Efficiency and Safety of Intravenous Injected Ketamine for Postoperative Pain during Spinal Anaesthesia for Caesarean Section: A Meta-Analysis

Objective To systematically evaluate the efficacy and safety of Ketamine on postoperative pain and side effects after spinal anaesthesia for caesarean section. Methods A systematic literature search was conducted in the Cochrane Library, PubMed, Springer, EBSCO, CNKI and CBM databases from January 1^st, 1990 to March 17^th, 2018 to identify randomized controlled trials （RCTs） on intravenous Ketamine during spinal anaesthesia for caesarean section. All included RCTs were assessed and the data were extracted according to the standard of Cochrane systematic review. The homogenous studies were pooled using RevMan 5.3 software. Results 13 RCTs, in total of 1 435 patients, were included herein. The results indicated that compare to the control group, intravenous infusion of Ketamine significantly reduced the visual analog scale （VAS） scores after 2^nd MD=-1.26,95%CI （-1.88,-0.63）,P<0.000 1 and 12^th MD=-2.22,95%CI （-3.74,-0.70）,P=0.004 hours since the spinal anaesthesia for ceasrean section. But the VAS scores after 1^st MD=-3.21,95%CI （-9.27,2.84）,P=0.30 and 3^rd MD=-1.41,95%CI （-3.52,0.69）,P=0.19 hours showed no significant difference to control groups. Bolus injected Ketamine considerably decreased the cumulative dose of non-steroid anti-inflammatory drug Diclofenac in the first MD=-86.48,95%CI （-128.52,-44.43）,P < 0.000 1 and second 24 h MD=-12.23,95%CI （-22.80,-1.67）,P=0.02 postoperatively. Meanwhile, the first requirement of analgesic MD=59.68,95%CI （43.98,75.38）,P<0.000 01 was dramatically prolonged in the Ketamine-treated groups. Ketamine attenuated the morbidity of pruritus MD=0.55,95%CI （0.32,0.95）,P=0.03, shivering MD=0.07,95%CI （0.01,0.71）,P=0.02 and illusion MD=2.65,95%CI （1.23,5.69）,P=0.01, respectively. Nevertheless, the incidents of postoperative nausea MD=0.70,95%CI （0.49,1.01）,P=0.06, vomit MD=0.77,95%CI （0.54,1.11）,P=0.17 and headache MD=1.29,95%CI （0.27,6.14）,P=0.75 were similar to control groups. Conclusion The intravenous Ketamine during spinal anaesthesia for caesarean section can dramatically decrease the postoperative pain and side effects, which can extremely enhance the satisfactory of maternal patients.