Efficacy Evaluation of Nitrous Oxide as Analgesic in the Pediatric Age: Prospective Study

  • Rosa Martins Serviço de Pediatria Médica, Departamento de Pediatria, Hospital de Santa Maria – Centro Hospitalar de Lisboa Norte, Centro Académico de Medicina de Lisboa.
  • Ana Teresa Soares Serviço de Pediatria, Hospital Garcia de Orta
  • Fátima Prior Serviço de Pediatria, Hospital Garcia de Orta
  • Ana Francisco Serviço de Pediatria, Hospital Garcia de Orta
  • Marta Almeida Serviço de Pediatria, Hospital Garcia de Orta
  • Rita Marques Serviço de Pediatria, Hospital Garcia de Orta
  • Manuela Braga Serviço de Pediatria, Hospital Garcia de Orta


Introduction: Inhaled nitrous oxide has been primarily used as a sedative but also as an analgesic in pediatric painful procedures. This study characterises the use of nitrous oxide in this age group and evaluates its effectiveness, safety and acceptance.

Methods: Observational and prospective study performed based on the application of a questionnaire to pediatric patients in which nitrous oxide was administered (50% mixed with oxygen). Wong-Baker and FLACC-R (face, legs, activity, cry, consolability – revised) scales were used for pain assessment by the patient and the physician, respectively. Statistical analysis was performed using non-parametric tests and a significance level of 0.05 was considered.

Results: A total of 65 patients with a median age of 8 years were evaluated. In 46 patients (70.8%), it was used in acute disease, mainly in fractures reduction (n = 33; 50.8%). The median of onset duration was 3 minutes and the action duration 7 minutes. There were reported side effects in 21 patients (32.3%), all mild and temporary.

Twenty patients (30.8%) underwent supplemental analgesia during the procedure. During the procedure, in the context of acute illness, pain was lower than previous pain when evaluated by the patient (p < 0.001).

Patients who were 5 years of age or older reported less pain during the procedure than patients who were of a younger age (p < 0.001). All the patients would accept its use again.

Discussion: Nitrous oxide is an effective, safe, easy to use and quick-action analgesic. Efficacy was higher in patients older than 5 years of age and was well accepted by the patients.


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