Understanding Malignant Hyperthermia: Causes, Symptoms, and Treatment

1. Malignant Hyperthermia

2. What is Malignant Hyperthermia? • Malignant hyperthermia (MH) is an inherited hypermetabolic syndrome, that when triggered, causes sustained skeletal muscle contractions. • Can lead to severe hyperthermia, left ventricular failure, brain damage, organ failure, disseminated intravascular coagulation (DIC), cardiac arrest, and death. • Usually triggered during or after administration of commonly used general anesthetics

3. History of MH • 19th century – monitoring of patients minimal, deaths with surgery not uncommon and often unexplained. • Early 20th century – first reports of fever and tachycardia during or after anesthesia that ended in death, cause unknown. • 1960’s- first documented case of MH • Past mortality was 70%-80%, now with treatment ~5% within treatment hospital, 20% surgery centers or transferring hospitals.

4. Incidences Of MH • One in every 100,000 hospital discharges complicated by MH • 500-600 cases in US each year • Most common between ages 2 – 42 • 2/3 cases are men • More common in adults than children • 1st degree relative of someone who has had MH or MH susceptible is at greater risk • Higher risk in someone with a muscle disorder

5. Goal of Treatment • Prevention • Perioperative nurse includes risk assessment during routine pre-op interview • prior complications from previous surgery • Personal history of muscle disorder • Family history of complications with surgery • Caffeine intolerance • If MH occurs • quickest response possible to prevent complications and death

6. Triggers • Known triggers: • Volatile anesthetics - sevoflurane, isoflurane, and desflurane • Inhaled anesthetics (except nitrous oxide) • Muscle relaxant – succinylcholine • Do Not Trigger: • All local anesthetics, barbiturates, Benzodiazepines, etomidate, Ketamine, nitrous oxide, Nondepolarizing muscle relaxants, propofol

7. Malignant Hyperthermia Screening • Only definitive diagnostic test for MH is caffeine halothane contracture test (CHCT). • Done with thigh muscle biopsy • Only 4 centers in the US perform test, 2 in Canada • Patient must travel to testing centers, biopsy must be fresh • Cost $6,000 (not including travel), Cost usually not covered by insurance • Can use DNA analysis but only 30% effective, cost $200.

8. What’s Going ON • A MH-susceptible person has an abnormal structure and function of a calcium channel within their skeletal muscle • When exposed to trigger drugs an abnormal release of calcium inside the muscle cell occurs causing sustained muscle contraction, abnormal increase in energy utilization and heat production. • The muscle cell eventually runs out of energy and dies releasing large amounts of K and myoglobin into the bloodstream leading to arrhythmias and kidney failure.

9. Signs & Symptoms • Unexplained tachyarrhythmia (96% of cases) • Unexplained tachypnea (85% of cases) • Increased end-tidal CO2, hypoxemia • Acidosis (80%) • General muscle rigidity – one of earliest signs, especially in masseter muscle of the jaw (80%) • Cyanotic or mottled skin – generally starts with a generalized flush (70%) • Rapid, sustained increase in body temperature – late sign only 30% of cases. Temperature can be as high as 110° • Cola-colored urine due to rhabdomyolysis (later sign)

10. LABORATORY FINDINGS OF ACUTE MH • ABG decreased pH decreased PO2 increased PCO2 • Electrolytes increased K increased Ca increased Mg decreased Na

11. LABORATORY FINDINGS OF ACUTE MH (cont.) • Serum increased Lactate increased Pyruvate increased CPK increased LDH increased Aldolase increased Myoglobin increased Glucose increased Creatinine decreased PT decreased PTT decreased Platelets

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13. Responding to MH • Stop procedure as soon as possible • Discontinue all anesthetics, change soda lime canister, change breathing circuit, and hyperventilate with 100% O2 • Initiates MH protocol, call for MH cart and additional help – will need a minimum of 4 nurses and additional help • Give 2.5 mg/kg Dantrolene Sodium rapid IV • Monitor and Treat acidosis, hyperkalemia, arrhythmias, hyperthermia, rhabdomyolysis and other symptoms • Transfer to ICU – where the patient will remain for 24 hours after symptoms have resolved.

14. Circulating Nurse (1) • Calls immediately for additional help and MH cart • Assist anesthesia with anesthesia machine and as needed • Place additional IV lines • Draws blood/ ABG’s • Monitors patient including urine output

15. Dantrolene Nurse (2) • Bring MH cart • Start mixing Dantrolene ( will need up to 36 vials and 2 liters sterile water) • Administer Dantrolene as soon as possible

16. Dantrolene • The key to controlling a MH crisis is the quick administration of Dantrolene. • It is the first-line defense against reducing MH mortality. • Dantrolene is a muscle relaxant that restores a healthy level of calcium in the muscle and reduces high body temperature.

