Malignant hyperthermia is a rare but deadly OR emergency the CNOR emphasizes. Drill the early-sign, dantrolene-dosing, and crisis-role scenarios below, each with a full rationale.
Question 1
A patient with a family history of malignant hyperthermia undergoes an orthopedic procedure using total intravenous anesthesia without depolarizing muscle relaxants. During the PACU handoff, what critical risk mitigation strategy must the perioperative nurse communicate?
- A) The requirement to administer prophylactic dantrolene immediately upon arrival.
- B) The requirement to maintain strict isolation precautions during recovery.
- C) The requirement to continue monitoring for delayed hypermetabolic crisis.✓
- D) The requirement to apply active cooling measures to the patient.
Show rationale
Even when a patient with malignant hyperthermia susceptibility receives a trigger-free anesthetic, there remains a risk for a delayed hypermetabolic crisis in the postoperative period. The PACU nurse must be informed to continue vigilant monitoring of end-tidal carbon dioxide, heart rate, and temperature. Prophylactic dantrolene (Option A) is not routinely administered without active signs of a crisis. Isolation precautions (Option B) are irrelevant to malignant hyperthermia. Active cooling measures (Option D) are only indicated if the patient is actively experiencing a hyperthermic crisis, not as a preventative measure for a stable patient who received a safe anesthetic technique.
Question 2
A patient develops a suspected malignant hyperthermia crisis intraoperatively. While the team manages the patient, the circulating nurse is preparing the anesthesia machine using supplies from the MH cart. Which action represents the correct use of activated charcoal filters?
- A) Attach filters to both inspiratory and expiratory machine limbs.✓
- B) Attach filters solely to the inspiratory anesthesia machine limb.
- C) Attach filters solely to the expiratory anesthesia machine limb.
- D) Attach filters directly to the common gas outlet connection.
Show rationale
The correct choice is A because activated charcoal filters must be placed on both the inspiratory and expiratory limbs of the anesthesia circuit. This configuration rapidly reduces the concentration of volatile anesthetics to safe levels within minutes. Options B and C are incorrect because placing a filter on only one limb fails to adequately clear the residual anesthetic gases from the continuous breathing circuit. Option D is incorrect because filters are designed for the circuit limbs, not the common gas outlet, which would not effectively scrub the gas already circulating in the system.
Question 3
A 30-year-old female is recovering in the ICU 24 hours after an intraoperative malignant hyperthermia crisis. The perioperative nurse reviewing the transfer orders knows which laboratory value will peak during this specific timeframe?
- A) The serum potassium level will reach its peak.
- B) The arterial carbon dioxide will reach its peak.
- C) The serum calcium level will reach its peak.
- D) The creatine kinase level will reach its peak.✓
Show rationale
Following a severe MH crisis, massive skeletal muscle breakdown occurs due to sustained intracellular calcium release. While potassium and myoglobin rise rapidly during the acute intraoperative phase, creatine kinase levels typically peak at 24 hours post-crisis and must be monitored closely in the ICU to assess the full extent of rhabdomyolysis. Option D correctly identifies the delayed peak of this specific muscle enzyme, guiding ongoing fluid resuscitation. Option A is incorrect because hyperkalemia is an acute, immediate complication of the crisis, not one that peaks a full day later. Option B is incorrect because arterial carbon dioxide peaks during the acute hypermetabolic phase and should be normalized by the 24-hour mark. Option C is incorrect because calcium levels often drop initially as calcium shifts intracellularly, and they do not predictably peak at 24 hours.
Question 4
During a departmental inservice on emergency preparedness, the educator discusses a crisis characterized by unexplained tachycardia and hypercarbia. Which of the following best describes the underlying cellular mechanism driving this crisis?
