GB1384306A - Automatic recording sphygmomanometer - Google Patents

Abstract

1384306 Sphygmomanometers M HURWITZ 16 May 1972 [2 Sept 1971] 22960/72 Heading ASK [Also in Division F2] A sphygnomanometer comprises an inflatable cuff 25 carrying a microphone 29 to detect Korotkoff sounds, an electronic circuit 123 which emits a digital output pulse for each Korotkoff sound pulse detected, a marker 54 responsive to said output pulses to record a single respective mark on a stationary recording medium 78 for each Korotkoff sound pulse, means for moving the marker so that its position relative to the recording medium is determined by the cuff pressure means 125 for indicating when the cuff has been inflated adequately to include the artery under cuff 25, a valve 84 operable in a closed mode during cuff-inflation, in a slow-leak mode to allow slow venting of the cuff during blood-pressure measurement, and in a quick-vent mode for releasing the cuff pressure after measurement, and a three-position switch 117, which may be operated by a lever 118 in synchronism with the valve 84, the switch 117 having a first position allowing Operation of signalling means 125 and preventing operation of the pulse recorder, a second position in which means 125 is cut off and the recorder is operational, and a third position in which all electrical parts of the apparatus are de-energised. Pressure in cuff 25 is transmitted to a bellows-assembly 38 operative to rotate a Shaft 46 carrying an arm 52 with a solenoid 53 having a plunger 54. Signals from microphone 29 are amplified and filtered by circuit 123 which includes a noise discriminator and gives output pulses which excite solenoid 53 to cause plunger 54 to produce dots on pressure-sensitive paper 78. An ink pen or a light and photosensitive paper may be alternatively used, and the marker may alternatively be moved rectilinearly. The positions of the first and last dots in a measurement correspond to the systolic and diastolic blood-pressures which may be read off on a scale around the periphery of a window 80. During cuff-inflation the arm 52 rotates until a pin 56 contacts an arm 72 of a disc 68, thereby completing a circuit to light a lamp 125 indicating that the cuff is adequately inflated, whereupon the operator moves lever 118 from an "inflate" to a "record" position. The pressure at which lamp 125 is energised is adjustable by rotating disc 68, this pressure being indicated through a window 81 by marks on the disc.