Inhaled nitrous oxide for painful procedures in children and youth: a systematic review and meta-analysis.

Abstract

The objective of this study was to synthesize indication-based evidence for N2O for distress and pain in children. We included trials of N2O in participants 0-21years, reporting distress or pain for emergency department procedures. The primary outcome was procedural distress. Where meta-analysis was not possible, we used Tricco et al.'s classification of "neutral" (p ≥ 0.05), "favorable," or "unfavorable" (p < 0.05, supporting N2O or comparator, respectively). We used the Cochrane Collaboration's Risk of Bias tool and the Grading of Recommendations Assessment, Development, and Evaluation system to evaluate risk of bias and quality of evidence, respectively. We included 30 trials. For pain using the Visual Analog Scale (0-100mm) during IV insertion, 70% N2O (delta:-16.5; 95%CI:-28.6 to -4.4; p = 0.008; three trials; I2 = 0%) and 50% N2O plus eutectic mixture of local anesthetics (EMLA) (delta:-1.2; 95%CI:-2.1 to -0.3; p = 0.007; two trials; I2 = 43%) were superior to EMLA. 50% N2O was not superior to EMLA (delta:-0.4; 95%CI:-1.2 to 0.3; p = 0.26; two trials; I2 = 15%). For distress and pain during laceration repair, N2O was "favorable" versus each of SC lidocaine, oxygen, and oral midazolam but "neutral" versus IV ketamine (five trials). For distress and pain during fracture reduction (three trials), N2O was "neutral" versus each of IM meperidine plus promethazine, regional anesthesia, and IV ketamine plus midazolam. For distress and pain during lumbar puncture (one trial), N2O was "favorable" versus oxygen. For distress and pain during urethral catheterization (one trial), N2O was "neutral" versus oral midazolam. For pain during intramuscular injection (one trial), N2O plus EMLA was "favorable" versus N2O and EMLA alone. Common adverse effects of N2O included nausea (4.4%), agitation (3.7%), and vomiting (3.6%) AEs were less frequent with N2O alone (278/1147 (24.2%)) versus N2O plus midazolam (48/52 (92.3%)) and N2O plus fentanyl (123/201 (61.2%)). There is sufficient evidence to recommend N2O plus topical anesthetic for IV insertion and laceration repair. Adverse effects are greater when combined with other sedating agents.