Effect of isoflurane preconditioning on brain injury in patients undergoing cardiac valve replacement under cardiopulmonary bypass

Abstract

Objective To evaluate the effect of isoflurane preconditioning on brain injury in patients undergoing cardiac valve replacement with cardiopulmonary bypass(CPB). Methods Forty patients of both sexes, aged 35-55 yr, with body mass index of 18-25 kg/m2, of American Society of Anesthesiologists physical status Ⅱor Ⅲ(New York Heart Association class Ⅱor Ⅲ), scheduled for elective cardiac valve replacement with CPB, were divided into 2 groups(n=20 each)using a random number table: control group(group C)and isoflurane preconditioning group(group P). After induction of anesthesia, 1.5% isoflurane was inhaled for 30 min followed by 15-min washout, and the end-tidal isoflurane concentration was less than 0.1% at the end of washout in group P. Immediately after internal jugular vein puncture(T1), immediately before beginning of CPB(T2), at 30 min after beginning of CPB(T3), immediately after the end of CPB(T4)and at 6 h and 1 day after the end of CPB(T5, 6), blood samples were collected for determination of serum S100β protein concentrations(by enzyme-linked immunosorbent assay)and the concentration of glutamic acid in serum(by ion exchange chromatography). Mini-Mental State Examination scores were recorded at 1 day before operation and 7 days after operation, and the occurrence of postoperative cognitive dysfunction was recorded. Results The serum concentrations of S100β protein and glutamic acid in the two groups are significantly higher at T3-5 than at T1(P<0.05). Compared with group C, the concentration of S100β protein in serum was significantly decreased at T3-5, and serum glutamic acid concentration was decreased at T4, 5 in group P(P<0.05). No postoperative cognitive dysfunction was found in the two groups. Conclusion Isoflurane preconditioning can reduce brain injury in patients undergoing cardiac valve replacement under CPB, and the mechanism may be related to inhibiting glutamic acid release. Key words: Isoflurane; Ischemic preconditioning; Cardiopulmonary bypass; Brain injuries