1 / 30

Malignant Hyperthermia A Review

Malignant Hyperthermia A Review. Jonathan Parmet, M.D. Society Hill Anesthesia Consultants. Objectives. Define Malignant Hyperthermia Review Triggering agents Diagnosis of Malignant Hyperthermia Treatment of Malignant Hyperthermia. Case Presentation.

dionne
Download Presentation

Malignant Hyperthermia A Review

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Malignant Hyperthermia A Review Jonathan Parmet, M.D. Society Hill Anesthesia Consultants

  2. Objectives • Define Malignant Hyperthermia • Review Triggering agents • Diagnosis of Malignant Hyperthermia • Treatment of Malignant Hyperthermia

  3. Case Presentation • 43 yr old male for renal transplant. He has had more than 30 previous general anesthetics most minor procedures. No family history of anethetic complications. • General anesthesia- thiopental / atricurium / nitrous oxide / isoflurane / midazolam / fentanyl • 1 1/2 hours into the procedure ABG pH= 7.29, PCO2 = 35, pO2=120 HCO3=17 BE= -8.3 K=4.2 meq/l • 2 1/2 hrs ABG pH=7.23, pCO2=44, pO2= 93, HCO3=18 BE=-9 K=5.8 meq/l Temp increase from 37.6 C to 38.8, HR= 120 beats/min • 3 1/2 hrs ABG pH=7.08, pCO2=66, PO2=111, HCO3=19, BE=-10.2 • Isoflurane discontinued Dantrolene 2.6 mg/kg

  4. Malignant Hyperthermia Definition • myopathy • genetically inherited (autosomal dominant w/ varying penetrance • hypermetabolic disease of the muscle • manifestations vary • Cand demonstrate following induction of GA w/ trigger agent, late into case, or hrs postoperatively • Pathophysiology - intracellular hypercalcemia activates metabolic processes yielding ATP depletion, acidosis, membrane destruction, and cell death

  5. Malignant Hyperthermia • Sustained hypermetabolic state due to impaired handling of intracellular calcium • Pathophysiology- still not fully understood- defect of the ryanidine receptor, elevated fatty acid production, sodium ATP-ase pump dysfunction • Genetic - autosomal dominant w/ variable penetrance. Varying presentations • MH susceptable patients multiple inhalational anesthetics • 1st manifestations in the operating room • “Triggering” by inhalational agents

  6. Trigger Agents Volatile Anesthetics (eg. halothane, isoflurane, sevoflurane, desflurane) Succinylcholine Non Triggers Intravenous agents Nitrous oxide Opioids Non-depolarizing agents (? Curare) Ketamine Propofol Anxiolytics Trigger Agents for MH

  7. Spectrum of Presentations of Malignant Hyperthermia • The classic case • Tachycardia, tachypnea w/ no paralysis • Hypercarbia • temperature elevation 1-2 degrees / 5-15 min • Masseter muscle rigidity • MH without anesthesia

  8. Specific Muscle Rigidity Increased CO2 Production Rhabdomyolysis Myoglobinuria coca-cola tea colored urine Marked Temperature Elevation1-2 degrees/ 5 min Non Specific Tachycardia Tachypnea Acidosis (Resp/Metabolic) Hyperkalemia Cardiac arrhythmias Signs of Malignant Hyperthermia

  9. Summary of Clinical Signs

  10. Masseter Muscle Rigidity and MH • Jaw muscle rigid after succinylcholine • Peripheral nerve stimulation = flacid • More common in children than adults • Peak ages 8-12 • MH susceptable by caffiene-contracture in 50% masseter muscle rigidity • Generalized rigidity not always present • Rigidity present, regularly associated with MH susceptibility • With muscle breakdown and creatine kinase >20,000 IU, MH is very high.

  11. Beware the indiscriminant use of succinylcholine • 1994 Package insert to succinylcholine to warn against routine use in children

  12. What to do when Masseter muscle rigidity occurs • If elective case- discontinue triggering agents- postpone case - awaken patient • Recommend muscle biopsy • If case emergent continue - CO2 monitoring, temp, monitoring, discontinue triggering agents. • If signs of MH develop initiate dantrolene therapy • Place foley catheter and monitor urine output as well as color of urine (myoglobinuria)

  13. Masseter Muscle rigidity • Monitor in hospital for 12-24 hrs • Measure CPK levels 6, 12, and 24 hrs • If CPK > 20,000 IU MH likely • Refer patient for muscle bx • If muscle bx - no further testing for family

  14. Differential Diagnosis Masseter Muscle rigidity • Myotonic syndrome • TMJ • Inadequate dose of succ • Inadequate time for succ • Inadequate anesthesia

  15. Fever (without rigidity) Thyrotoxicosis Sepsis Pheochromocytoma Iatrogenic overheating Anticholinergic syndrome Faulty equipment Tourniquet (children) Fever and muscle symptoms NMS Hypoxic encephalopathy Ionic contrast agents in CSF Cocaine, amphetamine, ecstasy Differential Diagnosis of Malignant Hyperthermia

