Effects of sevoflurane postconditioning on lung function after cardiopulmonary bypass in patients undergoing cardiac valve replacement

Objective To evaluate the effects of sevoflurane postconditioning on lung function after cardiopulmonary bypass (CPB) in patients undergoing cardiac valve replacement.Methods Thirty ASA physical status Ⅱ or Ⅲ patients,aged 33-64 yr,weighing 47-81kg,scheduled for cardiac valve replacement with CPB,were equally and randomly divided into control group (group C) or sevoflurane postconditioning group (group S).Anesthesia was induced with iv injection of midazolam,etomidate,fentanyl and rocuronium.The patients were endotracheally intubated and mechanically ventilated.Anesthesia was maintained with intermittent iv boluses of midazolam,fentanyl and pipecuronium.In group S,2％ sevoflurane was washed into the membrane oxygenator at 2 min before aortic unclamping and continuously washed into the membrane oxygenator for 15 min after aortic unclamping.Before anesthesia (T1),immediately after sternum splitting (T2),at 30 min after termination of CPB (T3),and at 6,12 and 24h after operation (T4-6),blood samples were taken from the radial artery for blood gas analysis and PaO2 and SaO2 were recorded.Oxygen index (OI),alveolar-arterial oxygen tension difference (DA-aO2),dynamic pulmonary compliance (Cdyn) and static pulmonary compliance (Cstat) were calculated.Arterial blood samples were collected at T1,T3,T4 and T6 for determination of serum concentrations of IL-17A,neutrophil elastase (NE) and matrix metalloproteinase-9 (MMP-9).The time of mechanical ventilation after surgery and development of dyspnea,re-intubation and pulmonary rales were recorded.Results Compared with group C,OI at T4T6,PaO2 at T4 and T5,SaO2 at T3 and T6,Cdyn at T3 and T4 and Cstat at T4 were significantly increased,DAaO2 at T5 and T6,serum concentrations of IL-17A,NE and MMP-9 at T3,T4 and T6,and the incidence of pulmonary rales were decreased,and the time of mechanical ventilation was shortened (P ＜ 0.05),and no significant change was found in the incidence of dyspnea in group S (P ＞ 0.05).No re-intubation was required in the two groups.Conclusion Sevoflurane postconditioning can improve the lung function after CPB in patients undergoing cardiac valve replacement and inhibition of inflammatory responses may be involved in the mechanism. Key words: Anesthetics, inhalation;  Respiratory function tests;  Cardiopulmonary bypass;  Heart valve prosthesis implantation