Perioperative ketamine to reduce and prevent acute and chronic post-thoracotomy pain: a randomized, double-blind, placebo-controlled clinical trial.

BACKGROUND

Moderate to severe postoperative pain is common among patients following thoracotomy and serves as a risk factor for developing chronic post-thoracotomy pain (CPTP). This randomized controlled trial evaluated the effects of pre-emptively administered ketamine compared to placebo and standard care on both acute postoperative pain and CPTP.

METHODS

Two hundred patients were enrolled in this prospective, randomized trial. The presence and severity of pain were assessed before surgery, first 6 hours after surgery, on postoperative days (PODs) 1-8, 30, and 90. For documentation of neuropathic pain, the Leeds Assessment Score for Neuropathic Symptoms and Signs (LANSS) was used pre- and postoperatively. The incidence and severity of CPTP was assessed by a telephone survey, the self-assessment LANSS (S-LANSS) 30 and 90 days after surgery.

RESULTS

There was significant difference in numeric rating scale (NRS) pain scores when coughing in the first 6 hours after surgery, with less pain in the ketamine group. No difference was seen in NRS pain scores at rest and coughing between the ketamine and placebo group on PODs 1-8. There was no difference in the opioid consumption between the two groups. Thirty-four (18.7%) of the patients had a S-LANSS score ≥12 30 days following surgery, 12 (12.8%) in the ketamine group 22 (25%) in the placebo group (P=0.001). Thirty-three (18.2%) of all patients had a S-LANSS score ≥12 90 days following surgery 8 (8.5%) in the ketamine group 25 (28.4%) in the placebo group (P<0.001).

CONCLUSIONS

In summary, pre-emptive ketamine does not reduce opioid consumption and NRS scores after thoracotomy but more importantly it lowers significantly the incidence of chronic postoperative pain, especially neuropathic pain.

TRIAL REGISTRATION

The study was registered at ClinicalTrials.gov (NCT03105765).