Prehospital analgesia in adults using inhaled methoxyflurane.

OBJECTIVE: For many years, ambulance services throughout Australia have been administering methoxyflurane as a first-line analgesic agent. However, there is a paucity of literature regarding its efficacy, safety and usage profile. The present study was designed to examine the efficacy of methoxyflurane in adults.
METHODS: An observational case series was conducted over a 10 month period. Adults to whom methoxyflurane was administered while traveling by ambulance to an urban teaching hospital were enrolled. Data analysed included indications for use, verbal numerical pain scores, depth of sedation and adverse effects. Data were collected via paramedic, patient and ED staff surveys.
RESULTS: Eighty-three adult patients were enrolled over a 10 month period. A mean reduction in verbal numerical rating scale (VNRS) scores of 2.47 +/- 0.24 (on a 10-point scale) was recorded 5 min post methoxyflurane, with a total reduction of 3.21 +/- 0.24 at time of arrival at the ED. Both VNRS scores were significantly different from baseline (P < 0.0001). Fifteen patients (18.1%, 95% CI 9.8-26.4%) reported mild side-effects either during or shortly after administration. A total of 68 (81.9%, 95% CI 72.0-89.5%) of the paramedics and 60 (72.3%, 95% CI 61.4-81.6%) of the patients interviewed said that they felt satisfied with the level of analgesia provided by methoxyflurane.
CONCLUSION: The use of methoxyflurane as a prehospital analgesic significantly reduced pain in patients, with no significant side-effects attributed to its use. The majority of patients and paramedics interviewed were satisfied with its effects and indicated a willingness to use it again.