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NA 1 > Malignant Hyperthermia > Flashcards

Malignant Hyperthermia Flashcards

1
Q

MH is

A

a life-threatening clinical hypermetabolic syndrome involving skeletal muscle

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2
Q

MH is triggered by

A
  • volatile IA
  • succinylcholine
  • stressors such as vigorous exercise and heat
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3
Q

T/F MH is an allergy

A

False!

it is an inherited disorder

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4
Q

__ genetic defects are associated with MH

(PPT)

A

80

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5
Q

on average a patient requires how many anesthetics before a triggering event occurs?

A

3

but this crisis may delevlop at first exposure to anesthesia

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6
Q

MH complicates 1 in how many surgical procedures in adults? and 1 in how many surgeries of children?

A

100,000

30,000

(pg. 841)

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7
Q

children under what age approximate 52% of all reactions

A

15 years of age

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8
Q

MH is more sustible in males or females?

A

males

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9
Q

3 co-existing disease are defineitly associated with MH

A
  • King-Denborough syndrome
  • central core disease
  • Multiminicore disease
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10
Q

factors that increase risk

A
  • geography: Wisconsin, Nebraska, West Virginia, Michigan
  • male sex
  • youth (peds accounts for 52% of cases)
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11
Q

what is the most common myopathy that triggers MH

A

Evans myopthay

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12
Q

What other genes are linked with MH suceptibility ?

A

CACNA1S
STAC3

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12
Q

all myopathies have what gene dysfunction?

A

RYR1

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13
Q

MH-associated genetic variants are found within what gene?

A

RYR1

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14
Q

RYR1

A

encodes the ryanodine receptor, the major calcium release channel of the SR

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15
Q

STAC3

A

gene variants are manifested most as native american myopathy in the Lumbee Native American tribe of North Cariolina

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16
Q

CACNA1S

A

encodes a subunit of a dihydropyridine calcium channel located in the skeletal muscle T tubule

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17
Q

the elevated IC calcium results in

A

muscle contraction and abnormal muscle metabolism

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18
Q

energy-dependent reuptake mechanisms attempt to remove excess calcium from the myoplasm, increasing muscle metabolism how many folds?

A

2-3

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19
Q

this accelerated cellular process does what?

A
  • increase oxygen consumption
  • increase CO2
  • increases heat production
  • depletes ATP
  • generates LA
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20
Q

what lab values markedly increase in the EC?

A
  • potassium
  • myoglobin
  • CK
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20
Q

what 3 things cause saroplama destruction?

A
  • acidosis
  • hyperthermia
  • ATP depletion
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21
Q

Patients with DMD have an absence of __ which stabilizes the sarcolemma during muscle contraction & increases membrane permeability

A

dystrophin

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22
Q

what happens at the cellular level with DMD

A
  • EC calcium is free to enter the cell, increases metabolism
  • IC K is free to exit the cell, can lead to hyperkalemic cardiac arrest
  • myoglobin is free to the cell, which can cause RF
  • halogenated agents/succ can initiate MH-like syndrome – avoid and use TIVA
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23
Q

this MH-like syndrom is associated with DMD d/t

A

rhabomyolysis

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24
Q

give TIVA for these conditions (5) because they hold calcium in their msucles

A
  • becker MD (progressive muscle weakness)
  • neuoleptic malignant syndrome (neuro emergency associated with use of antipsychotic agent causing mental staus change, rigidity and fever)
  • myotonia congenita (delayed relexation of the muscles after contraction- rigidity)
  • myotonic dystrophy (in ability to relax muscles at will)
  • osteogensis impeerfecta (fragile bones that break easily)
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25
Q

pathophysiology of MH causes

A
  • respiratory acidosis
  • metabolic acidosis
  • rigidity
  • altered cell permeability
  • hyperkalemia
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26
Q

MH risk may increase up to how many times higher when succ is used along with VIA?

A

20 times higher

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27
Q

MH symptoms may occur when?

A
  • immediatley after induction
  • several hours into surgery
  • even after surgery is completed
  • recovery room or ICU within 1 hour after GA
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28
Q

what is the most relaible sign that MH is occuring?

A

ETCO rise rapidly > 55

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29
Q

what is the other common sign with MH?

A

tachycardia

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30
Q

what are other common signs of MH?

