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APEX: Flashcards > Musculoskeletal Dz > Flashcards

Musculoskeletal Dz Flashcards

1
Q

Myasthenia Gravis Patho

A
  • autoimmune dz
  • IgG antibodies destroy POST-junctional receptors (nicotinic Ach)
  • thymus gland plays key role; thymectomy relieves s/s
  • Ach quantity sufficient
  • not enough Ach receptors
  • manifests as skeletal muscle wknss
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2
Q

Myasthenia gravis s/s

A
  • key features:
    ~ muscle wknss later in day or w/ exercise
    ~ improves w/ rest
  • diplopia, ptosis (early)
  • bulbar wknss (dysphagia, dysarthria, drooling)
  • dyspnea w/ exertion
  • proximal muscle wknss
  • may require postop ventilation
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3
Q

Myasthenia Gravis is exacerbated by:

A

Apple - aminoglycosides
P - pregnancy
I - infection
E - electrolyte abnormalities
S - stress

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4
Q

How does myasthenia gravis affect pregnant mother & fetus?

A
  • Pregnancy intensifies s/s in 1/3 of pregnant women
  • Anti-Ach IgG antibodies cross placenta in 15-20% of neonates & cause wknss (can last up to 2-4 weeks)
  • neonates require airway mgmt
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5
Q

Myasthenia Gravis Tx

A
  • 1st line = oral pyridostigmine
  • corticosteroids, cyclosporine, azathioprine, mycophenolate (immunosuppression)
  • thymectomy (reduces Anti-AchR IgG)
  • plasmapheresis
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6
Q

How can you differentiate b/t cholinergic crisis & myasthenic crisis?

A
  • pyridostigmine OD –> cholinergic crisis
  • Tensilon test = 1-2 mg IV edrophonium
    ~ muscle wknss worse = cholinergic crisis –>
    tx w/ anticholinergic
    ~ muscle wknss better = myasthenic crisis –>
    tx w/ anticholinesterase,
    immunosuppression, plasmapheresis
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7
Q

How do patients w/ myasthenia gravis respond to sux?

A
  • Fewer nicotinic Ach (Nm) receptors
  • Resistant
  • Require increased dose (1.5- 2.0 mg/kg)
  • pyridostigmine prolongs DOA of sux
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8
Q

How do patients w/ myasthenia gravis respond to ND-NMB?

A
  • Fewer nicotinic Ach (Nm) receptors
  • Sensitive (potency increased)
  • Reduce dose by 1/2 to 2/3
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9
Q

5 perioperative risks that increase postop mechanical ventilation in pt w/ myasthenia gravis

A
  1. Dz > 6 years
  2. pyridostigmine > 750 mg/day
  3. VC < 2.9 L
  4. COPD
  5. Surgical approach: median sternotomy> transcervical thymectomy
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10
Q

Eaton-Lambert Syndrome (Myasthenic Syndrome) Patho

A
  • IgG-mediated destruction of PRE-synaptic VG
    Ca+ channels
  • Ca+ entry in presynaptic neuron decreased
  • Decreased amount of Ach released into
    synaptic cleft
  • 60% have small-cell lung CA (oat-cell)
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11
Q

ELS S/S

A
  • Proximal muscles affected
  • wknss worse in AM, gets better throughout
    day
  • Respiratory muscles & diaphgram weak
  • ANS dysfunction:
    ~ orthostatic hypotension
    ~ slowed gastric motility
    ~ urinary retention
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12
Q

ELS Tx

A
  • 3, 4- diaminopyridine (DAP)
    ~ increases Ach release from presynaptic
    nerve

AchE not helpful
Tensilon test does NOT aid diagnosis

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13
Q

How do pt w/ ELS respond to NMBs?

