PS55 MH update: Increased minimum recommended dantrolene stocks

Important updates have been made to Appendix 2 Malignant hyperthermia of PS55 Minimum safe facilities to ensure adequate availability of dantrolene for the management of malignant hyperthermia (MH). ANZCA consulted with the Malignant Hyperthermia Australia & New Zealand (MHANZ) and recommendations are based on both the MHANZ and European Malignant Hyperthermia Group (EMHG) guidelines.

Updated guidance from the EMHG recommends that 720 mg of dantrolene be immediately available, with a further 480 mg accessible within 60 minutes, noting that 720 mg provides effective treatment for approximately 20–30 minutes in adults. Rising average body weights mean earlier assumptions based on a 70–72 kg adult are no longer appropriate, and in geographically remote facilities where timely resupply is not feasible, onsite stock of up to 1200 mg may be required to ensure safe and effective management of an MH crisis.

The previous recommendation of 180 mg immediately available is insufficient to deliver the recommended initial dose of 2.5 mg/kg to many adult patients, when dosing is based on actual body weight, as now advised to reduce the risk of poor outcomes.

Summary of key changes to PS55 Appendix 2 Malignant hyperthermia

• The minimum amount of dantrolene required to be immediately available has increased from 180 mg to 720 mg.
• Dantrolene dosing is based on actual body weight (2.5 mg/kg, maximum 300 mg per dose), rather than assumptions based on a standard adult weight.
• A further 480 mg of dantrolene must be available within one hour.
• Where additional dantrolene cannot be obtained within 60 minutes, facilities should stock a minimum total of 1200 mg.

These updates reinforce the importance of preparedness and timely access to life-saving treatment in managing malignant hyperthermia.