A
  • tachypnea
  • skin mottling
  • total body or jaw muscle rigisity
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31
Q

how often does hyperthermia climb?

A

1 to 2 degrees celcius every 5 mins till averaging out at 39.3

32
Q

hyperthermia can occur?

A

early or late

33
Q

myoglobin appears in the __ and puts the patient at risk for __ __ & __ __

A

urine

tubular obstruction & renal failure

33
Q

even with treatment, individuals are at risk for complications including:

A
  • cerebral edema
  • consumptive coagulopathy
  • myoglobinuric renal failure
  • compartment syndrome
  • hepatic dysfunction
  • pulmonary edema
34
Q

what can also share several of the same characteristics with MH that makes it difficult to diagnose?

A
  • insufficient anesthetic depth
  • hypoxia
  • neuroleptic malignantnt syndrome
  • thyrotoxicosis
  • pheochromocytoma
  • sepsis
35
Q

every surgical patient should be asked the following:

A
  • FH of unexpected intraop complications or deaths?
  • family or personal hx of MH, muscle rigidity/stiffness, and or high fever under anesthesia?
  • personal hx of dark/cola-colored urine after surgery or exercise?
  • personal or family hx of high temps or death during exercise?
36
Q

lab findings consistent with MH

A
  • ABG: MA/RA
  • Potassium > 6 mEq/L
  • CK > 20,000 units/L
  • serum myoglobin > 170 mcg/L
  • urine myoglobin > 60 mcg/L
37
Q

Clinical events during MH

A
  • rapid unexplainable rise in ETCO2 > 55
  • unexplained tachy
  • masseter muscle or generalized muscle rigidity
  • rising patient temp
  • cola-colored urine
  • mottled cyanotic skin
  • decreased SaO2
  • Tachypnea
  • labile BP
  • arrhythmias
38
Q

dantrolene works how

A

not at the NMJ, works by binding to the ryanodine calcium channel and reducing calcium efflux from the SR, counteracting the abnormal IC calcium levels

39
Q

Dantrolene can have what side effects?

A
  • significant muscle weakness
  • respiratory insufficiency
40
Q

what would happen if you gave CCB to a patient with MH?

A
  • myocardial depression
  • hyperkalemia
41
Q

once MH is identified it is important to

A
  • disconnect triggering agents
  • administer dantrolene
  • hyperventilate with 100% FiO2
  • cool the patient
  • treat symptoms
42
Q

Treatment sequence for MH

A
  • call for help
  • d/c VIA
  • 2.5mg/kg dantrolene IV and repeat Q 5-10 mins until symptoms stop
  • hyperventilate with 100% oxygen
  • apply activated charcoal filters to each limb
  • initiate cooling lavage (OG, bladder, open cavities)
  • treat arrhythmias NOT w/ CCB
  • check ABG, consider bicarb
  • treat hyperkalemia: CaCl 10mg/kg, Ca gluconate 30mg/kg, bicarb 1-2mEq/kg, glucose/insulin
  • maintain urine output
43
Q

administer dantrolene through the __ vein possible

A

largest

can be very irritating to the vessels

43
Q

replace charcoal filters how often?

A

every hour

44
Q

original preparation of dantrolene is?

A

20mg reconstituted with 60 mL of sterile water

45
Q

how many grams of mannitol are in each dantrolene vial?

A

3g

46
Q

ryanodex preparation is?

A

250mg vial reconstituted with 5 mL of sterile water

47
Q

how much mannitol in ryanodex?

A

.125 g

48
Q

for MHS patients what else should you set up for the procedure along with standard monitoring equipment?

A

cooling water mattress

49
Q

a link between statin-induced muscle toxicity and susceptibility to

A

MH

50
Q

what do you do to AWS to prep for a MHS patient?

A
  • remove trace anesthesia gas from the machine
  • flush the anesthesia machine and vent with O2 set at 10L/min (20 mins at least) or more by attaching a new breathing circuit y-piece and reservoir bag
  • apply charcoal filters
  • dantrolene kit
  • ice and at least 3L of cold IV solution
51
Q

a full complement of dantrium is how vials?

A

36

52
Q

what test is available for determining if someone has MH?

