A review articled carried out by the Cochrane Database of Systematic Reviews titled “Perioperative intravenous ketamine for acute postoperative pain in adults” written by Brinck et al. in 2018 (no. 12, art. no. CD012033) explored the efficacy and safety of intravenous ketamine in adults for pain management while having surgery under general anesthesia. The authors sought randomized, double-blind, controlled trials for inclusion in their analysis. The main outcomes were opioid consumption and pain intensity at 24 and 48 hours after surgery.
The authors included 130 studies with 8,341 participants. Types of surgery included wisdom teeth extraction and among many others like lumbar fusion surgery, anterior cruciate ligament (ACL) repair, abdominal surgery, and elective caesarean section. The researchers found by looking at 65 of these studies that perioperative intravenous ketamine reduced postoperative opioid consumption over 24 hours by 8 mg morphine equivalents. They also found by looking at 37 studies that over 48 hours opioid consumption was 13 mg lower. The authors found that perioperative intravenous ketamine reduced pain at rest at both 24 hours and 48 hours by 5/100 mm on a visual analogue scale. Ketamine was also found to increase the time when the patient made the first postoperative analgesic request by 54 minutes. The researchers also determined that 5% of those who received ketamine and 4% of those who received a control treatment experienced a central nervous
system adverse event.
Based on the results the authors feel that perioperative intravenous ketamine likely reduces postoperative analgesic consumption and pain intensity. They believe there are little differences of adverse events between ketamine or a control. Furthmore, it was found that ketamine slightly reduced nausea and vomiting to 23% of patients versus 27% using a control. The authors feel that perioperative intravenous ketamine can be beneficial in reducing opioid consumption after surgery and in particular for thoracic surgery, major orthopaedic surgery and major abdominal surgery. Since the use of opioids after wisdom teeth extraction has been a topic of interest of late it appears ketamine may play a role in that surgery in helping to prevent those from developing an opioid dependency while also allowing for pain management in patients.
The authors did point out that some of the studies they explored suffered from a small number of participants which can lead to issues with the sample size in statistical analysis. Therefore, the authors suggested that in the future multicentered, randomized, controlled studies with more than 200 participants would help increase the confidence in the findings. The authors also pointed out that in the future it would be beneficial to point out reporting the number of people with high opioid consumption. They also suggest additional studies to explore using ketamine as an adjuvant to specific opioids and further exploration on the effect of ketamine for deffierent timing and dosing regimens on pain and opioid use.
The bottom line is the authors feel that pain management for surgery is important because without it additional postoperative complications can result along with chronic postsurgical pain. They also feel that opioids are the most effective drugs for the treatment of acute postoperative pain but they have several adverse events that accompany their use. Therefore using ketamine at the time of surgery can also allow for pain management and less opioid use after surgery.