Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

2-General Principles Exam 3 > Malignant Hyperthermia > Flashcards

Malignant Hyperthermia Flashcards

1
Q

What is malignant hyperthermia?

A

Inherited disorder of skeletal muscle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What triggers Malignant Hyperthermia?

A

Triggered in susceptible humans or animals by volatile inhalation agents or succinylcholine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What anesthetics can cause Malignant Hyperthermia?

A
  • Sevoflurane
  • desflurane
  • isoflurane
  • halothane
  • enflurane
  • ether
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are other triggers for Malignant Hyperthermia?

A

Vigorous exercise and heat**

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is malignant hyperthermia characterized by?

A
  • Hyper metabolism
  • Skeletal muscle damage
  • Hyperthermia
  • Death
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

True incidence of Malignant Hyperthermia is ________

A

Unknown

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is the genetic component of Malignant Hyperthermia?

A

Autosomal dominant

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is the clinical incidence in adults with Malignant Hyperthermia?

A

1 in 3,000 – 1 in 50,000 anesthetics

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the pediatric incidence of Malignant Hyperthermia?

A

Children under 15 years comprise approx. 52% of all reactions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Which gender is more like to cause Malignant Hyperthermia?

A

More common in males (2.5-4.5 times)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is the autosomal dominant traits for Malignant Hyperthermia?

A

One abnormal gene needed to manifest symptoms

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

How many mutations are associated with Malignant Hyperthermia?

A

Associated with 34 genetic mutations

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What are the most common genetic mutations for Malignant Hyperthermia?

A
  • RYRI (70%) (ryanodine receptor for Ca++ release at SR)
  • CACNA1S (1%) (subunit of dihydropyrdine Ca++ channel on T-tubes)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is variable penetrance mean in association with Malignant Hyperthermia?

A

Susceptible patient does not necessarily trigger to every exposure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Review genetic components of Malignant Hyperthermia.

A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

The gene for the RYR 1 receptor is located on _________

A

chromosome 19

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Where are all of the genetic mutations associated with Malignant Hyperthermia located?

A

chromosome 19

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Where is calicum stored?

A

Invaginations of plasma membrane known as t-tubules which are surrounded by sarcoplasmic reticulum which stores intracellular calcium.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is the unique feater of the sarcolemma?

A
  • It has holes in it.
  • These “holes” lead into tubes called transverse tubules (or t-tubules for short).
  • These tubules pass down into the muscle cell and go around the myofibrils.
  • However, these tubules do not open into the interior of the muscle cell; they pass completely through and open somewhere else on the sarcolemma (i.e., these tubules are not used to get things into and out of the muscle cell).
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is the function of the T-tubules?

A

The function of t-tubules is to conduct impulses from the surface of the cell (sarcolemma) down into the cell and, specifically, to another structure in the cell called the sarcoplasmic reticulum.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

How is the muscle fiber excited?

A
  • A muscle fiber is excited via a motor nerve that generates an action potential that spreads along the surface membrane (sarcolemma) and the transverse tubular system into the deeper parts of the muscle fiber.
  • A receptor protein (DHP) senses the membrane depolarization, alters its conformation, and activates the ryanodine receptor (RyR) that releases Ca2+ from the SR. Ca2+ then bind to troponin and activates the contraction process
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Review the normal skeletal muscle.

A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Describe the normal skeletal muscle diagram.

A

Interior of skeletal muscle cell:

  1. Plasma membrane
  2. Invagination of plasma membrane into the cell (t-tubule)
  3. Protein embedded in the wall of the t-tubule – Dihydropyridine protein
  4. Large protein in sarcoplasmic reticulum - ryanodine
  5. Sarcoplasmic reticulum that stores calcium in the cell
  6. Contractile proteins in the cell
  7. Reuptake of intracellular calcium after contraction

Bottom left = mitochondria (energy producers)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What does the dihydropyridine receptor sense?

A
  • The dihydropyridine receptor senses the membrane depolarization, alters its conformation, and activates the ryanodine receptor (which releases Ca2 from the sarcoplasmic reticulum, a Ca2 storage area).
  • Ca2 binds to troponin and activates the contractile machinery.
  • In classic malignant hyperthermia, uncontrolled Ca2 release from the SR leads to an increased pump activity and heat production, mainly by the adenosine triphosphate-dependent Ca2 reuptake into the SR.
  • To cope with the increased energy consumption, glycogen stores will be depleted for maximal adenosine triphosphate production
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What can the myoplasmic Ca2 overload may stimulate?

A

also stimulate Ca2 sensitive proteases, liposomal enzymes, and nuclear DNases, potentially resulting in rhabdomyolysis.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What is the MOA of Malignant Hyperthermia?

