US3905353A - Blood pressure apparatus - Google Patents

Blood pressure apparatus Download PDF

Info

Publication number
US3905353A
US3905353A US446754A US44675474A US3905353A US 3905353 A US3905353 A US 3905353A US 446754 A US446754 A US 446754A US 44675474 A US44675474 A US 44675474A US 3905353 A US3905353 A US 3905353A
Authority
US
United States
Prior art keywords
pressure
reservoir
inflatable
valve
pump
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US446754A
Other languages
English (en)
Inventor
Abraham Lichowsky
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Medical Monitors Inc
Original Assignee
Medical Monitors Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Medical Monitors Inc filed Critical Medical Monitors Inc
Priority to US446754A priority Critical patent/US3905353A/en
Priority to GB593375A priority patent/GB1460412A/en
Priority to CA219,947A priority patent/CA1020768A/en
Priority to DE19752506652 priority patent/DE2506652A1/de
Priority to JP50022488A priority patent/JPS50119486A/ja
Priority to FR7506157A priority patent/FR2262507B1/fr
Application granted granted Critical
Publication of US3905353A publication Critical patent/US3905353A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/02—Detecting, measuring or recording for evaluating the cardiovascular system, e.g. pulse, heart rate, blood pressure or blood flow
    • A61B5/021—Measuring pressure in heart or blood vessels
    • A61B5/022—Measuring pressure in heart or blood vessels by applying pressure to close blood vessels, e.g. against the skin; Ophthalmodynamometers

