Malignant Hyperthermia Overview

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Questions and Answers

What is the primary genetic cause of malignant hyperthermia?

  • Dysfunction of calcium pump proteins
  • Mutation in the sodium channel gene
  • Mutation in the ryanodine receptor type 1 (RYR1) gene (correct)
  • Alteration of the ATP synthase enzyme

Which laboratory finding is often elevated in cases of malignant hyperthermia?

  • Increased albumin levels
  • Increased calcium levels
  • Increased pH levels
  • Increased creatinine kinase levels (correct)

Which symptom is considered an early sign of malignant hyperthermia during anesthesia?

  • Increased end-tidal carbon dioxide (ETCO2) (correct)
  • Bradycardia
  • Muscle rigidity
  • Increased body temperature

What is a contraindication during an episode of malignant hyperthermia?

<p>Calcium channel blockers usage (C)</p> Signup and view all the answers

Which of the following are potential complications of malignant hyperthermia?

<p>Severe electrolyte imbalances (B), DIC (Disseminated Intravascular Coagulation) (D), Myoglobinuria (A)</p> Signup and view all the answers

In the management of hyperkalemia during malignant hyperthermia, which treatment method is recommended?

<p>Provide calcium for life-threatening hyperkalemia (C)</p> Signup and view all the answers

What is the primary reason for mortality in malignant hyperthermia despite treatment with dantrolene?

<p>Hyperkalemia and hyperthermia (D)</p> Signup and view all the answers

What does the mutation in the RYR1 gene cause when exposed to volatile anesthetics and depolarizing neuromuscular blocking agents?

<p>Uncontrolled calcium release and sustained muscle contraction (A)</p> Signup and view all the answers

What causes patients with malignant hyperthermia to become hyperthermic?

<p>Hypermetabolism - Increased use of ATP and O2 = increased heat (A)</p> Signup and view all the answers

How does malignant hyperthermia (MH) lead to myoglobinuria?

<p>Increased muscle metabolism leads to excessive protein breakdown. (A), Inadequate oxygen supply results in muscle damage. (C)</p> Signup and view all the answers

Why are patients with Malignant Hyperthermia (MH) typically acidotic?

<p>Due to increased lactic acid and CO2 production from muscle metabolism (A)</p> Signup and view all the answers

What patient conditions are associated with Malignant Hyperthermia (MH)? (Select all that apply)

<p>King-Denborough syndrome (A), Central core disease (B), Multiminicore disease (C), Evans myopathy (D)</p> Signup and view all the answers

What are the anesthetic triggers for Malignant Hyperthermia (MH)?

<p>Volatile inhalation anesthetics (A), Depolarizing muscle relaxants (C)</p> Signup and view all the answers

What cardiac sign is typical of a patient with malignant hyperthermia?

<p>Tachycardia (B)</p> Signup and view all the answers

Rhabdomyolysis and coagulopathies are a late sign of MH

<p>True (A)</p> Signup and view all the answers

What is the gold standard for diagnosing Malignant Hyperthermia (MH)?

<p>Muscle biopsy with caffeine halothane contracture test (B)</p> Signup and view all the answers

What solution is used to reconstitute dantrolene?

<p>Sterile water for injection (B)</p> Signup and view all the answers

Which of the following are non-anesthetic or environmental triggers for Malignant Hyperthermia? (Select all that apply)

<p>Stress (A), Heat stroke (B), Exercise-induced rhabdomyolysis (C)</p> Signup and view all the answers

MH can occur at any point during anesthesia and emergence

<p>True (A)</p> Signup and view all the answers

Dantrolene therapy must continue for days after MH onset to prevent recurrence

<p>True (A)</p> Signup and view all the answers

What are the expected lab findings for a patient with Malignant Hyperthermia?

<p>Hyperkalemia, hypercalcemia, hyperphosphatemia (A), Increased creatinine kinase (CK) (B), Acidosis (C), Hypoxia (D)</p> Signup and view all the answers

You suspect your patient is experiencing a malignant hyperthermia crisis. Which of the following actions do you take first?

<p>Discontinue volatile anesthetics (D)</p> Signup and view all the answers

What type of gas flows should be used when you suspect a patient has malignant hyperthermia?

