What are neuromuscular blockers?
Neuromuscular blockers are a class of medications that block the transmission of nerve impulses to skeletal muscles, resulting in temporary paralysis.
What is the mechanism of action of neuromuscular blockers?
Neuromuscular blockers prevent acetylcholine from activating the nicotinic M receptors post-synaptically at the skeletal neuromuscular junction.
They paralyze all skeletal muscles, including those used for breathing (the diaphragm). Mechanical ventilation is required.
They do not affect the CNS. The client is completely paralyzed, but fully conscious. Sedatives should always be given before NMBs.
What are neuromuscular blockers used for?
- Surgery
- Endotracheal intubation
- Mechanical ventilation
Neuromuscular blockers classification
| Competitive neuromuscular blockers (antagonists) | Depolarizing neuromuscular blockers (agonists) | |
| Onset of paralysis | Rapid | Rapid |
| Peak | Peak effects persist 20–45 minutes and then decline. | Peaks after 1 minute, fades after 4–10 minutes |
| Recovery | Complete recovery in 1 hour | Ultrashort-acting |
| Used for longer procedures? | Yes | No |
| Reversed by | Acetylcholine | Acetylcholine inhibitors |
What are drug examples of neuromuscular blockers?
Competitive:
- Atracurium
- Pancuronium
- Vecuronium
- Cisatracurium
- Rocuronium
Depolarizing:
- Succinylcholine
What are adverse effects of neuromuscular blockers?
Competitive:
- Tachycardia
- Respiratory arrest
- Hypotension
- Hemodynamic instability
- Seizures
- Bronchospasm
Depolarizing:
- Bradycardia
- Respiratory arrest
- Post-op muscle pain
- Hyperkalemia
- Malignant hyperthermia
Nursing tips around neuromuscular blockers
- All neuromuscular blockers are given IV, there are no oral forms.
- Neuromuscular blockers cannot cross the blood-brain barrier. There is no impact on the CNS and minimal effects on a fetus.
- Dantrolene is used to treat malignant hyperthermia:
- Reduces heat production and rigidity within minutes
- Has a risk of hepatotoxicity
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