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Gen Exam 3 + Final > MH > Flashcards

MH Flashcards

1
Q

Signs of MH

A
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1
Q

most specific sign of impending MH

A

increased ETCO2 (hot/blue absorbent)
esp: acute increase

less specific:
tachy<3
HTN
tachyRR
increase Mv

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2
Q

expected lab findings

A

resp & metab. acidosis
(lactic acidosis)
increase a-v pCO2 gradient
Hyper K
Hyper CK
↑ serum & urine myoglobin
abnormal coags

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3
Q

how to adjust vent settings when MH is expected

A

1.0 FiO2 (100%)
High gas flows

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4
Q

dysrhythmias are d/t ____ so we must treat them with ….

A

acidosis & hyperK
bicarb (NaHCO3)

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4
Q

When cooling the pt, we should cease measures once pt reaches ____ C

A

37.5-38
pt will continue to cool once active measures are ceased

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5
Q

which drug class should be avoided when treating MH? why?

A

Ca channel blockers
adversely interact w/ dantrolene

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6
Q

hyperK mgmt

A
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7
Q

Post acute phase mgmt

A

sedation
monitor core temp
maintain U/O (IVF, diuretics)
ICU
serial CK labs x 24H
Dantrolene 1mg/kg Q6H x 24-48H (25% reoccurrence)
kidney protection: saline & bicarb

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8
Q

MH reoccurs in ___% of pts in the first 24H following the incident

A

25
whats why we give Dantrolene 1mg/kg Q6H x 24-48H

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9
Q

Differential diagnosis

A

muscle Dzs
neuroleptic malig. synd
myotonic synd
cereb ischemia
ascending tonic-clonic synd
rhabdo (statins, hypoperfusn)
exertional heat illness

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10
Q

Autosomal dominant means…

A

only requires 1 abnormal gene to manifest symptoms

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11
Q

variable penetrance

A

does not trigger with every exposure

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12
Q

Ryanodine receptor

A

embedded in SR wall
Ca release channel

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13
Q

Gene for encoding RYR1 protein location

A

chromosome 19

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14
Q

dihydropyridine receptor

A

mutations in the corresponding gene can lead to MH

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15
Q

T/F
Genetic testing is the gold standard for diagnosing MH

A

False
multiple proteins are likely involved in Ca release that have not yet been discovered

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16
Q

Caffeine-Halothane Contracture Test (CHCT)

A

not widely available

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17
Q

CHCT statistics

A

low specificity: many false +

high sensitivity: low false -

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18
Q

T/F
N2O can trigger MH

A

False
the volatiles do

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19
Q

(non/depolarizing) agents trigger MH

A

depolarizing (suxx)

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20
Q

Mgmt of pt with MH history

A

shut off VAs for 15 mins

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21
Q

T/F
Pretreat MH history pt with dantrolene.

A

False
avoid triggering agents, but do not pretreat

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22
Q

Flushing machine of VA’s

A

may take over 60 min
charcoal filter
contact manufacturer

  • Remove the vaporizers
  • Replace CO2 absorbent canisters
  • Replace the bellows and fresh gas hose
  • Flush machine for 20 min. with O2 @ 10 L/min.
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23
Q

T/F
In susceptible/suspected MH pts, a CHCT test is not needed if we do not use triggering agents.

A

True

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24
Q

Pretreating with Dantrolene

A

not recommended
can worsen muscle weakness if muscle Dz

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25
Q

MH patients:
Postop monitoring

A

uneventful Sx: d/c same day
1H+ PACU; VS Q15min
1H phase 2 PACU/step down

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26
Q

T/F
Dantrolene is necessary for pts susceptible to MH

A

False
use non-triggering agent
recc core T monitoring

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27
Q

T/F
Ca Cl/gluconate can be used to treat the hyperK in MH crisis.

