Exam 5 MH Flashcards
MH is a disorder of the
skeletal muscle (hypermetabolic)
Inhalation agents that trigger MH
Sevo
Iso
Des
halothane
NMB that triggers NH
Succinycholine
(accelerates onset and increases severity of MH episode)
States with high incidences
Wisconsin
Nebraska
West Virginia
Michigan
MH genetic pattern
autosomal dominant
(if one parent has it, 50% change child will get it)
What receptor is site of defect for MH
RYR1 (skeletal muscle)
Ryanodine receptor
What is the ryanodine receptor role
Calcium release channel of SR
MH pathophysiology
Uncontrolled release and regulation of calcium. Constant muscle contraction
Recycling Ca+ and contracting increases muscle metabolism 2-3 fold
Physiologic consequences of MH (5)
- increase O2 consumption
- augments carbon dioxide production
- augments heat production
- Depletes ATP stores
- Generates lactic acid
Acidosis, hyperthermia and ATP depletion cause
Sarcolemma destruction: loss of K, myoglobin, creatinine kinase (to extracellular fluid)
MH muscle defect is in
SKELETAL muscle (not cardiac)
Earliest sign of MH is
increased ETCO2
volatiles can cause MH as long as _____ after induction
6 hours
labs and clinical events during MH
Apex card game
Clincal events during MH:
- ETCO2 rise
- tacycardia, tachypnea
- labile BP or arythmias
- Masseter or muscle rigidity
- Rising temp
- Cola colored urine (myogolibinuria)
- Mottled, cyanotic skin
- Decreased Sa)2
MH ABG
- PACO2 > 60 mmhg
- Base excess more negative than -8mEq/L
- pH <7.25
MH serum K+
> 6 mEq/L
MH serum Creat Kinase
> 20,000
MH Serum myoglobin
> 170 mcg/L
MH Urine myoglobin
> 60 mcg/L