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Written by

Dr James Cooper

Dr James Cooper is an anaesthetist in private practice in Australia for 9 months of the year, and a professional ski patroller for the remaining 3 months. He has a special interest in mountaineering and steep/vertical terrain rescue.

Case study: Acute trauma pain management in a mountain rescue

Published 8 September 2017

Dr James Cooper describes rescuing an injured skier and the use of Penthrox® (methoxyflurane) in Australia.

Key learning points

  • Methoxyflurane has been shown to be a fast-acting, effective analgesic for moderate to severe pain in conscious adult patients with trauma and associated pain.
  • Methoxyflurane is widely used by emergency services in Australia and there is over 30 years of experience with its use.

Case report

 A 20-year-old male professional ski coach experienced a fall while demonstrating an aerial manoeuvre to a squad of younger skiers. During the fall, the ski pole of the coach snapped and pierced his thigh.

Upon arrival at the scene ski patrollers (Australian Mountain Rescue team) were presented with a front-to-back transfixion of the thigh with a 15mm diameter hollow aluminium pole with a ragged end. The patient was conscious and cooperative, and expressed that he was in severe pain. His pain score (verbal) was ‘9 out of 10’. 

Examination of the limb revealed the previously-described wound through the adductor and flexor groups of the medial proximal thigh with associated bleeding, bruising and swelling and tenderness. Distal neurovascular function appeared intact and clinical examination suggested the absence of fractures. 

The patient was familiar, as are many in the Australian ski industry, with the use of Penthrox®  for acute injuries, as all ski patrollers in Australia carry Penthrox®  with them.1He specifically requested to be administered the ‘green whistle’ to assist with his stabilisation and transport for further care. This allowed the immediate commencement of analgesia. Penthrox® was administered as per recommendations, with immediate effect. Within 90 seconds, the patient‘s pain had reduced enough to permit the significant movement required for evacuation, including the use of a portable angle-grinder to reduce the projecting sections of the pole to a manageable length. 

Upon arrival at the medical clinic, further clinical examination confirmed the absence of neurovascular injury and plain radiographs demonstrated a lack of bony involvement.

Intravenous fentanyl and morphine were administered in addition to cefazolin and ondansetron. Transfer was organised to a regional tertiary hospital where the pole was surgically removed. A full recovery ensued.

Discussion

In Australia Penthrox® use is widespread and supported by medical and government bodies and emergency services. The ‘green whistle’ is well integrated into the national psyche as a result of the high profile it enjoys in televised professional sports, ski patrol, ambulance services, surf lifesaving, search and rescue services and the military.

Penthrox®  has been shown to provide rapid relief from acute pain in patients with pain due to trauma.2 The most common Adverse events are dizziness, and somnolence. 3

When assessing the need for analgesia, the following contraindications need to be considered:3

  • Presence of significant head injury and impaired conscious state
  • Patients with known malignant hyperpyrexia
  • Clinically significant renal impairment
  • Clinically evident cardiovascular instability
  • Clinically evident respiratory depression
  • History of liver damage after previous methoxyflurane use

Methoxyflurane (MOF) is a member of the halogenated ether group of volatile agents. It provides a significant level of analgesia at alveolar concentrations well below those required for anaesthesia. It is a potent agent, with a minimum alveolar concentration (MAC) of 0.16%, but has very high lipid solubility and a high blood-gas partition coefficient, meaning that its use for induction of anaesthesia often required the use of adjuvant intravenous agents. It is these same qualities, however, that mean it can be used for patient self-administration with almost no risk of sedation/loss of consciousness.4,5 

Approximately 30% of inhaled MOF is recovered in expired gases, the remaining 70% being subject to metabolic conversion to inorganic fluoride (F-), dichloroacetic acid (DCAA) and methoxyfluroacetic acid (MFAA). MOF use at anaesthetic doses (> 2-3 MAC hrs) is associated with high-output renal failure. The dose employed to produce analgesia is limited to MOF 6 mL/day of 0.1-0.7%, and 15 mL/week, which results in exposure 0.59 MAC-hours, which is well below the reported level of risk of nephrotoxicity of 2 MAC-hours.4

Conclusion

The combination of efficacy, safety, portability and cost make MOF an analgesic agent of choice for rescuers and first-responders in Australia. There is over 30 years experience of use and 3 million doses administered. 

  • Dr James Cooper is an anaesthetist in private practice in Australia for 9 months of the year, and a professional ski patroller for the remaining 3 months. He has a special interest in mountaineering and steep/vertical terrain rescue.

The treatment options described in this case scenario are based on the global literature and the long clinical experience of the author. Not all the medications listed are licensed for use in the settings described and physicians should consult the relevant SPCs prior to prescribing.

References

  1. Australian ski patrol. Available at: http://www.fips-skipatrol.org/wp-content/files/BWP_-_ASPA_Model_-_R_Christiansen.pdf. Accessed 30 August 2017.
  2. Coffey F, Wright J, et al. Emergency Medicine Journal 2014;31:613-618.
  3. Penthrox SmPC: Available at: https://www.medicines.org.uk/emc/medicine/31391. Accessed 21 August 2017.
  4. Dayan AD. Human and Experimental Toxicology 2016;35(1):91-100.
  5. Frangos J, Mikkonen A, et al. Regulatory Toxicology and Pharmacology 2016;80:210-225.
Date of preparation: September 2017; MINT/PAEU-17040