A

True

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28
Q

Diseases linked to MH

A

Central Core Dz
King Denborough Synd

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29
Q

T/F
Neuromalignant Syndrome makes pts susceptible to MH.

A

False
not at increased risk for MH susceptibility
similar presentation (fever, muscle rigidity)

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30
Q

MH kit contents

A
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31
Q

Occurrence rate

A
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32
Q

MH may be more common in which gender?

A

males

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33
Q

T/F
MH monitoring is important for PACU as well

A

True
may occur minutes after induction
or
several hours after triggering agent

34
Q

Steps of contraction and MH

A
  1. Nerve signals muscle to contract
  2. Na into muscle cell
  3. induces electric current
  4. current: down T tubule thru DiHydroP & ryanodine receptor –> SR
  5. SR release Ca thru channel in ryanodine rcptr –> cell interior
  6. contractile proteins overlap to contract & signals mito to make more ATP
  7. after contraction, Ca uptaken back into SR
  8. relaxation

MH: abnormally high Ca release; actinomysin contracture

35
Q

cascde of abnormal events in MH

A

abnormally high Ca release:
1. actin-myosin contracture
2. heat
3. O2 consumed
4. CO2 (from mito making energy)
5. lactic acid (runs out of O2)
6. cell brkdn & release contents (out of energy)

the release of contents causes downstream effects of MH

36
Q

T/F
elevated T is a late sign of MH

A

true

37
Q

T/F
Before treating a pt with history of MH, its wise to change the CO2 absorber.

A

True

38
Q

Preparing Dantrolene

A

20 mg into 60 ml STERILE WATER
goal: 2.5 mg/kg

39
Q

MH is a ____ disorder

A

myopathic

40
Q

Triggers outside of the OR

A

○ heat exhaustion
○ Caffeine
○ strenuous exercise
○ other medical conditions

41
Q

One parent with the trait means the child will have a __% chance of having the
trait as well.

A

50

42
Q

(25 – 50%) of cases, MH occurs as a result of a mutation of …

A

the ryanodine receptor, type
1 (RYR1)

42
Q

mutant ryanodine receptor is a ___ disorder

A

heterogenic

43
Q

mutations in the ryanodine receptor (RYR) cause…

A

aberrant/abnormal calcium channel in the sarcoplasmic reticulum

44
Q

RYR1

A

● encodes protein for calcium movement into muscle cell, (regulates muscle contraction & metabolism)

● defective RYR1= reduced reuptake of Ca++

increased Ca
↓
sustained muscle contraction
↓
hypermetabolic state

● To reverse the process, the SR must re-uptake the excess calcium.

45
Q

thought to be induced by heat stress in children

A

“Awake-Triggered MH”

46
Q

“Awake-Triggered MH”

A

similar to “Broken Heart Syndrome” (or “Takotsubo Syndrome” aka a
stressed-induced cardiomyopathy)

47
Q

currently estimated that 1 in ___ have a defective ryanodine receptor.

A

1:500

48
Q

higher incidence noted in ___

A

children
undiagnosed muscle disorders (i.e. Core Central Disease (CCD))
and first time exposure.

49
Q

Approximately __ cases of anesthetic-induced MH occur in the United States each
year.

A

800

50
Q

Introduction of treatment with dantrolene has caused the mortality rate to fall from __% in
the 1970s to less than __% today.

A

80
10

51
Q

MH can occur by these 2 ways

A

excess calcium release
decreased calcium uptake

52
Q

body temperature rises as
much as

A

1°C every 5 minutes

53
Q

Why does Ca build up in MH?

A

the abnormal receptor does not close properly after having opened in response to a
stimulus

54
Q

What generates the heat?

A

sustained, uncoordinated muscle contractions

55
Q

What is happening to the brain and organs?

A

patient’s brain is frying like an egg – the proteins are denaturing

internal organs are destroyed in an acid bath

56
Q

What happens as the muscle tissue breaks down?

