FAQs: Stocking an MH Cart

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What Should Be On An MH Cart?


Therapy should be aimed at prompt administration of dantrolene, treatment of hyperkalemia, hyperventilation, and cooling to a target core temperature of no more than 38°C.

  1. Dantrolene – To treat an MH episode, an initial dose of dantrolene at 2.5 mg/kg is recommended. There are two formulations now available. DANTRIUM/REVONTO are the older formulation, which provides 20 mg dantrolene sodium/60 mL after reconstitution in sterile water. The second formulation, RYANODEX (dantrolene sodium), is a new formulation that is an injectable suspension of dantrolene sodium providing 250 mg of dantrolene sodium/5 mL after reconstitution. RYANODEX is manufactured by Eagle Pharmaceuticals, Inc. and was approved by the FDA in 2014.
    1. DANTRIUM/REVONTO – 36 vials should be available in each institution where MH can occur, each vial to be diluted at the time of use with 60 ml sterile water, USP (without a bacteriostatic agent). There are 3 grams of mannitol in each vial of 20 mg of dantrolene (0.15 g mannitol/ 1 mg dantrolene).
    2. RYANODEX – 3 vials should be available in each institution where MH can occur, each to be diluted at the time of use with 5 ml of sterile water for injection, USP (without a bacteriostatic agent). There are 0.125 grams of mannitol in each vial of 250 mg of Ryanodex (0.0005 grams mannitol/1 mg dantrolene).
  2. Sterile water for injection USP (without a bacteriostatic agent) – It is mandatory to get dantrolene sodium to its effective site, the skeletal muscle.
    1. DANTRIUM/REVONTO – Each 20 mg vial should be reconstituted by adding 60 ml of sterile water for injection, USP (without a bacteriostatic agent) and the vial shaken until the solution is clear. If the MH episode is proceeding rapidly, simply mix and inject. We advise that the sterile water be stored in 100 ml vials, not bags, to avoid accidental IV administration of this hypotonic solution.
    2. RYANODEX – Each 250 mg vial should be reconstituted with 5 ml of sterile water for injection, USP (without a bacteriostatic agent) and shaken to ensure an orange-colored uniform, opaque suspension. RYANODEX should be administered by intravenous push. Five percent dextrose injection, USP, 0.9% sodium chloride injection, USP, and other acidic solutions are NOT compatible with RYANODEX and should not be used. The contents of the vial must be used within 6 hours after reconstitution.
  3. Sodium bicarbonate (8.4%) – 50 ml x 5
  4. Dextrose 50% – 50 ml vials x 2
  5. Calcium chloride (10%) – 10 ml vial x 2
  6. Regular insulin – 100 units/ml x 1 (refrigerated)
  7. Lidocaine* for injection (2%) – 100 mg/5 ml or 100 mg/10 ml in preloaded syringes (3). Amiodarone is also acceptable. ACLS protocols, as prescribed by the AHA, would be followed when treating all cardiac derangements caused by MH.
  8. Refrigerated cold saline solution – A minimum of 3,000 ml for IV cooling

* Lidocaine or procainamide should not be given if a wide-QRS complex arrhythmia is likely due to hyper­kalemia; this may result in asystole.

General Equipment

  1. Charcoal Filters - Two pairs of activated charcoal filters (Vapor-Clean, Dynasthetics, Salt Lake City, UT). Attach activated charcoal filters to inspiratory and expiratory ports of the anesthesia machine to quickly reduce the concentration of gas (<5ppm) from the anesthesia machine. In this situation, even though the anesthetic gas has been discontinued when MH was first suspected, the Vapor-Clean filter may become saturated after one hour; therefore, a replacement set of filters should be substituted after each hour of use.
  2. Syringes – (60 ml x 5) to dilute Dantrium/Revonto and (5 ml x 3) for Ryanodex
  3. Intravenous catheters – 16G, 18G, 20G, 2-inch; 22G, 1-inch; 24G, 3/4-inch (4 each) (for IV access and arterial line)
  4. NG tubes – (sizes appropriate for your patient population)
  5. Toomey irrigation syringes – (60 ml x 2) with adapter for NG irrigation

