Abstract: Objective To investigate the effects of different doses of ketamine-assisted total intravenous anesthesia on
the early cognitive function and pain in patients undergoing segmental mastectomy. Methods A total of 120 patients
undergoing elective segmental mastectomy under total intravenous anesthesia were selected and randomly divided into four groups (n=30), including the control group (groupA) without ketamine and the observation group given ketamine at 0.5 mg/kg (group B), 1.0 mg/kg (group C) and 1.5 mg/kg (group D), respectively. The changes in mean arterial pressure (MAP) and heart rate (HR) of the four groups of patients were observed and recorded before anesthesia induction (t0), after laryngeal mask
placement (t1), 1 minute after skin incision (t2), and 25 minutes after skin incision (t3). The Visual Analogue Scale (VAS) was closely followed at 2 hours (T1), 6 hours (T2), 12 hours (T3) and 24 hours (T4) after surgery. The scoring methods of Mini Mental State Examination (MMSE) and Montreal Cognitive Assessment (MoCA) were used to evaluate the early postoperative cognitive dysfunction (POCD) 1 day (T0) before surgery, and 2 hours (T1), 6 hours (T2), 12 hours (T3) and 24 hours (T4) after surgery. Results The changes of MAP and HR in each time point during the operation were the smallest and stable in the group B (P＞0.05), and the different value of adjacent time point was the largest in group A (P＜0.05). The VAS scores of T1-T3 were lower in group B, C and D than those in group A (P＜0.05), and there was no significant difference between groups B, C and D (P＞0.05). There were no significant differences in MMSE and MoCA scores at T0 and T4 time points between the four groups (P＞0.05). T1 time point was significantly lower in group D＜group C＜group B ＜ group A (P＜0.05). T2 time point was group A ＞ group B ＞ group C and D (P＜0.05). The scores of T3 time points were significantly higher than those of T2 (P＜0.05). Conclusion Ketamine can reduce the early cognitive function in patients after segmental mastectomy with dose dependent manner, but no effect on the cognitive function 24 hours after operation. The low dose of ketamine has good analgesia effect and more stable vital signs during the operation.

Key words: ketamine, anesthesia, intravenous, analgesia, cognitive dysfunction, segmental mastectomy