In this episode, I’ll discuss what medications should be stocked on a malignant hyperthermia cart.
Malignant hyperthermia is a rare event, occurring in about 1 out of 100,000 administrations of anesthesia. MH is usually thought of as occurring in the operating room, but it can occur an hour after anesthesia or anywhere succinylcholine has been administered.
Dantrolene is a skeletal muscle relaxant that interferes with the release of calcium ions from the sarcoplasmic reticulum. By lowering the myoplasmic calcium ion concentration, the sustained muscular contraction present in MH is ended along with the acute catabolic process.
The main treatment for MH is dantrolene, however, MHAUS does not provide an exact amount of dantrolene that should be available on a cart, rather they suggest an amount that should be available within an institution.
Separate from the cart quantity recommendations, MHAUS suggests that enough dantrolene to treat a patient with MH be available within 10 minutes of diagnosis. This allows hospitals with multiple MH carts some flexibility to save on the expense of stocking the full recommended amount of dantrolene in each cart, as long as the balance of dantrolene can be brought to the patient within the 10-minute timeframe.
There are now 2 formulations of dantrolene – the original which comes in 20 mg vials and a nanoparticle version that comes in 250 mg vials. MHAUS recommends having either 36 vials (720 mg) of the original formulation or 3 vials (750 mg) of the newer formulation.
Both formulations of dantrolene require sterile water for injection to reconstitute, and enough should be kept on the cart to accomplish this task. The amount needed will vary greatly as the older formulation needs 60 mL SWFI per 20 mg dantrolene while the newer formulation requires only 5 mL SWFI per 250 mg dantrolene.
Hyperkalemia and acidosis are common complications in a patient with MH, and the majority of other medications on the cart are meant to deal with these:
Four 50 mL vials or syringes of Sodium bicarbonate (8.4%)
Two 50 mL vials of Dextrose 50%
Two 10 mL vials or syringes of Calcium chloride (10%)
One vial of Regular insulin – 100 units/ml x 1 (kept refrigerated)
Finally, three 100 mg syringes of lidocaine are recommended by MHAUS, however they state that amiodarone is an acceptable alternative and that standard ACLS protocols should be used should a patient with MH develop an arrhythmia. MHAUS also reminds us that Lidocaine should not be given for a wide-QRS complex arrhythmia that is likely due to hyperkalemia as this may result in asystole.
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