ABSTRACT
Objective: To investigate the effect of epidural anesthesia combined with inhalation or intravenous anesthesia on intrapulmonary shunt and oxygenation in patients undergoing long term single lung ventilation
Methods: Eighty patients, aged 35-75, American Society of Anesthesiology [ASA] classification of I-III, undergoing thoracic surgery with one lung ventilation more than three hour, were randomly divided into propofol group [group Pro], propofol combined with epidural anesthesia group [group Pro+Epi], isoflurane group [group Iso] and isoflurane combined with epidural anesthesia group [group Iso+ Epi], 20 patients in each group. Arterial blood and mixed venous blood were taken for blood gas analysis, and hemodynamic data were recorded at following time points: before induction in supine position [T1], 30min after bilateral lung ventilation [T2], 15min after one lung ventilation [T3], 30min after one lung ventilation [T4], 60min after one lung ventilation [T5], 180min after one lung ventilation [T6], intrapulmonary shunt [Qs/Qt] was calculated according to the correlation formula
Results: Qs/Qt values at T2-6 in four groups were significantly higher than that of T1, and Qs/Qt values at T3-6 was significantly higher than that of T2 [P< 0.05]; PaO2 at T2-6 were significantly higher than that of T1, with PaO2 at T3-6 were significantly lower than T2 [P< 0.05]. Between groups, Qs/Qt values in group Iso were significantly higher than that of group Pro, Pro+Epi and Iso+Epi at T3-5 [P< 0.05]. There was no significant difference in PaO2 between groups [P> 0.05]. CI at T3-6 in group Iso and Iso+Epi were significantly higher than that of T1 [P<0.05], and were significantly higher than that of propofol group [P<0.05]. MAP at T3-6 in group Pro+Epi and Iso+Epi were significantly lower than that at T1 [P <0.05]. Heart rate at T4-6 in group Iso were significantly higher than T1, and higher than group Pro and group Iso+Epi [P <0.05]
Conclusion: One lung ventilation may predispose to increase of intrapulmonary shunt and decrease in arterial partial pressure of oxygen; isoflurane inhalation anesthesia is more likely to cause intrapulmonary shunt, but no changes in arterial partial pressure of oxygen