Sphygmomanometer

Claim 2

In a sphygmomanometer having an inflatable cuff to be wrapped around a subject''s extremity and pressurizing means for inflating the cuff, an improved means for indirectly determining blood pressure comprising: a specific volume container having an inlet means for pressurizing said container; fluidic means connected to said container to process fluid from the container in a manner to produce pressure pulses of substantially equal pressure increments; isolating means for maintaining the pressure in the cuff proportional to the pressure in the container and for preventing fluid flow from the cufF to the container; and means for counting the pressure increments to obtain a digital measure of the pressure in the container and thereby pressure in the cuff so that blood pressure can be determined upon receipt of signals related to the events in the indirect measurement of a subject''s blood pressure.

Claim 3

The sphygmomanometer of claim 1 wherein said fluidic means includes a bistable fluidic flip-flop having an inlet port connected to the container, a pair of output ports stemming from a common junction leading from the inlet port, a pair of restricted exhaust paths leading from the output ports, a pair of control ports on opposite sides of said junction for deflecting fluid flow to one or the other output port, and a pair of flow restrictors each connecting an output port to one of the control ports to produce said pressure increments.

Claim 4

The sphygmomanometer of claim 1: including means for detecting Korotkoff sounds which occur when the blood first rushes through an artery after the pressure in the cuff has been raised to a level to completely occlude the artery and pressure in the cuff has then been reduced to permit blood to begin to flow through the artery, and means for detecting the absence of Korotkoff sounds which occur when the artery is no longer obstructed; and wherein said counting means includes a counter for registering systolic blood pressure and a counter for registering diastolic blood pressure; and including a signal processor having means for utilizing the systolic event for operating the systolic counter so as to obtain a systolic blood pressure reading on the counter and means for utilizing the diastolic event to enable the diastolic counter to obtain a reading of diastolic blood pressure.

Claim 5

The sphygmomanometer of claim 3 including means for detecting the subject''s pulse and means for utilizing the pulse signal with the Korotkoff signals so that the decision of systolic and diastolic pressures is made by correlating the Korotkoff signals and the pulse signals so that extraneous acoustical signals will not cause erroneous decisions.

Claim 6

The sphygmomanometer of claim 4 including electrical means for counting and multiplying the pulse signals to obtain a pulse reading in beats per minute.

Claim 7

The sphygmomanometer of claim 3 including means for resetting the systolic pressure counter when the Korotkoff sounds indicating the systolic event are first detected, and means for resetting the diastolic counter each time Korotkoff sounds are detected so that cessation of the sounds will indicate the diastolic event and will stop further resetting of the diastolic counter so that the diastolic counter will accumulate the count.

Claim 8

The sphygmomanometer of claim 1 including: means for indicating when the pressure in the cuff is in the systolic-diastolic blood pressure range; wherein said counting means includes a counter for registering systolic blood pressure and a counter for registering diastolic blood pressure; means for resetting the systolic counter when the cuff pressure is at systolic pressure; and means for resetting the diastolic counter each time a signal is received from the indicating means that the cuff pressure is in said range so that when the signals cease at the diastolic event the diastolic counter continues to accumulate the pressure count.

Claim 9

The sphygmomanometer of claim 7 including latch means for preventing resetting of said systolic counter once systolic pressure is reached and so long as periodic signals are received by the latch means indicating that the cuff pressure is in said range.

Claim 10

The sphygmomanometer of claim 1 wherein said isolating means includes a diaphragm having one side forming the wall of a chamber in communication with the container and having its other side forming a wall of the chamber in communication with the cuff, said diaphragm supporting a valve member for bleeding pressure from the cuff as the pressure is bled from the container.

Claim 11

The apparatus of claim 1 including signaling means for indicating when the fluidic means is operating.

Claim 12

The sphygmomanometer of claim 1 wherein said container is connected to be pressurized as the cuff is being inflated, and including a pneumatic diode connected between the cuff and the container permitting flow into the cuff but preventing flow out of the cuff, the diode having significant internal resistance to flow such that air flows smoothly into the cuff.

