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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.
* Lidocaine or procainamide should not be given if a wide-QRS complex arrhythmia is likely due to hyperkalemia; this may result in asystole.
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
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.
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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.
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.
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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.
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.
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.
Newer formulations of dantrolene are more soluble, making the warming of the sterile water unnecessary.
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.
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.
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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