single station a physiological
condition of each of a plurality of remotely located patients
comprising:
a. a radio receiver with each patient and each receiver having a
different frequency passband;
b. a radio transmitter with each patient and connected in
controlled relation to said receiver;
c. a signal producing means adapted to be operatively connected to
each patient for providing electrical signals having a parameter
which varies in accordance with changes in a physiological
characteristic of the particular patient;
d. decision circuit means with each patient and having an input
coupled to the output of said signal producing means, said decision
circuit means comparing the variations in said parameter with a
predetermined normal value and providing an output alarm signal in
response to abnormal variations in said parameter;
e. coding means with each patient coupled to said decision circuit
means and to said transmitter whereby the radiofrequency signal
generated by each transmitter is coded in terms of the alarm state
of the physiological characteristic of the particular patient;
f. a radio transmitter at said station for generating sequentially
a plurality of signals, the number being equal to the total number
of patients being monitored and the frequency of each one
corresponding to a particular passband of one of said receivers
whereby said transmitter with each patient is periodically
interrogated;
g. a radio receiver at said station for receiving signals from said
transmitter with each patient;
h. decoding means connected to the output of said station receiver
and operative sequentially in synchronism with said station
transmitter for decoding the physiological state signal from each
patient; and
i. a plurality of indicating means, one for each patient,
operatively connected to said decoding means.
2. Apparatus as defined in claim 1 wherein each signal producing
means comprises:
a. an input terminal adapted to be operatively connected to the
particular patient for sensing electrical signals indicative of
cardiac behavior; and
b. an amplifier having an input connected to said terminal and an
output; and
c. decision circuit means having an input connected to the output
of said amplifier, and wherein said decision circuit provides
output alarm signals in response to an abnormal rate of signals
applied to the input thereof.
3. Apparatus as defined in claim 2 further including magnetic tape
recording means, the recording element of which is connected to the
output of said amplifier and the drive means of which is connected
in controlled relation to the output of said decision circuit for
stopping said tape recording means in response to an alarm
signal.
4. Apparatus as defined in claim 2 further including means
connected in controlled relation to the output of said decision
circuit for coupling the output of said amplifier directly to said
patient transmitter in response to an alarm signal.
Description
BACKGROUND OF THE INVENTION
The present invention relates to the telemetry art and, more
particularly, to a system for monitoring the physiological
condition of each of a large number of patients by the
telemetry.
Physiological monitoring of a large number of patients by automatic
means is becoming increasingly necessary as shortages of hospital
personnel increase and as hospital activities expand and become
more highly specialized. Upon leaving intensive care units,
patients are in hospital areas which often are relatively less
rigidly observed, and in such areas automatic physiological
monitoring can reduce the mortality rate from cardiac arrest and
fibrillation. As hospital care progresses from its present state,
additional intensive care units, each of a more specialized nature,
are envisioned and will augment the need for automatic
physiological monitoring.
Automatic physiological monitoring by telemetry has been proposed
and is particularly advantageous because of the ability to
continuously monitor an ambulatory patient. Heretofore, the number
of patients that could be accommodated economically by telemetry
was limited to about 10 patients due to equipment and frequency
spectrum limitations. For example, there must be interference-free
reception from one patient about 200 feet from a receiving antenna
and delivering only 2 or 3 microvolts of signal to the receiver,
and yet another patient on an adjacent telemetry channel and
positioned only about 10 feet from the same antenna must not
contribute any crosstalk. Otherwise, an alarm might be received
from the wrong patient. In addition, the channel separations must
be unequal so as to avoid unwanted modulation products from mixed
transmitter signals, from mixed receiver local oscillators and from
various I.F. signals traveling through the system.
SUMMARY OF THE INVENTION
It is, therefore, an object of this invention to provide apparatus
for continuously monitoring the physiological condition of each of
a large number of patients, such as about 100, by telemetry.
It is a further object of this invention to provide such apparatus
which is readily usable with ambulatory patients.
It is an additional object of this invention to provide such
apparatus which provides a rapid indication of the type of patient
disorder giving rise to an alarm, deferred access to stored
physiological data, and continuous readout of data from a patient
in alarm.
It is a further object of the present invention to provide such
apparatus which can monitor a large number of patients at a
relatively fast rate, for example the total number of patients
every 10 or 20 seconds.