Definitions

  • a pressure transducer provides a feedback signal to the [56] References cued valve to control the rate of pressure drop and maintain NITED T T PATENTS it substantially constant all to the end that a doctor 3,508,537 4/1970 Kahn et a1. 128/205 A can more quickly and accurately take a patients 3,527,204 9/1970 Lem 128/205 A blood pressure. 3,550,582 12/1970 Wilhelmson....
  • the systolic blood pressure of a patient or person is a measure of the peak or maximum pressure in the patients circulatory system whereas the diastolic blood pressure is a measure of the average pressure of blood flowing through the circulatory system.
  • the conventional apparatus for determining these pressures includes an inflatable cuff arranged to be wrapped about a patients arm, for example, and inflated by a squeeze bulb to thereby close off the circulatory system in the arm.
  • a manometer or other pressure indicating device connects to the tube from the squeeze bulb to the inflatable cuff to indicate pressure in the cuff.
  • the doctor or nurse will gradually release the pressure in the cuff and carefully listen with the stethoscope for the start of blood flow to the lower portion of the arm.
  • a reading of the manometer or other pressure indicating device is taken, this reading indicating the systolic blood pressure.
  • the pressure is gradually decreased further until such time as there is an absence of pronounced acoustic pulses detected by the doctor listening in the stethoscope.
  • another pressure reading is taken which serves to indicate the diastolic blood pressure.
  • the gradual decreasing of the pressure is accomplished by a small screw-type bleeder valve usually disposed close to the squeeze bulb so that the doctor can control the flow of air from the inflated cuff in such a manner as to decrease the pressure at a constant rate.
  • the doctor or other professional must be able to detect the absence of acoustic pulses in his stethoscope while simultaneously squeezing the squeeze bulb to build up the pressure in the cuff. Moreover, this pressure build up should be fairly rapid and should occur at a fairly consistent rate if consistent results are to be achieved. Similarly, in gradually decreasing the pressure, the doctor must simultaneously manually manipulate the small screw bleeder valve, which is subject to particles and moisture in the air, listen for acoustic pulses or the absence of acoustic pulses, and observe the manometer or other pressure indicating device.
  • the acoustic pulses are divided into five phases based on changes in the characteristics of the sound as cuff pressure is decreased.
  • Phase IV is a muffled sound relative to the first three phases.
  • Phase V is silent.
  • the present invention contemplates an improved blood pressure taking apparatus wherein proper pressure build up rate in a cuff and the gradual decreasing of the pressure is effected in a consistent manner substantially automatically so that the doctor or other person taking the blood pres sure is relieved of the necessity to manipulate a squeeze bulb and subsequently control the opening in a relief or bleeder type valve.
  • a pneumatically sealed reservoir having outlet and inlet tubes communicating with its interior is provided. These tubes connect to an inflatable pressure means, such as acuff, exterior of the reservoir arranged to block off blood flow in a portion of a persons circulatory system when inflated to a given pressure.
  • a pump means is connected to the outlet tube for pumping air from the reservoir into the inflatable pressure means when energized.
  • this pump means is incorporated in the reservoir itself so that it is shielded against dirt and dust and also any sounds from the pump are muffled.
  • a single electrically controlled valve connects to the inlet tube for the reservoir to pass air from the inflatable pressure means back into the reservoir in a con trolled manner.
  • Actual control of the valve is effected by a pressure transducer means responsive to pressure in the inflated pressure means for generating an analog signal constituting a function of the pressure, this analog signal being fed back through a suitable feedback means for controlling the action of the valve to provide a given constant rate of pressure decrease from the inflatable pressure means.
  • FIG. 1 is a diagram partly in block form showing the basic components of the blood pressure apparatus in accord with the invention.
  • FIG. 2 shows a series of wave forms occurring at correspondingly lettered points in FIG. 1 useful in explaining the operation of the apparatus.
  • FIG. I there is shown in the central portion of the drawing a pneumatically sealed reservoir 10 having outlet and inlet tubes 11 and 12 connecting to an inflatable pressure means 13 such as the usual type cuff employed in conventional blood pressure taking apparatus.
  • the pressure inflatable means 13 is wrapped about a persons arm to close off blood flow in this portion of his circulatory system.
  • a pump means 14 is connected to the outlet tube 11 and in accord with a preferred embodiment of the invention, the pump is incorporated within the pneumatically sealed reservoir 10. By positioning the pump within the reservoir, it is not only protected from dust and moisture but any sounds generated by the pump are muffled.
  • the pump 14 is arranged to be energized by power leads 15 from any suitable power supply such as indicated at 16, upon depression of a push button switch SW-l. Operation of the pump will transfer air from the reservoir 10 to the inflatable means 13 as indicated by the arrows.
  • An electrically controlled valve 17 is shown in the reservoir inlet tube 12. When this valve is cracked open slightly, the compressed air in the cuff 13 passes back into the reservoir 10.
  • the apparatus comprises a closed air system, the same air being used again and again to operate the inflatable pressure means 13.
  • the air is thus kept dry and free of particles.
