TBL 2 Flashcards
Why do patients experiencing malignant hyperthermia have their body temperatures rise?
Hypermetabolism
What muscle relaxant can cause MH?
Succinylcholine
How is MH inherited?
Autosomal dominant with reduced or incomplete penetrance
What is MH a disorder in?
Genetic mutation in RyR1 (ryanodine receptor) in skeletal muscles or CACNA1S gene coding for L-type Ca2+ channel; dihydropyridine receptor
What does MH cause in patients?
CO2 production Oxygen consumption Metabolic and respiratory acidosis Hyperkalemia Heat production Sympathetic nervous system activation Problems coagulating Multi-organ dysfunction and failure
What test is standard for diagnosing MH?
Caffeine halothane contracture test
How much can oxygen consumption increase?
3 fold
How much can blood lactate levels increase?
15-20 fold
Why is the sympathetic nervous system stimulated in MH?
Release of catecholamines
What drug is given to treat MH?
Dantrolene
How does Dantrolene work?
Specifically inhibits the release of calcium from the SR in skeletal muscle and reverses the process
When does activation of the sympathetic nervous system begin in the disease process?
Early
Why does disseminated intravascular coagulation occur?
Due to release of tissue thromboplastin
Which chromosome is the RyR1 gene located on?
Chromosome 19
How many sites in the US test muscle biopsies for MH?
How many test for MH gene mutations?
5
2
What are known triggering agents of MH?
Depolarizing neuromuscular blockers such as succinylcholine and halogenated volatile anesthetics (end in -ane)
What are three agents suspected of causing MH but no longer used as general anesthetics?
Diethyl ether
Chloroform
Cyclopropane
What in general are considered safe for patient with MH?
Local anesthetics and non-depolarizing NM blockers
What is the earliest sign of MH?
Increase in end-tidal carbon dioxide
What are three disorders in patients that place them at high risk for MH?
King-Denborough syndrome
Central core disease
Minicore myopathy
What characterizes King-Denborough syndrome?
Short stature
Musculoskeletal abnormalities
Mental retardation
Sometimes central core disease
What characterizes central core disease? (Same symptoms of minicore myopathy)
Hypotonia
Muscle weakness
What can occur if you administer succinylcholine to a muscular dystrophy patient?
Hyperkalemia
Rhabdomyolysis
What is a more effective way of testing for MH?
Muscle biopsy
Positive genetic test does not mean they have it and a negative does not rule them out
