Abstract:

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: the ketamine group (n=20) and the control group (n=20).　In the ketamine group patients received ketamine(0.5mg/kg) intravenous injection after induction of anesthesia；In the control group patients received an equal volume of normal saline instead of ketamine. Blood samples were taken from the internal jugular vein before anesthesia(T1),　before CPB(T2), 30 minutes after CPB(T3),　at the end of CPB(T4), 4 hours(T5) and 24 hours (T6)-after the end of CPB. Serum S100β protein was determined by the ELLSA method, and TNF-α and IL-6 were assayed by radioimmunoassay. The mini-mental state examination (MMSE) scores on the day before surgery and 3 days after surgery were recorded to evaluate  brain function. Results   The plasma level of S100β significantly increased from T3 to T5,  as compared with the baseline value at T1 in both groups; S100β protein levels in the ketamine group were significantly lower than those in the control group from T3 to T5 (P<0.05). The plasma levels of TNF-α and IL-6 significantly increased from T3 to T6, as compared with the baseline value at T1 in both groups,  and TNF-α and IL-6 in the ketamine group were significantlylower than those in the control group from T3 to T5(P<0.05). MMSE scores in the ketamine group were higher than those in the control group, and the incidence of cognitive decline was lower than that in the control group. Conclusion   Low-dose ketamine can alleviate brain injury in patients undergoing openheart surgery with CPB, and its suppression of inflammatory reaction after CPB may be its partial mechanism.

Key words: Ketamine; Cardiopulmonary bypass; Brain injury