Effects of chest wall compressions in kittens.

Effects of chest compressions on the pattern of breathing were studied in pentobarbital anaesthetized 9- to 11-day-old kittens before and after vagotomy. The chest was compressed by means of a micrometer at three levels (T1-4, T6-8, T9-11). In intact and vagotomized kittens, the group mean values of inspiratory time (tI), expiratory (tE) time, peak amplitude of the integrated phrenic activity (PHR) and its rate of rise (PHR/tI) during compressions were not different from those of the control breaths. On the other hand, in intact kittens during chest compressions variability of all the measured variables significantly increased. In the vagotomized kittens, variability of parameters other than inspiratory time was unaffected. Nevertheless we cannot exclude contribution of extravagal receptors in control of tE. The tE effects could be masked by the increased variability of the control value in vagotomized kittens. The effects of chest compression on the integrated phrenic activity were mostly dependent on the intact vagal feedback.