- A) Massive release of potassium from the intracellular fluid
- B) Rapid depletion of sodium within the neuromuscular junction
- C) Uncontrolled release of calcium from the sarcoplasmic reticulum✓
- D) Sudden accumulation of magnesium in the skeletal muscle
Show rationale
Malignant hyperthermia is primarily caused by a genetic mutation affecting the ryanodine receptor in skeletal muscle. When exposed to triggering agents, this receptor malfunctions, leading to an uncontrolled release of calcium from the sarcoplasmic reticulum into the intracellular space. This flood of calcium forces the muscle fibers into a continuous state of contraction, driving the severe hypermetabolism, heat production, and eventual cell breakdown seen during a crisis. The crisis is not driven by a massive release of potassium from the intracellular fluid, though hyperkalemia is a dangerous secondary consequence of muscle cell death. It does not involve rapid depletion of sodium at the neuromuscular junction or a sudden accumulation of magnesium. Understanding this calcium-driven mechanism is essential for recognizing why dantrolene is the definitive treatment.
Question 5
A patient with suspected malignant hyperthermia susceptibility is scheduled for a diagnostic muscle biopsy under general anesthesia. When verifying the availability of emergency equipment, which specific supply must the nurse confirm is ready?
- A) The crash cart is positioned directly inside the suite.
- B) A forced-air warming blanket is connected and ready.
- C) Three thousand milliliters of refrigerated saline is available.✓
- D) Preservative-free sterile water is stored in the refrigerator.
Show rationale
For a patient with suspected malignant hyperthermia, the perioperative nurse must ensure that refrigerated cold saline is immediately available for rapid intravenous cooling if a crisis occurs. Guidelines recommend having at least 3,000 milliliters of cold saline readily accessible. Option A is incorrect because while a crash cart must be accessible, the MH cart and specific cooling supplies are the targeted priority for this susceptibility. Option B is incorrect because a warming blanket is contraindicated; active cooling is required during a hypermetabolic crisis. Option D is incorrect because the preservative-free sterile water used to reconstitute dantrolene must be stored at room temperature, not in the refrigerator, to facilitate rapid dissolving of the medication.
Question 6
During an acute malignant hyperthermia event, the team must administer traditional 20-mg dantrolene. Recognizing the time-sensitive nature of this intervention, the circulating nurse should:
- A) Assign one anesthesia provider to manage all medication reconstitution.
- B) Wait for the facility pharmacy to deliver premixed medication.
- C) Mobilize multiple available staff members to reconstitute the medication.✓
- D) Delegate the medication reconstitution entirely to the surgical technologist.
Show rationale
Reconstituting traditional 20-mg dantrolene is incredibly labor-intensive, requiring 60 mL of sterile water per vial and vigorous shaking. Because an adult dose often requires 10 to 13 vials initially, the circulating nurse must mobilize available personnel to assist with mixing, making Option C the best choice. Option A is incorrect because the anesthesia provider must focus on airway management and physiologic stabilization. Option B delays critical treatment, as dantrolene must be given immediately. Option D is incorrect because the surgical technologist must maintain the sterile field integrity and manage surgical hemostasis.
Question 7
A patient with a history of severe asthma is undergoing an abdominal laparotomy. The anesthesia provider notes a sudden increase in peak inspiratory pressures and an absence of end-tidal carbon dioxide on the monitor. Which intervention is most appropriate?
- A) Administer a rapid intravenous dose of depolarizing succinylcholine.
- B) Deepen the anesthetic depth and administer inhaled albuterol.✓
- C) Perform a forceful jaw thrust with positive pressure.
- D) Prepare the neck for an emergent surgical cricothyroidotomy.
Show rationale
The combination of high peak inspiratory pressures, loss of end-tidal carbon dioxide, and a history of asthma strongly indicates severe bronchospasm. The optimal treatment involves deepening the anesthetic to relax the smooth muscle and administering a beta-agonist bronchodilator like albuterol. Succinylcholine and a jaw thrust are specific treatments for laryngospasm, which involves the vocal cords, not the lower airways. A surgical cricothyroidotomy bypasses the upper airway but provides no benefit for lower airway constriction, making it an ineffective and inappropriate choice for this specific emergency.
Question 8
During a complex spinal fusion, a 16-year-old patient exhibits sudden masseter muscle rigidity and a rapidly rising end-tidal carbon dioxide level. Initial arterial blood gas results reveal a pH of 7.15 and a base excess of -12 mEq/L. The team has already administered the initial dose of dantrolene.
- A) Prepare an infusion of regular insulin and dextrose for the acidosis.
- B) Prepare an immediate intravenous bolus of calcium chloride for the acidosis.
