title: Positive end-expiratory pressure attenuates positional effect after thoracotomy.
abstract: BACKGROUND
  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.
  
  
  OBJECTIVE
  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.
  
  
  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
  PaO2 was decreased after thoracotomy and higher in RLD after left thoracotomy and in LLD after right thoracotomy. PaO2 in groups II and IV was higher than in groups I and III if with the same position. In group I and III, PaCO2 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 PaCO2 changes in different positions after thoracotomy. Lung compliance (Crs) 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 Crs regardless of the different positions.
  
  
  CONCLUSIONS
  There were significant changes with regards to pulmonary gas exchange, hemodynamics and Crs after thoracotomy. The best position was non-operated lung lowermost Applying PEEP attenuates the positional effects.
authors.affiliation: Division of Pulmonary Medicine, Department of Internal Medicine, Taipei Tzuchi Hospital, The Buddhist Tzuchi Medical Foundation, New Taipei City, Republic of China ; School of Medicine, Tzuchi University, Hualien, Republic of China.
authors.forename: Chou-Chin
authors.initials: CC
authors.lastname: Lan
authors.affiliation: Department of Radiology, Tri-Service General Hospital, Taipei, Republic of China.
authors.forename: Hsian-He
authors.initials: HH
authors.lastname: Hsu
authors.affiliation: Department of Critical Care Medicine, Li-Shin Hospital, Tao-Yuan County, Taipei, Republic of China.
authors.forename: Chin-Pyng
authors.initials: CP
authors.lastname: Wu
authors.affiliation: Department of Surgery, Division of Thoracic Surgery, Taipei, Republic of China.
authors.forename: Shih-Chun
authors.initials: SC
authors.lastname: Lee
authors.affiliation: Division of Pulmonary Medicine, Department of Internal Medicine, Tri-Service General Hospital, Taipei, Republic of China.
authors.forename: Chung-Kan
authors.initials: CK
authors.lastname: Peng
authors.affiliation: Department of Surgery, Division of Thoracic Surgery, Taipei, Republic of China ; Department and Graduate Institute of Physiology and Biophysics, National Defense Medical Center, Taipei, Taiwan, Republic of China.
authors.forename: Hung
authors.initials: H
authors.lastname: Chang
keywords: Positive end-expiratory pressure; position; pulmonary gas exchange; thoracotomy