Malignant Hyperthermia

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  • Becker’s Muscle Dystrophy Onset in adolescence of muscle weakness Genetic defect on X chromosome Affects males Pathologically, an abnormal dystrophin protein Relatively normal life span
  • Some signs of MH may be more specific to the diagnosis than others. Specific signs are muscle rigidity , increased carbon dioxide production, rhabdomyolysis and marked temperature elevation. Less specific signs include tachycardia , tachypnea, acidosis and hyperkalemia. In most cases patients developing MH will demonstrate metabolic acidosis.
  • Malignant Hyperthermia

    1. 1. Malignant Hyperthermia What is it and how can it be prevented?
    2. 2. Malignant Hyperthermia <ul><li>What is it? </li></ul><ul><ul><li>Also known as MH or hyperpyrexia it is a rare, genetic autosomal-dominant and life threatening disease. </li></ul></ul><ul><ul><li>It is a hypermetabolic disorder of skeletal muscle which is a true emergency in the OR. </li></ul></ul><ul><ul><li>It is a biochemical chain reaction response “triggered” by commonly used general anesthetics and the paralytic agent succinylcholine within the skeletal system of susceptible individuals. </li></ul></ul><ul><ul><li>Usually triggered by general anesthetics either during or after administration in the Operating Room. </li></ul></ul>
    3. 3. Malignant Hyperthermia <ul><li>Who is susceptible? </li></ul><ul><ul><li>Over 80 genetic defects have been associated with MH. </li></ul></ul><ul><ul><li>It is inherited with an autosomal dominant pattern. </li></ul></ul><ul><ul><ul><li>If a child is born to a parent with MH susceptibility there is a 50% chance that the child will inherit a gene defect linked to MH. The child may develop an MH reaction upon exposure to triggers. The family may not be aware of the risk unless a family member has developed MH. </li></ul></ul></ul>
    4. 4. Malignant Hyperthermia <ul><li>Triggers: </li></ul><ul><ul><li>Drugs </li></ul></ul><ul><ul><ul><li>Sevoflurane </li></ul></ul></ul><ul><ul><ul><li>Desflurane </li></ul></ul></ul><ul><ul><ul><li>Isoflurane </li></ul></ul></ul><ul><ul><ul><li>Halothane </li></ul></ul></ul><ul><ul><ul><li>Enflurane </li></ul></ul></ul><ul><ul><ul><li>Methoxyflurane </li></ul></ul></ul><ul><ul><ul><li>Succinylcholine </li></ul></ul></ul>
    5. 5. Malignant Hyperthermia <ul><li>Triggers: </li></ul><ul><ul><li>Certain myopathies such as Evans, King-Denborough, and Multiple sclerosis, Becker’s Muscular dystrophy, kyphoscoliosis, and mytonis congenita </li></ul></ul><ul><ul><li>Emotional stress </li></ul></ul><ul><ul><li>Heat stroke </li></ul></ul><ul><ul><li>Neuroleptic Malignant syndrome </li></ul></ul><ul><ul><li>Strenuous exercise exertion </li></ul></ul><ul><ul><li>Trauma </li></ul></ul>
    6. 6. Malignant Hyperthermia <ul><li>Not MH Triggers </li></ul><ul><ul><li>Intravenous agents </li></ul></ul><ul><ul><li>Opioids </li></ul></ul><ul><ul><li>Non-depolarizing agents </li></ul></ul><ul><ul><li>Ketamine </li></ul></ul><ul><ul><li>Propofol </li></ul></ul><ul><ul><li>Anxiolytic </li></ul></ul>
    7. 7. Malignant Hyperthermia <ul><li>When does it Occur and who is the most susceptible? </li></ul><ul><ul><li>Occurs most commonly in men </li></ul></ul><ul><ul><li>Usually occurs between the ages of 2 and 42. </li></ul></ul><ul><ul><li>Incidence is usually between 1 in 50,000 to 100,00 adults and 1 in 300,000 children. </li></ul></ul>
    8. 8. What are the Clinical Manifestations of MH? <ul><li>Original Concepts: </li></ul><ul><ul><li>All patients have muscle rigidity </li></ul></ul><ul><ul><li>High fever, acidosis </li></ul></ul><ul><ul><li>High death rate </li></ul></ul><ul><ul><li>Current Concepts: </li></ul></ul><ul><ul><li>Muscle rigidity may or may not be present </li></ul></ul><ul><ul><li>Temperature is a late sign </li></ul></ul><ul><ul><li>End tidal CO2 is an early sign </li></ul></ul><ul><ul><li>MH may occur at any point during anesthesia - or become an emergency </li></ul></ul>
    9. 9. Malignant Hyperthermia <ul><li>Signs of Malignant Hyperthermia </li></ul><ul><ul><li>Specific </li></ul></ul><ul><ul><ul><li>Muscle Rigidity </li></ul></ul></ul><ul><ul><ul><li>Increased CO2 Production </li></ul></ul></ul><ul><ul><ul><li>Rhabdomyolysis </li></ul></ul></ul><ul><ul><ul><li>Marked Temperature Elevation </li></ul></ul></ul><ul><ul><li>Non Specific </li></ul></ul><ul><ul><ul><li>Tachycardia </li></ul></ul></ul><ul><ul><ul><li>Tachypnea </li></ul></ul></ul><ul><ul><ul><li>Acidosis (Resp/Metabolic) </li></ul></ul></ul><ul><ul><ul><li>Hyperkalemia </li></ul></ul></ul>
