GB978074A - Automatically operating sphygmomanometer - Google Patents

Abstract

978,074. Sphygmomanometers. SIEMENS REINIGER WERKE A.G. April 30, 1963 [May 5, 1962 (2)], No. 17035/63. Heading A5K. An automatic sphygmomanometer, employing a pick-up for receiving pulse sounds during a measurement, has an amplifier which has a two-position control for increasing the gain from one valve, during setting up the equipment, to a second valve, for carrying out the actual measurements and / or means for automatically increasing the gain in a fixed ratio when changing over from diastolic to systolic measurement. The equipment comprises a control unit 11 which, at appropriate intervals, inflates a cuff 2 by means of a pump 20, records the diastolic pressure on a gauge 28, further increases the pressure above systolic and subsequently decreases the pressure slowly until the systolic pressure is recorded on a second gauge 29. Pulse sounds are detected by a microphone 3, the output from which passes through amplifier stages 4, 6 to a pulsing circuit 8 for controlling the unit 11. Since, under certain conditions of the patient, the initial pulse sounds at the diastolic and systolic pressures may be very faint, the equipment is set up with a control switch 40 moved to the left, so that the amplification gain is approximately halved. The cuff pressure is then allowed to fall through the systolic pressure until pulse indications are received and the pressure is dropped by a further 15 mm. Hg., at which point strong signals are obtained. The equipment is then adjusted as necessary, to give satisfactory recording, and, finally, before actual measurements are made, the switch 40 is returned to the position shown, where full gain of the amplifier is restored. It is also found that, in some eases, the pulse is much more difficult to detect at systolic pressure than at diastolic pressure. For this reason a switch 46, under control of the unit 11, is closed during diastolic measurement and opened during systolic measurement, thereby giving a predetermined greater gain during the latter. Specification 792,875 is referred to.