Malignant hyperthermia: Difference between revisions

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==Background==
==Background==
*Inherited disorder of skeletal muscles triggered most often by anesthesia inhalation agents and/or succinylcholine
*Inherited disorder of skeletal muscles triggered most often by anesthesia inhalation agents, succinylcholine, heat or exercise<ref>Denborough, M. (1998) ‘Malignant hyperthermia’, The Lancet, 352(9134), pp. 1131–1136. doi: 10.1016/s0140-6736(98)03078-5</ref>
*Results in hypermetabolism, skeletal muscle damage, hyperthermia, and death if not treated quickly
*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.
*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===
===Likelihood of Complications===
*Increased time from 1st sign to 1st dantrolene
*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.
**For every 30 minute increase in the interval, complication likelihood increases x 1.6  
* Increased maximal temperature
*Increased maximal temperature
** For every 2°C increase in maximal temperature, the complication likelihood increased 2.9 times.
**For every 2°C increase in max temp, complication likelihood increases x 2.9


==Diagnosis==
==Clinical Features==
#Muscle contraction
*Muscle contraction
#Fever
*[[Fever]]
 
*May have dark colored urine from myoglobinuria
#First signs
*First signs
##Hypercarbia
**Hypercarbia
##Sinus tachycardia
**Sinus tachycardia
##Masseter spasm
**Masseter spasm
##Temperature abnormalities (may be early)
**Temperature abnormalities (may be early)
#Most common pattern
*Most common pattern
##Respiratory acidosis and muscular abnormalities
**Respiratory acidosis and muscular abnormalities


===Presentations===
===Presentations===
*99% Respiratory Acidosis
*99% [[Respiratory Acidosis]]
*26% Metabolic Acidosis
*26% [[Metabolic Acidosis]]
*80% Muscular Abnormalities
*80% Muscular Abnormalities
Watch for it with succinylcholine use.
Watch for it with [[succinylcholine]] use.
 
===Types===
*Fulminant MH
**muscle rigidity, high fever, increased HR shortly after induction of anesthesia
*Masseter muscle rigidity
**jaw muscle rigidity after succinylchoine
**More common in children
**Presages MH in 20-30% cases
**All patients demonstrate elevated CK and often gross myoglobinuria
**CK >20,000IU = high likelihood of MH
*Late onset MH
**Uncommon, may begin shortly after anesthesia termination (usually within first hour)


==Work-Up==
==Differential Diagnosis==
#Core temperature
{{AMS and fever DDX}}
#CBC
#Chem 7
#Total CK
#PT/PTT
#ABG


===Types===
==Evaluation==
#Fulminant MH
*Core temperature
##muscle rigidity, high fever, increased HR shortly after induction of anesthesia
*CBC
#Masseter muscle rigidity (MMR)
*Chem 7
##jaw muscle rigidity after succinylchoine may be an early sign of MH
*Total CK
##More common in children
*PT/PTT
##Presages MH in 20-30% cases
*ABG
##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.
==Management==
# Late onset MH:
*Discontinue Triggering Agents
##uncommon, may begin shortly after anesthesia finish time (usually within first hour)
*100% Oxygen at High Flow
*Give [[Dantrolene]]
*Provide [[bicarbonate]] for metabolic acidosis temporization
*Actively cool the patient
*Treat any [[dysrhythmia]]
===Dantrolene===
*60ml sterile water into each vial of [[dantrolene]] may need up to 36 vials
*If using Dantrium® (20mg/vial), each vial contains 3 g of mannitol (renal vasodilation); newer nanocrystalline dantrolene (250mg/vial) has 250mg mannitol per vial and requires mannitol supplementation
*'''2.5mg/kg IV push'''
*Titrate to effect; may need more than 10mg/kg
*Call [https://www.mhaus.org/healthcare-professionals/ MHAUS Hotline] if needed: 1-800-644-9737
*Continued Care
**Dantrolene 1mg/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
 
===Bicarb===
*1-2 mEQ/kg if blood gas values not yet available
===Cooling Measures===
*Most patietns will have a core temperature >39 deg C (102.2 deg F)
*Stop cooling when temperature reaches 100.4
===Dysrhythmic therapy===
*Dysrhythmias usually respond to treatment of acidosis and hyperkalemia
*AVOID CA CHANNEL BLOCKERS as they may cause hyperkalemia or cardiac arrest in presence of dantrolene
===[[Hyperkalemia]]===
*Not always present but can occur
*Treat hyperkalemia with standard treatment, remember to check glucose levels q1h after treatment with insulin/glucose