  • a pressure transducer 18 connected to the outlet tube 11 and thus responsive to the pressure in the inflatable cuff 13. This pressure transducer generates an analog signal constituting a function of the pressure at all times within the inflatable means 13.
  • a feedback line 19 passes from the pressure transducer 18 to a differentiating circuit 20, the output of which connects to one side of a differential amplifier 21.
  • the other sideof the differential amplifier receives a reference voltage signal indicated at 22. Any difference in these signals gives rise to an error signal passed to the electrically controlled valve 17 by the differential amplifier 21.
  • the valve is controlled to provide a constant rate of pressure decrease in the cuff 13.
  • a visual display of the pressure also derived from the pressure transducer 18 may be provided as at 23.
  • FIG. 1 Also shown in FIG. 1 is a conventional stethoscope including the usual acoustic tube 24 terminating at one end in a pick up 25 and at its other end in ear inserts 26.
  • An operator such as a doctor or nurse or other professional is represented by the box 27 and this person will manually operate the switch SW-l as indicated by the dashed line 28.
  • the stethoscope would be used by the person taking the blood pressure and the push button switch SW-l operated manually. It should be understood, however, that detection of acoustic pulses could be accomplished electronically and automatic controls actuated to record the pressure displayed at 23 at the initiation and termination of acoustic pulses thereby recording the systolic and diastolic pressures. In a completely automated device, the same controls could be utilized to terminate operation of the pump 14 by opening of the switch SW-l when the desired given pressure sufiicient to assure complete block-off of blood flow is achieved. Such a completely automated blood pressure measuring system is shown and described in my copending patent application Ser. No. 443,442 filed Feb.
  • the present invention is concerned solely with the closed air system and feedback control for respectively inflating the cuff l3 and controlling the rate of decrease of pressure in the cuff in a consistent, constant manner.
  • the analog signal from the pressure transducer 18 is indicated at A in the top diagram. It will be noted that the pressure build up when the pump is energized is quite rapid as indicated by the rise line 30. This rate may be, for example, 50 millimeters per second. The remaining portion of the analog curve indicated at 31 represents the gradual decreasing of the pressure in the cuff at a constant rate.
  • Diagram B indicates the output of the differentiating circuit 20 of FIG. 1 and this output constitutes a constant negative voltage signal 32 depicting the constant negative slope of the decreasing pressure curve portion 31 in diagram A.
  • Diagram C shows the reference negative voltage at 33 fed to the other side of the differential amplifier 21. Adjustment of the negative magnitude of the voltage C will control the rate of discharge of the air through the valve 17 of FIG. 1.
  • the doctor or other professional need only position the inflatable means in the form of the cuff 13 about the patients arm in the usual manner and position the pick up 25 of the stethoscope at a lower portion downstream of the circulatory system to be blocked off. While listening to the stethoscope, the doctor will then simply press the push button switch SW-l which will energize the pump 14 to rapidly inflate the cuff 13. As mentioned heretofore, the closure con trol 29 is also energized upon closing of the switch SW-l so that the valve 17 is closed and pressure can build up in the cuff 13. The air utilized to inflate the cuff 13 is simply drawn from the reservoir so that the reservoir pressure decreases.
  • the doctor will maintain the switch button SW-l depressed until he no longer detects acoustic pulses in the stethoscope the same as he does when operating a squeeze bulb. Releasing of the push button then deenergizes the pump 14 and simultaneously removes the valve closure control 29. The valve will then automatically be cracked the correct amount to cause a gradual decrease of the pressure in the cuff as defined by the analog signal portion 31 in FIG. 2. As mentioned, this rate of decrease is controlled by the value of the reference voltage set into the differential amplifier 21 and normally would be at a rate of two millimeters of mercury per second.
  • the recording of the systolic and diastolic blood pressure is done by the doctor in the same manner as is conventionally done, the doctor simply recording the pressure reading at the initiation of the acoustic pulses to provide the systolic pressure and at the termination of the acoustic pulses to provide the diastolic pressure.
  • a blood pressure apparatus comprising, in combination:
  • pump means connected to the outlet tube for pumping air from said reservoir into said inflatable pressure means when energized;
  • an electrically controlled valve connected to said inlet tube for passing air from said inflatable pressure means back into said reservoir in a controlled manner after said given pressure is reached to cause a continuous gradual decrease in the pressure
  • pressure transducer means responsive to pressure in said inflatable pressure means for generating an analog signal constituting a function of said pressure
  • feedback means connected between said pressure transducer means and said electrically controlled valve, said feedback means including:
  • An apparatus including pressure display means for visually indicating the pressure in said inflatable pressure means.
  • said pump means includes means, when energized, to build up pressure at a desired rate.
  • An apparatus including means connected to said electrically controlled valve and responsive to energization of said pump means to automatically hold said valve closed while said pump means is energized.

