W2 D3 - Neuromuscular Blocking Agents

Question 1

What are some indications for neuromuscular blocking agents?

Answer 1

• intubation
• ARDS severe
• profound hypoxemia
• elevated intra-abdominal pressure
• stop shivering for temperature management

Question 2

Which type of muscle cells do NMBAs work on?

Answer 2

Skeletal muscle cells
Therefore no effect on BP

Question 3

What is the neurotransmitter of the motor divison?

What is its role in NMBAs?

Answer 3

Acetylcholine
* when it binds to enough receptors, a contraction follows
* NMBAs interfere with acetylcholine to induce paralysis

Question 4

What does the action potential of the muscle cell look like?

Answer 4

A quick spike up and back down past -70 then returning to resting at -70
1. Resting at -70
2. Depolarizing with Na channel, absolute period is short
3. Repolarization with K channel, relative period is longer than in cardiac cell
4. Resting potential with Na/K pump

Question 5

How do non-depolarizing NMBAs work?

Answer 5

Ach is blocked before depolarization
Requires more drug than Ach to prevent contraction, a slow effect

Question 6

Differentiate each non-depolarizing NMBA

Answer 6

Pancuronium
* long elimination
* renal elminination
* PSNS blocked, HR increase

Cisatracurium
* intermediate
* eliminated via blood stream
* used for pt with renal/hepatic failure

Atracurium
* intermediate
* eliminated via blood stream
* histamine release !!
* used for pt with renal/hepatic failure

Rocuronium
* intermediate
* rapid onset
* hepatic elimination
* rapid intubation

*

Question 7

Differentiate between non-depolarizing and depolarizing NMBAs

Answer 7

Non-depolarizing
* blocks acetylcholine from binding with its receptors and therefore contraction cannot occur once more med is present than acetylcholine
* it is slow paralysis

Depolarizing
* mimics acetylcholine and binds to its receptors to cause a muscle contraction followed by paralysis
* paralyzed in depolarized state
* rapid paralysis

Question 8

What is the only depolarizing medications used?

how does it work?

Answer 8

Succinycholine
Action
* initiates an action potential and maintains muscle in the absolute refractory period
* it binds to ach receptor sites to mimic it and paralyzes muscles in a depolarized state
* the muscles will contract before paralysis, painful

Indication
* intubation

Considerations
* physician must give IVP
* rapid onset of 1 min
* short acting 2-6 mins

Side effects
* hyperkalemia
* cardiac arrhythmias
* increased salivation
* bradycardia
* muscle pain

Watch for malignant hyperthermia!
* increase in intracellular calcium ions which leads to prolonged contracture

Question 9

How does the train of four work with NMBAs?

Answer 9

Between 20-80 mAs are administered to the ulnar nerve to measure muscle contractions/twitches in order to titrate NMBAs
* 4 twitches = 0-75% of muscles blocked
* 3 twitches = 75%-80% blocked
* 2 twitches = 80-90% blocked
* 1 twitch = 90-95% blocked
* 0 twitch = 95-100% blocked, bad

Question 10

What should you consider in your nursing care for patients on NMBAs?

Answer 10

• Eye drops and eye care
• Patient must be intubated and fully ventilated
• Analgesia and sedation prior and during
• Monitor train of 4
• Reposition frequently
• Family and patient teaching