A

(occurs d/t ATP depletion)

cells “leak” potassium, myoglobin,
creatine and creatine kinase

57
Q

How did farmers find out if their pigs were MH-susceptible?

A

expose piglets to halothane

Those that die are MH-susceptible

58
Q

Why is the pig model useful in MH research?

A

“awake trigger” in
stressful situations occurs in piglets

awake trigger is thought to be induced by heat stress in children

59
Q

Early vs late signs

A
60
Q

Dantrolene dosing

A

dantrolene sodium 2.5 mg/kg IV
every five minutes (up to 10 mg/kg)

use central vein

61
Q

Diuresis

A

UO goal: >2 ml/kg/hr
mannitol 25 mg IV
furosimide 20 mg IV
IV fluids

○ mannitol 0.5 g/kg to force diuresis
○ Lasix will help bring down K+ levels.

62
Q

Potassium management

A

insulin drip: 10 units/hr

100 ml of 50% glucose to (prevent hypoglycemia)

63
Q

Albuterol

A

4 puffs MDI via ETT

64
Q

arrhythmia mgmt

A

(10-30 mg/kg of calcium chloride)
antagonizes the cardiac effects of hyperkalemia

can also use procainamide

65
Q

most common cause of death

A

VFIB

66
Q

T/F
You must have confirmed diagnosis of MH to give Dantrolene

A

False
must be instituted rapidly on clinical suspicion of the onset of malignant
hyperthermia

67
Q

Dantrolene MoA

A

muscle relaxant that works directly on the ryanodine receptor to prevent the
release of calcium from SR

68
Q

Dantrolene HL

A

6 H
redosing is important!

69
Q

only sure way to prevent MH

A

avoid the use of triggering agents

70
Q

Azumolene

A

water-soluble analogue
less irritating
smaller volume for dilution

short shelf half life of only six months and more expensive

71
Q

Dantrium/Revonto vs Ryanodex

A

Dantrium:
-36 vials on hand
-dilute w 60 ml sterile water
-3 g of mannitol in each vial of 20 mg of dantrolene
(0.15 g mannitol/ 1 mg dantrolene).

RYANODEX:
-3 vials on hand
-dilute w 5 ml sterile water
-0.125 grams of mannitol in each vial of 250 mg of Ryanodex
(0.0005 grams mannitol/1 mg dantrolene)

both: do not use bacteriostatic agent

72
Q

During an MH code, the anesthesia provider will

A

run the code

73
Q

How many people to prepare the Dantrium?

A

2 teams of 2 ppl

74
Q

Patient history should include:

A

history of MH
adverse response to anesthesia
muscle disorders
strabismus
myalgia during exercise
caffeine intolerance

75
Q

Prevention
Explore a persistent, elevated ___

A

creatinine kinase (an enzyme of skeletal muscle and the myocardium, which helps produce ATP)

76
Q

Your patient is suspected to have MH by history. His CHCT biopsy was negative. How do you proceed with his anesthesia plan?

A

use non-triggering anesthetics (TIVA or regional)
Negative biopsies are not definitive

77
Q

Sensitivity

A

probability that a symptom is present (or screening test is positive)
given that the person has the disease.
“True Positive Test”

78
Q

Specificity

A

probability that a symptom is not present (or screening test is negative)
given that the person does not have the disease .
“True Negative Test”

79
Q

its recommended to perform this test in addition to the CHCT to
make the test more specific

A

“Calcium Induced Calcium Releasing” (CIRC)

80
Q

Any pt with suspected/confirmed MH should be the ___ case of the day

A

first

81
Q

Notify ___ of any MH occurrence

A

MHAUS.org
(Malignant Hyperthermia Association of the United States )

82
Q

T/F
A pt with history of MH must undergo anesthesia in an inpatient setting.

A

False
If the patient has a history of MH, but does not trigger, he or she is required to
stay in the PACU for observation before going home.

Gen Exam 3 + Final (13 decks)

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