Malignant hyperthermia

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Mostafa Mahmoud Anesthesia Resident Suez Canal University Hospitals

Transcript of Malignant hyperthermia

1. Mostafa Mahmoud Anesthesia Resident Suez Canal University Hospitals 2. 21 y o Engineering student after MCA with Fracture Rt tibia and fibulaand fibula His main concern was that 10 close relatives have died under ether general anesthesia. 3. Worked on porcine models of MH which were previously diagnosed withdiagnosed with Porcine stress syndrome 4. A seminal figure in the identification and the introduction ofintroduction of dantrolene sodium the only effective treatment for an MH crisis. 5. 1979 Dantrolene FDA approved, greatly reduces mortality. 1980s susceptible swine prove to be most reliable animal models in study ofmost reliable animal models in study of MH. 1990s Focus on genetics to isolate responsible gene. 2000 Properly treated, mortality still approx 10%. 6. A pharmacogenetic syndrome of skeletal muscles triggered in susceptible individuals when exposed to certain anesthetic agents.anesthetic agents. Unfortunately some of our best drugs, the drugs used most commonly and are best for most people are the ones that can trigger MH reaction. 7. 1 in 5000 pediatric cases 1 in 30000 adult anesthesia 1 in 2000 of populationhas genetic predispositionpredisposition In US: 40 confirmed cases a year and 200- 300 cases a year of probable diagnosis. Mortality went down from 80% to 10%. 8. If any institution does not feel it can manage the MHS child then they should not be anaesthetising any children at all, since it is not the identified child with asince it is not the identified child with a nontriggering technique who will cause grief, but the undiagnosed child given a trigger. 9. Uncontrolled elevation of intracellular calcium in skeletal muscle cells. Ryanodine receptor (RYR1) mutations responsible for majority of MH casesresponsible for majority of MH cases (>70%). Dihydropyridine receptor gene (DHPR) mutations responsible for less than 2% 10. Autosomal dominant inheritance with reduced penetrance and variable expressivity. However, as many as 30 (or more 80)However, as many as 30 (or more 80) different mutations may be responsible for MH = (inconsistent presentation). 11. All Halogenated inhalational agents: Halothane Depolarizing Muscle Relaxant: SuccinlycholineHalothane Isoflurane Sevoflurane Desflurane Succinlycholine 12. MH can occur anywhere triggers are given (ED, ICU). MH can have delayed onset, usually presenting within 2 hours after triggers (PACU). 13. Unexplained tachycardia (earliest, most consistent sign, seen in 96% of cases) Suddenly increased & rising ETCO2 (2-3 Xs normal, despite adequate MV)Xs normal, despite adequate MV) Muscle rigidity (75-80%) Cyanosis (70%) Hemodynamic instability (85%), BP initially increases then decreases. 14. Masseter muscle rigidity (50%) Tachypnea Rhabdomyolysis Arrhythmeas (e.g. PVCs and VT)Arrhythmeas (e.g. PVCs and VT) Exhausted CO2 absorber Labs: Ca, K, CPK, myoglobin, lactate mixed venous O2 & pH Marked temperature elevation 15. Hyperthermia is a late & inconsistent sign. If present, very specific sign. Skin temp doesnt adequately reflect core temp. Skin temp doesnt adequately reflect core temp. Can rise 1* Celsius Q 5 mins, may reach 43*C. Cold environments may mask temp rise (large field, cold room, cold transfusions). 16. Pulmonary artery Distal esophagus Nasopharynx TympanicTympanic Bladder Axilla Forehead skin 17. Thyroid storm Pheochromocytoma Sepsis Light anesthesiaLight anesthesia Drug reaction CO2 insufflation during laparoscopy Over Dose: cocaine, amphetamines, ecstasy Neuroleptic Malignant Syndrome (NMS) 18. 