Non-Depolarizing NMBA Effects Flashcards
ND-NMBA MOA
A nondepolarizing neuromuscular blocker (NDNB) circulates to all tissues, including skeletal muscle.
The nondepolarizing neuromuscular relaxant diffuses from the vascular compartment into the synaptic cleft of the neuromuscular junction.
The nondepolarizing agent combines with the nicotinic receptors of the channels of the motor end-plate.
The nondepolarizing agent has no direct effect on the channel.
The nondepolarizing agent, however, competitively blocks acetylcholine from attaching to its receptors so the channel cannot open.
The channel stays closed, and the postsynaptic membrane remains polarized. Thus, a nondepolarizing neuromuscular blockade is established.
ND-NMBA Unique Characteristics
Quarternary ammonium compounds
Steroids or benzoisoquinolines
Do not depolarize membrane
Reversible
Do not trigger MH
ND-NMBA CV Effects
Atracurium and mivacurium cause histamine release and may produce hypotension and tachycardia.
Pancuronium is vagolytic and causes slight catecholamine release (indirect sympathomimetic), producing tachycardia.
ND-NMBA Hepatic and Renal Effects
The steroidal relaxants rocuronium, vecuronium, and pancuronium depend to varying degrees on renal and hepatic elimination
ND-NMBA Allergy Considerations
Neuromuscular blocking agents and antibiotics are the most common drugs involved in intraoperative allergic reactions
The initial diagnosis is presumptive, whereas the etiological assessment is linked to the clinical presentation, tryptase levels, and skin test results.
Anaphylaxis presents with significant hypovolemia and vasoplegia,
Aggressive fluid therapy and epinephrine are the cornerstones of management.
ND-NMBA Temperature Effects
Hypothermic patients exhibit a prolonged duration of action to all muscle relaxants.
Things that prolong ND-NMBA Effects
Volatiles [des > sevo > iso], not clinically significant
Hypothermia: 10-15% ↓ for every degree below 36 ▪ Most with cis and atrac due to
Hofmann (colder = slower)
Magnesium ▪ Opposite of calcium
Lithium
IV local anesthetic ▪ If on drip, check dosing!
Things that shorten ND-NMBA Effects
Long term anti-epileptics – resistant to NMB
Steroids antagonize NMB
