BACKGROUND
The effects of perioperative low-dose ketamine in caesarean section are not well understood.
OBJECTIVE
To evaluate the clinical effects of various subanesthetic doses and regimens of intravenous ketamine in early postoperative period after caesarean section.
MATERIAL AND METHODS
Searching in the PubMed, MEDLINE, EMBASE and Cochrane Central Register of Controlled Trials (CENTRAL) databases was performed until December 31, 2019. Heterogeneity of samples was assessed using chi-square test. I2 index was used to assess heterogeneity. Both fixed-effect model and random-effect model were applied to assess the cumulative effect. Continuous results are presented as weighted differences between the means of two groups with 95% confidence intervals (95% CI). Differences in dichotomous variables are represented as relative risk (RR) and 95% CI.
RESULTS
A total of 11 randomized controlled trials with 1243 patients were included. In 120-240 min after surgery, difference in mean pain intensity was 2.43 scores, mean level was lower in the ketamine group [–3.69; –1.18]. After 6-8 hours, mean pain intensity was 1.4 scores lower in the ketamine group [–1.71; –1.10] compared to the control group. After 12 hours, analgesic effect of low-dose ketamine was not confirmed, difference in mean pain intensity was 0.60 [–1.40; 0.21]. Low-doses ketamine reduced the risk of postoperative pruritus by 30-40% (RR 0.64, 95% CI 0.41-0.97), did not affect the incidence of nausea/vomiting (RR 1.0, 95% CI 0.76-1.31) and severity of newborn asphyxia (RR 0.01, 95% CI –0.04-0.06].
CONCLUSION
Low-dose ketamine reduces pain syndrome within 6 hours after caesarean section. Further research is needed to confirm the efficacy and safety of ketamine as a component of multimodal analgesia after abdominal delivery.