MH Flashcards
incidence of malignant hyperthermia
1:8000 or 1:30,000
incidence of malignant hyperthermia is higher in
children
MH is linked to mutations in
RYR-1 gene mutation.
RYR1 on chromosome 19
CACNA1S - chromosome 1
and STAC3 of chromosome 12
all volatile agents (except N2O) can trigger MH via
direct action on RYR-1
Depolarizing NMB trigger MH via
over activation of VGCC that lead to opening of RYR-1 ( on the SR) –> indirect
early signs of MH
Hypercarbia tachypnea tachycardia MMR Hyperthermia*
MMR is a common SE of
succinylcholine
Of the people with MMR
20% will have an MH episode
rate of temperature rise in MH
1-2 degrees Celsius ever 5 minutes
milder MH triggers =
exercise in hot conditions
neuroleptic drugs
alcohol
infections
mild increase in masseter tone + limb flaccidity following succinylcholine =
normal reaction after succinylcholine
if MH is suspected immediately draw:
potassium and ABG
MH mortality without dantrolene =
70%
MH mortality with dantrolene =
5%
Dantrolene MOA
reduces muscle tone and metabolism -> stabilizes and restores balance between release and uptake of Ca++
- prevents on going release of calcium from muscle (@SR)
- Blocks external entry of Ca++ into cell
- Hypothesized to inhibit calcium conductance through RYR1
half life of dantrolene =
10 to 15 hours
calcium channel blockers + dantrolene =
life threatening hyperkalemia and myocardial depression.
avoid calcium channel blockers with history of MH
phlebitis often follows
administration of dantrolene
traditional minimum and ryanodex minimum
traditional minimum: 36 vials (20 mg/vial)
or 3 vials of (250 mg/vial) of ryanodex must be available
h2o mixed with traditional dantrolene =
60 mL sterile H2O PER VIAL.
36 vials = average loading dose
dantrolene dosing
- 5 mg/kg bolus.
maintenance: 2 mg/KG IV q 5 minutes to a total of 10 mg/kg
then 1 mg/kg q 6 hours for 72 hours
goal temperature in cooling for MH
38 degrees C
ABG drawn
q 15 min with active MH
Iced IV NS bolus =
15 mL/kg q 10 min
maintain UO to be
2 ml/kg/hr. ensure adequate urine output by hydration and diuretics
treatment of dysthymia =
ensure hyperkalemia is treated. GIC.
If needed: lidocaine or procainamide 15 mg.kg
IV
hyperkalemia tx dosing
1 ml/kg D50 + 0.15 units/kg regular insulin and/or calcium chloride 5-10 mg/kg
reoccurrence of MH occurs in
25% of cases
Coagulation labs should be drawn for
DIC
labs drawn with MH
Asses K and ABG at onset
ABG q 15 min during attack?
CKs q 6 hours
Coags- evaluate for DIC
preferred fluids with MH
Normal saline not lactated or anything with potassium
halothane-caffeine biopsy has specificity of
80% therefore negative result does not rule out MH susceptibility
recrudescence occurs in about
25% of MH cases
dantrolene dosing:
onset: 2.5 mg/kg
maintenance 2 mg/kg iv Q 5 minutes, not to exceed 10mg/kg
for 72 hours, 1 mg/kg q 6 hours
hyperkalemia tx:
1 mL/kg D50.
0.15 units/kg regular insulin
5-10 mg/kg calcium chloride