- C) Prepare an immediate intravenous bolus of sodium bicarbonate for the acidosis.✓
- D) Prepare an infusion of chilled normal saline to correct the acidosis.
Show rationale
A severe metabolic acidosis is a hallmark of an MH crisis due to intense hypermetabolism and lactate production. Option C is correct because sodium bicarbonate is the standard treatment for significant metabolic acidosis in this setting, guided by arterial blood gas results. Option A is incorrect because insulin and dextrose are used to treat hyperkalemia, not primarily the metabolic acidosis. Option B is incorrect because calcium chloride is an intervention for hyperkalemia-induced arrhythmias, not acidosis. Option D is incorrect because while cold saline aids cooling, it does not directly buffer a severe metabolic acidosis.
Question 9
An anesthesia provider notes an unexplained sudden rise in end-tidal carbon dioxide and reports a rigid jaw during intubation during an emergency appendectomy. Which action should the circulating nurse take to manage this situation?
- A) Administer intravenous dantrolene sodium and apply external cooling blankets immediately.
- B) Call for the malignant hyperthermia cart and alert the surgical team.✓
- C) Request iced intravenous saline and prepare for an immediate surgical incision.
- D) Obtain arterial blood gas samples and prepare the emergency defibrillator pads.
Show rationale
An unexplained sudden rise in end-tidal carbon dioxide combined with a rigid jaw during intubation are classic early warning signs of malignant hyperthermia. The nurse must immediately recognize this hypermetabolic crisis and call for the malignant hyperthermia cart while alerting the team. This action mobilizes the specific resources needed to save the patient. Administering dantrolene and applying cooling blankets are indeed the correct physiological treatments, but you cannot perform these actions until the specialized cart is brought into the room. Requesting iced saline and preparing for incision ignores the immediate need to halt the anesthesia trigger and manage the crisis. Obtaining blood gases and preparing defibrillator pads are supportive measures for later stages of the crisis, but they do not take precedence over securing the primary reversal agent and emergency supplies.
Question 10
The perioperative committee is transitioning to a new dantrolene formulation and orders Ryanodex for the facility MH carts. To maintain compliance with current malignant hyperthermia management guidelines, how should the nurse update the cart inventory?
- A) Maintain thirty-six vials of the new formulation.
- B) Maintain twenty-four vials of the new formulation.
- C) Maintain exactly three vials of the new formulation.✓
- D) Maintain exactly twelve vials of the new formulation.
Show rationale
The correct choice is C because the Ryanodex formulation is highly concentrated, containing 250 mg of dantrolene per vial, meaning only three vials are required to deliver the initial therapeutic loading dose. Option A is incorrect because 36 vials are only required for the traditional 20 mg dantrolene formulation. Options B and D represent incorrect inventory counts that do not align with any established guidelines for this specific medication. Stocking the correct amount prevents inventory waste while ensuring the cart remains uncluttered and immediately ready for a crisis.
Question 11
During a laparoscopic cholecystectomy using sevoflurane, the patient's end-tidal carbon dioxide steadily rises over forty minutes. The heart rate remains stable, and the patient exhibits no muscle rigidity. The perioperative nurse should attribute this presentation to which physiological process?
- A) Expected absorption of the pneumoperitoneum insufflation gas✓
- B) Early onset of a malignant hyperthermia crisis
- C) Inadequate depth of the volatile anesthetic agent
- D) Systemic reaction to the neuromuscular blocking agent
Show rationale
A is correct because a slow, steady rise in ETCO2 without tachycardia or rigidity during laparoscopic surgery is typically due to the systemic absorption of carbon dioxide used for pneumoperitoneum. B is incorrect because malignant hyperthermia presents with an abrupt ETCO2 spike and unexplained tachycardia. C is incorrect as inadequate anesthesia usually presents with hypertension and tachycardia alongside patient movement. D is incorrect because neuromuscular blockers do not cause a steady ETCO2 rise without other hypermetabolic crisis signs.
Question 12
A patient undergoing a complex spinal fusion experiences a sudden loss of end-tidal CO2 and palpable pulse. Because the surgical site is open, rapid supination is contraindicated. Which action should the perioperative nurse anticipate next?
- A) Initiate compressions directly over the mid-thoracic spine.✓
- B) Immediately reposition the patient into a supine posture.
