Exam 5 MH Flashcards

1
Q

MH is a disorder of the

A

skeletal muscle (hypermetabolic)

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2
Q

Inhalation agents that trigger MH

A

Sevo
Iso
Des
halothane

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3
Q

NMB that triggers NH

A

Succinycholine
(accelerates onset and increases severity of MH episode)

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4
Q

States with high incidences

A

Wisconsin
Nebraska
West Virginia
Michigan

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5
Q

MH genetic pattern

A

autosomal dominant
(if one parent has it, 50% change child will get it)

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6
Q

What receptor is site of defect for MH

A

RYR1 (skeletal muscle)
Ryanodine receptor

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7
Q

What is the ryanodine receptor role

A

Calcium release channel of SR

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8
Q

MH pathophysiology

A

Uncontrolled release and regulation of calcium. Constant muscle contraction

Recycling Ca+ and contracting increases muscle metabolism 2-3 fold

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9
Q

Physiologic consequences of MH (5)

A
  1. increase O2 consumption
  2. augments carbon dioxide production
  3. augments heat production
  4. Depletes ATP stores
  5. Generates lactic acid
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10
Q

Acidosis, hyperthermia and ATP depletion cause

A

Sarcolemma destruction: loss of K, myoglobin, creatinine kinase (to extracellular fluid)

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11
Q

MH muscle defect is in

A

SKELETAL muscle (not cardiac)

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12
Q

Earliest sign of MH is

A

increased ETCO2

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13
Q

volatiles can cause MH as long as _____ after induction

A

6 hours

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14
Q

labs and clinical events during MH

A

Apex card game

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15
Q

Clincal events during MH:

A
  1. ETCO2 rise
  2. tacycardia, tachypnea
  3. labile BP or arythmias
  4. Masseter or muscle rigidity
  5. Rising temp
  6. Cola colored urine (myogolibinuria)
  7. Mottled, cyanotic skin
  8. Decreased Sa)2
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16
Q

MH ABG

A
  1. PACO2 > 60 mmhg
  2. Base excess more negative than -8mEq/L
  3. pH <7.25
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17
Q

MH serum K+

A

> 6 mEq/L

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18
Q

MH serum Creat Kinase

A

> 20,000

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19
Q

MH Serum myoglobin

A

> 170 mcg/L

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20
Q

MH Urine myoglobin

A

> 60 mcg/L

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21
Q

Why is MH such a big deal?

A

Acidosis + hyperkalemia +hyperthermia = cardiac irritability, labile BP, arrhythmias, cardiac arrest

22
Q

Late MH complications (5)

A
  1. cerebral edema
  2. myoglobinuric renal failure
  3. coagulopathy
  4. hepatic dysfunction
  5. pulmonary edema
23
Q

Diseases that have genetic link to MH (4)

A
  1. Central core disease
  2. king denborough syndrome
  3. multiminicore disease
  4. Evans myopathy

*apex matching game

24
Q

They key to successful MH management is

A

early recognition and prompt treatment

25
Q

MH treatment steps

A
  1. Stop triggering agent
  2. call for help and stop procedure
  3. hyperventilate with 100% O2 at high flows
  4. Dantrolene
26
Q

Dantrolene dosing

A

2.5 mg/kg every 5-10 min until symptoms abate

27
Q

At what dose of dantrolene should you consider other causes of symptoms?

A

20 mg/kg

28
Q

in MH, keep temp at

A

38 deg C

29
Q

Treat life threatening dysrhythmias with

A
  1. Lidocaine
  2. Procainamide

NOT CALCIUM CHANNEL BLOCKERS LIKE VERAPAMIL

30
Q

Procainamide MH dose

A

200 mg IV

31
Q

Sodum bicarb dose (MH acidosis)

A

1-2 mEq/kg IV

32
Q

Hyperkalemia MH treatment

A

dextrose 25-50 g
Insulin 10 units in 50 mL 50% dextorse in water

33
Q

MH urin output goal

A

2 mL/kg/hr with lasix and mannitol as needed

34
Q

Mannitol MH dose

A

0.25 mg/kg IV for up to 4 doses (may be enough in dantrolene to be effective)

35
Q

lasix dose MH

A

1mg/kg up to 4 doses

36
Q

Dantrolene MOA

A

reducing calcium efflux from SR, counteracting abnormal intracellular calcium levels

37
Q

How to prepare dantrolene

A

reconstitute 20mg vial with 60 mL sterile water for injection

38
Q

Know how to calculate how many vials you’ll need

A

2.5 mg/kg up to 20 mg/kg
20 mg vials

39
Q

For a 70 kg patient, how many vials of dantrolene do you need?

A

9 vials

40
Q

Mix dantrolene with

A

sterile water, or it precipitates

41
Q

Even if symptoms stop, dantrolene should be repeated after symptoms stop at

A

1mg/kg q 4-6 hrs for 24 hrs

42
Q

Why can’t you give calcium channel blockers with MH

A

causes marked hyperkalemia and cardiac depression
(dilt, verapamil)

use procainamde (sodum channel blocker) or lidocaine for dysrhythmias

43
Q

Ryanodex is

A

dantrolene in a more concentrated vial

44
Q

One vial of ryanodex is

A

250mg per vial

45
Q

How to reconstitiute ryanodex

A

5 mL of sterile water per vial

46
Q

Gold standard for MH diagnosis

A

caffeine halothan contracture test (CHCT)

47
Q

For susceptible patient:

A
  1. place cooling mattress under
  2. avoid GA and LA, use TIVA
  3. avoid succs and volatiles
48
Q

Machine prep for susceptible patient:

A
  1. remove vaporizers
  2. change soda lime
  3. change circuits
  4. flush machine with O2 high and high flows 10L/min for 20-150 min
  5. add charcoal filter in inspiratory limb
  6. have MH cart in OR and 36 vials of dantrolene and sterile water ready
  7. observe in PACU 2.5 hrs after surgery
49
Q

Trismus

A

sustained and foreceful contracture of masseter muscle
(normal)

50
Q

Masseter muscle rigidity means

A

impossible to open mouth - sign of MH, STOP

51
Q

If masseter muscle rigidity occurs, patient should be addmitted:

A

24 hours ICU

52
Q

If MH criss, pt should be admitted:

A

36 hrs ICU