Development and Experimental Evaluation of Respiratory Assist Device by Use of Right Thoracic Negative Pressure Ventilation / 대한구급학회지

ABSTRACT

BACKGROUND: A diaphragm pacing with electrical stimulation is a new respiratory assist device which has advantages over mechanical ventilation. Unilateral phrenic nerve stimulation makes uneven distribution of intrathoracic negative pressure and most likely relates to paradoxical motion of the diaphragm. Our purpose is to investigate a respiratory effect of right phrenic nerve pacing after thoracotomy compared with bilateral pacing. METHODS: Five dogs were examined under the general anesthesia. Right 5th intercostal space was opened. Two pacing leads were placed around the phrenic nerve and connected to the stimulator. Chest wall was closed after chest tube insertion. Ventilator was off without self respiration. Swan-Ganz catheter was introduced to the pulmonary artery, cardiac output, central venous pressure (CVP), pulmonary capillary wedge pressure (PCWP). Arterial blood gases (PO2 & PCO2), end-tidal PCO2 (PETCO2) and tidal volume were measured with nerve stimulation. Left phrenic nerve was managed as the same manner. RESULTS: Right phrenic nerve pacing resulted in a tidal volume of 186+/-5 ml, PETCO2 of 55.0+/-2.3 mmHg, Arterial PO2 of 115+/-12 mmHg, PCO2 of 59+/-4 mmHg, Cardiac output of 2.3+/-0.5 L/min, CVP of 12.0+/-2.3 mmHg, PCWP of 14.2+/-2.5 mmHg. Bilateral phrenic nerve pacing resulted in a tidal volume of 418+/-3 ml, PETCO2 of 47.0+/-2.7 mmHg, PO2 of 289+/-10 mmHg, PCO2 of 42+/-3 mmHg, Cardiac output of 3.1+/-0.4 L/min, CVP of 10.2+/-2.5 mmHg, PCWP of 14.5+/-2.7 mmHg. Right phrenic nerve pacing showed significantly lower tidal volume, PO2 and higher PETCO2 and arterial blood PCO2 (p<0.05). CONCLUSIONS: Right phrenic nerve pacing plays a role to develop respiratory assist. However the effect is less than the bilateral pacing.