Effect Of Low-dose Ketamine On Brain Injury In Patients Undergoing Open-heart Surgery With Cardiopulmonary Bypass

Objective To investigate if low-dose ketamine can alleviate brain injury in patients undergoing open-heart surgery with cardiopulmonary bypass (CPB) and explore its possible mechanisms.Methods Forty patients undergoing selective open-heart surgery with cardiopulmonary bypass were randomly divided into two groups:ketamine group (n=20) and control group (n=20).In the ketamine group patients received ketamine(0.5 mg/kg) intravenous injection after induction of anesthesia, in the control group the patients received equal volume of normal saline instesd of ketamine. Blood samples were taken from internal jungular vein before anesthesia(T1),before CPB,(T2)at 30 minutes after CPB(T3),at the end of CPB(T4),4 hours(T5) and 24 hours (T6)after the end of CPB. Serum S100βprotein was determined by ELLSA method, and TNF-a and IL-6 was assayed by radioimmunassay. The mini-mental state examination (MMSE) scores the day before surgery and 3 days after surgery were recorded to evaluate the brain function.Results1. The plasma level of S100βsignificantly increased form T3to T5, as compared with the baseline value at T1 in the both group;S100βprotein levels in the ketamine group were significantly lower than those in the control group from T3 to T5(P<0.05).2. The plasma levels of TNF-a and IL-6 significantly increased from T3 to T6, as compared with the baseline value at T1 in the both groups, and TNF-a and IL-6 in the ketamine group were significantly lower than those in the control group from T3 to T5(P<0.05).3. MMSE scores in the ketamine group were higer than those in the control group,and the incidence of cognitive decline was lower than that in the control group.ConclusionLow-dose ketamine can alleviate brain injury in patients undergoing open-heart surgery with CPB,and its suppression to inflamatory reaction afer CPB may be its partial mechanism.