A device to trigger automatically electrical stimulation at different states of in- or expiration on the background of variable lung inflation in the rabbit

A device is described which permits to obtain a signal at the beginning of in- or expiration respectively. This signal may be used to trigger an electrical stimulator. To permit studies at different states of lung inflation the tracheal cannula is connected to a spirometer circuit. To produce constant positive or negative air pressure this bellows-type spirometer is loaded with exchangeable metal weights. The tracheal pressure is recorded by means of a pressure transducer, the output of which is taken as signal. The device allows accurate compensation of the DC-component of the transducer output resulting from spirometer operation at a maintained positive or negative pressure.