A
  • Sensitive to sux & NDNMBs
  • Reduce dose
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14
Q

ELS Mgmt

A
  • Reversal may be inadequate
  • High risk postop resp failure
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15
Q

ELS vs. Myasthenia Gravis

A
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16
Q

Guillain-Barre (acute idiopathic polyneuritis)

A
  • Destruction of myelin prevents nerve conduction in peripheral nerves
  • Precipitated by flu-like illness followed by paralysis
  • Causes: epstein-barr, campylobacter, cytomegalovirus
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17
Q

Guillain-Barre S/S

A
  • Flaccid paralysis begins in distal extremtities & ascends bilaterally
  • Impaired ventilation (intercostal muscles)
  • Difficulty swallowing (facial & pharyngeal muscles)
  • Paresthesias, numbness, pain
  • ANS dysfunction
    ~ tachycardia, bradycardia, hyper/hypotension, diaphoresis, anhidrosis
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18
Q

Guillain-Barre Tx

A
  • plasmapheresis
  • IV IgG
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19
Q

Guillain-Barre Mgmt

A
  • avoid sux (hyperkalemia)
  • sensitive to NDNMBs (decrease dose)
  • increased aspiration risk
  • may require postop ventilation
  • autonomic dysfx = HD instability = a-line
  • exaggerated response to indirect-acting sympathomimetics (avoid ephedrine)
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20
Q

Hypokalemic periodic paralysis

A
  • Skeletal muscle wknss follows a glucose-insulin infusion
  • pt becomes weak after K+ decreases
  • Ca+ channelopathy

AVOID:
- glucose solutions
- K+ wasting diuretics
- B2 agonists
- Sux
- hypothermia

Safe:
- NDNMBs
- Acetazolamide

Tx: Acetazolamide (creates non-anion gap acidosis, protects against hypokalemia)

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21
Q

Hyperkalemic periodic paralysis

A
  • skeletal muscle wknss follows oral K+ administration
  • pt becomes weak after K+ increases
  • Na+ channelopathy

AVOID:
- Sux
- LR (solutions w/ K+)
- hypothermia

Safe: everything listed in AVOID on hypokalemia card + acetazolamide

Tx: Acetazolamide (facilitates K+ excretion)

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22
Q

MH patho

A
  • Inherited disease of skeletal muscle characterized by disordered Ca+ homeostasis
  • Genetic mutation of ryanodine receptor (RYR1)
  • Defective RYR1instructs SR to release too much Ca+ into cell
  • Increase O2 consumption
  • Increased CO2 production
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23
Q

Consequences of increased intracellular Ca+

A
  • rigidity from sustained contraction
  • accelerated metabolic rate
  • depletion of ATP
  • increased O2 consumption
  • increased CO2 production
  • increased heat production
  • mixed resp & lactic acidosis
  • sarcolemma breaks down
  • K+ & myoglobin leak out into blood
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24
Q

Conditions NOT associated w/ MH

A
  • Becker MD
  • Neuroleptic malignant syndrome
  • myotonia congenita
  • myotonic dystrophy
  • osteogenesis imperfecta
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24
Q

3 conditions associated w/ MH

A
  1. King-Denborough syndrome
  2. Central core dz
  3. Multiminicore dz
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25
Q

MH triggers

A
  • VA
  • sux
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26
Q

MOST sensitive indicator of MH

A

EtCO2

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27
Q

Early s/s MH

A
  • tachycardia
  • tachypnea
  • masseter spasm
  • warm soda lime
  • irregular heart rhythm
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28
Q

Intermediate s/s MH

A
  • cyanosis
  • pt warm to touch
29
Q

Late s/s MH

A
  • muscle rigidity
  • cola- colored urine
  • coagulopathy
  • overt hyperthermia
30
Q

Trismus

A
  • tight jaw that CAN still be opened
  • normal occurrence w/ sux
31
Q

Masseter spasm

A
  • tight jaw that CANNOT be opened
  • NMB will not relax jaw
32
Q

What is the definitive test for MH?

A

Halothane Contracture Test
- requires live muscle biopsy

33
Q

How do you prepare for a patient at risk for MH?

