Premixed nitrous oxide/oxygen as an analgesic for dressing in patients with perianal abscess after surgery: study protocol for a randomized, within-patient, controlled trial

Abstract

Background:Perianal abscess is mainly treated by surgery in the clinic. However, the pain induced by dressing is the most prominent problem in postoperative patients and available analgesics is limited. The short- acting analgesia, premixed nitrous oxide/ oxygen, may be an ideal analgesic for acute pain induced by dressing change after perianal abscess surgery. This study aims to evaluate the safety and analgesic efficacy of premixed nitrous oxide/oxygen mixture for patients with dressing change after surgery around the anus. Methods/design:This protocol for a randomized, double-blind, placebo- controlled trial will be implemented in the Anorectal Department, Yinchuan Hospital of Traditional Chinese Medicine affiliated to Ningxia Medical University. Study subjects are hospitalized patients underwent perianal abscess surgery and suffered from moderate to severe pain due to dressing. Two hundred subjects will be selected and randomly assigned to other intervention or control group. The intervention group will get regular pain treatment plus premixed nitrous oxide/oxygen and the control group will be treated with regular pain treatment plus oxygen. The patients, medical staffs or investigators are blinded to the nature of the gas mixture in each cylinder and the randomization list. Data will be collected at baseline (T0, 2 min before dressing) and at 5 min (T1) after the beginning of intervention and at 5 min (T2) past dressing. The primary outcome will be the change in pain score at T1 and T2. Secondary outcomes cover physiological parameters, adverse events, patients and medical staffs’ satisfaction as well as patients’ acceptance. Discussion:The findings of this trial will provide a valuable therapeutic regimen for pain caused by dressing after perianal abscess surgery and identify the efficacy and safety of the gas.