Background: Methoxyflurane administered via an inhaler is a common analgesic agent used by ambulance services in Australia; however little published data exists as to its efficacy or effectiveness in this setting. There have been several reports that have suggested that the use of Methoxyflurane may be associated with the occurrence of hepatitis and renal disease. Such concerns have led to an increasing reluctance to use Methoxyflurane as an analgesic agent in the prehospital setting. The aim of this study was to determine whether the event rates of heart disease, renal disease, hepatic disease, diabetes or cancer in patients who received Methoxyflurane compared with those not receiving Methoxyflurane prehospital.
Methods: Routinely collected administrative data for ambulance, emergency department, hospital morbidity and mortality were linked by using probabilistic matching to establish a cohort of patients managed by the ambulance service in Western Australia. The cohort covered a period of 10 years (1990 – 2000) with follow-up until 2004 allowing for a minimum of four and maximum of 14 years follow-up. Primary outcome was defined as a composite end point of any record indicating either hospital admission or death for the diseases under investigation. Event rates were age standardised and odd ratios plus 95% confidence intervals were to determine risk estimates.
Results: Total 135,770 patients were entered into the study of which 17, 629 (13%) had received Methoxyflurane. There were 14, 410 (81.7%) patients, where Methoxyflurane was administered only once with one patient receiving Methoxyflurane on 27 occasions. Trauma was the most common indication for Methoxyflurane being administered to 9, 755 (55.3%) patients. The odd ratios for each of the five disease groups under investigation ranged from 0.87 to 1.06 with the 95% confidence interval for each estimate including 1.0.
Conclusion: There was no difference observed in event rates for heart disease, renal disease, hepatic disease, diabetes or cancer in patients who received Methoxyflurane in the pre-hospital setting as compared with those not receiving Methoxyflurane.