The comparative efficacy of inhaled methoxyflurane and intranasal fentanyl for the pre hospital management of cardiac and or visceral pain

Date of Award


Degree Type


Degree Name

Master of Science


School of Exercise, Biomedical and Health Sciences


Faculty of Computing, Health and Science


OBJECTIVE: To investigate the comparative safety and efficacy of inhaled Methoxyflurane and intranasal Fentanyl for the management of pain of cardiac or viscera/ aeitology and to secondly assess the usefulness of an alternative pain assessment tool utilised by the WA Ambulance Service. DESIGN: Retrospective study. PARTICIPANTS: Patients suffering pain of a cardiac or visceral pain origin as coded by ambulance paramedics from the WA Ambulance Service. METHODS: This study was conducted based on the treatment regimes laid out in the WA Ambulance Service Clinical Practice guidelines and the data recorded by the Ambulance Paramedics when managing patients. RESULTS: 1009 Patient Core Record Forms were examined and 27 pieces of data were collected from each case. Most cases (62.5%) were 50 years of age and over while 25% of all patients were over 75 years of age. Patients belonging to the under twenty age group were relatively few, accounting for only 1.1% of the cases. The numbers of male and female patients were not strictly similar, with the number of males being slightly greater at 57.9% while females represented 42.1% of the study population. Patients receiving Methoxyflurane mode up 46.1% of cases and Fentanyl cases mode up 39.3% of cases. Patients receiving a combination of the agents represented 14.6% of all patients. For patients that were administered Methoxyflurane, the median dosage required to achieve analgesic effect was 1 vial (3mls). The doses of Fentanyl administered to achieve analgesia ranged from 90 to 840µg with a mean of 362.3µg and a median of 260µg (STD deviation =191.7). The numbers of patients in the major categories of aetiology of pain were almost equal with cardiac pain representing 48.1% and the subcategories of visceral pain analysed totalled 51.9% i.e. renal 28.7% and abdominal 23.2%. There was no significant safety issue noted for either agent, in fact, there was improvement in many vital signs following administration of both agents. Patients to whom Methoxyflurane was administered demonstrated a mean fall in pain of 2.0cm and a median change in pain of 2.0cm after an initial dose of the agent. There were no significant changes in pain scores on arrival at hospital relative to scores after the initial dose. Patients to whom Fentanyl was administered demonstrated similar pain reduction scores as those observed for MethoxyfiLirone following on initial dose of the agent, with a mean reduction in pain of 1.7cm and a median reduction in pain of 2.0cm. However, patients to whom Fentanyl was administered demonstrated greater pain reduction scores after additional doses or longer periods prior to arrival at hospital, with a mean pain reduction of 3.2cm and median of 3cm prior to hospital admission. With respect to analysis of the aetiology of pain, there was no statistical difference in pain score reduction in any of the categories following Initial doses of agents however Fentanyl demonstrated a statistically better reduction for longer journeys over 15 minutes or when additional doses were administered. The exception was renal aetiology pain for which no difference was identified. Assessment of an alternate pain assessment tool utilised by the WA Ambulance Service demonstrated a correlation with the commonly utilised VAS pain assessment tool. CONCLUSION: Inhaled Methoxyflurane and intranasal Fentanyl are extremely safe agents that provide effective pain reduction from visceral or cardiac pain in the pre hospital setting. If is noted that for pain of a cardiac origin, intranasal Fentanyl is extremely beneficial and as a result of this study a trial will be recommended to assess the safety and efficacy of Fentanyl relative to intravenous Morphine. Moreover, the alternate pain assessment fool utilised by the WA Ambulance Service was found to correlate with standard methods of pain assessment and to have value for the assessment of pain. Although this study included greater than 1000 cases a study with greater numbers and specifically designed at Testing the sensitivity and validity of this tool is recommended

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