GB1290537A - - Google Patents

Abstract

1290537 Electro-medical apparatus F HOFFMANN-LA ROCHE & Co AG 2 Oct 1969 [2 Oct 1968] 48382/69 Heading GiN In apparatus for detecting a respiratory distress condition, a signal representative of heart-beat activity is applied to a sensor 32 which produces a signal when the heart-beat falls below a predetermined frequency level, and a signal representative of respiratory activity is applied to a sensor 43 which produces a signal when a respiratory arrest exceeds a predetermined time interval, an AND gate 33 being responsive to coincidence of the signals from the sensors to actuate an alarm 18. As shown, a heart-beat signal is applied, via a transducer, to electrodes 21, amplifier 25, filter 26 and pulse-shaper 27 to produce identical pulses at a frequency corresponding to the heart-beat frequency, Fig. 3c (not shown). This pulse signal is integrated at 28, over a pre-selected period and the integrated signal, Fig. 3d (not shown), is applied to a meter 31, calibrated in beats per min., and to a level sensor 32 which produces an output pulse, Fig. 3e (not shown), when the integrated signal falls below a preset value, e.g. representative of 90 beats/min. A respiratory signal is applied, via a transducer to electrodes 34 energized by a high frequency source 35 to produce a high frequency carrier amplitude-modulated signal, Fig.3f (not shown), which is applied to amplifier 36, high pass filter 37, demodulator 38, zero-crossing detector 39 and pulse shaper 41 to produce identical pulses at the breathing frequency. The pulses are applied to a multivibrator 43 which produces an output if breathing stops for a period exceeding a pre-set time. The pulses from 41 may also be applied to an integrator 47, similar to integrator 28, the integrated signal being applied to a meter 49 and a sensor 51 whose output, when breathing rate is below a pre-set minimum, is applied to a delay circuit 54 and whose output, when the breathing rate is above the pre-set minimum, is applied to reset the delay circuit. If the delay circuit is not reset within a period set by the delay circuit, the alarm 18 is actuated via OR gate 45.