Beta blockers Atracurium

BETA-BLOCKERS NON-DEPOLARIZING 1. Modest t in efficacy of muscle relaxants, particularly with propanolol 2. Risk of 1 BP with atracurium and alcuronium 1 and 2. Uncertain 1. Watch for prolonged muscular paralysis after muscle relaxants 2. Monitor BP at least weekly until stable... 

Increases or decreases (often only modest) in the extent of neuromuscular blockade have been seen In patients taking beta blockers. The bradycardia and hypotension sometimes caused by anaesthetics and beta blockers Is not counteracted by atracurium. 

Eight out of 42 patients taking unnamed beta blockers given atracurium developed bradycardia (less than 50 bpm) and hypotension (systolic pressure less than 80 mniHg). Most of them had been premedicated with diazepam, induced with methohexital, and maintained with droperidol, fentanyl and nitrous oxide/oxygen. A further 24 showed bradycardia, associated with hypotension on 9 oeeasions. All responded promptly to 300 to 600 micrograms of intravenous atropine. ... 

The changes in the degree of blockade are not understood but the interaction appears to occur at the neuromuscular junction. It has been seen in animal studies. The bradycardia and hypotension (c) were probably due to the combined depressant effects on the heart of the anaesthetics and the beta blocker not bdng offset by atracurium, which has little or no effect on the vagus nerve at doses within the recommended range. Note that neuromuscular blockers with vagolytic activity can cause tachycardia and hypotension. 

Information is fairly sparse, but these interactions appear normally to be of relatively minor importance. Be aware that changes in neuromuscular blockade (increases or decreases) can occur if beta blockers are used, but they seem to be unpredictable, and then often only modest in extent. The possible combined cardiac depressant effects of beta blockade and anaesthesia are well known (see Anaesthetics, general + Beta blockers, p.97). These effects may not be prevented when a neuromuscular blocker is used that has little or no effect on the vagus (such as atracurium or vecuronium). 

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See also in sourсe #XX -- [ ]

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