A

Dysregulation in intracellular calcium homeostasis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

MH: Calcium released from the sarcoplasmic reticulum in quantities that _______ normal

A

far exceed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What does excess calcium release lead to?

A

Leads to actin and myosin continually contracting = contracture

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

What do accelerations in cellular processes lead to? (8)

A
  • Heat production
  • Excess lactate
  • Oxygen consumption → Anaerobic metabolism, lactic acid
  • Carbon dioxide production
  • Depleted ATP stores
  • Cell breakdown with contents entering circulation and causing downstream effects
  • Acidosis, hyperthermia and ATP depletion lead to destruction of the sarcolemma
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

What moves into the extracellular fluid with malignant hyperthermia?

A

K+, myoglobin and creatine kinase move into extracellular fluid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

What are the clinical signs of Malignant Hyperthermia?

A
  • Tachycardia**
  • Unanticipated increase in ETCO2 levels (>55mmHg) that are out of proportion to MV**
  • Tachypnea
  • Skin mottling
  • Rigidity
  • Hyperthermia
  • Myoglobinuria
  • Mottled, cyanotic skin
  • Decreased SaO2
  • Arrhythmias and labile BP
  • Mixed metabolic and respiratory acidosis
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

What are the hallmark signs of malignant hyperthermia?

A
  • Tachycardia**
  • Unanticipated increase in ETCO2 levels (>55mmHg) that are out of proportion to MV**
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

What are the characteristics of Rigidity with malignant hyperthermia?

A

Rigidity (present in 75% of cases): masseter muscle or generalized

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

What are the characteristics of hyperthermia with malignant hyperthermia?

A
  • Hyperthermia (1-2 degrees Celsius increased every 5 min)
  • May be early or late sign
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

What are the characteristics of Myoglobinuria with malignant hyperthermia?

A
  • Myoglobinuria (cola colored urine)
  • Myoglobin released from inside muscle cell
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

What causes of arrhythmias and labile BP with malignant hyperthermia?

A

Caused by acidosis, hyperkalemia and hyperthermia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

What are the laborarotry findings for Malignant Hyperthermia?

A
  • ABG: Respiratory and metabolic acidosis
  • Serum potassium >6 mEq/L
  • CK >20,000 units/L
  • Serum myoglobin >170 mcg/L
  • Urine myoglobin >60 mcg/L
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

What is the onset of Malignant Hyperthermia?

A

Intraoperatively or shortly afterwards

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

What is the different types of rate of onset?

A
  • Fulminant
  • Indolent
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

Define Fulminant.

A

Onset of full-blown syndrome within minutes of induction of general anesthesia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

What effects does succinylcholine have on the timing of malignant hyperthermia?

A

Succinylcholine may accelerate onset and increase MH severity

42
Q

What is the compenents of differential diagnosis for malignant hyperthermia?

A

Tachycardia, hyperpyrexia, tachypnea, hypercapnia and masseter muscle rigidity can be found in other disease states

43
Q

Other than MH, what could lead to an elevated end tidal carbon dioxide? (3)

A
  • Malfunction in the one-way valves of the circle system
  • Problem with carbon dioxide absorbent
  • Retained CO2 with pneumoperitoneum and subcutaneous air
44
Q

What other (disease) states may mimic malignant hyperthermia?

A
  • Insufficient anesthetic depth
  • Hypoxia
  • Pheochromocytoma
  • Sepsis
  • Hyperthyroidism/Thyrotoxicosis
  • Neuroleptic malignant syndrome
45
Q

What would an end tidal waveform look like in a patient with malignant hyperthermia?

A
46
Q

What is the overall treatment of Malignant Hyperthermia Crisis?

A
  • Call for help / Alert operating room staff
  • Turn off triggering agents (inhalational anesthetics)
  • Hyperventilation with FIO2 1.0
  • Cool
  • Consider cognitive aid
47
Q

What is the medication treatment for malignant hyperthermia?

A

Dantrolene or Ryanodex

48
Q

What is the malignant hyperthermia phone number?

A

1-800-MH-HYPER (MHAUS)

49
Q

What is the hyperventilation components of malignant hyperthermia?

A
  • High gas flows
  • Adding charcoal filter to circuit to scrub residual agent
50
Q

What diseases have a strong clinical and/or genetic links to MH susceptibility found with?

A
  • Central Core disease
  • King Denborough syndrome
  • Multi-minicore disease
51
Q

Define Multi-minicore disease.

A

A rare, inherited condition which causes degeneration of the muscle fibers

52
Q

Define central core disease.

