Synchronization of Respiratory Rhythm with Electrical Stimulation of the Phrenic Nerve

A single stimulation is applied at the desired time during a breathing cycle. The interval (TR) between the onset of the stimulation and that of the subsequent inspiration varies with the time (ts) when the stimulation is applied. The relationship between ts and TR is piecewise linear. Further experiment shows that this relationship holds for the case of a double stimulation as well. A theory of synchronization constructed on the basis of this relationship predicts the range of the stimulation period producing synchronization. Theoretical predictions are in agreement with the experimental results. Synchronization is of clinical importance, because ventilation cannot be fully performed if remaining spontaneous breathing is asynchronous with a respirator.