1. Discontinue triggers: Get HELP STAT! Get MH cart. Inform surgeon stop surgery! 2. Hyperventilate:2. Hyperventilate: 3-4 xs normal minute volume. 100% O2 at high flows >10 L/minute. via clean source?. 3. Dantrolene: 2.5 mg/kg rapid IV push. repeat Q 5-30 minutes. 19. 4. Multiple large bore IVs and central venous line. 5. Foley (3-way): monitor urine + active coolingcooling 6. A-line to monitor BP and serial lab draws. 7. Monitor core temp continuously. 8. Active core cooling measures 9. Bicarb 1-2 mEq/kg given empirically. 20. 10. Treat dysrhythmias with usual ACLS drugs: Ca Ch blockers absolutely contraindicated if Dantrolene given! Dysrhythmias = tx acidosis + hyperkalemia. Dysrhythmias = need more Dantrolene.Dysrhythmias = need more Dantrolene. 11. Treat hyperkalemia: hyperventilation bicarb diuresis dextrose + insulin(10 units regular insulin /50cc D50) avoid parenteral potassium (LR) Calcium chloride 21. 12. D50 + insulin: provides quick acting energy substrate. 13. Prevent myglobin induced renal failure: non-K IVF: (cold NSS 15 ml/kg Q15 min X3). Mannitol / Lasix: keep U/O >2 ml/kg/hr.Mannitol / Lasix: keep U/O >2 ml/kg/hr. Alkalinize urine w/Bicarb. 13. Watch for and treat DIC Check coags. Replace clotting factors (FFP, plts, cryo). 22. 1. DIC: results from cell destruction + death 2. Renal failure: myoglobin induced 3. Recrudescence:3. Recrudescence: 24-36 hour window occurs in 25% of all MH cases 23. A Hydantoin derivative Half-life 4-8 hours, pH 9.5 Metabolized in liver to 5-hydroxydantrolene which also is active Must be dissolved in sterile water Must be dissolved in sterile water Takes 1.5 minutes to disolve Mechanism of action Decreases calcium-induced calcium release from SR Toxicity Occasional profound muscle weakness GIT upset Phlebitis 24. 1st case of day. MH cart readily available & Dantrolene not expired. Continuous monitoring: HR, ETCO2 + temp.Continuous monitoring: HR, ETCO2 + temp. 1. Prepare gas machine: Remove vaporizers & change soda lime. 2. Flush system with 10 lpm O2 via circuit X 20minutes (using disposable bag on end of circuit). 3. Replace with clean circuit & soda lime after flushing. 25. Nontrigger technique, 3 options: 1. TIVA (G/A). 2. Regional (spinal / epidural). 3. Local + sedation.3. Local + sedation. Minimum 2.5 hour PACU. Pregnant mother with a MH partner should be managed as an MHS patient. 26. The caffeine halothane contracture test (CHCT) is the criterion standard for establishing the diagnosis of malignant hyperthermia (MH).The test is performed on freshly biopsied muscle tissue.on freshly biopsied muscle tissue. The administration of a bolus of halothane, or incremental exposure to caffeine, to the fresh muscle sample produces characteristic mechanical responses to stimulation in muscle susceptible to MH, which are diagnostic. 27. Individuals who have been diagnosed susceptible to MH by muscle contracture testing should undergo genetic testing. Several chromosomes: 19q11.2-13.2 Ryanodine (RyR1) 19q11.2-13.2 Ryanodine (RyR1) Release of Ca2+ stores from sarcoplasmic reticulum 17q11.2-q24 Altered sodium channel functioning 7q21.1 Dihydropyridine (DHP), voltage sensor for RyR1 1q32 CACNL1A3 gene encoding the alpha 1-subunit of the voltage-gated DHP receptor that interacts with RyR1 28. King-Denborough syndrome: RYR1 Short stature Lumbar lordosis Lumbar lordosis Pectus excavatum Low set ear Developmental delay Proximal myopathy 29. Central Core disease: Variably severe myopathy No bulbar or diaphragmatic involvement RYR1 RYR1 Multiple minicore disease: Severe axial myopathy Respiratory, bulbar, and ocular involvement 30. Muscular dystrophies: X linked proximal weakness waddling gait calf pseudohypertrophy calf pseudohypertrophy eg Duchennes Beckers