Rethinking Ketamine: The Effect of Postoperative Ketamine Infusions on Pain and Opioid Consumption Following Major Limb Amputation.

BACKGROUND

Poorly-controlled, acute postoperative pain (APOP) following major limb amputations (MLAs) is associated with increased opioid requirements and worse quality of life. Although there is robust data on ketamine use for APOP in orthopedic procedures, there is less information on ketamine use for APOP following MLA. This study evaluates the effect of postoperative ketamine on pain scores (PSs) and opioid consumption in patients who underwent MLA.

METHODS

A single-center, retrospective chart review of patients who underwent MLA between May 2022 and April 2025 was conducted. Patients were divided into 2 cohorts based upon receipt of postoperative ketamine infusions. Case matching for preoperative comorbidities and intraoperative pain regimen was performed. Preoperative, intraoperative, and postoperative oral morphine equivalent (OME) use was assessed until the fifth postoperative day. Pain scores were recorded daily.

RESULTS

Sixty patients were assessed. There was no significant difference in PS between groups from POD 0 to POD 5 (P = 0.334). Patients receiving ketamine had significantly higher OME use in the immediate postoperative period (P = 0.025) and POD 5 (P = 0.026). Case-matched analysis demonstrated no statistically significant differences in OME use, PS, or length of stay.

CONCLUSION

Postoperative ketamine infusions appear to not improve PS following amputation. Ketamine was associated with significantly higher opioid consumption immediately post-surgery and on POD 5 compared to the control group. This suggests ketamine may not confer an opioid-sparing benefit and highlights the need for further research into analgesic strategies for amputations.