A
  1. flush anesthesia machine w/ high flow O2 (20-100 min depending on machine)
  2. replace all external parts (CO2 absorbent, circuit, breathing bag)
  3. remove vaporizers from machine
  4. monitor in PACU 1-4 hours

Alternative to flushing machine:
- charcoal filter (vapor-clean)
- place on inspiratory/expiratory limbs
- flush w/ 10 L O2 for 90 sec

34
Q

Dantrolene MOA

A

muscle relaxant

  1. reduces Ca+ release from RyR1 in skeletal muscle
  2. prevents Ca+ entry into myocyte –> reduces stimulus for Ca+ induced Ca+ release
35
Q

Dantrolene vial & reconsitution

A

each vial contains 20 mg dantrolene + 3 mg mannitol

reconstitute w/ 60 ml preservative free water

36
Q

Dantrolene dose

A
  • 2.5 mg/kg IV repeat q 5-10 min
  • stop when s/s subside
  • continue 1 mg/kg q 6 hr in ICU
  • ## SE: venous irritation, muscle weakness
37
Q

MH Treatment

A
  1. D/C triggering agent, convert to TIVA
  2. Call for help
    3a. Hyperventilate w/ 100% O2 min FGF 10L/min (CO2 elim, O2 delivery, drives K+ into cell)
    3b. Apply charcoal filter (change q 1 hr), change breathing circuit & bag
  3. Administer Dantrolene or Ryanodex
  4. Cool until temp < 38 C
  5. Correct lactic acidosis
    • NaHCO3 1-2 mEq/kg (titrate per ABG)
  6. Treat K+
    • Cacl 5-10 mg/kg IV
    • insulin 0.15 u/kg+D50 1ml/kg
    • hyperventilate
  7. Protect against dysrhythmias
    • Procainamide 15 mg/kg IV
    • Lido 2 mg/kg IV
  8. Maintain UOP > 2 ml/kg/hr
    • IVF, mannitol, furosemide
  9. DIC (late sign) –> check coags
38
Q

Duchenne muscular dystrophy (DMD)

A
  • dystrophin helps anchor actin & myosin to cell membrane
  • absence destabilizes sarcolemma during muscle contraction & increases membrane permeability
  • allows CK & myoglobin to enter blood
  • Ca+ freely enters cell
  • extrajunctional receptor populate (hyperkalemia)
39
Q

DMD clinical presentation

A
  • males
  • atrophy, painless muscle degeneration
  • kyphoscoliosis
  • resp muscle wknss
  • degeneration of cardiac muscle (reduced contractility, papillary muscle dysfx, mitral regurg, CHF, cardiomyopathy)
    -EKG changes: ST, short PR interval, deep Q wave
  • impaired airway reflexes
40
Q

Pt w/ DMD susceptible to what life-threatening condition?

A

Sux can cause hyperkalemia & cardiac arrest leading to sudden death

Also avoid VA

41
Q

Scoliosis

A

lateral & rotational curvature of spine & ribcage

42
Q

Cobb angle

A

Describes magnitude of spinal curvature
- 2 most displaced vertebrae identified
- line is drawn parallel to each
- perpendicular line drawn from each of these lines
- angle where they intersect = cobb angle

43
Q

Cobb angle 40-50

A

indication for surgery

44
Q

Cobb angle 60

A

decreased pulmonary reserve

45
Q

Cobb angle 70

A

pulmonary symptoms

46
Q

Cobb angle 100

A
  • impaired gas exchange
  • increased risk postop pulmonary complications
47
Q

Scoliosis pulmonary changes

A
48
Q

Scoliosis cardiac changes

A
  • RV hypertophy
  • EKG: RV strain RA enlargement
  • MV prolapse
  • mitral regurg
  • coarctation of aorta
49
Q

Scoliosis Mgmt

A
  • cervical scoliosis - difficult intubation
  • N2O increases PVR
  • correction higher than T8 may require one-lung ventilation
  • significant blood loss
  • at risk VAE
50
Q

Somatosensory Evoked Potentials (SSEP_

A
  • monitors posterior spinal cord (dorsal column), which is perfused by posterior spinal arteries
  • monitors sensory fx
  • NMBs do not interfere w/ monitoring
51
Q

Motor Evoked Potentials (MEPs)

A
  • monitors anterior spinal cord, which is perfused by anterior spinal artery
  • monitor motor fx
  • do NOT use NMBs
52
Q