- C) Apply chest compressions over the lower lumbar vertebrae.
- D) Place a rigid backboard underneath the patient's sternum.
Show rationale
When a patient suffers cardiac arrest prone and cannot be safely turned due to an open spine, AHA guidelines recommend initiating prone CPR. Compressions should be applied directly over the mid-thoracic spine (T7-T10) to compress the heart against the sternum. Option A is the correct standard of care. Option B is incorrect because rapid supination is contraindicated with an open spinal wound, risking severe neurological injury. Option C targets the wrong anatomical area, which would be ineffective for cardiac output and could damage the kidneys or lumbar spine. Option D is a near-miss; while firm counter-pressure is needed under the sternum, placing a backboard underneath a prone patient during an active arrest is often impractical, and the OR table usually provides sufficient firmness.
Question 13
A 28-year-old male develops an MH crisis during an open appendectomy. The perioperative team initiates active cooling with ice packs and cold intravenous fluids. His initial temperature was 40.2°C. The circulating nurse monitors his esophageal temperature probe and notes the reading has just reached 38.0°C (100.4°F).
- A) Discontinue all active cooling measures immediately to prevent profound hypothermia.✓
- B) Continue active surface cooling until the core temperature reaches 37.0°C.
- C) Remove surface ice packs but continue infusing cold intravenous fluids.
- D) Administer warmed intravenous fluids to stabilize the rapid temperature drop.
Show rationale
During an MH crisis, active cooling must be stopped when the core temperature reaches 38°C to prevent overshoot hypothermia. Option A is correct because continuing cooling past this point risks severe hypothermia and dangerous cardiac arrhythmias. Option B is incorrect as 37°C is too low a threshold to stop cooling. Option C is incorrect because all active cooling methods, including intravenous fluids, must stop simultaneously at 38°C. Option D is incorrect because applying active warming is unnecessary and counterproductive during the acute hypermetabolic phase of an MH crisis.
Question 14
A perioperative nurse conducts a monthly malignant hyperthermia cart audit and is currently verifying the cooling supply inventory. Which fluid configuration is required to properly support rapid patient cooling during an acute crisis?
- A) Three liters of refrigerated sterile water for intravenous infusion.
- B) Three liters of room-temperature normal saline for intravenous infusion.
- C) Three liters of room-temperature sterile water for intravenous infusion.
- D) Three liters of refrigerated normal saline for intravenous infusion.✓
Show rationale
The correct choice is D because treating a malignant hyperthermia crisis requires rapid core cooling using refrigerated normal saline administered intravenously. Option A is incorrect because sterile water is hypotonic and administering it intravenously would cause severe hemolysis and fluid shifts. Options B and C are incorrect because room-temperature fluids will not effectively lower the patient's dangerously high core body temperature. Maintaining a dedicated supply of cold isotonic fluids is a critical standard for emergency preparedness in the perioperative setting.
Question 15
A 28-year-old male experienced an MH crisis during an open appendectomy. The MH crisis is now resolved, and the patient is being prepared for ICU transfer. The nurse ensures the post-crisis maintenance plan includes which medication regimen?
- A) Administer dantrolene 1 mg/kg every 4 to 6 hours.✓
- B) Administer dantrolene 2.5 mg/kg every 4 to 6 hours.
- C) Administer dantrolene 1 mg/kg every 8 to 12 hours.
- D) Administer dantrolene 2.5 mg/kg every 8 to 12 hours.
Show rationale
Post-MH crisis care requires continuous vigilance because recrudescence can occur in a significant percentage of patients. The standard MHAUS recommendation for maintenance therapy is to administer dantrolene 1 mg/kg every 4 to 6 hours for at least 24 to 36 hours following the initial event. Option A correctly identifies this standard maintenance dose and frequency to prevent relapse. Option B uses the initial bolus dose rather than the appropriate maintenance dose, which could lead to severe muscle weakness. Option C uses the correct dose but an incorrect, extended interval that leaves the patient vulnerable to a secondary hypermetabolic episode. Option D uses both the incorrect initial bolus dose and the incorrect extended interval. Transferring the patient to the ICU with the correct maintenance dosing schedule ensures continuous protection while the patient stabilizes.
