Malignant hyperthermia is a potentially fatal syndrome.etic;
Although the incidence of the MH trait in the general
population is quite low, reportedly ranging from 1:4,500
(when succinylcholine is used) to 1:60,000 anesthetics, the
incidence varies depending on the prevalence of the gene(s)
for MH in any given geographic area, the type of general
anesthetic given and a multitude of patient factors. MH is
reported worldwide and affects all racial groups; however, it
is rare in infants and the incidence decreases after 50 years
of age. Most cases occur in children and young adults. Males
are more frequently affected than females, although this may
be related to other demographic factors such as the incidence
of emergency surgery in this group.
It is characterized by a rapid elevation of temperature as
high as 42.8 C to 44 C (109 F to 111 F). The complication is
triggered by the anesthetic agent. The patient with the
tendency to be affected apparently has an inherited defect in
the muscle cell membrane allowing the above chemicals to
trigger a sudden release of calcium within the muscle cells.
The increased amount of calcium sets off a series of
biochemical reactions that increase the patient's metabolic
rate, eventually liberating heat. Muscle contractures also
increase, liberating more heat.
Symptoms of malignant hyperthermia include elevated end-tidal
CO2, rigidity, tachycardia, hypercarbia, tachypnea, cardiac
dysrhythmia, respiratory and metabolic acidosis, fever,
unstable/rising blood pressure, cyanosis/mottling of the skin
None of the agents known to be Malignant Hyperthermia
triggers are currently in use in this facility. The protocol
for management of a Malignant Hyperthermia episode is
included to raise consciousness in the medical industry of
Malignant Hyperthermia Syndrome.
The following (2) questions have been recorded from the
Malignant Hyperthermia Association of the United States
WHAT DRUGS TRIGGER MH?
The volatile gaseous inhalation anesthetics (e.g., halothane,
enflurane, isoflurane, sevoflurane and desflurane,
methosyflurane, cylopropane) are MH triggers, as is the
depolarizing muscle relaxant succinylcholine.
ARE OTHER ANESTHETICS SAFE?
Yes, Some examples of safe anesthetics are: local
anesthetics, narcotics, propofol, thiopental, curare,
The prescribed protocol recommended by the Malignant
Hyperthermia Association of the United States will be
immediately implemented to reverse malignant hyperthermia.
Patients will be transferred as soon as possible to an acute
facility for continuing specialized treatment.
Medical protocol (from MedicAlert & Malignant Hyperthermia
Association of the United States) is attached.
Acute Phase Treatment:
1. GET HELP. GET DANTROLENE. Immediately discontinue all
volatile inhalation anesthetics and succinylcholine.
Hyperventilate with 100% oxygen at high gas flows; at
least 10 L/min. The circle system and CO2 absorbent need
not be changed.
2. Administer dantrolene sodium 2.5 mg/kg bolus rapidly.
Continue bolus administration as needed until signs of MH
(e.g. tachycardia, rigidity, increased end-tidal CO2, and
temperature elevation) are controlled. Occasionally, a
total dose greater than 10 mg/kg may be needed. Each
vial of dantrolene contains 20 mg of dantrolene and 3
grams mannitol. Each vial should be mixed with 60 mL of
sterile water for injection USP without a bacteriostatic
3. Administer bicarbonate to correct metabolic acidosis as
guided by blood gas analysis. In the absence of blood
gas analysis, 1-2 mEq/kg should be administered.
4. Simultaneous with the above, actively cool the
hyperthermic patient. Use IV iced saline (not Ringer's
lactate) 15 mL/kg q 15 min X 3.
A. Lavage stomach, bladder, rectum and open cavities
with cold saline as appropriate.
B. Surface cool with ice and hypothermia blanket.
C. Monitor closely since overvigorous treatment may lead
5. Dysrhythmias will usually respond to treatment of
acidosis and hyperkalemia. If they persist or are life
threatening, standard anti-arrhythmic agents may be used,
with the exception of calcium channel blockers (may cause
hyperkalemia and CV collapse).
6. Determine and monitor end-tidal CO2, arterial, central or
femoral venous blood gases, serum potassium and other
electrolytes, urine output, PT/PTT and calcium for
baseline values. Repeat as clinically indicated.
7. Hyperkalemia is common and should be treated with
hyperventilation, bicarbonate, intravenous glucose and
insulin (10 units regular insulin in 50 mL 50% glucose
titrated to potassium level or 0.15 u/kg regular insulin
in 1 cc/kg 50% glucose). Life threatening hyperkalemia
may also be treated with calcium administration (e.g. 2-5
mg/kg of CaCl2). Check blood glucose every two hours if
insulin has been given.
8. Ensure urine output of greater than 2 mL/kg/hr by
hydration and/or administration of mannitol or
furosemide. Consider central venous or PA monitoring
because of fluid shifts and hemodynamic instability which
9. Sudden Unexpected Cardiac Arrest in Children:
Children less than about 10 years of age who experience
sudden cardiac arrest after succinylcholine in the
absence of hypoxemia should be treated for acute
hyperkalemia first. In this situation, calcium chloride
should be administered along with other means to reduce
serum potassium. They should be presumed to have
subclinical muscular dystrophy.
1. Observe the patient in an ICU setting for at least 24
hours since recrudescence of MH may occur.
2. Administer Dantrolene 1 mg/kg IV q 4-6 hours for 24-48
hours post episode.
3. Follow ABG, CK, potassium, urine and serum myoglobin,
clotting studies and core body temperature until such
time as they return to normal values (e.g. q 6 hours).
Central temperature (e.g. rectal, esophageal) should be
continuously monitored until stable.
4. Counsel the family and patient regarding MH and further
precautions. Refer the patient to MHAUS. Fill out an
Adverse Metabolic Reaction to Anesthesia (AMRA) report
available through MHAUS.
CAUTION; THIS PROTOCOL MAY NOT APPLY TO EVERY PATIENT AND
MUST OF NECESSITY BE ALTERED ACCORDING TO SPECIFIC PATIENT
NOTES: Names of on-call physicians available to consult in MH
emergencies may be obtained 24 hours a day through: MHAUS
EMERGENCY HOTLINE, 800/644-9737 OR by calling Medic Alert
Foundation International, 209/634-4917, ask for Index Zero.
For non-emergency information and patient referrals, contact:
Malignant Hyperthermia Assn of the United States (MHAUS),
800/986-4287; PO Box 1069, Sherburne NY 13460-1069.
E-mail: email@example.com; Web site: www.mhaus.org;
MH info-by-fax: 800/440-9990.
Approved By Governing Board