Indications for treatment of malignant hyperthermia
Indications for treatment of malignant hyperthermia (MH) with dantrolene include signs of hypermetabolism, a rapid rise in carbon dioxide in the face of an increase in the minute ventilation, tachycardia, muscle and or jaw rigidity (after succinylcholine), and fever (a late sign).

Not all of these indications are present in all patients. If an acute MH reaction appears likely, it is best to start giving dantrolene and other recommended treatment modalities promptly rather than wait too long and have a bad outcome. The longer the wait before initiation of therapy, the lower the likelihood of a complete recovery. If an MH reaction is suspected, referral to a MH muscle biopsy testing center is indicated.

A fulminant, rapidly progressive MH reaction requires early diagnosis and early rapid administration of dantrolene, discontinuance of triggering agents, and assistance from extra personnel. The surgeon should be notified immediately and should stop the procedure as soon as possible.

Cooling and early treatment of hyperkalemia are desirable. Calcium-channel blockers should be avoided if dantrolene is used, because they may cause hyperkalemia. An MH tote or cart containing dantrolene and the necessary supplies should be readily available to help reverse the process more quickly. The recommendation is that 36 dantrolene vials (containing 20 mg/vial) should be immediately available wherever general anesthesia is administered. It is helpful to place an MH treatment poster in the operating room.

Dantrolene is a hydantoin derivative that directly interferes with muscle contraction by inhibiting calcium ion release from the sarcoplasmic reticulum, possibly by binding to ryanodine receptor type 1 (RYR-1). The initial dose is 2.5 mg/kg, repeated every 5 minutes until reversal of the reaction occurs or a total dose of 10 mg/kg (or 20 mg/kg, according to some practitioners) is reached. If there is no clinical response, another diagnosis should be considered.