Claim 13

Blood pressure measuring apparatus comprising: an inflatable cuff to be wrapped around the subject''s extremity; a specific volume container to be pressurized to the level of the inflated cuff while isolated from the cuff; means for pressurizing said cuff and said container; means for bleeding fluid from the cuff while maintaining the pressure in the cuff substantially equal to the pressure in the container; a bistable fluidic flip-flop means connected to said container to process fluid from the container in a manner to produce decreasing asynchronous output pressure pulses of substantially equal pressure increments; pressure operated switch means responsive to said oscillating pressure increments; display means including a systolic counter and a diastolic counter for counting the signals received from said oscillator switch means; a microphone means associated with said cuff for detecting the Korotkoff sounds which occur when the blood first rushes through an artery after the pressure in the cuff has been raised to a level to completely occlude the artery and the pressure in the cuff has then been reduced to permit blood to begin to flow once more through the artery; and an electronic processor means for processing signals received from the microphone to reset the systolic counter when a signal is received from the microphone indicating that the cuff is at systolic pressure and to subsequently reset the diastolic counter when signals from the microphone are present as defined by Korotkoff until the cessation of such signals indicating that the pressure in the cuff is at diastolic pressure.

Claim 14

Blood pressure measuring apparatus comprising: an inflatable cuff to be wrapped around the subject''s extremity; a specific volume container to be pressurized to the level of the inflated cuff while isolated from the cuff; means for pressurizing said cuff and said container; means for bleeding fluid from the cuff while maintaining the pressure in the cuff substantially equal to the pressure in the container; a bistable fluidic flip-flop means connected to said container to process fluid from the container in a manner to produce decreasing asynchronous output pressure pulses of substantially equal pressure increments; pressure operated switch means responsive to said oscillating pressure increments; display means including a systolic counter and a diastolic counter for counting the signals received from said oscillator switch means; a microphone means associated with said cuff for detecting the Korotkoff sounds which occur when the blood first rushes through an artery after the pressure in the cuff has been raised to a level to completely occlude the artery and the pressure in the cuff has then been reduced to permit blood to begin to flow once more through the artery; and an electronic processor means for processing signals received from the microphone to reset the systolic counter when a signal is received from the microphone indicating that the cuff is at systolic pressure and to subsequently reset the diastolic counter when signals from the microphone are present as defined by Korotkoff until the cessation of such signals indicating that the pressure in the cuff is at diastolic pressure.

Claim 15

The apparatus of claim 12: including a transducer means for detecting the subject''s pulse; and wherein said processor means includes means for processing the pulse signals from the transducer in a manner such that signals from the microphone must coincide with the pulse signals before said counters can be reset.

Claim 16

The apparatus of claim 12 wherein said processor means includes an electrical gate which receives signals from said microphone means and said transducer means and which will not open unless both signals are present at approximately the same time, the output signal from said gate being utilized to initiate resetting of said counters.

Claim 17

The apparatus of claim 14 wherein: said processor means further includes electrical means for processing the pulse signals received from the transducer to determine the subject''s pulse in beats per minute; and said display means further includes a counter for counting and displaying the subject''s pulse directly in beats per minute.

Claim 18

The apparatus of claim 12 wherein said processor means includes dynamic latch means connected to said microphone and said systolic counter for preventing further resetting of the systolic counter, after the initial resetting indicating systolic pressure, so long as signals from the microphone are received by the latch means in a time interval slightly greater than the interval between two periods of the subject''s nominal heart beats.

Claim 19

The apparatus of claim 12: including a restrictor in a tube connecting the container and the fluidic device and a pressure differential responsive switch exposed to the cuff pressure and the pressure downstream from the restrictor to detect when the pressure in the cuff is falling; and said processor means includes means for processing the signal received from said differential switch to prEvent resetting of the counters after the occurrence of the systolic and diastolic events until such time as a signal is received from said differential switch indicating that the pressure in the cuff is once more falling.

Claim 20

The apparatus of claim 17 wherein the means within said processor for preventing resetting of the counters until a proper signal is received from said differential switch includes latching means which receives a signal upon indication of the diastolic event and prevents the resetting of said counters until such time as an appropriate signal is received from said differential switch.

Claim 21

The apparatus of claim 12 including means for preventing the processor means from providing signals to reset the counters after the diastolic event during the deflation cycle and until a new deflation cycle is initiated.

Claim 22

The apparatus of claim 12 including signalling means for indicating when Korotkoff sounds start and cease.

