RESUMO
BACKGROUND: Electrical breathing pacing has many advantages over mechanical ventilation. However, clinically permanent diaphragmatic pacing has been applied to limited patients and few temporary pacing has been reported. Our purpose is to investigate the feasibility of temporary electrical diaphragm pacing in explothoracotomy canine cases. METHODS: Five dogs were studied under the general anesthesia. Left 5th intercostal space was opened. Self designed temporary pacing leads were placed around the left phrenic nerve and connected to the myostimulator. Chest wall was closed after tube insertion with underwater drainage. Millar catheter was introduced to the aorta and right atrium. Swan-Ganz catheter was introduced to the pulmonary artery. When the self respiration was shallow with deep anesthesia, hemodynamic and tidal volume were measured with the stimulator on. RESULTS: Tidal volume increased from 143.3 +/- 51.3 ml to 272.3 +/- 87.4 ml(p=0.004). Right atrial diastolic pressure decreased from 0.7 +/- 4.0 mmHg to -10.5 +/- 4.7 mmHg(p=0.005). Pulmonary arterial diastolic pressure decreased from 6.1 +/- 2.5 mmHg to 1.2 +/- 4.8 mmHg(p<0.001). The height of water level in chest tube to show intrathoracic pressure change was from 10.3 +/- 6.7cmH2O to 20.0 +/- 5.3 cmH2O. CONCLUSION: Temporary electrical diaphragmatic pacing is a simple method to assist respiration in explothoracotomy canine cases. Self designed pacing lead is implantable and removable. Negative pressure ventilation has favorable effects on the circulatory system. Therefore, clinical application of temporary breathing pacing is feasible in thoracotomy patients to assist cardiorespiratory function.