Oxycodone is superior to morphine for pain relief following peroral oesophageal myotomy: a prospective, randomized, controlled trial

Introduction
Patients underwent peroral endoscopic myotomy (POEM) for treating achalasia suffered with mild to moderate, sometimes even severe postoperative pain.

Aim
To evaluate the efficacy of oxycodone on postoperative analgesia of patients undergoing PEOM.

Material and methods
In this prospective, double-blinded, randomized, controlled trial, patients with achalasia were recruited and received 0.08 mg/kg oxycodone or morphine 15 min before the end of the POEM procedure. The short-form McGill questionnaire (SF-MPQ) was used to measure the postoperative pain at 0, 2, 6, 24, and 48 h after surgery, which included the visual analogue scale (VAS), the present pain intensity (PPI) scale, and the pain rating index (PRI).

Results
A total of 73 patients were included, of whom 36 received oxycodone, and 37 received morphine. Compared with morphine, patients received oxycodone were associated with lower VAS in the first 24 h postoperatively (1.64 ±0.76 vs. 2.14 ±1.23, p = 0.042) as well as PPI at 2 h (1.11 ±0.40 vs. 2.22 ±0.89, p < 0.001), 6 h (1.42 ±0.55 vs. 2.08 ±0.92, p < 0.001) and 24 h (1.06 ±0.23 vs. 1.30 ±0.46, p = 0.006). Patients who received oxycodone experienced lower sensory McGill pain score than those who received morphine at 2, 6, 24, and 48 h after surgery (p < 0.05). Significantly lowered affective McGill pain score was observed in the oxycodone group at 0, 2, and 24 h postoperatively. Regarding the PRI, the sum of both sensory and affective McGill pain scores, patients with oxycodone therapy were associated with better scores postoperatively.

Conclusions
Oxycodone appears to be superior to morphine in dealing with post-POEM pain, which has distinct visceral pain characteristics.