<p>High flow 100% FiO2 (A)</p> Signup and view all the answers

What is the initial dose of dantrolene used in Malignant Hyperthermia?

<p>2.5 mg/kg (B)</p> Signup and view all the answers

Dysrhythmias in malignant hyperthermia (MH) are secondary to which of the following conditions? (Select all that apply)

<p>Acidosis (A), Hyperkalemia (B)</p> Signup and view all the answers

What are the preferred treatments for hyperkalemia during malignant hyperthermia? (Select all that apply)

<p>Bicarbonate (A), Glucose/Insulin (B)</p> Signup and view all the answers

How does calcium help treat hyperkalemia?

<p>It stabilizes the cardiac membranes against the effects of high potassium. (B)</p> Signup and view all the answers

Calcium does not directly lower serum potassium levels; it helps stabilize cellular membranes

<p>True (A)</p> Signup and view all the answers

Once the malignant hyperthermia patient has stabilized, which interventions can be done to maintain urinary output? (Select all that apply)

<p>Intravenous fluids (A), Diuretics (B)</p> Signup and view all the answers

What is the recurrence rate for Malignant Hyperthermia (MH)?

<p>25% (A)</p> Signup and view all the answers

What is the maintenance dose for dantrolene?

<p>1 mg/kg every 4-6 hours for 24-48 hours (A)</p> Signup and view all the answers

What does it mean that Malignant Hyperthermia (MH) is an autosomal dominant disorder?

<p>There is a 50% chance of passing the disorder to a child if one parent has the mutated gene. (B)</p> Signup and view all the answers

Which of the following conditions can mimic Malignant Hyperthermia? (Select all that apply)

<p>Pheochromocytoma (D), Thyroid storm (A), Iatrogenic overheating (B), Neuroleptic malignant syndrome (C)</p> Signup and view all the answers

What is the purpose of a vapor clean anesthesia filter?

<p>To remove harmful volatile from the anesthesia circuit (A)</p> Signup and view all the answers

Should patients at risk for Malignant Hyperthermia (MH) be pretreated with dantrolene?

<p>No, it is not necessary. (B)</p> Signup and view all the answers

What are the recommended PACU holding times for patients with Malignant Hyperthermia?

<p>1 hour in Phase 1, 1 hour in Phase 2 (A)</p> Signup and view all the answers

Which of the following medications should be available in a malignant hyperthermia (MH) kit? (Select all that apply)

<p>Furosemide (C), Dantrolene (A), Mannitol (B), Sodium Bicarbonate (D), Antiarrhythmics (E)</p> Signup and view all the answers

Which group is most likely to experience intraoperative malignant hyperthermia?

<p>Pediatric males (C)</p> Signup and view all the answers

What is the appearance of the skin of a patient with Malignant Hyperthermia?

<p>Mottled (A)</p> Signup and view all the answers

What is an abnormal length of masseter muscle rigidity post-succinylcholine administration?

<p>Greater than 1 minute (C)</p> Signup and view all the answers

What is the mechanism of action of dantrolene?

<p>Blocks calcium release from the sarcoplasmic reticulum (A)</p> Signup and view all the answers

How is dantrolene reconstituted?

<p>20 mg in 60 cc of sterile water (B)</p> Signup and view all the answers

Match the sign with its timing

<p>Tachycardia and tachypnea = Early Warm soda lime = Early Masseter spasm = Early Muscle rigidity = Late</p> Signup and view all the answers

Early signs of MH = tachycardia, tachypnea, warm soda lime, increased ETCO2, masseter spasm

<p>True (A)</p> Signup and view all the answers

Late signs of MH = hyperthermia, rhabdomyolysis, coagulopathy, muscle rigidity

<p>True (A)</p> Signup and view all the answers

Flashcards

Malignant Hyperthermia (MH)

A genetic disorder causing uncontrolled muscle contractions, triggered by certain anesthetics.

RYR1 gene

The gene often mutated in Malignant Hyperthermia patients.

Triggers of MH

Volatile anesthetics and depolarizing neuromuscular blockers.

Calcium Release

Uncontrolled calcium release that leads to sustained muscle contractions in MH.

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Hypermetabolic Response

Increased oxygen, heat, and CO2 production in MH.

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ETCO2

Early indication of MH: Increased end-tidal carbon dioxide.

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Increased Body Temperature

A late sign of MH.