A

Genetic disease of the ryanodine receptor

53
Q

Define king denborough syndrome.

A

Rare genetic non-dystrophic myopathy characterized by the triad of congenital myopathy, dysmorphic features and susceptibility to malignant hyperthermia

54
Q

What diseases have no risk or link to MH?

A

There is NO risk for MH beyond the normal general population in patients with Duchenne or Becker muscular dystrophy, neuroleptic malignant syndrome, myotonia congenita or myotonic dystrophy

55
Q

What should be done first if MH is suspected?

A

Notify surgeon to halt surgery ASAP

56
Q

What needs to be done for your anesthetic in a MH crisis?

A
  • D/C inhalational agents (succinylcholine)
  • If surgery must continue - switch to TIVA
57
Q

Who needs to be called in a MH Crisis?

A

Call for help! (call 911 if at an ASC); call MHAUS

58
Q

What needs to be brought into the room in a MH Crisis?

A

MH cart

59
Q

Why is hyperventilation of MH Crisis needed?

A
  • Hyperventilate (to rid agent and drive down PaCO2) at high flows (at least 10L/min)

•Remove vaporizers

  • flush machine
  • add charcoal filter (saturate at about 1 hour)
60
Q

What is the dose of the medication for MH Crisis?

A

Dantrolene 2.5 mg/kg rapidly via large bore IV until patient responds (lower HR, lower CO2, decreased rigidity (may require up to 10 mg/kg)

61
Q

What labs need to be monitored for MH Crisis?

A
  • Obtain ABG and treat metabolic acidosis (BE > 8)
  • Monitor serum electrolytes, blood glucose, coagulation profile, CK, blood and urine myoglobin and liver enzymes
62
Q

What is the dose of bicarbonate for the treatment of metabolic acidosis with MH Crisis ?

A

1-2 mEq/kg of bicarbonate

63
Q

What is the process of cooling a patient for MH Crisis?

A

Cool patient if temp > 39 C, stop when < 38.5 C – cooling lavage (orogastric, bladder, open cavities), chilled IV saline, cooling blanket, ice (groin axilla and neck)

64
Q

What electrolytes need to be treated with MH crisis?

A
  • Hyperventilation, bicarbonate, glucose/insulin
65
Q

What can be used to treat refractory hyperkalemia?

A

B-agonist such as albuterol, kayexalate, dialysis, ECMO

66
Q

What should be avoided for the treatment of dysrhythmias?

A

avoid Ca++ channel blockers – When given with dantrolene may cause life threatening myocardial depression and hyperkalemia

67
Q

What kidney interventions need to happen when treating MH?

A

Diurese to >1ml/kg/hr urine output with hydration, furosemide (0.5-1mg/kg and mannitol prn

68
Q

What needs to be followed as a result of MH crisis?

A

HR, core temperature, ETCO2, minute ventilation, blood gases, K+, CK, urine myoglobin and coagulation studies as warranted by the clinical severity of the patient

69
Q

What is the MOA of Dantrolene?

A
  • Muscle relaxant that doesn’t work at neuromuscular junction
  • Binds to ryanodine calcium channel and reduces calcium efflux from sarcoplasmic reticulum
70
Q

What are the two preparations of Dantrolene?

A
  • Dantrium/Revonto
  • Ryanodex
71
Q

What is the dose for Dantrium/Revonto?

A
  • 20mg vial to be reconstituted with 60mL of sterile water
  • 3 grams of mannitol in each 20mg vial
  • Dose is 2.5mg/kg for initial dose
72
Q

What is the solubility of Dantrium/Revonto?

A

Very poor water solubility

73
Q

What is the dose of Ryanodex?

A
  • 250mg vial to be reconstituted with 5mL of sterile water
  • 0.125 gram of mannitol in each 250mg vial
74
Q

Review the effect of dantrolene.

A
  • Effect of dose of dantrolene on MH symptoms
  • Time on x-axis
  • Minute ventilation and end tidal carbon dioxide on y-axes
  • After 6 hours of anesthesia time minute ventilation (blue line) and end tidal carbon dioxide increase
  • At 12 hours recognized as MH
  • Dantrolene administered at white arrow and symptoms resolve quickly
75
Q

What happens After Immediate Crisis?

A

Transfer to hospital

76
Q

If admitted to the ICU how long is the admission for MH last.

A

ICU admission for 36 hours minimum

77
Q

What are the monitoring that should be completed after the immediate crisis?

A
  • Continuous central temperature monitoring
  • Serial labs
78
Q

What needs to be monitored for peak levels?

