Contains reports on two research projects.National Institutes of Health (Grant 5T1 HE 5550-02

Barnett, G. O.

Jackson, W. D.

Katona, P. G.

Lowell, F. C., Jr.

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XXII. CARDIOVASCULAR SYSTEM STUDIESProf. W. D. Jackson R. F. Lercari R. K. PollakDr. G. O. Barnett F. C. Lowell, Jr. D. H. PruslinP. G. Katona S. R. Maimon L. D. TurnerA. WORK COMPLETED1. BIOLOGICAL CONTROL SYSTEMSThe present phase of this work has been completed and the results have been pre-sented as theses to the Department of Electrical Engineering, M. I. T.W. H. Levison, Nonlinear Analysis of the Pressoreceptor Reflex System, Sc.D. Thesis,June 1964.D. H. Pruslin, Neural Patterns in Blood Pressure Regulation, S. M. Thesis,June 1964.W. D. Jackson, G. O. BarnettR. F. Lercari, Mathematical Relation between Baroreceptor Neural Activity andArterial Pressure, S. M. Thesis, June 1964.G. O. Barnett2. MEASUREMENT OF BLOOD FLOWThe present phase of this work has been completed and the results have been pre-sented as theses to the Department of Electrical Engineering, M. I. T.R. K. Pollak, A Catheter Tip Hot Wire Anemometer, N. E. thesis in Naval Archi-tecture and Marine Engineering and S. M. thesis in Electrical Engineering,June 1964.T. N. Charchut, The Calibration of a Magnetohydrodynamic Flowmeter, S. B. Thesis,June 1964.W. D. Jackson3. MEDICAL ENGINEERINGThe present phase of this work has been completed and the results have been pre-sented as theses to the Department of Electrical Engineering, M. I. T.R. J. Hinde, A Sensory Air in Communications for the Paraplegic, S. B. Thesis,June 1964.G. O. BarnettG. M. Sullivan, Pressure Regulator for Cardiovascular Research, S. B. Thesis,June 1964.G. O. BarnettThis work was supported in part by the National Institutes of Health (Grant5T1 HE 5550-02).QPR No. 74 273(XXII. CARDIOVASCULAR SYSTEM STUDIES)A. N. Pappalardo, Special Purpose Analog Computor for Processing of PatientMonitoring Data, S. B. Thesis, June 1964.G. O. BarnettD. J. Alusic, The Chronic Measurement of Nerve Impulses, S. B. Thesis, June 1964.P. G. Katona, G. O. BarnettD. E. Easterday, A Mathematical Model for the Heart Rate Regulation System,S.B. Thesis, June 1964.G. O. Barnett, P. G. KatonaG. A. Larson, Numerical Computation of the Impulse Response of the Cardiovas-cular System, S. B. Thesis, June 1964.G. O. Barnett, P. G. KatonaP. J. Stiffler, Design and Construction of a Frequency Modulated Pulse Generator,S.B. Thesis, June 1964.P. G. KatonaB. AN EXTERNALLY POWERED TRANSMITTER FOR TELEMETERINGINTRATHORACIC PRESSURE VARIATIONSAs part of a study of heaves in horses being conducted by Dr. Francis C. Lowell,Chief of the Allergy Unit at Massachusetts General Hospital, an FM pressure transducerfor telemetering pressure changes in the lung of a horse has been designed, constructedand calibrated. (See Fig. XXII-1.)CAPACITOR PLATEEMBEDDED INPOTTING POTTINGCOMPOUND COMPOUNDCIRCUITRY 1 CIRCUITRYSHED COAXIAL CABLEOUTPUT AMPLIFIER, POWER SUPPLYAIR VENTS AND OUTPUT TANK, POTTEDBELLOWSSCALE: APPROXIMATELY FULL SIZENOTE THE ENTIRE DEVICE WOULD BE SEALED IN At AIR TIGHT LOOSE FITTING PLASTIC BAGTO ALLOW PRESSURE VARIATION TO REACH THE BELLOWS, AND TO PREVENT LIQUIDSFROM SHORTING OUT THE CAPACITORFig. XXII-1. Over-all plan of the telemetering capsule.The general objectives in the design were the stability, accuracy, and radiatedpower requirements determined by preliminary experiments. The circuit is given inFigs. XXII-2 and XXII-3; it comprises a Hartley oscillator with a grounded-base tran-sistor and a specially designed variable-frequency crystal-controlled feedback circuit.The frequency-varying element is the capacitor C 2 , which takes the form of a metalQPR No. 74 274(XXII. CARDIOVASCULAR SYSTEM STUDIES)Cl2 L2 OAR2R R3R1LILl cR T2 TO AMPLIFIERC4T1L3 3 Z Z2OAR1  2.2 KQ C 1  15 pfd LI  14phy TI  MM 1151 (MOTOROLA)R2  2.2KO C 2  15 pfd VARIABLE L2  16 phy T2  2N708 (RCA)R3  100KO C 3 180 pfd L3  1.4phy Z1  3 VOLT ZENERC4 33 pfd Z2 6 VOLT ZENERFig. XXII-2. Oscillator and first-stage amplifier.2.2KQ C5  120 pfd L 2phy Z 3  12V ZENER100KO C6  .02mfd L6  .8mhy Z 4  14V ZENER1.5 K2 C7 1000 pfd T3  2 N 708 RCA3300 C8  1 pf 25V D 1 - D4  1N 464C9 100 pfFig. XXII-3. Output amplifier and power supply.bellows whose length is proportional either to internal or external pressure. The freeend of the bellows is near a plate and forms a capacitor with it.A typical pressure versus frequency curve is shown in Fig. XXII-4. The trans-mitter is powered by means of a 40-kc oscillator and coil, placed outside the animalbut as near as possible to a second coil inside the transmitter, which is tuned to thesame frequency. The induced AC voltage at the terminals of the second coil (L 6 ) isQPR No. 74 275(XXII. CARDIOVASCULAR SYSTEM STUDIES)in 80^^10,800,10,799,10,799,10,798,.,Fig. XXII-4. Frequency vs pressure curve.rectified, filtered, and regulated.The maximum distance between coils is approximately 4 inches. When surgicallyinstalled in the animal, the transmitter will have two sections, connected with coaxialcables. The first, containing the oscillator and first-stage amplifier, will be locatedat the point of pressure measurement. Connected to it will be the second section, nearthe skin of the animal, which will contain the output amplifier and the transmitter.The design pressure range is ±1 psi from atmospheric, although this is flexible,and may be adjusted over a wide range. The sensitivity is approximately 10 cps/cmH20, and the stability is ±5 cm H20 for one month, l but this has not yet been confirmedby direct measurement.F. C. Lowell, Jr.References1. R. Kent, private communication, 1964.QPR No. 74000500000500-70 -60 -50 -40 -30 -20 -10 0 10 20 30 40 50 60 70PRESSURE (Cm H2 0)276

Cardiovascular System Studies

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Cardiovascular System Studies

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