Kaneyuki T, Hogan J F, Glenn W W, Holcomb W G
J Thorac Cardiovasc Surg. 1977 Jul;74(1):109-15.
To evaluate the effectiveness of the configuration of the stimulating waveform on diaphragm pacing, we evaluated several different current forms: UDC-bipolar, UDC-monopolar cathodal, UDC-monopolar anodal, and ABDC. During stimulation with a pulse interval of 37 msec., a decrease in tidal volume was observed during the initial 30 hours with UDC-bipolar and UDC-monopolar anodal waveforms. Both UDC-monopolar cathodal and ABDC stimulation maintained the initial effectiveness for 6 hours. The decrease in tidal volume of UDC-monopolar anodal closely paralleled that of UDC-bipolar stimulation. Decreasing the pulse interval to 20 msec. caused a decrease in tidal volume with both UDC-monopolar cathodal and ABDC waveforms. Arterial oxygen tension (PaO2) in these experiments decreased to about 60 mm. Hg soon after the onset of unilateral diaphragm pacing. The concomitant decrease in tidal volume seen with UDC-bipolar stimulation could be avoided through the administration of oxygen to keep the animal's PaO2 about 100 mm. Hg. The amplitude of the evoked diaphragmatic action potentials decreased significantly under hypoxemia and returned to normal with hyperoxygenation. From these short-term experiments, our findings indicate that waveform configuration does influence the time of onset of diaphragm fatigue due to either an neuromuscular junction. Further, hypoxemia accelerates the occurrence of fatigue.
为评估刺激波形配置对膈神经起搏的有效性，我们评估了几种不同的电流形式：UDC双极、UDC单极阴极、UDC单极阳极和ABDC。在脉冲间期为37毫秒的刺激过程中，使用UDC双极和UDC单极阳极波形时，在最初30小时内观察到潮气量下降。UDC单极阴极和ABDC刺激在6小时内维持了初始有效性。UDC单极阳极的潮气量下降与UDC双极刺激密切平行。将脉冲间期缩短至20毫秒会导致UDC单极阴极和ABDC波形的潮气量下降。在这些实验中，单侧膈神经起搏开始后不久，动脉血氧分压（PaO2）降至约60毫米汞柱。通过给予氧气使动物的PaO2保持在约100毫米汞柱，可以避免UDC双极刺激时伴随出现的潮气量下降。在低氧血症状态下，诱发的膈肌动作电位幅度显著降低，而在高氧状态下恢复正常。从这些短期实验中，我们的研究结果表明，波形配置确实会影响由于神经肌肉接头导致的膈肌疲劳的起始时间。此外，低氧血症会加速疲劳的发生。
