Positive end-expiratory pressure attenuates positional effect after thoracotomy

CONTEXT: Thoracotomy is a common procedure. However, thoracotomy leads to lung atelectasis and deteriorates pulmonary gas exchange in operated side. Therefore, different positions with operated side lowermost or uppermost may lead to different gas exchange after thoracotomy. Besides, PEEP (positive end-expiratory pressure) influence lung atelectasis and should influence gas exchange. AIMS: The purpose of this study was to determine the physiological changes in different positions after thoracotomy. In addition, we also studied the influence of PEEP to positional effects after thoracotomy. MATERIALS AND METHODS: There were eight pigs in each group. Group I received left thoracotomy with zero end-expiratory pressure (ZEEP), and group II with PEEP; group III received right thoracotomy with ZEEP and group IV with PEEP. We changed positions to supine, LLD (left lateral decubitus) and RLD (right lateral decubitus) in random order after thoracotomy. RESULTS: PaO(2) was decreased after thoracotomy and higher in RLD after left thoracotomy and in LLD after right thoracotomy. PaO(2) in groups II and IV was higher than in groups I and III if with the same position. In group I and III, PaCO(2) was increased after thoracotomy and was higher in LLD after left thoracotomy and in RLD after right thoracotomy. In groups II and IV, there were no PaCO(2) changes in different positions after thoracotomy. Lung compliance (C(rs)) was decreased after thoracotomy in groups I and III and highest in RLD after left thoracotomy and in LLD after right thoracotomy. In groups II and IV, there were no changes in C(rs) regardless of the different positions. CONCLUSION: There were significant changes with regards to pulmonary gas exchange, hemodynamics and C(rs) after thoracotomy. The best position was non-operated lung lowermost Applying PEEP attenuates the positional effects.