Use of fixed 50% nitrous oxide-oxygen mixture for lumbar punctures in pediatric patients.

To the Editors: A lumbar puncture is one of the most commonly painful procedures performed in pediatric medical practice. Despite evidence to suggest that analgesia and sedation are both efficacious and safe in children, clinical practices do not adhere to these findings. A study carried out in 1993 by Quinn et al showed that 95% of children who had a lumbar puncture performed in a pediatric emergency department did not receive any local anesthesia. Another recent report found that only less than 25% of children had received any form of pain management during the execution of a lumbar puncture. These results demonstrate the ongoing issue of the lack of pain treatment in children. Although numerous studies have shown that children have similar physiological pain responses as adults, children often receive less pain medication compared with adults, under similarly painful conditions. Therefore, the provision of adequate sedation and analgesia for children undergoing painful procedures in the emergency department is a challenging proposition. The ideal agent for sedation during a brief but painful procedure must be safe and easy to administer, provide adequate amnesia, and have a rapid onset and recovery time. A good choice for this kind of procedures in children is the equimolecular mixture of oxygen and nitrous oxide (EMONO). Nitrous oxide, a gas with analgesic properties, has been known about for more than 2 centuries. Its modern use outside the operating theater started in 1961 when Tunstall introduced a stable mixture of nitrous oxide and oxygen in equal proportions in a single cylinder for the relief of pain during labor. From that moment on, the anxiolytic and the analgesic properties of the EMONO have been very useful to relieve numerous painful procedures both in adults and children. When used in low concentrations, nitrous oxide allows the maintenance of the laryngeal reflex and has a well-documented safety record. The technique requires minimal advance preparation of staff, equipment, and the patient. The maskadministered gas has rapid onset and is short acting; an empty stomach is not required, and it provides excellent control of pain, anxiety, awareness, and motion during the uncomfortable procedure. Postoperatively, memory of the event is blunted, and no monitoring is necessary. The purpose of this study was to analyze the safety and effectiveness of EMONO when it is used as method of sedation and analgesia during lumbar punctures in pediatric patients.