6 potential risk of wake-up test

A
  1. IV removal
  2. extubation
  3. awareness
  4. pain
  5. air embolism
  6. damage to spinal instrumentation
53
Q

Rheumatoid arthritis: airway

A
  1. TMJ- limited mouth opening
  2. Cricoarytenoid joints
    • decreased diameter of glottic opening
    • hoarseness, stridor, dyspnea, airway
      obstruction
    • use smaller ETT
  3. c-spine
    • atlanto-occipital subluxation w/ flexion
    • limited extension
    • at risk for quariparesis or paralysis
54
Q

RA patho

A
  • autoimmune dz targeting synovial joints
  • systemic involvement
  • cytokines play central role
  • Hallmark: AM stiffness that improves w/ activity
  • painful, swollen, warm joints
    -more common in women
  • affects proximal interphalangeal & metacarpophalangeal joints in hands & feet
55
Q

Complications of RA

A
56
Q

What labs are increased w/ RA?

A
  • C-reactive protein
  • Erythrocyte sedimentation rate
57
Q

RA Tx

A
  • antirheumatics (methotrexate, cyclosporine, entanercept)
  • NSAIDs
  • glucocorticoids
58
Q

Systemic Lupus Erythematosus (SLE) patho & S/S

A
  • autoimmune dz characterized by proliferation of antinuclear antibodies
59
Q

What can exacerbate SLE?

A
60
Q

SLE Tx

A
  • corticosteroids
  • NSAIDs
  • immunosuppressants
  • antimalarials
61
Q

SLE Mgmt

A
  • cricoarytenoid arthritis = airway obstruction, swelling; smaller ETT
62
Q

What immunosuppressant drugs increased DOA sux?

A

cyclophosphamide

63
Q

Marfan Syndrome

A

Connective tissue d/o w/ autosomal dominant inheritance
- associated w/: aortic insufficiency, AAA, aortic dissection, mitral prolapse, spontaneous pneumo (high)
- tall w/ pectus excavatum (sunken chest), kyphoscoliosis, hyperflexible joints
- pregnancy increases risk of CV complications

64
Q

Ehlers-Danlos Syndrome

A

Inherited d/o of procollagen & collagen
- associated w/ aneurysms, increased bleeding tendency, AAA
-* bleeding into joints
- avoid regional
- risk of pneumo

65
Q

Osteogenesis imperfecta

A

Connective tissue d/o w/ autosomal dominant inheritance
- * brittle bones
~ careful w/ positioning, BP cuff
- careful airway mgmt (risk cspine fracture)
- kyphoscolisos
- pectus excavatum
- increased serum thyroxine ( increased BMR & VO2 –> hyperthermia)
- *Blue sclera

66
Q

Multiple Sclerosis

A

Demyelinating dz of CNS
- sensory, motor, ANS dysfunction
- bulbar muscle dysfx
- AVOID sux (hyperkalemia)
- S/S exacerbated by stress and increased temp
- Tx w/ corticosteroids, interferon, azathioprine

67
Q

Myotonic Dystrophy

A

Prolonged contracture after a voluntary contraction
- dysfx Ca+ sequestration by SR
- can interfere w/ ventilation & intubation
- at risk for:
~ aspiration
~ resp muscle wknss
~ cardiomyopathy, dysrhythmias
~ sensitive to anesthetic agents

68
Q

3 things that increase risk of contractures in pt w/ myotonic dystrophy

A
  1. Sux
  2. NMB reversal w/ AchE
  3. Hypopthermia
69
Q

Scleroderma

A

Excessive fibrosis in skin & organs, particularly microvasculature

CREST syndrome

70
Q

CREST syndrome

A

Calcinosis
Raynaud’s
Esophageal hypomotility
Sclerodactyly
Telangiectasia (spider veins- increase risk mucosal bleeding; problematic during airway manipulation-esp nasal intubation)

71
Q

Paget’s Dz

A

Excessive osteoblastic & osteoclastic activity causes thick, weak bone deposits
- excessive PTH or Ca+ deficiency
- pain & fractures most common

APEX: Flashcards (13 decks)

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