Malignant HyperthermiaA. Bonet, MSN, BHSA, RN, CNOR

• Objectives

• Outline the history of MH as a known disorder.

• Identify risk factors for MH.

• Identify the pathophysiology of MH.

• Identify triggering agents for MH.

• Identify methods of treating a patient during an MH crisis.

• Identify steps in post MH crisis patient care.

Outline the history of MH as a known disorder

• Malignant hyperthermia (MH) was first identified in the 1960s when a patient with a strong family history of anesthetic complications demonstrated increased body temperature, a rapid heart rate, and decreased blood pressure after induction ofSoon after this incident, clinicians realized that MH is a hypermetabolic state occurring within skeletal muscle cells that is often triggered by administration of common general anesthetics, such as halothane, isoflurane, sevoflurane, desflurane, or enflurane, alone or in combination with succinylcholine, a depolarizing muscle relaxant and neuromuscular blocker. Emotional stress, trauma, or strenuous exercise also can trigger MH.

Identify risk factors for MH.

• Malignant hyperthermia can occur in patients who are young or old, male or female. Patients at risk for MH often have inherited skeletal muscle abnormalities associated with MH, such as congenital myopathies and some muscular dystrophies. Susceptibility to MH is hereditary, with an autosomal dominant inheritance pattern. Family members (ie, children, siblings) of a patient with MH susceptibility have a 50% chance of inheriting a gene defect for MH and becoming MH susceptible. A rare muscular disorder called central core disease, which affects the muscles used for movement, and a muscular syndrome called King-Denborough syndrome, a congenital myopathy, are associated with patients who are carriers of the genetic factors that make them susceptible to MH.

Pre-op questions to ask patients to determine risk for MH

• Have you or any of your family members ever had a “bad” reaction to general anesthesia? Not nausea or vomiting.

• Have you or any members of your family had dark brown urine after receiving general anesthesia?

• Have you or any members of your family had an instance of overheating while at play or doing sports that resulted in rapid heart rate (after cessation of activity), elevated body temperature, and brown colored urine?

• Do you or any members of your family have a history of any type of Muscular Dystrophy or Central Core disease?

Do you or any members of your family have a history of any type of Muscular Dystrophy or Central Core disease?

The pathophysiology of MHWhat is a hypermetabolic state?

• During an MH event, a biochemical chain reaction occurs that is often characterized first by an unexpected rise in end-tidal carbon dioxide (ETCO2) and muscle rigidity. Characteristics of MH include hypercarbia, hypoxia, metabolic and respiratory acidosis, tachypnea, dysrhythmias, and an increase in body temperature. This sign may be missed early in the course of the reaction because of the decrease in temperature that often accompanies anesthesia and surgery. Therefore, an increase in body temperature, which can exceed 43.3° C [109.9° F]), is often a later sign of an MH event. This rise in body temperature can increase dramatically by 1° C to 2° C [1.8° F to 3.6° F] every five minutes.

The pathophysiology of MH

Early clinical signs

• Increased body temperature, increased ETCO2, masseter muscle spasm, and tachycardia may appear with little obvious explanation.

• Clinicians should consider the presence of MH whenever there are unexplained signs, such as increased temperature, muscular rigidity, and respiratory or ventilatory problems.

• Any increase in temperature requires immediate consideration of MH.

Results of untreated MH

• cardiac arrest, kidney and liver failure, abnormal blood coagulation, internal hemorrhage, neurologic injury, cardiovascular collapse, and death.

Identify triggering agents for MH.

When does onset of MH begin

• An MH response is often triggered during anesthetic induction with the identified triggering agents. Malignant hyperthermia may first occur after repeated exposure to anesthesia, or it may occur postoperatively in the postanesthesia care unit (PACU) or the intensive care unit (ICU).