A

CK peaks many after hours the event. Monitor for peak and declination

79
Q

How long should dantrolene be administered?

A
  1. Continue dantrolene for minimum 24 hours
  2. Dose: 1mg/kg every 4-6 hours as a bolus OR 0.25mg/kg/hr via continuous infusion
80
Q

What is the rate of reoccurrence of MH?

A

Recrudescent rate 25% in first 24 hours, mean 13 hours

81
Q

What can be administered for kidney protection?

A
  • Saline and NaHCO3
  • Myoglobin is toxic to kidneys
82
Q

What needs to be done after the MH crisis?

A
  • Patient and family counseling
  • ID bracelet/necklace
83
Q

What registry does patient needed to be added to after MH crisis?

A

North American Malignant Hyperthermia Registry

84
Q

What form needs to be completed following a MH crisis?

A

AMRA (Adverse Metabolic Reaction to Anesthesia) form

  • To be completed by anesthesia providers involved in case
  • Can be anonymous or with patient information with patient consent
85
Q

What do patients need to be referred to after a MH crisis?

A
  • Testing
  • Refer to MH testing center
86
Q

What is not the gold standard for MH testing?

A

Genetic testing is not the gold standard because we don’t yet understand all of the mutations that may make an individual susceptible to MH

87
Q

What is the gold standard for MH testing?

A

Caffeine Halothane Contracture Test

  • Skeletal muscle sample contractile response to caffeine, halothane or both
88
Q

What is the MOA of the Caffeine Halothane Contracture Test?

A

Invasive - Uses fresh vastus lateralis muscle biopsy and test must be completed within hours of muscle harvest

89
Q

What are properties of the Caffeine Halothane Contracture Test?

A
  • Requires travel to 1 of 4 designated centers in North America
  • Expensive
90
Q

Review components of the Caffeine Halothane Contracture Test.

A
91
Q

Identify the normal versus abnormal test.

A
  • X-axis = time
  • Y-axis = tension
  • Top graph – tension increases after exposure to caffeine or halothane
  • Bottom graph – muscle tension significantly increases with exposure.
  • Diagnosed with MH susceptibility
92
Q

Define sensitivity.

A
  • (measures how often a test correctly generates a positive result for people who have the condition that’s being tested for)
  • Very few false negatives
93
Q

Define specificity.

A
  • (measures a test’s ability to correctly generate a negative result for people who don’t have the condition that’s being tested for)
  • Significant number of false positives
94
Q

What is the sensitivity and specificity?

A
95
Q

What should be done for MH Susceptible Patients?

A
  • Standard monitors and consider a cooling blanket under the patient
  • Consider regional or local anesthetic if possible
  • Use of a non-triggering general anesthetic
96
Q

What should be done to the AGM for MH Susceptible Patients?

A

Remove trace anesthetic gases from AGM (review specific AGM instructions)

  • Change CO2 absorbant
  • Ensure vaporizers are disabled by removing or taping them off
  • Flush AGM and ventilator with oxygen at ≥10 L/min for 20-104 minutes
  • Use new breathing circuit and reservoir bag
  • Add charcoal filters to inspiratory and expiratory limbs
  • Have MH cart in OR
  • Monitor postoperatively for a minimum of 2 hours
97
Q

Where can you find information regarding the AGM for MH susceptible patients?

A

review specific AGM instructions

98
Q

How long should MH susceptible patients be monitored after uneventful anesthesia?

A
  • The patient susceptible to MH undergoing outpatient surgery may be discharged on the day of surgery if the anesthesia has been uneventful.
  • A minimum period of 1 hour in PACU monitoring vital signs at least every 15 minutes and an additional hour is phase II PACU/step down unit is recommended.
99
Q

Can calcium gluconate or calcium chloride be used when treating hyperkalemia cardiac toxicity during an MH crisis?

A

Yes

100
Q

Is MH linked to other serious medical problems? If so, which ones?

A
  • Central core disease
  • King Denborough syndrome
  • Multi-minicore disease
101
Q

If you were responsible for making the MH kit for your operating room, what supplies would you include?

A
  • Required Medications
    • Dantrolene 36 vials
      • Ryanodex?
    • Sterile water
    • Sodium bicarbonate
    • Dextrose
    • Mannitol
    • Furosemide
    • Antidysrhythmic drugs
  • Necessary Equipment
    • Temperature probes
    • Nasogastric tubes
    • Assorted catheters
    • Blood collection tubes
    • Syringes
    • Needles
    • Normal saline
102
Q

What is the hotline number to call during a MH crisis?

A

1-800-MH-HYPER

2-General Principles Exam 3 (11 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions