Diaphragm pacing. Evaluation of current waveforms for effective ventilation
Kaneyuki, T.; Hogan, J.F.; Glenn, W.W.; Holcomb, W.G.
Journal of Thoracic and Cardiovascular Surgery 74(1): 109-115
1977
ISSN/ISBN: 0022-5223 PMID: 875425 Document Number: 119914
To evaluate the effectiveness of the configuration of the stimulating waveform on diaphragm pacing, several different current forms were evaluated in dogs: UDC. During stimulation with a pulse interval of 37 ms, a decrease in tidal volume was observed during the initial 3 h with UDC-bipolar and UDC-monopolar anodal waveforms. UDC-monopolar cathodal and ABDC stimulation maintained initial effectiveness for 6 h. The decrease in tidal volume of UDC-monopolar anodal closely paralleled that of UDC-bipolar stimulation. Decreasing the pulse interval to 20 ms caused a decrease in tidal volume with UDC-monopolar cathodal and ABDC waveforms. Arterial O2 tension (PaO2 decreased to about 60 mm Hg soon after onset of unilateral diaphragm pacing. The concomitant decrease in tidal volume seen with UDC-bipolar stimulation could be avoided through administration of O2 to keep the animal's PaO2 about 100 mm Hg. The amplitude of evoked diaphragmatic action potentials decreased significantly under hypoxemia and returned to normal with hyperoxygenation. Waveform configuration apparently influenced time of onset of diaphragm fatigue due to an electrochemical disturbance at the electrode-nerve interface or exhaustion of acetylcholine in the neuromuscular junction. Hypoxemia accelerated occurrence of fatigue.