A

caffeine halothane contracture test (CHCT)

gold standard

52
Q

a full complement of ryanodex is how vials

A

3

53
Q

what does the test involve?

A

taking a biopsy of skeletal muscle and measuring its contractile response to caffeine, halothane, or both

54
Q

where is this test avilable?

A

5 centers in North America

55
Q

MHAUS recommends the CHCT test for the following patients

A
  • MHS family member
  • past suspected MH even
  • severe masseter muscle rigidity during A
  • pt with mild to moderate MMR with evidence of rhabdomyolysis
  • unexplained rhabdomyolysis during or after surgery
  • the patient with exercised-induced rhabdomyolysis after a neg rhabdomyolysis workup
  • signs suggestive of MH but not definitive
56
Q

IV dantrolene should be continued at least

A

24 hours

57
Q

what is the dose of dantrolene post surgery

A

1mg/kg Q 4-6 hours
or
0.25/mg/kg/hour continuous infusion (.1-.3mg/kg/hr for 48-72 hours)

58
Q

dantrolene can be stopped or the interval between doses increased if the following criteria are met:

A
  • metabolic stability for 24 hours
  • core temp is less that 38
  • CK is decreasing
  • no evidence of myoglobinuria
  • muscular rigidity resolved
58
Q

recrudescence of an MH episode may occur in up to __ % of cases with a mean time

A

25%

13 hours

59
Q

MMR presages MH in how many % of cases?

A

20-30%

60
Q

T/F a mild increase in masseter muscle tone or incomplete jaw relaxation after succ is fairly common

A

true

61
Q

T/F is there a MH hotline?

A

true

available 24 hours a day

62
Q

early S/S of MH

A

hypercarbia
tachycardia
masseter spasm/muscle rigidity
tachypnea
cyanosis

63
Q

late S/S of MH

A

overt hyperthermia
irregular arrhythmias
cola-colored urine
coagulopathy
hyperkalemia

64
Q

Trismus

A

describes a tight jaw that can still be opened –> can happen with succ (normal response)

65
Q

whats the usual cause of death when temp exceeds 41 degrees celsius?

A

DIC

65
Q

definition of rhabdomyolysis

A

breakdown of skeletal muscle

66
Q

how many deaths are reported via the hotline each year?

A

1 to 2

67
Q

mortality of MH currently?

A

less than 5%

used to be greater than 70% before the approval of dantrolene in the 1970’s

68
Q

following conditions should be considered in your differential diagnosis for MH:
(PPT)

A
  • thyroid storm
  • MNS
  • sepsis
  • pheochromocytoma
  • serotonin syndrome
  • Heatstroke
  • metastatic carcinoid
  • cocaine intoxication
69
Q

What do I do?

(PPT)

A
  • d/c trigger
  • TIVA
  • call for help
  • tell the surgeon finsih ASAP
  • remove patient off circuit and hyperventilate with 100% fiO2 (min FGF 10L/min) — facilitates CO2 elimination, enhances O2 delivery, drives K into cells
  • apply charcoal filters, change circuit, change bag (may place pt back on vent after 2 mins when the above is completed)
  • administer dantrolene
70
Q

dantrolene has two mechanisms of action

A
  • it reduces Ca release from the RYR1 receptor in the skeletal myocyte
  • it prevents Ca entry into the myocyte, which reduces the stimulus for Ca induced Ca release
71
Q

max dose of Na Bicarb?

A

50mEq

72
Q

glucose/insulin for adults

A

10 units of regular insulin IV and 50 mL 50% glucose

73
Q

glucose/insulin for pediatric patients?

A

0.1 unit regular insulin/kg IV and 0.5 grams/kg dextrose

74
Q

not so common sense steps for an MH event

A
  • start new IVs
  • arterial line for frequent ABGs
  • turn off remove Bair Hugger
  • turn off remove fluid warmer
  • need foley
  • need a team dedicated to mixing dantrolene
  • dont delay placing pt back on vent
  • assign help to change out soda lime canisters
  • OGT insertion cool lavage
  • central temp monitoring
  • call MHAUS early for help/guidance
  • stay calm, you have been trained and you know what to do :)
75
Q

how long does the A gas machine need to be flushed with HFGF before placing activated charcoal filters on both inspiratory and expiratory ports?

A

90 seconds

NA 1 (15 decks)

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