    10. 10. Malignant Hyperthermia <ul><li>What causes an episode of MH? </li></ul><ul><ul><li>MH susceptible persons have a gene mutation that results in the presence of abnormal proteins in muscle cells. </li></ul></ul><ul><ul><li>When these persons are exposed to certain anesthetic agents there is an abnormal release of calcium inside the muscle cell. </li></ul></ul><ul><ul><li>This calcium release results in sustained muscle contraction and an abnormal increase in energy utilization and heat production. </li></ul></ul><ul><ul><li>This contraction will cause the muscle to run out of energy and eventually die releasing a large amount of potassium into the blood- stream. </li></ul></ul><ul><ul><li>This release of potassium will lead to heart rhythm abnormalities as well as lethal rhythms such as V-fib and V- tach. </li></ul></ul>
    11. 11. Malignant Hyperthermia <ul><li>Causes Cont’d: </li></ul><ul><ul><li>At the onset of muscle cell death, the pigment myoglobin is also released and is potentially toxic to the kidneys. </li></ul></ul><ul><ul><li>If left untreated the patient will experience cardiac arrest, kidney failure, blood coagulation problems, internal hemorrhage, brain injury, and possibly death. </li></ul></ul>
    12. 12. Malignant Hyperthermia <ul><li>How is it treated? </li></ul><ul><ul><li>Early identification is essential to a positive outcome. </li></ul></ul><ul><ul><ul><li>Procedure is stopped immediately (or ASAP). </li></ul></ul></ul><ul><ul><ul><li>All anesthetics are discontinued immediately and anethesia person delivers 100% oxygen and flushes the CO2 circuit with 100% oxygen. </li></ul></ul></ul><ul><ul><ul><li>Anesthesia provider hyperventilates the patient with 100% O2. </li></ul></ul></ul><ul><ul><ul><li>The circulating nurse will initiate the MH protocol and call for additional OR support. </li></ul></ul></ul>
    13. 13. Malignant Hyperthermia <ul><li>Treatment Cont’d: </li></ul><ul><ul><li>Circulator will continue to assist anesthesia and draw blood, insert IV lines etc and assign a dantrolene nurse. </li></ul></ul><ul><ul><li>The Dantrolene nurse will retrieve or assign someone to retrieve the MH cart. This nurse will be responsible for the mixing and administration of the dantrolene. </li></ul></ul><ul><ul><li>A third nurse will be assigned as the medication nurse and will bring the crash cart into the OR room. This nurse will function along side the anesthesia person to assist with correction of metabolic disturbances. (insulin, glucose, calcium, antiarhythmic agents, and diurectics) </li></ul></ul><ul><ul><li>A fourth nurse will be responsible for cooling the patient. This nurse will place ice packs, hypothermia blankets and cooled fluids. Remember LR is NOT given. Cooling is stopped when the core temp reaches 100 degrees F. </li></ul></ul><ul><ul><li>Once these procedures have been completed, the patient will be transported to ICU. </li></ul></ul>
    14. 14. Malignant Hyperthermia <ul><ul><li>A fourth nurse will be responsible for cooling the patient. This nurse will place ice packs, hypothermia blankets and cooled fluids. Remember LR is NOT given. Cooling is stopped when the core temp reaches 100 degrees F. </li></ul></ul><ul><ul><li>Once these procedures have been completed, the patient will be transported to ICU. </li></ul></ul>
    15. 15. Dantrolene for MH crisis: Acute <ul><li>Recommended dosing is 2.5mg/kg </li></ul><ul><li>Typical packaging : 20 mg/60 ml = 1 mg/3ml </li></ul><ul><li>70 kg patient: </li></ul><ul><ul><li>2.5 mg/kg = 175 mg or 525 ml ( 9 vials) </li></ul></ul><ul><ul><li>Give as soon as diagnosed. </li></ul></ul><ul><ul><li>Dantrolene is the only specific treatment for MH </li></ul></ul>
    16. 16. Prevention of Malignant Hyperthermia <ul><li>Preop personal/family history of anesthetic problems, neuromuscular disorders </li></ul><ul><li>Temperature/end tidal CO2 monitoring during general anesthesia </li></ul><ul><li>Recognition of masseter rigidity </li></ul><ul><li>Investigation of unexplained tachycardia, hypercarbia, hyperthermia </li></ul><ul><li>Availability of Dantrolene </li></ul><ul><li>Avoiding MH triggers in MH susceptibles </li></ul><ul><li>Using Succinylcholine in indication </li></ul>
    17. 17. Your Role in MH <ul><li>Be certain the patient has a CBC, SMA 7 and coagulation studies performed results are normal and located on the medical record. </li></ul><ul><li>Be certain any abnormal values have been discussed with the Anesthesiologist. </li></ul><ul><li>Be certain the patient has no negative surgical/anesthestic history. (if history is noted- be certain Anesthesiologist is aware) </li></ul>
    18. 18. Your Role Cont’d: <ul><li>Place MH cart in the OR suite if the potential for MH is identified in your patient. </li></ul><ul><li>Discuss with the anesthesia provider the need for a dedicated machine for this individual patient. </li></ul><ul><li>Prepare intra-operative monitoring: </li></ul><ul><ul><li>ECG - Capnometry - ABG </li></ul></ul><ul><ul><li>BP - Temp </li></ul></ul><ul><ul><li>HR - UOP </li></ul></ul>
    19. 19. Malignant Hyperthermia <ul><li>QUESTIONS ??????????? </li></ul>

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