Effects of positive end-expiratory pressure on the oxygenation and shunt fraction during ventilation with solitary lung

Objective To explore the effects of positive end-expiratory pressure (PEEP) on the oxygenation and shunt fraction during ventilation with solitary lung in open thoracic surgery. Methods Sixty patients (42 males and 18 females, aged 38-72 years, American Society of Anesthesiologist classification Ⅰ-Ⅱ) received lung lobectomy from Jun. to Aug. 2010 were randomly divided into 2 groups (n=30). The patients in group A received solitary lung intermittent positive pressure ventilation (IPPV), and those in group B received solitary lung IPPV combined with PEEP (5cmH2O). The arterial blood gas analysis, pulmonary artery pressure (PAP), mean arterial pressure (MAP), heart rate (HR), arterial partial pressure of oxygen (PaO2) and mixed venous oxygen saturation (SvO2) were monitored and recorded in both groups at the following time points: horizontal position two-lung ventilation (T1), lateral position two-lung ventilation 10 minutes (T2), solitary lung ventilation 10 minutes (T3) and solitary lung ventilation 30 minutes (T4), and the pulmonary shunt fraction (Qs/Qt) was calculated. Results In group A, the PaO2 was obviously lower at T3 and T4 than at T1 (P