The present invention provides physiological monitoring apparatus
including a radio receiver with each patient and connected in
controlling relation to a corresponding radio transmitter with each
patient, each receiver having a different frequency passband. The
receivers are addressed sequentially by a radio transmitter at a
monitoring station which generates sequentially a corresponding
plurality of coded tones on a common carrier. Each receiver, when
addressed, activates the transmitter which is controls which, in
turn, transmits a coded signal indicative of the patient's
physiological condition to a single radio receiver at the
monitoring station whereupon the signal is routed and decoded.
The foregoing and additional advantages and characterizing features
of the present invention will become clearly apparent upon a
reading of the ensuing detail description of an illustrative
embodiment together with the included drawing depicting the
same.
BRIEF DESCRIPTION OF THE DRAWING FIGURES
FIG. 1 is a schematic block diagram of physiological monitoring
apparatus in accordance with the present invention; and
FIG. 2 is a schematic block diagram showing in more detail a
portion of the apparatus of FIG. 1.
DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENT
In a preferred arrangement of physiological monitoring apparatus
constructed in accordance with the present invention, the equipment
designated generally at 10 on the left hand side of FIG. 1 is
stationary, being in a fixed location relative to the patients
being monitored. For convenience hereafter, the components in this
portion of the apparatus will be designated with the term, station.
The nurses's station on a hospital floor or the central monitoring
station in an intensive care unit are examples of where station
apparatus 10 can be located.
Station apparatus 10 comprises a radio transmitter 11 having a
radiating antenna 12 which transmitter functions, briefly, to
generate a radiofrequency signal consisting of a plurality of coded
tones on a common carrier. There would be generated, more
specifically, a different tone or a combination of different tones
for each patient, and the tones would be transmitted sequentially.
A sequencing means 13 suitable for this purpose is operatively
connected through a line 14 to transmitter 11. Station apparatus 10
further comprises a radio receiver 15 having a receiving antenna 16
which receiver functions, briefly, to receive radiofrequency
signals on a different channel relative to that of transmitter 11.
More specifically, receiver 15 responds to signals received from
patients being monitored which signals indicate the physiological
condition of each patient. Receiver 15 is operatively connected
through a line 17 to a decoding circuit 18 which also is
operatively connected to sequencing means 13 through a line 19. The
purpose of this arrangement is to route properly a received and
decoded signal to a particular one of a plurality of indicators 20,
one for each patient, which are connected to the output of decoder
18 through lines designated 21. Indicators 20 preferably are lamps
or other visual devices which tell the observer immediately when a
particular patient is experiencing a physiological disorder, as
will be described in more detail hereafter.
The physiological monitoring apparatus of the present invention
also includes components, designated 25, 25', 25", etc., in FIG. 1,
there being one component or unit for each patient, and the
different units for different patients being distinguished in FIG.
1 by the use of primed designations. Each unit 25 preferably is of
a size and construction readily adapted to be carried by an
ambulatory patient and for this reason will be referred to as being
patient-carried. Each patient-carried unit includes, briefly, a
radio receiver, the antenna of which is designated 26 in FIG. 1,
adapted to respond to a particular one of the coded tones generated
by transmitter 11 at station 10. Each unit 25 further includes a
radio transmitter connected in controlled relation to the receiver
and which functions, when activated, to transmit from an antenna
27, radiofrequency signals indicative of that patients's
physiological condition. These signals are received by receiver 15
at station 10. Each unit 25 further includes input terminals 28, 29
for receiving electrical signals indicative of the patient's
physiological condition. For example, when the apparatus of the
present invention is used to monitor the cardiac behavior of each
of a number of patients, input terminals 28, 29 are connected
directly to the patient, being placed in or on his chest in a
conventional manner, and the voltages thereon indicative of cardiac
behavior are amplified and processed by additional circuitry in
component 25 as will be described hereafter. Alternatively,
terminals 28, 29 may be connected to the output of an appropriate
transducer operatively connected to the patient.
FIG. 2 shows in more detail a preferred form of each
patient-carried unit 25 especially suitable for monitoring cardiac
behavior. A radio receiver 30 is operatively connected to antenna
26 and has a particular frequency passband which permits reception
of a particular one of the coded tones from station transmitter 11.