Monitoring Equipment

  1. Esophageal or other core (e.g., nasopharyngeal, tympanic membrane, rectal, bladder, pulmonary artery catheter) temperature probes
  2. CVP kits (sizes appropriate to your patient population).  We recommend these are used in patients who are critically ill.
  3. Transducer kits for arterial and central venous cannulation

Nursing Supplies

  1. Large sterile Steri-Drape (for rapid drape of wound)
  2. Urine meter x 1
  3. Irrigation tray with piston (60cc irrigation) syringe
  4. Large clear plastic bags for ice x 4
  5. Small plastic bags for ice x 4
  6. Bucket for ice
  7. Test strips for urine hemoglobin

Laboratory Testing Supplies

  1. Syringes (3 ml) for blood gas analysis or ABG kits x 6 or point of care monitors; ISTAT with TB syringes (the point of care ISTAT device has replaced lab blood gene and electrolyte measurement).
  2. Blood specimen tubes for CK, myoglobin, SMA 19 (LDH, electrolytes, thyroid studies), PT/PTT, fibrinogen, fibrin split products; and lactate, CBC, platelets. If no immediate laboratory analysis is available, samples should be kept on ice for later analysis. This may well prove useful on retrospective review and diagnosis. Blood cultures are very useful and should be included to rule out bacteremia.
  3. Urine collection container for myoglobin level. Pigrnenturia (e.g , brown or red urine and heme positive dipstick) indicates that renal protection is mandated, when the urine is centrifuged or allowed to settled, and the sample shows clear supernatant, i.e., the coloration is due to red cells in the sample.

1.       Sodium bicarbonate (8.4%) – 50 ml x 5

2.       Dextrose 50% – 50 ml vials x 2

3.       Calcium chloride (10%) – 10 ml vial x 2

4.       Regular insulin – 100 units/ml x 1 (refrigerated)

5.       Lidocaine* for injection (2%) – 100 mg/5 ml or 100 mg/10 ml in preloaded syringes (3). Amiodarone is also acceptable. ACLS protocols, as prescribed by the AHA, would be followed when treating all cardiac derangements caused by MH.

6.       Refrigerated cold saline solution – A minimum of 3,000 ml for IV cooling

Who Should Stock Dantrolene?

All facilities, including ambulatory surgery centers and offices, where MH triggering anesthetics (isoflurane, desflurane, and sevoflurane) and depolarizing muscle relaxants (succinylcholine) are administered, should stock dantrolene as indicated below, along with the other drugs and devices necessary to treat an MH reaction. If none of these agents are ever in use in the facility, then dantrolene need not be kept on hand.

Succinylcholine is a potentially life-saving medication used to treat upper airway obstruction, and should be immediately available in any facility that administers anesthesia or sedative agents that have the potential to cause airway obstruction. In the absence of succinylcholine, practitioners should be prepared to administer an immediate-acting paralytic agent to treat life-threatening airway obstruction.

Watch this video FAQ for more information.

How Much Dantrolene Should Be Kept On Hand?

To treat an MH episode, an initial dose of dantrolene at 2.5 mg/kg is recommended, with a suggested upper limit of 10 mg/kg. If a patient of average weight (approximately 70 kg) were to require dantrolene at the upper dosing limit, then at least 700 mg of dantrolene would be needed.

  • DANTRIUM/REVONTO – stock a minimum of 36 - 20 mg vials
  • RYANODEX– stock a minimum of 3 - 250 mg vials

In addition, a review of cases has shown that in a “worse case” scenario of a very large person (i.e., about 100-110 kg or 220 – 250 pounds) having an acute MH incident, as much as 8-10 mg/kg will be needed for treatment; higher doses may be requiredon rare occasions.

This regimen of dantrolene will allow for initial stabilization and treatment while more vials are being acquired to continue treatment, as needed.

Watch this video FAQ for more information.

Where Should Dantrolene Be Kept?