Landscapes

  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Vascular Medicine (AREA)
  • Cardiology (AREA)
  • Biomedical Technology (AREA)
  • Heart & Thoracic Surgery (AREA)
  • Physiology (AREA)
  • Biophysics (AREA)
  • Pathology (AREA)
  • Engineering & Computer Science (AREA)
  • Ophthalmology & Optometry (AREA)
  • Physics & Mathematics (AREA)
  • Medical Informatics (AREA)
  • Molecular Biology (AREA)
  • Surgery (AREA)
  • Animal Behavior & Ethology (AREA)
  • General Health & Medical Sciences (AREA)
  • Public Health (AREA)
  • Veterinary Medicine (AREA)
  • Measuring Pulse, Heart Rate, Blood Pressure Or Blood Flow (AREA)
US446754A 1974-02-28 1974-02-28 Blood pressure apparatus Expired - Lifetime US3905353A (en)

Priority Applications (6)

Application Number Priority Date Filing Date Title
US446754A US3905353A (en) 1974-02-28 1974-02-28 Blood pressure apparatus
GB593375A GB1460412A (en) 1974-02-28 1975-02-12 Blood pressure apparatus
CA219,947A CA1020768A (en) 1974-02-28 1975-02-12 Blood pressure measuring apparatus with closed air system
DE19752506652 DE2506652A1 (de) 1974-02-28 1975-02-17 Blutdruckmessgeraet
JP50022488A JPS50119486A (enrdf_load_stackoverflow) 1974-02-28 1975-02-25
FR7506157A FR2262507B1 (enrdf_load_stackoverflow) 1974-02-28 1975-02-27

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US446754A US3905353A (en) 1974-02-28 1974-02-28 Blood pressure apparatus

Publications (1)

Publication Number Publication Date
US3905353A true US3905353A (en) 1975-09-16

Family

ID=23773722

Family Applications (1)

Application Number Title Priority Date Filing Date
US446754A Expired - Lifetime US3905353A (en) 1974-02-28 1974-02-28 Blood pressure apparatus

Country Status (6)

Country Link
US (1) US3905353A (enrdf_load_stackoverflow)
JP (1) JPS50119486A (enrdf_load_stackoverflow)
CA (1) CA1020768A (enrdf_load_stackoverflow)
DE (1) DE2506652A1 (enrdf_load_stackoverflow)
FR (1) FR2262507B1 (enrdf_load_stackoverflow)
GB (1) GB1460412A (enrdf_load_stackoverflow)

Cited By (21)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4011860A (en) * 1975-10-20 1977-03-15 Filac Corporation Calibrated blood pressure measuring system and method
USD244235S (en) 1975-09-02 1977-05-03 Medical Monitors, Inc. Automatic blood pressure measuring apparatus
US4088126A (en) * 1976-05-24 1978-05-09 Gemind John M Device for measuring blood pressure
US4116230A (en) * 1976-09-10 1978-09-26 Gorelick Donald E Blood pressure cuff automatic deflation device
US4167181A (en) * 1975-09-26 1979-09-11 Milstein Medical Research Foundation, Inc. Apparatus for automatically depressurizing a variable-volume inflatable enclosure
USD253427S (en) 1978-05-24 1979-11-13 Sharp Corporation Electronic hemadynamometer
US4178918A (en) * 1977-09-15 1979-12-18 Cornwell Lionel B Automatic blood pressure measuring and recording system
US4378807A (en) * 1980-12-03 1983-04-05 Clinical Data, Inc. Blood pressure measurement apparatus
US4459991A (en) * 1980-02-18 1984-07-17 Asulab A.G. Blood pressure measuring equipment
US4493326A (en) * 1979-10-03 1985-01-15 United States Surgical Corporation Automatic blood pressure system with servo controlled inflation and deflation
US4496342A (en) * 1981-03-20 1985-01-29 Surgical Design Corporation Surge prevention system for an ophthalmic instrument
EP0418873A1 (en) * 1989-09-20 1991-03-27 Cas Medical Systems, Inc. Automatic blood pressure measurement in hyperbaric chamber
US5025793A (en) * 1986-10-07 1991-06-25 Richley Edward A Finger blood pressure measurement system
US5027823A (en) * 1989-03-29 1991-07-02 Terumo Kabushiki Kaisha Gas flow valve, and automatic sphygmomanometer using same
US5092338A (en) * 1985-07-25 1992-03-03 Terumo Corporation Automatic sphygmomanometer
US5099851A (en) * 1987-09-14 1992-03-31 Terumo Kabushiki Kaisha Automatic sphygmomanometer
US20050182331A1 (en) * 2004-02-03 2005-08-18 Pharma-Smart, Llc Cuff for measurement of blood pressure
US20110112411A1 (en) * 2006-05-30 2011-05-12 Colin Dunlop Blood pressure monitor
WO2012129044A3 (en) * 2011-03-21 2012-12-06 Welch Allyn, Inc. Cuff integrity detection during inflation of an automated blood pressure device
WO2015041925A1 (en) * 2013-09-23 2015-03-26 Koven Technology Semi-automatic sphygmomanometer system
US20160331245A1 (en) * 2013-09-23 2016-11-17 Koven Technology Semi-automatic sphygmomanometer system

