Premixed nitrous oxide/oxygen analgesia for removal of vacuum assisted closure dressing: a randomized, double-blinded placebo-controlled trial

Vacuum assisted closure (VAC) is commonly used in clinical practice to promote wound healing. During the dressing removal of VAC, patients may suffer from different degrees of pain, or even discontinue treatment due to severe pain. Our study sought to determine whether or not nitrous oxide analgesia decreases pain compared to oxygen placebo during removal of VAC dressing. This study is a double-blind, placebo-controlled randomized trial targeting patients who underwent replacement of VAC dressings in orthopedics. All patients were randomized in a 1:1 ratio to receive 65% premixed nitrous oxide/oxygen versus 100% oxygen. The primary outcome was the intensity of pain during the intervention. Secondary outcomes included adverse effects, satisfaction of patients, and physiological parameters (blood pressure, heart rate, oxygen saturation). Between 18 February, 2022 and 9 May, 2023, 114 participants were enrolled, 57 patients were allocated to the intervention group (premixed nitrous oxide/oxygen), 57 patients were enrolled in the control group (oxygen). The baseline and procedural characteristics were comparable between the two groups. The pain score reported by patients immediately after removing the dressing in the intervention group was significantly lower than that in the control group (median 3.0 vs. 6.3, P < 0.001). The satisfaction of patients in the intervention group significantly increased (Z=-6.861, P < 0.001). There were no significant differences in vital signs, operation duration, and adverse reactions between the two groups. Premixed nitrous oxide/oxygen can reduce the pain caused by removal VAC dressing in patients and can be considered an effective analgesic measure.