17. Dantrolene • Mix: • Mix each vial with 60cc sterile H20 (without bacteriostatic agents) use IV spike transfer pins to reconstitute • Shake vigorously to reconstitute, mix until clear- this may take several minutes • Give rapid continuous IV push. Administer 2.5 mg/kg. Repeat up to 10mg/kg or until symptoms subside • When mixed keep from light and use within 6 hours • Avoid use of calcium channel blockers with dantrolene - may cause life-threatening hyperkalemia and myocardial depression.

18. Dantrolene Dose Chart2.5mg/kg initial dose Weight (kg) Dose # Vials 15 37.5 mg ~ 2 30 75 mg ~4 45 112.5 mg ~5.5 60 150 mg ~7.5 75 187.5 mg ~9.5 90 225 mg ~11.25 105 262.5 mg ~13 120 300 mg ~15 135 337.5 mg ~17 150 375 mg ~18.75 These are approximate dose and vials used. Please check your calculations.

19. New research • Recent research revealed that • intravenous administration of life-saving Dantrolene can occur significantly faster by warming the diluent used in mixing • Thirty seconds or more can be shaved off the process which normally take at least two minutes EVERY SECOND COUNTS WHEN TREATING A PATIENT WITH MALIGNANT HYPERTHERMIA This research indicates that it is possible to administer Dantrolene faster, therefore increasing the chances of a successful patient outcome. • Journal of the American Association of Nurse Anesthetist April 2007

20. Medication Nurse (3) • Brings crash cart into room • Mix and administer drugs as needed: • Sodium bicarbonate to correct metabolic acidosis • IV glucose, insulin and calcium chloride to treat hyperkalemia • Antiarrhythmic agents to treat arrhythmias (Do not use calcium channel blockers) • Diuretics to prevent rhabdomyolysis • Lasix, mannitol and IV NS to maintain urine output of 1-2 ml/kg/hr

21. Cooling Nurse (4) • Obtains cooled IV solutions and ice • Monitor patient’s temperature • Cools the patient by : • Use of hypothermia blanket • Cooling room • Placing ice packs around patient • IV refrigerated solutions • Cold lavage through NG • Insert 3-way foley and irrigate with cool saline • If patient has open abdominal or thoracic cavity give scrub sterile refrigerated saline for surgeon to use in cavity STOP COOLING WHEN PATIENT’S TEMP IS 38° C (100° F) TO PREVENT HYPOTHERMIA

22. Additional Help • Help cooling nurse get ice from cafeteria and cooled saline from anesthesia fridge • Help make ice packs • Bring other supplies as needed • Run labs • Limit excessive traffic in room

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24. Post - Op • MH is most likely to occur in the OR, however, it can also occur in PACU within the first hour and up to 24 hours post-op. • MH may recur within hours of the initial episode and temperature fluctuations may continue for several days. • Dantrolene should be continued at 1 mg/kg every 4-6 hours for 48 hours in the ICU to prevent reappearance of symptoms.

25. Documentation Documentation should include: • All medications and times given • Labs drawn and times • Cooling methods used on patients • Vitals including temp. • All personal involved • All procedures completed (foley, NG, IV’s)

26. Legalities • Perioperative nurses should be aware of the legal considerations of MH. Lawsuits have been decided for the plaintiff when: • Risk factors were not identified preoperatively • Body temperature not monitored continuously • Failure to recognize signs and symptoms of MH • Failure to institute prompt and appropriate treatment

27. In Conclusion: EVERY SECOND COUNTS WHEN TREATING A PATIENT WITH MALIGNANT HYPERTHERMIA A malignant hyperthermia event is life-altering and can be deadly. But, with proper preparation, training, and teamwork a MH crisis can be managed without loss of life or serious adverse consequences. The MH Association of the US (MHAUS), maintains a 24-hour hot line that is staffed by anesthesiologists who are available to help those dealing with a MH event. There is a 1-800 number posted on all phones in the OR rooms, PACU and stage II.

28. References • Malignant hyperthermia-the perioperative nurse’s role. Ruth Hommertzheim, RN & Elaine Steinke, RN. AORN January 2006 pg 151 • Standards, Recommended Practices, and Guidelines. AORN, Inc. 2007 Ed. Pg 219-227. • Journal of the American Association of Nurse Anesthetist April 2007 Pg. 101-106 • Additional information also available on Malignant Hyperthermia carts and the Malignant Hyperthermia Association web site : www.mhaus.org