Claim 23

A sphygmomanometer comprising: an inflatable cuff to be wrapped around the subject''s extremity; pressurizing means connected to inflate the cuff; a known volume container connected to said pressurizing means to be pressurized simultaneously with the inflation of the cuff; a pneumatic diode in the line between the pressurizing means and the cuff permitting fluid flow into the cuff but preventing fluid flow from the cuff to the pressurizing means or to the container; a bistable fluidic flip-flop device having an input port connected to said container, the device having a pair of output ports connected to a common junction in communication with the input port, a restricted exhaust path leading from each of said output ports, and a control port on opposite sides of the common junction to oscillate the flow between the two outlet ports upon the application of alternate pneumatic control signals, each control port being connected by a restrictor to a respective one of said outlet ports so that as the pressure rises within an outlet port a pressure pulse is created for oscillating the fluid flow to the other outlet port; an interface device comprising a housing have a flexible diaphragm dividing the housing into a pair of chambers, one chamber being connected to the reservoir and the other chamber being connected to the cuff, an exhaust port being formed in a wall of the chamber connected to the cuff, and a valve member carried by the diaphragm for permitting air to be bled from the cuff at a rate to maintain the pressure in the cuff equal to that of the pressure in the reservoir; a microphone means for detecting Korotkoff sounds through the artery as the pressure from the cuff is bled from a point above systolic blood pressure; electrical means for counting the oscillating pressure pulses produced by the fluidic flip-flop device upon receiving a signal from the microphone that Korotkoff sounds corresponding to systolic blood pressure have been detected; electrical means for counting the pressure pulses produced by the fluidic flip-flop upon receiving a signal from the microphone corresponding to diastolic blood pressure; and the counting means being calibrated to allow for the minimum pressure required to operate the fluidic device and thereby provide a digital reading of the blood pressures.

Claim 24

A sphygmomanometer comprising: an inflatable cuff to be wrapped around the subject''s extremity; pressurizing means connected to inflate the cuff; a known volume container connected to said pressurizing means to be pressurized simultaneously with the inflation of the cuff; a pneumatic diode in the line between the pressurizing means and the cuff permitting fluid flow into the cuff but preventing fluid flow from the cuff to the pressurizing means or to the container; a bistable fluidic flip-flop device having an input port connected to said container, the device having a pair of output ports connected to a common junction in communication with the input port, a restricted exhaust path leading from each of said output ports, and a control port on opposite sides of the common junction to oscillate the flow between the two outlet ports upon the application of alternate pneumatic control signals, each control port being connected by a restrictor to a respective one of said outlet ports so that as the pressure rises within an outlet port a pressure pulse is created for oscillating the fluid flow to the other outlet port; an interface device comprising a housing have a flexible diaphragm dividing the housing into a pair of chambers, one chamber being connected to the reservoir and the other chamber being connected to the cuff, an exhaust port being formed in a wall of the chamber connected to the cuff, and a valve member carried by the diaphragm for permitting air to be bled from the cuff at a rate to maintain the pressure in the cuff equal to that of the pressure in the reservoir; a microphone means for detecting Korotkoff sounds through the artery as the pressure from the cuff is bled from a point above systolic blood pressure; electrical means for counting the oscillating pressure pulses produced by the fluidic flip-flop device upon receiving a signal from the microphone that Korotkoff sounds corresponding to systolic blood pressure have been detected; electrical means for counting the pressure pulses produced by the fluidic flip-flop upon receiving a signal from the microphone corresponding to diastolic blood pressure; and the counting means being calibrated to allow for the minimum pressure required to operate the fluidic device and thereby provide a digital reading of the blood pressures.

Claim 25

The sphygmomanometer of claim 21 wherein said electrical means includes separate counters for recording diastolic and systolic pressures, each of said counters being connected to count all of the oscillating pressure pulses produced by the flip-flop device, and means for resetting each of the counters at the appropriate times corresponding to diastolic and systolic pressures.