Receiver 30 is connected through a line 31 in controlling relation
to a radio transmitter 32 which, in turn, is operatively connected
to antenna 27. By virtue of this arrangement, receiver 30 when
addressed by one of the coded tones from station transmitter 11
activates transmitter 32 which, in turn, radiates from antenna 27 a
coded signal indicative of that patient's physiological condition,
in this particular example a signal coded in terms of cardiac
behavior.
Transmitter 32 is provided with information concerning the
patient's cardiac behavior by the following arrangement. Input
terminals 28, 29 are connected to the input of a preamplifier 33
which is designed to have an amplification factor of about 1,000
when the apparatus is employed in cardiac monitoring. In this
particular situation the signals on terminals 28, 29 indicative of
the patient's heartbeat will have an amplitude of only about 2-3
microvolts. The amplified signals appearing at the output of
preamplifier 33 are applied through a line 34 to the input of a
decision circuit 35, the purpose of which is to determine whether
the signals are indicative of normal or abnormal physiological
behavior. For example, in monitoring of cardiac activity, the
repetition rate of signals applied to circuit 35 is the information
parameter. Circuit 35, which can include standard frequency
responsive and logic networks, in this particular example makes a
comparative determination as to whether the rate is normal,
indicating that the cardiac condition of the patient is
satisfactory, too fast indicating tachycardia/fibrillation, or too
slow indicating bradycardia/arrest. The frequency parameter on the
input signal to circuit 35 can be converted therein to an amplitude
or pulse width parameter on the output thereof. For example,
circuit 35 can be constructed to provide no output when the rate is
normal but to provide an output or alarm signal when either of the
above-mentioned disorders is detected, the particular one being
determined by output signal amplitude, duration or even
polarity.
There is also included a command circuit 36, the input of which is
connected through a line 37 to the output of decision circuit 35.
The output of command circuit 36 is applied through a line 38 to a
coding means 39, operatively connected to transmitter 32 through a
line 40. The purpose of command circuit 36 is to transform the
signals received from decision circuit 35, indicative of the
patient's condition, into corresponding signals which are suitable
to command operation of coding means 39 to generate a coded signal
corresponding to the particular condition of the patient. Coding
means 39 can have several known forms, depending upon the manner in
which the output signal of transmitter 32 is to be modulated in
terms of information concerning the physiological condition of the
patient. The signal from transmitter 32 can, for example, be a
coded tone in a one of three code indicating patient satisfactory,
bradycardial/arrest alarm or tachycardia/arrest alarm. A fourth
state might be added to the code indicating no signal from the
transmitter so that the particular patient's equipment can be
repaired or replaced. Instead of coded tones, other types of
modulation, for example pulse width, might be employed.
It is apparent, therefore, that command circuit 36 can have several
known forms depending upon the nature of coding means 39 and the
type of signals required to operate it. In certain applications it
also may be possible to incorporate the function of command circuit
36 into either or both of decision circuit 35 and coding means
39.
The patient-carried apparatus 25 also includes a tape-loop
recorder, designated generally at 45, for providing deferred access
to stored physiological data, for example about 10 minutes of
recorded ECG activity. The output of preamplifier 33 accordingly is
connected by lines 46 and 47 to a recording head 48 of tape
recorder 45. Tape recorder 45 would be placed in operation at the
patient's location whenever it is desired that recording begin.
Preferably, alarm activation would stop the tape so as to store the
previous ten minutes of data preceding the event and to this end
the output of decision circuit 35 is connected by a line 49 to a
controlled tape drive means 50.
The physiological monitoring apparatus of the present invention
operates in the following manner. It is, in effect, an
interrogation system, and is somewhat similar to the IFF system
(Identification, Friend or Foe) used in military aircraft. The
patient-carried radio transmitters, such as transmitter 32, all
operate at the same frequency but transmit only when interrogated.
In monitoring of cardiac behavior, the response modulation can be
one of four audio tones, one for "no alarm," the second for
"bradycardia/arrest alarm," the third for "tachycardia/fibrillation
alarm," and the fourth for "no signal alarm."
Station transmitter 11 together with the patient-carried receivers,
one of which is receiver 30, constitute an interrogator.
