Neuromuscular blockers

Question 1

What are indications for NMBAs?

Answer 1

Emergency intubation, ARDs (thoracic relaxation improves lung compliance), intra-abdominal pressure, prevent shivering, resp states that require full ventilation

Question 2

How does acetylcholine work?

Answer 2

Is a NT of the motor division, stored in axonal presynaptic membrane and released in response to nerve impulse from CNS.

One released, binds to specific receptor sites and initiate AP leading to contraction

Broken down by enzyme acetylcholinerase or reuptakes back into pre-synaptic membrane

Question 3

What are depolarizing NMBAs?

Answer 3

Mimics Ach, binds to receptors and causes depolarization and muscle contraction. Then remains in receptor and blocks more APs entering and holds muscle cells in the absolute refractory period.

Eventually get broken down by pseudoacetylcholinerase.

Short acting, broken down in 1-2 mins. Pt will contract then relax

Question 4

What are side effects of NMBAs?

Answer 4

Bradycardia, salivation, cells shift K extracellularly leading to hyperkalemia, MD needs to be at bedside

Question 5

What is an example of depolarizing NMBA?

Answer 5

Succinylcholine

Rarely used, given by MD IV push

Question 6

What are non-depolarizing NMBAs?

Answer 6

Blocks Ach from binding to receptors and initiating APs. No muscle contractions, no refractory period. Paralysis is gradual.

Drugs ending in -ium.

Question 7

What are the steps of rapid sequence intubation RSI?

Answer 7

1) Opioid
2) Sedative
3) Unconsciousness agent / anesthetic
4) NMBA
5) Intubation

Question 8

How is train of four testing done?

Answer 8

Stimulates motor nerve at ulnar site to elicit muscle contraction to assess extent of neuromuscular blockade. Tof 1-2 usually ideal range

Question 9

What do the twitches in Tof represent?

Answer 9

Percentage of neuromuscular blockade.

4 --> 0-75%
3 --> 75 - 80%
2 --> 80 - 90%
1 --> 90 - 95%
0 --> 95 - 100% 

TOF 1-2 correlates clinically to absence of spontaneous resps