Claim 26

Blood pressure measuring apparatus comprising: an inflatable cuff to be wrapped around the subject''s extremity; a specific volume container to be pressurized to the level of the inflated cuff while isolated from the cuff; means for pressurizing said cuff and said container; mEans for releasing air from the cuff while maintaining the pressure in the cuff substantially equal to the pressure in the container; a bistable fluidic flip-flop means connected to said container to process fluid from the container in a manner to produce asynchronous output pulses of substantially equal pressure increments; pressure operated switch means responsive to said oscillating pressure increments; display means including a systolic counter and a diastolic counter for counting the signals received from said oscillator switch means; transducer means associated with said cuff for detecting when the blood first rushes through an artery after the pressure in the cuff has been raised to a level to completely occlude the artery and the pressure in the cuff has then been reduced to permit blood to begin to flow once more through the artery; and an electronic processor means for processing signals received from the transducer means to reset the systolic counter when a signal is received from the transducer means indicating that the cuff is at systolic pressure and to reset the diastolic counter each time a signal from the transducer means is received indicating that the pressure in the cuff is still in the systolic to diastolic range, said processor means including an electrical gate which receives signals from said transducer, a dynamic latch connected to said gate and said systolic counter for preventing further resetting of the systolic counter after the systolic event so long as signals are received by the latch from the gate indicating that the pressure is in the systolic to diastolic range, said latch means being adapted to reset upon cessation of such signals from the gate; and means for closing said gate upon the resetting of the latch.

Claim 27

Blood pressure measuring apparatus comprising: an inflatable cuff to be wrapped around the subject''s extremity; a specific volume container to be pressurized to the level of the inflated cuff while isolated from the cuff; means for pressurizing said cuff and said container; mEans for releasing air from the cuff while maintaining the pressure in the cuff substantially equal to the pressure in the container; a bistable fluidic flip-flop means connected to said container to process fluid from the container in a manner to produce asynchronous output pulses of substantially equal pressure increments; pressure operated switch means responsive to said oscillating pressure increments; display means including a systolic counter and a diastolic counter for counting the signals received from said oscillator switch means; transducer means associated with said cuff for detecting when the blood first rushes through an artery after the pressure in the cuff has been raised to a level to completely occlude the artery and the pressure in the cuff has then been reduced to permit blood to begin to flow once more through the artery; and an electronic processor means for processing signals received from the transducer means to reset the systolic counter when a signal is received from the transducer means indicating that the cuff is at systolic pressure and to reset the diastolic counter each time a signal from the transducer means is received indicating that the pressure in the cuff is still in the systolic to diastolic range, said processor means including an electrical gate which receives signals from said transducer, a dynamic latch connected to said gate and said systolic counter for preventing further resetting of the systolic counter after the systolic event so long as signals are received by the latch from the gate indicating that the pressure is in the systolic to diastolic range, said latch means being adapted to reset upon cessation of such signals from the gate; and means for closing said gate upon the resetting of the latch.

Claim 28

The apparatus of claim 23 wherein said means for closing said gate includes a sequence latch connected to the gate and connected to receive a signal from said dynamic latch when it resets upon cessation of signals from the gate.

Claim 29

The apparatus of claim 24 wherein said means for closing said gate further includes a second gate connected between the dynamic latch and the sequence latch, the second gate when closed preventing signals from the dynamic latch from reaching the sequence latch, and a systolic timing circuit connected to said dynamic latch and said second gate to open said second gate after an interval of time slightly less than the time between the systolic and diastolic events so that said sequence latch for closing the first mentioned gate will only receive a signal corresponding to a true diastolic event.

Claim 30

The apparatus of claim 25 including means connected to said sequence latch to indicate when said cuff is deflating and to cause said latch to close said first mentioned gate except when the cuff is deflating.

Claim 33

The method of claim 27 wherein said signals relating to blood pRessure are obtained by detecting the Korotkoff sounds of the blood as cuff pressure decreases and blood commences to once more flow through the artery indicating the systolic blood pressure, and by detecting the cessation of the Korotkoff sounds which occurs when the artery is no longer occluded, thus indicating diastolic blood pressure, and utilizing the detected sound signals to initiate counting of said pressure increments to thereby obtain digital readings of systolic and diastolic blood pressure.

Claim 34

The method of claim 28 including the step of detecting the subject''s pulse and combining it with said detected sound signals such that counting of said pressure increments is not initiated until such times as a signal of the subject''s pulse occurs at the same time as a sound signal is detected thereby reinforcing the accuracy of the system.

Claim 35

The method of claim 29 including the step of counting the signals corresponding to the subject''s pulse and electrically converting such count into beats per minute.

Claim 36

The method of claim 27 including the steps of counting the pressure pulses with two digital counters; resetting one of said counters with the receipt of a signal corresponding to systolic blood pressure; and resetting the other of said counters with each Korotkoff signal until absence of signal corresponding to diastolic blood pressure.