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i&m final > Neuromuscular Blockade Monitoring > Flashcards

Neuromuscular Blockade Monitoring Flashcards

1
Q

How do local anesthetics relax muscles?

A

Interfering with transmission along the nerve trunk blocks signals from reaching the terminal bouton

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2
Q

How do drugs relax muscles presynaptically? Which drugs do this?

A

Interfering with Ach production, storage or release
hemicholinium, botulinus toxin, pentamethonium, NMBAs
(Hemicholinium prevents re-uptake into presynaptic neuron
Botulinum toxin blocks release of vesicles
Pentamethonium A ganglionic blocking agent used as an antihypertensive)

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3
Q

How do drugs relax muscles in the synaptic cleft?

A

Inactivate neurotransmitter

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4
Q

How do drugs relax muscles postsynaptically? Which drugs do this?

A

Interfere with depolarization or activation of the end-plate (NMBAs)

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5
Q

*Mature vs. immature (fetal) nicotinic acetylcholine receptors

A

Immature subunits are characterized by 10-fold greater ionic activity, rapid metabolic turnover, and extra junctional proliferation
Use of a depolarizing muscle relaxant in patients with proliferating, immature nAChR’s will lead to severe, acute hyperkalemia

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6
Q

*In nicotinic acetylcholine receptors the acetylchole binds to the two _____ subunits so convert the channel into an _____ state

A

alpha, open

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7
Q

T/F Age effects depth of neuromuscular blockade

A

True

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8
Q

Two types of electrodes used to stimulate the nerve

A

Surface and needle

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9
Q

Methods of Recording/Monitoring Muscle Function

A

Observation (qualitative), visual, tactile
Mechanomyography (MMG, force displacement)
Electromyography (EMG)
Acceleromyography (AMG)
Kinemyography (KMG)

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10
Q

*Neuromuscular blockade monitoring pulse must be less than ____ in duration. Why?

A

0.5 msec, So not to induce repetitive neural firing or direct muscle stimulation

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11
Q

*Supra-maximal current

A

10%-20% above the current needed to stimulate all of the fibers in the nerve bundle
Assures that the same number of nerve fibers are being stimulates each time the blockade is monitored

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12
Q

*Needle electrodes achieve supra-maximal current at

A

10 mA

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13
Q

*Surface electrodes may achieve supra-maximal current at

A

50-70 mA

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14
Q

*Low stimulation level used for needle electrodes

A

0-40 mA

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15
Q

What determines the penetrating depth of the stimulation current?

A

The distance between the two electrodes

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16
Q

Distance between electrodes when monitoring the ulnar nerve

A

3-6 cm

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17
Q

Prepping the skin before placing the electrodes

A

Lowers skin resistance by up to 70%

Otherwise, skin resistance in increased for the first 10-30 minutes after applying the electrodes

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18
Q

Recording and Monitoring Muscle Function: Observation

A

Observe the movement of muscle (what we normally use)

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19
Q

Mechanical Transduction (MMG)

A

Force transducer, similar to blood pressure transducer – measure the force produced or the distance moved

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20
Q

*Electromyography (EMG)

A

Using electrodes, monitor the electrical activity induced in muscle by contraction – similar to ECG
*Uses a detection electrode

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21
Q

*Acceleromyography (AMG)

A

Measure the acceleration of the muscle body or the attachment of the muscle
Accelerometer attached to the thumb

22
Q

Kinemyography (KMG)

A

Motion converted to electricity

23
Q

Which monitoring techniques are subjective/objective

A

Subjective: Visual and Tactile
Objective: MMG, EMG, AMG

24
Q

T/F Except for time, no difference in the strength of the evoked responses exists between non-depolarizers vs. depolarizers

A

True

25
Q

*T/F When monitoring blockade, one should avoid direct muscle stimulation

A

True

26
Q

Locations for suitable monitoring

A

Ulnar Nerve innervating Adductor pollicis and Flexor Pollicis Brevis
Facial Nerve innervating Frontalis and Orbicularis Oculi
Posterior Tibial innervating Flexor Hallucis Brevis

27
Q

*Anodal Block

A

Do not place the anode between the cathode and the muscle being observed

28
Q

Anodal threshold vs. Cathodal threshold

A

Anodal is approximately 25% greater

29
Q

Commonly used peripheral nerves

A

Ulnar, Posterior Tibial, Peroneal, Facial, Mandibular

30
Q

*Ulnar nerve monitoring stimulates what muscle?

A

Adductor pollicis

31
Q

*Median nerve monitoring stimulates what muscle?

A

Adductor pollicis brevis

32
Q

Posterior Tibial Nerve

A

Medial placement on the ankle

Toe stimulation

33
Q

? Moving electrodes to the middle of the wrist may reduce

A

PONV

34
Q

*Rocuronium (0.5 mg/kg) Maximal Block (% Depression)

Laryngeal Adductors vs. Adductor Pollicis

A

77 +/- 5

98 +/- 1

35
Q

Vecuronium Recovery

Diaphragm vs. Adductor Pollicis

A

Recovery of diaphragm comes first

36
Q

T/F The facial nerve may be used to assess recovery from NMB

A

Fasle

It may not because it may show complete recovery when there is still significant block

37
Q

It is best to use peripheral muscle to monitor recovery because

A

Its complete recovery indicates that residual muscle weakness contributing to problems with airway latency or respiration is unlikely

38
Q

T/F The probability of detecting fade is greater with the index finger than the thumb or the toe

A

True

39
Q

Reliable detection of NMB using train of four

A

Cannot be done via visual or tactile

Better with DBS, best with ACG

40
Q

*Posttetanic potentiation

A 
After tetanus (5 sec), there is a stronger response to stimulus
Present during phase II and non-depolarizing block
41
Q

Time between each TOF stimulation

A

500 msec

42
Q

Depolarizing vs. Non-depolarizing block

A

Depolarizing - no fade

43
Q

TOF count & Max possible blockade

A 
0/4: 95-100
1/4:  90
2/4: 85
3/4: 80
4/4: 70-80
44
Q

Post Tetanic Count (PTC)

A

0: little chance of reversal
5 – 10 count: possible reversal
>10 count: reversal very likely
The higher the count the more likely the reversal

45
Q

Most Reliable Tests of Postop Recovery

A

Sustained head lift, leg lift, or hand grip for 5 seconds
Sustained “tongue depressor test”
Maximum inspiratory pressure 40-50 cmH2O or greater

46
Q

Unreliable Tests of Postop Recovery

A

Sustained eye opening, protrusion of the tongue, arm life to opposite shoulder, normal tidal volume, normal or nearly normal vital capacity, Maximum inspiratory pressure less than 40-50

47
Q

nAChR upregulation causes

A

Resistance to nondepolarizing relaxants and increased sensitivity to depolarizing relaxants

48
Q

Drugs that potentiate the action of non depolarizing NMB drugs

A

Desflurane > sevoflurane > isoflurane > halothane > TIVA

49
Q

Hypothermia effet on NMB

A

Significantly prolongs onset and duration

50
Q

BBLUDS

A 
Bradycardia
Bronchospasm
Lacrimation
Urination
Defecation
Salivation

i&m final (5 decks)

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