[Effects of small-dose lidocaine combined with ketamine on early postoperative cognitive function in elderly patients undergoing gastrointestinal tumor surgery].

OBJECTIVE: To observe the effects of anesthetic intervention with small-dose lidocaine and ketamine on early postoperative cognitive function in elderly patients undergoing surgeries for gastrointestinal tumors.

METHODS: Sixty patients (ASA I-III, aged 63-82 years) scheduled for surgeries for gastrointestinal tumors were randomized into intervention group (n=30) and control group (n=30). After intravenous induction and tracheal intubation, the patients in the interventional group received intravenous infusion of 0.5 mg/kg lidocaine and 0.5 mg/kg ketamine, followed by continuous infusion of lidocaine at the rate of 0.5 mg·kg(-1)·h(-1) till the end of the operation; the patients in the control group received saline infusion only. The cognitive function of the patients was assessed at 3 day before and 2 day after the operation using comprehensive neuro-psychological tests. Peripheral venous blood was extracted before anesthesia induction (T0), at the end of the surgery (T1), and at 1 day (T2) and 2 days (T3) after the operation for measurement of serum S-100β protein, NSE and IL-6 levels using ELISA.

RESULTS: The difference between the test scores before and after the operation (X values) was significantly smaller in the intervention group than in the control group (P<0.05). The intervention group showed a significantly lower incidence rate of postoperative cognitive dysfunction (POCD) than the control group (6.7% vs 33.3%, P<0.05). Compared with the control group, the intervention group exhibited significantly lower serum levels of S-100β protein, NSE and IL-6 at T1 (P<0.05), significantly lower NSE and IL-6 levels at T2 (P<0.05) time point, and significantly lower IL-6 level at T3 (P<0.05).

CONCLUSION: Intravenous injection of small-dose lidocaine and ketamine during the operation can reduce the incidence of POCD in elderly patients undergoing surgeries for gastrointestinal tumors possibly in relation to decreased serum S-100β, NSE and IL-6 levels.