Artificial respiration in the anesthetized horse using bilateral, percutaneous, cervical phrenic-nerve stimulation...

In this preliminary study, artificial respiration was produced in four anesthetized horses using trains of stimuli applied to long needle electrodes inserted bilaterally at the base of the neck. The needles were insulated to within 1 cm of the tips. The frequency of the stimuli (0.1 msec) was 35/sec and the train duration (duration of inspiration) was 1 sec. Inspired volume increased with increasing stimulus intensity. In two animals, inspired volumes of 6 liters were achieved. In another animal 4.5 liters was achieved and in another, 2.5 liters. This lower value probably represented less-than-optimal electrode placement. Artificial percutaneous electrophrenic respiration was maintained for half an hour in every animal using a minute volume equivalent to that when breathing spontaneously.