When a patient’s muscles become rigid, end-tidal CO2 levels start to rise and core body temperature begins to climb, immediately call the hotline of the Malignant Hyperthermia Association of the United States (800-644-9737). One of the first questions the MHAUS expert who answers will ask: Do you have a fully stocked MH cart? How will you respond? Take this short quiz to find out if your staff will have immediate access to the medications and supplies they might someday need to save a life.

1. How much dantrolene should be stocked in your MH cart?

• a. 250 mg
• b. 500 mg
• c. 1,000 mg
• d. 2,000 mg
• Reveal

  • Answer: d
    The reason: If your center uses MH triggering agents — the volatile general anesthetics halothane, enflurane, isoflurane, desflurane and sevoflurane, and the muscle relaxant succinylcholine — you need enough dantrolene to provide an initial loading dose of 2.5mg/kg (250 mg if the patient weighs 100 kg). However, the initial 2.5mg/kg dose would not be sufficient to treat larger patients (100-plus kg), who require 1,000 mg to 2,000 mg of dantrolene to deliver the 10mg/kg to 20 mg/kg dose needed for stabilization. Answer “c” is acceptable for outpatient centers close to an affiliated tertiary care medical center with more dantrolene immediately available. But most standalone facilities, especially those in remote locations, should have immediate access to 2,000 mg of dantrolene.
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2. Which cooled IV fluid should be available on your MH cart?

• a. normal saline solution
• b. half-normal saline solution
• c. Ringer’s lactate
• d. dextrose 5% in water
• Reveal

  • Answer: a
    The reason: Cooled saline should be available for immediate infusion in age/size appropriate quantities for management of a patient’s rapidly rising body temperature. IV volume expansion is also critical in the management of MH, so that a solute diuresis will maintain urine flow and reduce the risk of myoglobinuric renal failure following muscle damage. That’s why MHAUS does not recommend the use of fluids such as half-normal saline, dextrose 5% in water and dextrose 5% half or quarter in normal saline to help cool a patient, because they are less effective for plasma volume expansion. Hyperkalemia is an immediate consequence of the marked metabolic and respiratory acidosis that occur during an MH crisis and that often follow the severe muscle injury associated with MH. That means the typical surgical fluid, Ringer’s lactate, is not the best treatment option.
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3. How much sterile water should you have on hand to reconstitute dantrolene?

• a. 5 5-ml to 10-ml vials
• b. 15 50-ml to 60-ml vials
• c. 2 1-liter bags
• d. a or b
• e. a, b & c
• Reveal

  • Answer: d
    The reason: The 3 available preparations of dantrolene (Dantrium, Revonto and Ryanodex) appear to be equally efficacious in reversing MH episodes. Ryanodex comes in 250-mg vials, one of which can be reconstituted in 5 ml to 10 ml sterile water and rapidly infused for an initial loading dose in patients who weigh up to 100 kg. But with increasing numbers of obese patients presenting for surgery, more might be required, so having (a) 5 vials on hand would be best if you stock Ryanodex.

    Dantrium and Revonto, the other formulations of dantrolene, come in 20-mg vials, each of which requires 50 ml to 60 ml of sterile water to reconstitute. Up to 250 mg, or 12 to 13 vials, may be required for the initial loading dose of these formulations. It’s therefore recommended that you stock (b) 15 50-ml to 60-ml vials of sterile water to prepare these drugs for administration.

    The only answer that doesn’t work here is “c,” because stocking IV bags of sterile water creates the possibility that staff, during the rush of an emergency response, might instead hang bags of saline solution and administer it to the patient. MHAUS has received reports of providers making that exact mistake during a crisis.
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4. MH-susceptible patients should not be operated on in the outpatient setting.

• a. true
• b. false
• Reveal

  • Answer: b
    The reason: It’s safe to operate on patients who’ve had a MH episode in the past or with a family history of the condition so long as you take certain precautions. First, move the MH cart into the OR for more immediate access to its supplies. Second, attach commercially available charcoal filters, which can be kept in the MH cart, to the anesthesia machine’s breathing circuit. The filters absorb trace amounts of triggering agents that remain in the circuit in preparation for using it on MH-susceptible patients. The filters can also be inserted into the breathing circuit during a MH crisis to remove volatile anesthetic gases as the anesthesia provider hyperventilates the patient with 100% oxygen at flows of 10L/min to flush volatile anesthetics from the patient and lower his end-tidal CO2 level.
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5. How long should it take to get the MH cart to a patient’s bedside?