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS54113192U (enrdf_load_stackoverflow) * 1978-01-25 1979-08-09
US4328810A (en) * 1979-10-03 1982-05-11 United States Surgical Corporation Automatic blood pressure system
JPH0657200B2 (ja) * 1984-06-06 1994-08-03 コ−リン電子株式会社 血圧測定用カフの昇圧装置
EP0225949A1 (en) * 1985-12-09 1987-06-24 American Hospital Supply Corporation Linear pressurizing and depressurizing device
US4627440A (en) * 1985-07-05 1986-12-09 Critikon, Inc. Sphygmomanometric cuff pressurizing system
JP2018015506A (ja) * 2016-07-26 2018-02-01 コベン テクノロジー 半自動式血圧計システム

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3508537A (en) * 1965-04-20 1970-04-28 Beckman Instruments Inc Method and apparatus for automatic blood pressure monitoring
US3527204A (en) * 1965-05-28 1970-09-08 Ibm Pressure cuff system
US3550582A (en) * 1967-03-30 1970-12-29 Hoffmann La Roche System for closely monitoring a blood pressure over an extended period of time
US3552381A (en) * 1967-05-23 1971-01-05 Bell Telephone Labor Inc Sphygmomanometric method and apparatus
US3654915A (en) * 1969-12-19 1972-04-11 Del Mar Eng Lab Apparatus for automatically measuring and indicating blood pressure
US3779235A (en) * 1971-06-18 1973-12-18 Searle Medidata Inc Cardiovascular test station pressurometer interface system

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3508537A (en) * 1965-04-20 1970-04-28 Beckman Instruments Inc Method and apparatus for automatic blood pressure monitoring
US3527204A (en) * 1965-05-28 1970-09-08 Ibm Pressure cuff system
US3550582A (en) * 1967-03-30 1970-12-29 Hoffmann La Roche System for closely monitoring a blood pressure over an extended period of time
US3552381A (en) * 1967-05-23 1971-01-05 Bell Telephone Labor Inc Sphygmomanometric method and apparatus
US3654915A (en) * 1969-12-19 1972-04-11 Del Mar Eng Lab Apparatus for automatically measuring and indicating blood pressure
US3779235A (en) * 1971-06-18 1973-12-18 Searle Medidata Inc Cardiovascular test station pressurometer interface system