Dantrolene should be kept in or very close to the operating room, so that it is available immediately if MH occurs. Dantrolene may be stored at room temperature. A supply of sterile water for injection USP (without a bacteriostatic agent) should be kept nearby to mix with dantrolene before injection (60 ml/vial); the water for diluting dantrolene should not be stored in a refrigerator; it may be stored in a warming cabinet designed to maintain fluid temperatures between 35-40° C. All anesthesia and surgical team members should be aware of this location. NOTE: Dantrolene should not be mixed with any other diluent other than sterile water. The drug will not completely dissolve in crystalloid-containing solutions.

How Quickly Must Dantrolene Be Accessible?

Dantrolene must be available for all anesthetizing locations within 10 minutes of the decision to treat for MH. Dantrolene must be available for all anesthetizing locations where MH trigger agents are used.” This is a slight modification of the current recommendation that the drug be available within five minutes because the five minute recommendation was not made based on consensus discussion and it is often not practical to have a large supply of dantrolene in every area where anesthesia is administered. For example anesthesia administration is now common in locations far from the operating rooms such as interventional radiology suites. This comment and others were made at the MH Hotline – Professional Advisory Council meeting held on May 14, 2011. Read this and other comments made at the meeting.

Are There Any Advantages In Sharing A Supply of Dantrolene?

No. Minutes count in an MH emergency.

The Professional Advisory Council of MHAUS strongly recommends that an adequate supply of dantrolene be available wherever general anesthesia is administered. Responsibility for treatment rests with the facility where the surgery is performed. Sharing is not a good alternative.

Can Warming the Sterile Water Facilitate Mixing?

Newer formulations of dantrolene are more soluble, making the warming of the sterile water unnecessary.

What Is The Cost Of Dantrolene?

The cost of maintaining dantrolene in stock is a tiny fraction of most facility budgets and a very small price to pay for patient safety. By analogy, a cardiac defibrillator, a necessary emergency tool in all OR suites, is seldom used, and is paid for in time by each patient’s charges. In fact, many hospitals have 30-50 such units deployed at all times. Dantrolene, an emergency drug that is kept in only one location within most institutions, is an appropriate parallel to that situation and is relatively inexpensive when prorated.

*Contact manufacturer for current pricing. Although fulminant MH episodes are unusual, they do happen, and patients still die form MH. Remember that dantrolene is like a defibrillator; it is kept ready for use at all times, even though the need is rare. The cost can be prorated among all patients.

Why were procainamide and mannitol taken off the list of drugs to stock for an MH episode?

Procainamide, a secondary drug used in the treatment of arrhythmias, is not readily available, and people are generally not familiar with its use. Lidocaine is a primary drug that all physicians have used for years; however, it was previously thought that lidocaine might aggravate MH. Based on a review of the literature and consensus of MH experts, we have determined that it does not, and thus, our MH experts have approved its use during an MH episode. Mannitol has been taken off the list of drugs because dantrolene (Dantrium® IV) has 3 grams of mannitol included in each vial. The patient will receive 0.375gm/kg mannitol when given 2.5 mg/kg dantrolene.

Watch this FAQ video for more information.

How do I supply a surgicenter for an MH emergency?

A surgicenter in which general anesthesia with potent volatile agents is administered should be equipped to manage MH by stocking an MH cart as outlined here.  Surgicenters that propose to use succinylcholine as an emergency agent should also have dantrolene available and an appropriate MH crisis protocol in place. Timely access to blood gas and electrolyte analysis is recommended.


Preparation of the anesthesia machine for MHS patients

  • Shanahan H, O’Donoghue R, O’Kelly P, Synnott A, O’Rourke J. Preparation of the Drager Fabius CE and Drager Zeus anaesthetic machines for patients susceptible to malignant hyperthermia. Eur J Anaesthesiol. 2012;29 (5): 229-34.
  • Jones C, Bennett K, Kim T, Bulger T, Pollock N. Preparation of Datex-Ohmeda Aestiva and Aisys anaesthetic machines for use in malignant hyperthermia susceptible patients. Anaesth Intensive Care. 2012;40 (3): 490-7.
  • Kim TW, Nemergut ME. Preparation of modern anesthesia workstations for malignant hyperthermia-susceptible patients: a review of past and present practice. Anesthesiology. 2011: 114(1): 205-12.

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