The effect of ketamine on acute and chronic wound pain in patients undergoing breast surgery: a meta-analysis and systematic review.
Perioperative use of ketamine has been discussed widely in many kinds of surgery. The aim of our study is to evaluate the short-term and long-term benefits and safety of ketamine after breast surgery.We performed a quantitative systematic review. Randomized controlled trials that compared intravenous administration of ketamine to a placebo control group or bupivacaine in combination with ketamine to bupivacaine alone in thoracic paravertebral block or pectoral block for patients undergoing breast surgery and took the pain or morphine consumption as a primary or secondary outcome were included. The primary outcome was postoperative pain intensity. Secondary outcomes included cumulative opioid consumption during 0-24-hour postoperative period, the effect in postmastectomy pain syndrome, the effect in postoperative depression, and the adverse events associated with the use of ketamine.13 randomized controlled trials with 1182 patients were included for analysis. Compared with placebo, intravenous ketamine was effective to reduce the wound pain intensity during the first 6 hours after the surgery (WMD -0.83; 95%CI-1.65, -0.01; p=0.048) and during the first 24 hours after the surgery(WMD -0.65; 95%CI, -0.95, -0.35; p<0.001), and decrease the opioid consumption(WMD -4.14; 95%CI -8.00, -0.29; p=0.035) for the first 24 hours after the surgery, without increasing the risks of gastrointestinal and CNS adverse events. Adding ketamine to bupivacaine in thoracic paravertebral block was also effective to reduce the postoperative wound pain during the 6 hours after the surgery (WMD -0.59; 95%CI, -1.06, -0.12; p=0.014) and during the first 24 hours after the surgery(WMD -0.90; 95%CI, -1.27, -0.53, p<0.001), and decrease the opioid consumption(WMD -4.59; 95%CI -5.76, -3.42; p<0.001) for the first 24 hours after the surgery. Perioperative use of ketamine was associated with improved postoperative depression symptoms (SMD -0.80; 95%CI -1.34, -0.27; p=0.003) and less incidence of postmastectomy pain syndrome (RR 0.79; 95%CI 0.63,0.99; p=0.043).Ketamine is an effective and safe multimodal analgesic in patients undergoing breast surgery both intravenously and adding to bupivacaine in paravertebral block. Besides, ketamine showed long-term benefit for preventing postoperative depression and postmastectomy pain syndrome.