Tolerability of an equimolar mix of nitrous oxide and oxygen during painful procedures in very elderly patients.

BACKGROUND AND OBJECTIVE: Although an equimolar mix of nitrous oxide-oxygen (N(2)O/O(2)) [Kalinox] is widely used as an analgesic, there have been few specific studies of this product in the elderly. In this article, we investigate the tolerability of this equimolar mix in very elderly patients undergoing painful procedures.

METHODS: This was a prospective, observational study of patients hospitalised in the geriatric short-stay unit of a teaching hospital between July 2001 and September 2003. All patients aged >/=80 years who were scheduled for invasive care procedures were eligible for inclusion. Sixty-two patients were recruited and underwent a total of 68 procedures. The procedures were divided into four classes based on the degree of pain they were expected to cause and their duration. Patients received the equimolar N(2)O/O(2) mix (Kalinox) for 5 minutes before the beginning of the procedure and throughout its duration. The inhaled treatment was administered via a high-concentration mask. Assessments were carried out during the inhalation and over the 15 minute period following inhalation. The primary endpoint of the study was tolerability of the equimolar N(2)O/O(2) mix, and all adverse events were recorded. Secondary endpoints were the efficacy of the product (assessed on a verbal rating scale and/or the Doloplus scale), its ease of use and its acceptability to patients and staff.

RESULTS: Fourteen patients (22.6%) each reported at least one adverse event: impaired hearing (n = 1), altered perception of the environment (n = 8), anxiety (n = 1), headache (n = 3) and drowsiness at the end of the procedure (n = 2). All these disorders subsided rapidly after treatment was completed.

CONCLUSION: This study shows the favourable tolerability of the equimolar N(2)O/O(2) mix in very elderly subjects, which makes this product a valuable tool for the management of acute pain in this age group.