  16. Diseases Associated with MH Susceptibility • Myopathies • Central Core Disease • King-Denborough syndrome • Schwartz-Jampal syndrome • Myotonias • Myotonia fluctuans • Muscular dystrophies • Hyperkalemic arrest • Hypokalemic Periodic Paralysis • Metabolic diseases- osteogenesis imperfecta

  17. Diagnosis MH Current Concepts: • Halothane-caffeine contracture test • European MH group versus North American MH group • MH (+) for EMH group (+) caffeine (+) halothane • MH (+) for NAMH either caffeine or halothane (+) • Either MH (-) or MH susceptible • False (-) reported as well as false (+) I.e. not 100% senistive nor 100% specific

  18. Current Investigations: • Molecular genetics • Nuclear magnetic resonance for assessing ATP and creatine phosphate with/without exercise in vivo • Calcium flux measurement in cultured muscle cells • Local increase in pC02 following IM caffeine • EMG changes in MH patients

  19. What is the Incidence of MH? • Original Concepts: • Rare. 1 in 50,000 anesthetics • Current Concepts: • Clinically based information: 1 in 20,000 to 50,000 anesthetics depending on drugs, population • Molecular Genetics based information: MH trait in 1 in 2,000-3,000 patients. Low penetrance

  20. Treatment for Malignant Hyperthermia episode Call for help and the MH hotline • Discontinue inhalation agents, • Dantrolene 2.5mg/kg Push. Can bolus up to 10 mg/kg- Repeat every 4-6 hrs • Titrate to patient temp and heart rate • Hyperventilate with 100% 02 • Bicarbonate 2-4 meq /kg as needed • Cool patient: gastric lavage, surface, wound • Treat arrhythmias-do not use calcium channel blockers increase hyperkalemia when used with Dantrolene • Arterial or venous blood gases(preferably venous gas) • Electrolytes, coagulation studies

  21. Treatment - Acute Dantrolene-1 • The only specific treatment for MH • Mechanism- prevents release of calcium from the sarcoplasma reticulum. Does not prevent calcium reuptake • Prior to dantrolene approval MH mortality 80% • W/ dantrolene mortality at 10%- further reduction may by dependent on early recognition and help • Administer immediately • 20mg / bottle-dissolve with 60ml sterile water • Shake vigorously or warm bottles to dissolve • Give 2.5mg/kg STAT • Repeat as needed to control signs of MH

  22. Treatment of Malignant Hyperthermia Dantrolene-2 • After crisis controlled, give dantrolene 1mg/kg every 4-6 hours • Continue dantrolene for 36 hours • Recrudescence rate is 25%

  23. Management of Malignant Hyperthermia • Blood gasses – pCO2, pH, CPK (> 20,000 units) • Hyperkalemia, hypercalcemia, lacticacidemia • Myoglobinuria • Diuretics, hydration bicarbinate • PT, PTT, INR, fibrin split products • Liver enzymes, BUN

  24. Prevention Recognition of Malignant Hyperthermia • Preop pt / family history of anesthetic problems, neuromuscular disorders • Temperature / end-tidal CO2 monitoring during general anesthesia • Recognition of masseter rigidity • Investigate unexplained tachycardia, hypercarbia, hyperthermia • Availability of Dantrolene • Avoid triggering agents in MH susceptible patients • Succinylcholine only when indicated

  25. Anesthetic Management ofMH Susceptible • Prophylactic Dantrolene not necessary (dantrolene available) • Avoid Triggering Agents • Succinylcholine • potent inhalation agents • TIVA anesthesia safe • No Temp change Discharge after about 4 hours in the recovery room if all signs are stable

  26. Preparation for MH Susceptible • Anestheia machine • Shut/disable vaporizers • High Flow 02 @ 10L/min for 20 minutes (through machine and ventilator) • Change carbon dioxide absorbent • Use TIVA (propofol infusion, narcotic, anxiolytic) or regional anesthesia • Monitor temperature • Have dantrolene available

  27. Suggested Regimen for MH Patient • Anxiolytic (ketamine permissible) • Propofol / opioid induction • Non-depolarizing relaxant • Nitrous/narcotic/propofol • Reversal of muscle relaxant • Observe 4 hours

  28. MH Trigger Agents Potent Volatile Anesthetics (eg. halothane, sevoflurane, desflurane) Succinylcholine Not MH Triggers Intravenous agents Opioids Non-depolarizing agents Ketamine Propofol Anxiolytics Drug Safety in MH

  29. Conclusion • 1979- Dantrolene approved by food and drug administration • 1980s workshop on MH, MH registry created • 1985 recognition intracellular calcium increased during MH crisis w/ dantrolene reversing this process • 1990s molecular genetics

  30. Conclusion • Mortality from MH without dantrolene >80% • With dantrolene mortality < 10% • APSF goal to reduce patient mortaliy

More Related