Unsafe Anesthetic Agents for Malignant Hyperthermia–Susceptible Patients

• Inhaled general anesthetics

• ■Desflurane

• ■Enflurane

• ■Isofluran

• ■Sevoflurane

Depolarizing neuromuscular blockers

■Succinylcholine

Safe Anesthetic Agents for Malignant Hyperthermia–Susceptible Patients

Barbiturate and IV anestheticsLocal anesthetics

• Articaine

• ■Bupivicaine

• ■Dibucaine

• ■Lidocaine

• ■Mepivacaine

• ■Prilocaine

• ■Proparacainehydrochloride

• ■Ropivacaine

• ■Tetracaine

• ■Diazepam

• ■Etomidate

• ■Ketamine

• ■Methohexital

• ■Midazolam

• ■Pentobarbital

• ■Propofol

Inhaled nonvolatile general anesthetics

■Nitrous oxide

Safe Anesthetic Agents for Malignant Hyperthermia–Susceptible Patients

Narcotics (ie, opioids

• Alfentanil

• ■Codeine

• ■Fentanyl

• ■Hydromorphone

• ■Meperidine

• ■Methadone

• ■Morphine

• ■Naloxone

• ■Oxycodone

• Remifentanil

• ■Sufentanil

Muscle relaxants (ie, nondepolarizingneuromuscular blockers

• ■Cisatracurium

• ■Vecuronium

• ■Pancuronium

• ■Rocuronium

Safe Anesthetic Agents for Malignant Hyperthermia–Susceptible Patients

• Anxiety-relieving medications• ■Chlordiazepoxide• ■Clidinium and chlordiazepoxide• ■Clonazepam• ■Clorazepate• ■Diazepam• ■Flurazepam• ■Lorazepam• ■Midazolam• ■Oxazepam• ■Temazepam• ■Triazolam

Treating a patient during an MH crisis will require large numbers of staff to

work quickly in organized manner, there must be a team leader

• The goal of treatment in an MH crisis is to arrest the abnormal metabolic process with dantrolene and to return to normal temperatures, hemodynamic conditions, and metabolic functions.

You can use a 1 liter bag of sterile injectable water and draw the 60mls with a 60ml syringe

Have the MH management poster visible at all times. All staff should know location of MH cart or kit.

Check the cart or kit on a periodic basis to ensure all supplies are available and Dantrolene is not expired. Keep a log of inspection dates.

All staff must know where….

• ■Know where to access emergency resources, including medications, sterile water, chilled solutions, and contact information for the Malignant Hyperthermia Association of the United States (MHAUS).

• ■ Know where to locate laboratory and blood bank supplies, including laboratory testing tubes and labels, arterial blood gas supplies, rapid infusion and lavage devices and tubing, and pressure bags.

• ■MH help line telephone number attached to the top of the cart.

• ■MH policy/protocols attached to the top of the cart.

Treating a patient in MH crisis;

• Discontinue volatile agents and succinylcholine.

• Hyperventilate patient with 100% o2 at 10L/min.

• Rapidly start Dantrolene2.5mg/kg IV with large bore needle, repeat as needed until resolved

• Change breathing circuits.

• Change Soda Lime canister.

• Draw labs-STAT

• Treat symptoms of hyperkalemia, arrhythmias, and monitor renal function.

• Stop Lactated Ringers

Have lab kit ready with appropriate tubes and Stat requisitions (alert the

Lab)– ■basal metabolic panel (ie, Chemistry 7)

• ■sodium

• ■potassium

• ■chloride

• ■bicarbonate or carbon dioxide

• ■blood urea nitrogen

• ■creatinine

• ■glucose

– ■chemistry 8 (ie, all the components of a basal metabolic panel plus calcium)

– ■myoglobin (ie, serum and urine-use urine test strip)

Make sure Blood Gases are also drawn to check for acidosis

– ■serum creatine kinase

–■coagulation studies

• ■platelets

• ■prothrombin time

• ■activated partial thromboplastin time

• ■fibrinogen

• ■d-dimer (ie, fibrin degradation test)

Treatment for hyperkalemia and for arrhythmia

• Treat hyperkalemia with insulin or 50% dextrose. For adults use 10mg/kg calcium chloride or 10 to 50 mg/kg calcium gluconate

• Treat arrhythmias with lidocaine or amiodarone, beta blockers but DO NOT USE CALCIUM CHANNEL BLOCKING AGENTS

Additional supplies

• ■Nasogastric tubes and 60-mL irrigation/evacuation syringes for internal lavage

• ■Rectal tubes for internal lavage

• ■Arterial pressure monitoring lines

• ■Arterial blood gas kit

• ■Venous blood gas kit

• ■Ice for plastic bags to place around the patient

• ■Padding to protect the patient’s ears and nose from frostbite

• ■Indwelling urinary catheter kits

• ■Clipboard

• ■Cold normal saline irrigation

• ■Cold IV saline

In a outpatient setting

• Outpatient preparation is comparable to inpatient preparation except that fewer resources and personnel may be available (eg, limited medications, fewer personnel, limited laboratory testing capabilities).

• Determine amount of Dantrolene that will be needed for time patient is at ASC and potentially for transport time.

• Determine what Labs can be done on site and which will have to be done upon arrival to a tertiary care center.

• The necessary steps for preparing an MH patient for transfer should be identified before a full-blown crisis occurs, put into a formal policy and procedure, and made quickly available when needed.

