GB1399717A - Apparatus for supervising the breathing of a subject - Google Patents

Abstract

1399717 Apparatus for monitoring and stimulating breathing SIEMENS AG 15 June 1972 [16 June 1971] 28174/72 Headings ASK and A5R Apparatus for supervising the breathing of a patient by means of electrodes 2, 3, comprises a supply-current generator 4 for supplying current to the electrode 3, a high frequency amplifier 5, a detection device 6-8 connected to the amplifier 5 and providing an output signal in dependence upon the patient's breathing, and a stimulating current generator 11 for supplying a pulse to the electrode 3. The detection device comprises a rectifier 6, a demodulation low-pass device 7, and a lowfrequency amplifier 8. A switch 13 is arranged to short-circuit the amplifier 5 in step with synchronising pulses of a pulse generator 12. The output from the detection device is connected to a measuring device 9 and an indicator 10, and to a monitoring device 16 arranged to supply a stimulation control signal if a respiratory interruption occurs. The control signal from the monitoring device and the pulses from the generator 12 pass to the inputs of an AND gate 15 which provides an output pulse to a counter 14 when the two input pulses co-incide. The output from the counter 14 is a triggering pulse to operate the stimulating current generator 11. A transistor switch 20 and a monostable flip-flop 21 prevent the monitoring device from responding to interference signals. A Schmitt trigger 22 generates a signal to the monitoring device if, for instance, an electrode becomes loosened. A further counter 19 can limit the number of pulses supplied by the generator 11 in any given sequence. A manually actualble arrangement may replace the monitoring device. The frequency of the synchronising pulses may be 50 Hz, each pulse having a duration of 10 m.sec. Adjusting devices 17, 18 associated with the monitoring device and the counter 14 respectively are used to adjust respectively the period of time which elapses between respiratory interruption and the emission of a signal to the AND gate, and the "interval for expectancy of success" i.e. the period after which a further stimulation pulse is emitted if respiration is not restored. A lamp 23 and an acoustic device 25 are used as alarms.