==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
##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
## 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==
==Prognosis==
Stable if (may transfer):
===Stable to Transfer Criteria===
#ETCO2 is declining or normal
*ETCO2 is declining or normal
#HR is stable or decreasing
*HR is stable or decreasing
#No ominous dysrhythmias
*No ominous dysrhythmias
#Temperature is declining
*Temperature is declining
#Generalized muscular rigidity is resolving (if present)
*Generalized muscular rigidity is resolving (if present)
#IV dantrolene administration has begun
*IV dantrolene administration has begun


===Complications===
===Complications===
#Consciousness Level Change/Coma
*Consciousness Level Change/Coma
#Cardiac Dysfunction
*Cardiac Dysfunction
#Pulmonary Edema
*Pulmonary Edema
#Renal Dysfunction
*Renal Dysfunction
#Disseminated Intravascular Coagulation
*Disseminated Intravascular Coagulation
#Hepatic Dysfunction
*Hepatic Dysfunction
#Relapse
*Relapse
#Death
*Death
 
==References==
<references/>


==See Also==
==See Also==
*[[Succinylchoine]]
*[[Succinylcholine]]
*[[Acute Fever (DDX)]]
*[[Toxidromes]]


[[Category:Tox]]
[[Category:Toxicology]]

Latest revision as of 20:55, 11 May 2023

Background

  • Inherited disorder of skeletal muscles triggered most often by anesthesia inhalation agents, succinylcholine, heat or exercise[1]
  • 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

Likelihood of Complications

  • Increased time from 1st sign to 1st dantrolene
    • For every 30 minute increase in the interval, complication likelihood increases x 1.6
  • Increased maximal temperature
    • For every 2°C increase in max temp, complication likelihood increases x 2.9

Clinical Features

  • Muscle contraction
  • Fever
  • May have dark colored urine from myoglobinuria
  • First signs
    • Hypercarbia
    • Sinus tachycardia
    • Masseter spasm
    • Temperature abnormalities (may be early)
  • Most common pattern
    • Respiratory acidosis and muscular abnormalities

Presentations

Watch for it with succinylcholine use.

Types

  • Fulminant MH
    • muscle rigidity, high fever, increased HR shortly after induction of anesthesia
  • Masseter muscle rigidity
    • jaw muscle rigidity after succinylchoine
    • More common in children
    • Presages MH in 20-30% cases
    • All patients demonstrate elevated CK and often gross myoglobinuria
    • CK >20,000IU = high likelihood of MH
  • Late onset MH
    • Uncommon, may begin shortly after anesthesia termination (usually within first hour)

Differential Diagnosis

Altered mental status and fever

Evaluation

  • Core temperature
  • CBC
  • Chem 7
  • Total CK
  • PT/PTT
  • ABG

Management

  • Discontinue Triggering Agents
  • 100% Oxygen at High Flow
  • Give Dantrolene
  • Provide bicarbonate for metabolic acidosis temporization
  • Actively cool the patient
  • Treat any dysrhythmia

Dantrolene

  • 60ml sterile water into each vial of dantrolene may need up to 36 vials
  • If using Dantrium® (20mg/vial), each vial contains 3 g of mannitol (renal vasodilation); newer nanocrystalline dantrolene (250mg/vial) has 250mg mannitol per vial and requires mannitol supplementation
  • 2.5mg/kg IV push
  • Titrate to effect; may need more than 10mg/kg
  • Call MHAUS Hotline if needed: 1-800-644-9737
  • Continued Care
    • Dantrolene 1mg/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

Bicarb

  • 1-2 mEQ/kg if blood gas values not yet available

Cooling Measures

  • Most patietns will have a core temperature >39 deg C (102.2 deg F)
  • Stop cooling when temperature reaches 100.4

Dysrhythmic therapy

  • Dysrhythmias usually respond to treatment of acidosis and hyperkalemia
  • AVOID CA CHANNEL BLOCKERS as they may cause hyperkalemia or cardiac arrest in presence of dantrolene

Hyperkalemia

  • Not always present but can occur
  • Treat hyperkalemia with standard treatment, remember to check glucose levels q1h after treatment with insulin/glucose

Prognosis

Stable to Transfer Criteria

  • 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

References

  1. ↑ Denborough, M. (1998) ‘Malignant hyperthermia’, The Lancet, 352(9134), pp. 1131–1136. doi: 10.1016/s0140-6736(98)03078-5

See Also

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