Thoracoscopic electrode implantation for diaphragm pacing in dogs

Background: Diaphragm pacing is an attractive method of ventilatory support; however, it requires electrode implantation to the phrenic nerve or diaphragm. The thoracic approach is favored for several reasons, and it usually accompanies invasive bilateral thoracotomy. Objectives: This study was conducted to develop a new electrode suitable for video-assisted thoracoscopic implantation, which is less invasive than the conventional thoracic approach. Methods: The feasibility of video-assisted thoracoscopic implantation was tested with newly designed electrodes using 5 mongrel dogs. Furthermore, diaphragm pacing was performed for 60 min to test whether or not the implanted electrodes were functional. Results: Video-assisted electrode implantation was successful in all 5 cases. No complications occurred during the implantation procedure. In acute-phase pacing trials, the electrodes stimulated the phrenic nerves for 60 min without any pacing failures. The mean value of PaCO2 increased gradually from 32.2 +/- (SEM) 1.52 to 54.6 +/- 4.58 mm Hg, and the value of tidal volume decreased gradually from 242.9 +/- 31.3 to 147.5 +/- 24.5 ml in 60 ruin pacing. Conclusions: The thoracoscopic implantation of new electrodes was less invasive, and was a safe procedure for diaphragm pacing. Meticulous care should be taken to avoid muscle fatigue. Copyright (C) 2002 S. Karger AG, Basel.