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Tachycardia

Fast heart rate, almost always present in MH.

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Muscle Rigidity

Muscle stiffness, might be observed in MH.

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Tachypnea

Increased breathing rate in MH.

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Myoglobinuria

Myoglobin in the urine, a serious MH symptom

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DIC

Disseminated intravascular coagulation, a serious complication of MH

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Dysrhythmias

Irregular heartbeats, sometimes occurring in MH.

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Onset of MH

During anesthesia, on emergence, or in PACU.

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Fulminant MH

Rapid onset MH, occurring soon after induction.

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Dantrolene

Medication used to treat MH.

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Hyperkalemia

High potassium levels, potentially fatal in MH.

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Hyperphosphatemia

Elevated phosphate levels, a complication of MH.

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Hypercalcemia

High calcium levels associated with MH.

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Creatine Kinase (CK)

Elevated levels indicate muscle damage, often in MH.

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Acidosis

Acid build-up, a potential consequence of MH.

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100% FiO2

100% oxygen, vital in immediate MH treatment.

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Dantrolene Dosage

2.5 mg/kg mixed with sterile water.

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Cooling Measures

Reducing body temperature is crucial in MH treatment.

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Contraindication (Calcium Channel Blockers)

Should not be used to treat MH.

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Study Notes

Malignant Hyperthermia Overview

  • Malignant hyperthermia (MH) is a genetic disorder linked to mutations in the ryanodine receptor type 1 (RYR1 gene).
  • Triggered by volatile anesthetics and depolarizing neuromuscular blockers.
  • Results in uncontrolled calcium release leading to sustained muscle contractions.

Hypermetabolic Response

  • Increased oxygen consumption and ATP usage lead to heightened heat production.
  • Enhanced production of carbon dioxide (CO2) and lactate.
  • Cellular breakdown releases myoglobin into the bloodstream.
  • Increased sympathetic nervous activity results in stress responses.

Signs and Symptoms

  • Early indication of MH includes increased end-tidal carbon dioxide (ETCO2).
  • Increased body temperature is a late sign of MH.
  • Tachycardia is almost universally present during an episode.
  • Muscle rigidity may or may not be observed.
  • Symptoms may include tachypnea (increased breathing rate) and signs of exhausted CO2 absorbent.
  • Myoglobinuria (presence of myoglobin in urine), disseminated intravascular coagulation (DIC), and dysrhythmias may occur.

Onset and Triggers

  • Onset can occur at any stage during anesthesia, on emergence, or during the post-anesthesia care unit (PACU) stay.
  • Fulminant MH can manifest within minutes of induction of general anesthesia.
  • Environmental factors such as hyperthermia, stress, and exercise-induced rhabdomyolysis can trigger episodes.

Associated Conditions

  • MH is linked with several myopathies including central core disease, multi-minicore disease, and King Denborough syndrome.

Electrolyte Abnormalities

  • Patients may exhibit mixed respiratory and metabolic acidosis.
  • Elevated creatinine kinase levels indicate muscle damage.
  • Electrolyte disturbances include hyperkalemia, hyperphosphatemia, and hypercalcemia.
  • Abnormal coagulation profiles may be present.

Immediate Treatment Protocol

  • Obtain the red MH bag and vapor-clean filters for emergency management.
  • Discontinue the use of volatile anesthetic agents or succinylcholine.
  • Hyperventilate the patient with 100% fraction of inspired oxygen (FiO2).
  • Administer dantrolene at a dosage of 2.5 mg/kg mixed with sterile water; reconstitute 250 mg/vial with 5 mL of sterile water.
  • Utilize large bore IV access to minimize phlebitis risks.
  • Cool the patient using cold normal saline fluids, ice packs, and by lowering room temperature.
  • Address acidosis and hyperkalemia with bicarbonate, glucose/insulin, and calcium for severe cases.

Contraindications and Follow-up Care

  • Calcium channel blockers are contraindicated in MH management.
  • Dantrolene therapy must be continued for days following an episode to prevent recurrence.
  • Maintenance dosing of dantrolene is 1 mg/kg every 4-6 hours for 24-48 hours.

Prognosis

  • Acute mortality in MH patients often results from complications like hyperkalemia and hyperthermia, underscoring the urgency of treatment.

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