Malignant Hyperthermia

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 The perioperative nurse’s role in caring for the patients who are susceptible to MH is aimed at eliminating the cause, treating any derangements of normal physiology, and preventing further complications. This role is critical, requiring rapid response and cooperation of the entire perioperative team. An MH event is life-altering, and the consequences can be serious.

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. In the 19th century monitoring of the patients was minimal, and usually included only placing a finger on the patient’s pulse and observing respirations and skin color changes. Body temperature was rarely measured. The first documented case of MH to be reported was in the 1960’s. The case involved a 21-year-old trauma patient who had a strong family history of temperature-related complications of anesthesia. The patient experienced hypotension and tachycardia and became cyanotic and extremely hot after 10 min. under general anesthesia. The anesthesia care provider immediately stopped the anesthesia, and team members packed the patient in ice. The patient recovered.

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

Goal of Treatment Prevention If MH occurs 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 . Identifying patients at risk decreases the mortality and morbidity that’s associated with the syndrome. Assess prior complications from previous anesthesia, including any unexplained fever, cola-colored urine, or muscle weakness, cramps, or muscle group hypertrophy.

Triggers Known triggers: Do Not Trigger: 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 All of the above triggers are used here. Examples of nondepolarizing muscle relaxants are: rochronium (Zemeron), norcurion

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. Until recently, there were no simple diagnostic tests for MH screening Halothane contracture test requires removal of a portion of muscle from the thigh. This segment is stretched on a clamp and immersed in a caffeine solution. When a baseline state is obtained, halothane is introduced into the solution and contraction is observed. In a patient who is positive for MH, the rate of contracture is markedly higher than in a patient who is negative for MH. This is where a DNA analysis is obtained from a blood sample. Unfortunately, not all people susceptible have evidence of a DNA change, so it cannot yet replace the CHCT of biopsied muscle. The CHCT is a very sensitive test that detects virtually all patients who are susceptible to MH.

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.

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) Many health care providers believe the the most immediate symptom of MH is rapid and sustained rise in body temperature. Although this is a cardinal sign, it is a relatively late symptom, that actually only occurs in 30% of the patients experiencing MH. Mortality during MH is a result of acidosis, hyperkalemia, organ failure because of hyperthermia, disseminated intravascular coagulation (DIC), and renal failure. Rhabdomyolysis – accumulation of broken/ lysised skeletal muscle cells in the renal tubules, producing acute renal failure. It is an acute sometimes fatal disease.

LABORATORY FINDINGS OF ACUTE MH ABG decreased pH decreased PO2 increased PCO2 Electrolytes increased K increased Ca increased Mg decreased Na The above lab values are a quick reference if needed in an acute crisis of malignant hyperthermia. A copy has been laminated, and placed with the Dantrolene cards on our MH cart.

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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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.

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 Assist anesthesia: change circuit, change soda canister starting IV get supplies (or assign someone else) as needed

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

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.

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. Demonstrate dantrolene, sterile water, spring loaded syringe Emphasize use of STERILE WATER when mixing dantrolene. Deaths have been caused when saline used – because it would not mix and could not be given. Patient died due to prolonged time before dantrolene administered. Example of calcium channel blocker: verapamil, Procardia, cardiazim or norvasc

Dantrolene Dose Chart 2.5mg/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. Normal 165# almost 10 vials 250 # man 113.6 kg. ~14 vials for a starting dose. This is just a starting dose amount given could be four times as much. Dantrolene also continued in ICU every 4-6 hours for 48 hours.

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

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

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

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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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.

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) This incident becomes a part of our legal document, therefore it is very important to record as accurately as possible.

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 According to AORN, every facility should maintain a well-stocked MH treatment cart with dantrolene readily available, and there should be evidence that all staff members have had periodic inservice education in dealing with MH

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. Placement of Malignant Hyperthermia carts.

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