TORONTO — In France, a 50/50 mixture of inhaled nitrous oxide and oxygen is widely used for painful procedures in emergency departments and pediatric wards, noted Dr. Ricardo Carbajal, of the Hôpital d'enfants Armand-Trousseau in Paris.
“This is used in millions of patients,” he said in an interview. “Every time there is a painful procedure people should consider nitrous oxide. It is very short-acting and has an excellent to very good effect for children aged 24 to 30 months old or older, with a little bit less of an effect in younger children.”
At the annual meeting of the Pediatric Academic Societies, Dr. Carbajal presented his randomized, double-blind study involving 55 children younger than 24 months who received intramuscular injections of palivizumab for the prevention of severe lower respiratory tract infections due to respiratory syncytial virus. Patients received three consecutive monthly injections using three different analgesic protocols: inhaled nitrous oxide and oxygen (N20/02) and a placebo cream; EMLA (Eutectic Mixture of Local Anesthetics) cream and inhaled air (placebo); and a combination of both treatments.
All injections were videotaped, and infant pain levels were assessed from the time of needle insertion until 30 seconds after needle withdrawal; the researchers used the Modified Behavioral Pain Scale (MBPS) running from 0 (no pain) to 10. A secondary outcome was pain as assessed by parents on a 0 to 100 numeric scale.
The combination of inhaled N20/02 and EMLA cream was the most effective in alleviating injection pain, compared with either medication alone, Dr. Carbajal said. EMLA cream was the least effective, with a score of 9.25 during injection and 7.76 post injection, compared with 8.76 and 7.42, respectively, for inhaled N20/02. When both medications were combined, the pain score during the injection was 8.24, dropping to 6.95 after injection.
Parents scored the medications similarly: EMLA alone scored 36, inhaled N20/02 scored 35, and the combination scored 26.
Dr. Carbajal noted that, given the high level of pain caused by intramuscular palivizumab, “the development of new analgesic strategies is still needed.”
North American delegates at the meeting were intrigued by the common use in France of inhaled N20/02, which Dr. Carbajal said has a well-established safety profile “if you don't mix it with other [systemic] medications … probably we have had more than a million users now with no accidents.”
He said French nurses are trained to give the medication and physicians are not required to be present because in France the 50/50 ratio of N20/02 is not considered to be an anesthetic.
Dr. Shetal Shah, a neonatologist at the State University of New York at Stony Brook, commented in an interview, “I think there may be barriers in the United States toward implementing this… specifically, if it gets classified as a conscious sedation technique, then you may wind up having to create a whole new level of certification for outpatient nursing staff.”