Effects Of Propofol And Sevoflurane On Oxygenation During One-lung Ventilation In Patients Undergoing Thoracic Surgery

[Objective]One-lung ventilation(OLV),a non-physiological breathing mode,is widely used in various thoracic operations,can cause increase in intrapulmonary shunt and intraoperative hypoxemia.The effects of propofol and sevoflurane on oxygenation during one-lung ventilation are still inconclusive.This study was intended to investigate the effects of propofol and sevoflurane on oxygenation and intrapulmonary shunt during one-lung ventilation during OLV in patients subjected to thoracoscopic surgery.[Methods]Forty-eight patients scheduled for thoracoscopic surgery were randomly divided into two groups by computerized random number table method:propofol group(Group P)and sevoflurane group(Group S),(n=24 in each group).All patients were infused dexmedetomidine(lug/kg for 10 minutes),followed by maintenance dose(0.4ug/kg.h-1).The anesthesia was included with:etomidate(0.3-0.6mg/kg iv),fentanyl(3ug/kg iv),rocuronium(0.6-1 mg/kg iv),A double-lumen endotracheal tube(F35 or F37)was inserted orally after induction.Both groups were ventilated with Intermittent Positive Pressure Ventilation(IPPV)mode,tidal volume of 8-10ml/kg,ventilation frequency of 10-12 times/min,inspiration-expiration ratio of 1:2,oxygen flow of 2L/min.Peak airway pressure and pressure of end-tidal carbon dioxide were monitored.During one-lung ventilation,the patients were ventilation with tidal volume of 6-8 ml/kg,and respiratory rate of 12-14 breaths/min.Anesthesia was maintained by continuous infusion of propofol(4-8mg/kg.h-1)in group P,inhalation of 1%-3%sevoflurane in group S,and infusion of remifentanil(0.15-2ug/kg.min-1)in both groups.Intravenous fluid therapy consisted of compound electrolyte and succinyl gelatin.When blood pressure dropped by 20%of baseline,ephedrine administered.The infusion rates in group P and the concentrations of sevoflurane in group S were changed to maintain brain Bispectral index(BIS)with the range of 40-60.HR,MAP and SpO2 were recorded when the patient entered the operating room(TO),before one-lung ventilation(T1),one-lung ventilation for 30 minutes(T2),and one-lung ventilation for 1 hour(T3).The volume of fluid infusion,urine volume,blood loss and ephedrine consumption during one-lung ventilation for 1 hour were recorded.Blood was drawn from arterial and central venous lines respectively at T1-T3 for analysis of arterial and venous blood gases,and calculate of shunt fraction(QS/QT).[Result]The intraoperative ephedrine dosage in group S was significantly higher than that group P(P<0.05).pH value of the two groups at T3 were significantly lower than those at T1(P<0.05);pH value of group S at T3 was significantly lower than that at T2(P<0.05);pH value of group S at T3 was significantly lower than that of group P(P<0.05).PaO2 of the two groups at T2 and T3 were significantly lower than that at of T1(P<0.05);PaO2 of group S were significantly lower than those of group P at T2 and T3(P<0.05).PaCO2 of group S at T3 was significantly higher than that at T1(P<0.05);PaCO2 of group S were significantly higher than those of group P at T2 and T3(P<0.05).PAO2 of group S at T2 and T3 were significantly lower than those of group P(P<0.05).A-aDO2 at T2 and T3 were significantly higher than that at T1(P<0.05).A-aDO2 of group S was significantly higher than group P at T3(P<0.05).OI of the two groups of patients at T2 and T3 were significantly lower than that at T1(P<0.05);OI of group S was significantly lower than those of group P at T2 and T3(P<0.05).K+ in group S at T3 was significantly higher than that at T1(P<0.05).QS/QT of two groups at T2 and T3 were significantly higher than that at T1(P<0.05);QS/QT of group S was significantly higher than those of group P at T2 and T3(P<0.05).[Conclusions]Compared with propofol,sevoflurane increases shunt fraction and impairs oxygenation during one-lung ventilation in patients undergoing thoracic surgery,and propofol is more conducive to the stability of intraoperative hemodynamics during one-lung ventilation.