Malignant hyperthermia: Difference between revisions
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*[[ | *[[Succinylcholine]] | ||
[[Category:Tox]] | [[Category:Tox]] |
Revision as of 22:33, 1 January 2012
Background
- Inherited disorder of skeletal muscles triggered most often by anesthesia inhalation agents and/or succinylcholine
- Results in hypermetabolism, skeletal muscle damage, hyperthermia, and death if not treated quickly
- Generalized rigidity NOT always present; if it occurs, MH is almost certain.
- Patients with occult or known myopathies may have a higher risk for an MH or MH-like episode upon exposure to a triggering anesthetic agent.
Likelihood of Complications
- Increased time from 1st sign to 1st dantrolene
- For every 30 minute increase in the interval between 1st MH sign and 1st dantrolene dose, the complication likelihood increased 1.6 times.
- Increased maximal temperature
- For every 2°C increase in maximal temperature, the complication likelihood increased 2.9 times.
Diagnosis
- Muscle contraction
- Fever
- First signs
- Hypercarbia
- Sinus tachycardia
- Masseter spasm
- Temperature abnormalities (may be early)
- Most common pattern
- Respiratory acidosis and muscular abnormalities
Presentations
- 99% Respiratory Acidosis
- 26% Metabolic Acidosis
- 80% Muscular Abnormalities
Watch for it with succinylcholine use.
Work-Up
- Core temperature
- CBC
- Chem 7
- Total CK
- PT/PTT
- ABG
Types
- Fulminant MH
- muscle rigidity, high fever, increased HR shortly after induction of anesthesia
- Masseter muscle rigidity (MMR)
- jaw muscle rigidity after succinylchoine may be an early sign of MH
- More common in children
- Presages MH in 20-30% cases
- All patients with MMR demonstrate elevated CK and often gross myoglobinuria
- With muscle breakdown and CK >20,000IU, the likelihood of MH is very high.
- Late onset MH:
- uncommon, may begin shortly after anesthesia finish time (usually within first hour)
Treatment
- Initial
- Declare MH Emergency: (call OR for anesthesia to bring MH cart)
- Discontinue Triggering Agents
- 100% Oxygen at High Flow
- Give Dantrolene
- Designate 2 or 3 people to mix sterile water into Dantrolene \
- 60ml sterile water into each vial of dantrolene; may need up to 36 vials
- 2.5 mg/kg IV push
- Titrate to effect; may need more than 10 mg/kg
- Designate 2 or 3 people to mix sterile water into Dantrolene \
- Bicarb for metabolic acidosis
- 1-2 mEQ/kg if blood gas values not yet available
- Cool the patient if core temp >39 deg C (102.2 deg F)
- Stop cooling when temp reaches 100.4
- Dysrhythmias usually respond to treatment of acidosis and hyperkalemia
- Standard therapy EXCEPT NO CA CHANNEL BLOCKERS:
- may cause hyperkalemia or cardiac arrest in presence of dantrolene
- Standard therapy EXCEPT NO CA CHANNEL BLOCKERS:
- Treat hyperkalemia: standard treatment, remember to check glucose levels q1h after treatment with insulin/glucose
- Call MHAUS Hotline if needed: 1-800-644-0737
- Continued Care
- Dantrolene 1 mg/kg every 4-6 hours for 24–48 hours
- Monitor for recrudescence (rate is 25%)
- Follow electrolytes, blood gases, CK, core temperature, urine output and color, coagulation studies
Prognosis
Stable if (may transfer):
- ETCO2 is declining or normal
- HR is stable or decreasing
- No ominous dysrhythmias
- Temperature is declining
- Generalized muscular rigidity is resolving (if present)
- IV dantrolene administration has begun
Complications
- Consciousness Level Change/Coma
- Cardiac Dysfunction
- Pulmonary Edema
- Renal Dysfunction
- Disseminated Intravascular Coagulation
- Hepatic Dysfunction
- Relapse
- Death