Transmitter 11 operates on a frequency different from that on which
patient-carried transmitters 32 operate so that the overall system
uses only two radiofrequency channels. The coded tones provided by
transmitter 11, one for each patient, are generated sequentially
under control of sequencer 13 which in one form can be a two-gang
stepping switch. One gang provides sequencing of code generation by
transmitter 11, represented schematically by line 14, and the other
gang controls routing of signals from receiver 15 through decoder
18 to the particular one of the patient indicator 20. Since only a
tone is elicited from each patient transmitter 32 in response to
interrogation, i.e., the corresponding patient receiver 30 being
addressed by the particular coded tone from transmitter 11, the
patient scanning rate is very fast, sampling 100 patients every 10
or 20 seconds.
The interrogator portion of the apparatus of the present invention
can comprise one of several interrogation systems commercially
available, modified so as to be coded with respect to the patients
being monitored. One is an induction coupled, low frequency variety
wherein station antenna 12 would comprise a wire surrounding the
patients being monitored and antennae 26, 26', etc., each with a
particular patient, would be induction-coupled to the wire in a
manner similar to the coupling between transformer secondary and
primary coils. A second variety is of the radiofrequency type,
operating in the range of about 27 to about 54 megacycles, and
including vibrating needs in the receivers for decoding.
Decoder 18 at the monitoring station 10 would include standard
radio receiver detector circuitry, the exact nature depending upon
the type of modulation employed in the patient transmitters 32. It
is contemplated that the speed of operation of sequencer 13 in
relation to the time needed for a radio signal to travel from
station 10 and for a response signal to return is such that one
response signal will be properly routed to a patient indicator 20
before sequencer 13 advances to the next step for generation of the
next coded tone in transmitter 11. The output of decoder 18, routed
to the particular line 21, could be one of three voltage levels
depending upon the nature of the alarm received. Each indicator 20
could include three lamps differentiated by color or by indicia
according to the nature of the alarm, and there would be included
also suitable voltage level responsive circuitry for energizing the
lamps.
The alarm signals generated by patient transmitters 32 rather than
being coded tones could be microsecond duration pulses. In this
case, three radio receivers instead of a single-station receiver
15, could be employed to locate the particular patient by vector
resolution techniques. Such techniques are well known, for example
Loran, and in this particular situation three receivers measure the
time difference in arrival of a signal from a single transmitter
(patient transmitter 32) rather than three transmitters sending
signals to a single receiver which is the usual case.
The apparatus of the present invention advantageously provides
continuous monitoring of a large number, for example about 100,
ambulatory patients. Monitoring is done at an extremely fast rate,
such as the total number of patients every 10 or 20 seconds.
Moreover, the patient-carried transmitters 32 operate only upon
interrogation, in a time-sharing mode, thereby reducing battery
drain and permitting less frequent battery replacement. All patient
transmitters are identical units and only the coding elements in
the patient receivers 30 are different so transmitter construction
and tuning is advantageously quite simple.
The apparatus of the present invention can include an additional
arrangement whereby in response to the occurrence of an alarm, a
continuous readout of the patient's ECG signal automatically is
transmitted to the station. To this end line 46, on which the ECG
signal is available from the output of preamplifier 33, is
connected by a line 55 to the input of a component designated 56 in
FIG. 2 for controlling the operation of transmitter 32 in this
continuous readout mode. Component 56 is to operate only in
response to the occurrence of an alarm signal provided by decision
circuit 35, and for this reason component 56 is connected in
controlled relation through a line 57 and line 49 to the output of
decision circuit 35. Circuit 56 is connected by a line 58 to
transmitter 32 whereby the carrier thereof is modulated with the
patient's ECG signal. Circuit 56 in addition would be constructed
to provide an additional tone which when transmitted to station 10
would stop sequencing of transmitter 11 and hold it on the
particular channel where the alarm had been received. To this end a
frequency-responsive circuit, designated 60 in FIG. 1, is connected
to the output of receiver 15 by a line 61 and adapted to respond to
this particular tone. Circuit 60, in turn, is connected to
sequencing means 13 by a line 62 to command stopping thereof.
The receiver 15 at station 10 then would receive continuous ECG
data from the patient and would ignore all other patients on the
system until that particular patient's transmitter had been cleared
whereupon the system would again start sequencing through the total
number of patients. Readout and possibly also storage of the
particular patient's continuous ECG signal is performed by
conventional equipment, designated 65, connected to the output of
receiver 15.
It is therefore apparent that the present invention accomplishes
its intended objects. While a single specific embodiment thereof
has been described in detail, this is done for the purpose of
illustration without thought of limitation.
* * * * *