The steps of the process should include the

following:

• Decide when to transfer the patient.• Ensure that the transport carrier is capable of treating a

patient experiencing an MH crisis (eg, able to provide intensive care unit–level care, support ventilation, administer IV medications).

• Ensure that the receiving facility is capable of treating MH and providing intensive care.

• Speak directly with the person receiving the patient with MH to facilitate both a safe transfer and an effective receipt of the patient (generally this requires direct physician-to-physician communication).

• Make an MH report form available to the receiving institution, including MH-related patient details, anesthetic agents used, and amount of dantrolene given.

• Ensure that transfer actions and policies are included in the organization’s MH drills.

Post Acute Phase Management in PACU or ICU

• Post Acute Phase Management in PACU or ICU – If assistance is needed, call the MHAUS Hotline (1-800-644-

9737).

• Monitor ECG, ETCO2, minute ventilation, core temperature, urine output (with bladder catheter if necessary), and consider arterial and/or central venous monitoring if warranted by the clinical severity of the patient. Document muscle tone.

• Follow: Continuously for the first 24 hours: – HR– RR– Core temperature– ETCO2 (if intubated)– Oxygen saturation– Muscle tone

Post Acute Phase Management in PACU or ICU

Follow: Every 8 hours:– Blood pH and lactate– K+

– CK (until decreasing)Coagulation studies should be obtained as a baseline and when there is evidence of bleedingBaseline renal function, i.e., creatinine - should be measured and followed at least q 24h if myoglobinuria has occurredA search for infectious causes for a hypermetabolic state may be appropriateFollow urine color and institute therapy to prevent myoglobin precipitation in renal tubules and acute renal failure. CK levels above 10,000 IU/L are a presumptive sign of rhabdomyolysis and myoglobinuria.

• Alkalinize urine with sodium bicarbonate, use diuretics to maintain urine output >2ml/kg/hr.

Post Acute Phase Management in PACU or ICU

• Follow urine and serum pH values, serum electrolytes, and creatinine.– Watch for MH relapse by continuously evaluating the patient for at least 24 hours

following cessation of signs of MH. 25% of MH events relapse and relapses can be fatal. Treat immediately if relapse occurs. Signs of MH relapse include: • Increasing muscular rigidity in the absence of shivering• Inappropriate hypercarbia with respiratory acidosis• Metabolic acidosis without other cause• Inappropriate temperature rise

– Give dantrolene, 1mg/kg IV q 4-6h or 0.25mg/kg/hr by infusion and continue for at least 24 hours and sometimes longer as clinically indicated. Dantrolene can be stopped, or the interval between doses increased to q8 or q12h if all of the following criteria are met: • Metabolic stability for 24 hours• Core temp is less than 38°C• CK is decreasing• No evidence of myoglobinuria• Muscle is no longer rigid

Post Acute Phase Management in PACU or ICU

– Monitor for MH Complications: • Change in consciousness level/coma

• Cardiac dysrhythmias and dysfunction

• Pulmonary edema

• Renal dysfunction due to acute tubular necrosis

• Disseminated intravascular coagulation

• Hepatic dysfunction

• Muscular weakness (Secondary to both rhabdomyolysisand dantrolene)

• Compartment syndrome (Secondary to rhabdomyolysis)

Post Acute Phase Management in PACU or ICU

• Report this anesthetic complication on the AMRA form to the MH Registry of MHAUS. Forms are available on line at www.mhaus.org/registy as a pdf that can be printed out and by contacting:

• North American MH Registry of MHAUSUPMC Mercy Hospital8th Floor, Ermire Building (B)Room 8522-31400 Locust StreetPittsburgh, PA 152191-888-274-7899www.mhaus.org/registry

References

Larach, M.G., Gronert, G.A., Allen, G.A., Brandom, B.B., and Lehman, E.B. Clinical presentation, treatment, and complications of malignant hyperthermia in North America from 1987 to 2006. Anesth Analg. 2010; 110: 498–507

FAQs: general MH questions. Malignant Hyperthermia Association of the United States. http://www.mhaus.org/faqs/about-mh. Accessed May 10, 2014.

Seifert, P.,C., Wahr, J.,A., Pace, M., cochrane,A.,B., Bagnola, A.,J., Crisis Management of Malignant Hyperthermia in the OR. AORN Journal, 8/2014, v100, 189-202

Post Acute Phase Management in PACU or ICU http://www.mhaus.org/healthcare-professionals/after-a-crisis/post-acute-phase, Accessed March 11,2016