The use of methoxyflurane (Penthrox®) for procedural analgesia in the emergency department and pre-hospital environment

Abstract

Background Methoxyflurane is an inhaled analgesic agent licensed in the United Kingdom for the relief of moderate to severe pain in conscious patients with trauma. Methoxyflurane has been widely used by Australian ambulance services since the 1970s. Aims Primary aim: To assess the efficacy of methoxyflurane for procedural analgesia in the emergency department and pre-hospital environment. Secondary aims: to assess the efficacy of methoxyflurane for analgesia in the emergency department and pre-hospital environment; to assess the safety of methoxyflurane as an analgesic. Method A literature search of Medline, EMBASE, CINAHL and Cochrane databases was performed. A total of 59 articles were reviewed. Results One study using methoxyflurane for procedural analgesia in the emergency department was found. Multiple studies demonstrate the use of methoxyflurane for procedural analgesia for painful procedures outside the emergency department. Compared to other analgesics, methoxyflurane provides adequate analgesia. Overall, methoxyflurane is inferior to fentanyl or morphine, but it provides quicker onset analgesia compared to fentanyl and tramadol. It provides similar analgesia to nitrous oxide. Nephrotoxicity is dose dependent. Used in the analgesic doses, the risk of clinically significant kidney injury is negligible. Rare cases of unpredictable, severe hepatitis are reported. Discussion The efficacy of methoxyflurane and its acceptability to patients and clinicians has been shown in a number of studies. As would be expected in any procedural analgesic choice, patient and clinician factors and the procedure planned are all important considerations. Compared to other analgesic agents, methoxyflurane performs favourably with a low chance of adverse events. Conclusion Methoxyflurane is an efficacious analgesic agent in the emergency department and pre-hospital environment. It is easily portable and has a rapid onset. Methoxyflurane is suitable for use in procedural analgesia and as a bridging analgesic agent. Risks to the patient from renal or hepatic injury, cardiorespiratory depression or malignant hyperthermia are low.

Comparison of three regimens with inhalational methoxyflurane versus intranasal fentanyl versus intravenous morphine in pre-hospital acute pain management: study protocol for a randomized controlled trial (PreMeFen)

“…Methoxyflurane in low dose is a non-narcotic analgesic widely used in Australia and New Zealand [ 11 ]. The slightly volatile gas is administered as a liquid via an inhalation chamber in a whistle-like pipe, while the exhaled air is filtered in a coal chamber on the same whistle [ 12 ].…”