Use of one lung anesthesia for thoracic surgery may compromize PaO2. The aim of this study was to compare the shunt and oxygenation effects of the application of CPAP and CPAP/PEEP between right and left thoracic surgery under one lung anesthesia.

10 patients for right thoracic surgery were selected as group 1, and 10 patients for left thoracic surgery were selected as group 2. Measurements in each group, were made during each of the following stage. First 30 minutes, One lung anesthesia alone with 50% oxygen (control value), next 30 minutes, CPAP 10 cmH2O to upper lung with 50% oxygen (CPAP), and then CPAP 10 cmH2O to upper lung and PEEP 10 cmH2O to down lung with 50% oxygen for 30 minutes (CPAP/PEEP).

PaO2 in CPAP and CPAP/PEEP were significantly increased as compare to control value at both group (P<0.05). Shunt percentage in CPAP and CPAP/PEEP were significantly decreased as compare to control value at both group (P<0.05). But, no statistically significant differences were observed between right and left thoracic surgery group in the PaO2 and shunt percentage.

We confirmed that CPAP and CPAP/PEEP during one lung ventilation is thought to be effective method in preventing hypoxemia, but no differences were observed between right and left thoracic surgery group.