Cited By (24)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
USD244235S (en) 1975-09-02 1977-05-03 Medical Monitors, Inc. Automatic blood pressure measuring apparatus
US4167181A (en) * 1975-09-26 1979-09-11 Milstein Medical Research Foundation, Inc. Apparatus for automatically depressurizing a variable-volume inflatable enclosure
US4011860A (en) * 1975-10-20 1977-03-15 Filac Corporation Calibrated blood pressure measuring system and method
US4088126A (en) * 1976-05-24 1978-05-09 Gemind John M Device for measuring blood pressure
US4116230A (en) * 1976-09-10 1978-09-26 Gorelick Donald E Blood pressure cuff automatic deflation device
US4178918A (en) * 1977-09-15 1979-12-18 Cornwell Lionel B Automatic blood pressure measuring and recording system
USD253427S (en) 1978-05-24 1979-11-13 Sharp Corporation Electronic hemadynamometer
US4493326A (en) * 1979-10-03 1985-01-15 United States Surgical Corporation Automatic blood pressure system with servo controlled inflation and deflation
US4459991A (en) * 1980-02-18 1984-07-17 Asulab A.G. Blood pressure measuring equipment
US4378807A (en) * 1980-12-03 1983-04-05 Clinical Data, Inc. Blood pressure measurement apparatus
US4496342A (en) * 1981-03-20 1985-01-29 Surgical Design Corporation Surge prevention system for an ophthalmic instrument
US5092338A (en) * 1985-07-25 1992-03-03 Terumo Corporation Automatic sphygmomanometer
US5025793A (en) * 1986-10-07 1991-06-25 Richley Edward A Finger blood pressure measurement system
US5099851A (en) * 1987-09-14 1992-03-31 Terumo Kabushiki Kaisha Automatic sphygmomanometer
US5027823A (en) * 1989-03-29 1991-07-02 Terumo Kabushiki Kaisha Gas flow valve, and automatic sphygmomanometer using same
EP0418873A1 (en) * 1989-09-20 1991-03-27 Cas Medical Systems, Inc. Automatic blood pressure measurement in hyperbaric chamber
US20050182331A1 (en) * 2004-02-03 2005-08-18 Pharma-Smart, Llc Cuff for measurement of blood pressure
US7166077B2 (en) * 2004-02-03 2007-01-23 Pharma-Smart, Llc Cuff for measurement of blood pressure
US20110112411A1 (en) * 2006-05-30 2011-05-12 Colin Dunlop Blood pressure monitor
WO2012129044A3 (en) * 2011-03-21 2012-12-06 Welch Allyn, Inc. Cuff integrity detection during inflation of an automated blood pressure device
US8911378B2 (en) 2011-03-21 2014-12-16 Welch Allyn, Inc. Cuff integrity detection during inflation of an automated blood pressure device
US9480433B2 (en) 2011-03-21 2016-11-01 Welch Allyn, Inc. Cuff integrity detection during inflation of an automated blood pressure device
WO2015041925A1 (en) * 2013-09-23 2015-03-26 Koven Technology Semi-automatic sphygmomanometer system
US20160331245A1 (en) * 2013-09-23 2016-11-17 Koven Technology Semi-automatic sphygmomanometer system

Also Published As

Publication number Publication date
CA1020768A (en) 1977-11-15
GB1460412A (en) 1977-01-06
FR2262507A1 (enrdf_load_stackoverflow) 1975-09-26
JPS50119486A (enrdf_load_stackoverflow) 1975-09-18
FR2262507B1 (enrdf_load_stackoverflow) 1978-10-27
DE2506652A1 (de) 1975-09-04

Similar Documents

Publication Publication Date Title
US3905353A (en) Blood pressure apparatus
US4116230A (en) Blood pressure cuff automatic deflation device
US2753863A (en) Sphygmomanometers
US5052397A (en) Oscillometric blood pressure monitor employing non-uniform pressure decrementing steps
US4459991A (en) Blood pressure measuring equipment
US4627440A (en) Sphygmomanometric cuff pressurizing system
US4326536A (en) Sphygmomanometer
US3319623A (en) Blood pressure monitors
Yamakoshi et al. Indirect measurement of instantaneous arterial blood pressure in the rat
EP0407463A1 (en) Circulatory assist method and apparatus
EP3681387B1 (en) Inflation apparatus for an inflation-based non-invasive blood pressure monitor and a method of operating the same
JPS62500220A (ja) 較正された動脈血圧測定装置
JPS5841529A (ja) 血圧測定装置
US4567899A (en) Cuff pressure controller for blood pressure measurement apparatus
GB1466620A (en) Method and apparatus for controlling the pressure variation of a respirator
US3906939A (en) Blood pressure measuring means
US5022403A (en) Automatic blood pressure measuring device and method with cuff size determination
US3143111A (en) Blood pressure follower
US4458690A (en) Blood pressure monitor
US5201320A (en) Blood pressure measuring device
EP0322711B1 (en) Blood pressure measuring device
EP0208520A2 (en) Oscillometric blood pressure monitor employing non uniform pressure decrementing steps
US2624334A (en) Blood pressure taking device
EP0537715B1 (en) Automatic cuff for blood pressure measurement
US3533401A (en) Apparatus for automatically measuring blood pressure