• a. less than 1 minute
• b. 5 minutes
• c. 10 minutes
• d. 15 minutes
• Reveal

  • Answer: c
    The reason: MHAUS recommends that dantrolene should be “immediately” available; which means it should take no longer than 10 minutes to bring the drug bedside for administration. Many third-party state and national medical facility review organizations have endorsed dantrolene availability within that time frame. Surveyors from the Joint Commission often ask about dantrolene availability during surveys of both inpatient and outpatient surgical facilities.
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6. Who should retrieve the MH cart during a crisis?

• a. surgeon
• b. anesthesia provider
• c. scrub tech
• d. circulating nurse
• e. someone outside the OR
• Reveal

  • Answer: e
    The reason: The anesthesia provider is immediately involved in the MH crisis recognition and management, and both the surgeon and members of the surgical team are tied up in crisis management, so another individual who knows the location of the MH cart and can retrieve it quickly should be assigned that role. Keep the cart in a standard location. Make sure it’s never moved, and that every staff member in your facility knows exactly where it’s stored. Remember that MH can occur in the OR immediately following anesthesia emergence or after more lengthy exposure to triggering anesthetic agents. It can also occur in the recovery area. In some facilities, keeping the cart in the PACU, with its immediate access to the OR, might make the most sense.
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7. How often should you audit and restock the supplies in your MH cart?

• a. every month
• b. every 3 months
• c. every 6 months
• d. once a year
• Reveal

  • Answer: a
    The reason: Answers a, b, & c are actually all acceptable, but it’s best to check the contents of a cart as often as practically possible to ensure all supplies and drugs are present and current. Have different staff members conduct audits of a cart’s contents so they become familiar with where supplies are located. That familiarity will prove invaluable during a crisis when a fast response can mean the difference between life and death. Staff who know where needed supplies are located are more likely to respond calmly and coolly during a real-life emergency.
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8. Your anesthesiologists never use potent inhaled anesthetic agents, but have succinylcholine on hand to assist intubation during airway emergencies. Do you still need to have a fully stocked MH cart available?

• a. No, because the risk of MH is so low
• b. No, because succinylcholine is used only for emergency airway management
• c. Yes, because you need to manage treatable emergencies
• Reveal

  • Answer: c
    The reason: Patients can develop MH in response to succinylcholine alone. A practical alternative to stocking succinylcholine for emergency airway management might make this question moot. Rocuronium, a non-depolarizing muscle relaxant given intravenously in relatively large doses, induces paralysis as rapidly as the MH-triggering agent succinylcholine. The advantages of using succinylcholine — rapid onset and short duration — as an emergency agent to facilitate airway management can therefore be achieved with a less risky alternative.
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9. Do you need a MH cart if your providers use only propofol and do not stock succinylcholine?

• a. No, there is no risk of MH crisis if triggering agents are not used
• b. Yes, MH can occur in some patients who are not exposed to triggering agents
• Reveal

  • Answer: a
    The reason: This is a difficult call. Sudden death can occur in individuals who present with MH under stressful circumstances like vigorous exercise and heat stress. Moreover, some individuals who experience muscle cramping and weakness have been found to be MH susceptibles. Surgery can be very stressful for some patients, despite use of sedative, analgesic and hypnotic agents like propofol. There is no guideline or standard that requires facilities to have a MH cart if triggering agents are not in use. However, with the increased recognition that surgical stress might cause MH without exposure to triggering agents, I recommend always having stocked MH carts available.
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10. Your clinical team can continue to perform surgery and administer anesthesia after the MH cart has been used and before it’s been restocked.

• a. true
• b. false
• Reveal

  • Answer: b
    The reason: Although nearly simultaneous MH events are unlikely, this issue is one of preparedness. The reason for checking and maintaining the MH cart is to ensure that its supplies are available for every patient under your care. If your facility is small enough — only 1 procedure is performed at a time — it would be best to delay or postpone the next case until the MH crisis has been completely managed, the patient has been moved to a tertiary care inpatient facility and the MH cart has been fully restocked. OSM
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