Vecuronium with anesthesia

A 77-year-old man is admitted to the hospital for a coronary artery bypass. He has been treated with a (3-blocker (Tenormin 100 mg per day), which he took every morning. He is induced with propofol 1 mg/kg, fentanyl 5 jjig/kg and vecuronium 8 mg for muscle relaxation. After 3 minutes a decreasing heart rate becomes a worry for the anesthesiologist. The heart rate continues to fall until it reaches 38 BPM. At this point the patient s blood pressure is 80/60 and the anesthesiologist gives atropine 0.4 mg and ephedrine 10 mg. This treatment results in a stable patient. What effects were most likely produced by the anesthesia procedure Could this have been avoided ... 

Nevertheless, some interactions of benzodiazepines with muscle relaxants used in anesthesia have been described. Diazepam has been reported to potentiate the effects of tubocurare (163) and gallamine (164) and to reduce the effects of suxamethonium (164). However, in 113 patients undergoing general anesthesia, intravenous diazepam 20 mg, lorazepam 5 mg, and lormetaze-pam 2 mg did not potentiate the neuromuscular blocking effects of vecuronium or atracurium (162). 

In 113 patients undergoing general anesthesia, intravenous midazolam 15 mg slowed recovery of the twitch height after vecuronium and atracurium compared with diazepam. The recovery index was not altered (162). However, in another study in 20 patients, midazolam 0.3 mg/kg did not affect the duration of blockade, recovery time, intensity of fasciculations, or adequacy of relaxation for tracheal intubation produced by suxamethonium 1 mg/kg, nor the duration of blockade and adequacy of relaxation for tracheal intubation produced by pancuronium 0.025 mg/kg in incremental doses until 99% depression of muscle-twitch tension was obtained (161). Furthermore, in 60 patients undergoing maintenance anesthesia randomly assigned to one of six regimens (etomidate, fentanyl, midazolam, propofol, thiopental plus nitrous oxide, or isoflurane plus nitrous oxide), midazolam did not alter rocuronium dosage requirements (165). 

A 65-year-old man undergoing elective sternal debridement and rewiring was given a prophylactic infusion of vancomycin 1 g preoperatively. Anesthesia was induced with thiopental, suxamethonium, and fentanyl, and maintained with fentanyl, vecuronium, and isoflurane. A few minutes after wound irrigation with bacitracin (about 25U/ml), his blood pressure fell precipitously, necessitating intravenous fluids and adrenaline. His face and arms were flushed. Afterwards, he reported having had a rash several years before after the use of an over-the-counter ointment composed of polymyxin B, bacitracin, and neomycin. 

Etomidate is the indnction agent of choice in atopic patients, in whom etomidate, fentanyl, and vecuronium comprise the safest combination of drugs for general anesthesia. However, non-allergic anaphylactic (anaphylactoid) reactions have been observed, even with this combination (23,24), and it can even be life-threatening one patient also had a myocardial infarction (24). 

A 65-year-old woman, who had had normal preoperative serum electrolytes and a normal QT interval with sinus rhythm, received hydroxyzine and atropine premedication followed by thiopental and vecuronium for anesthetic induction. Endotracheal intubation was difficult and precipitated atrial fibrillation, which was refractory to disopyramide 100 mg. Anesthesia was then maintained with sevoflurane 2% and nitrous oxide 50%. Ten minutes later ventricular tachycardia ensued, refractory to intravenous lidocaine, disopyramide, and magnesium. DC cardioversion resulted in a change to a supraventricular tachycardia, which then deteriorated to torsade de pointes. External cardiac massage and further DC cardioversion were initially unsuccessful, but the cardiac rhythm reverted to atrial fibrillation 10 minutes after the sevoflurane was switched off. Two weeks later she had her operation under combined epidural and general anesthesia, with no changes in cardiac rhythm. 

Pancuronium can be administered i.v. during general anesthesia at a dose rate of 0.08 mg/kg (Muir Hubbell 1989). If used appropriately, adverse effects are rare. Pancuronium and vecuronium produce minimal cardiovascular effects, although pancuronium can potentially stimulate the release of norepinephrine (noradrenaline), resulting in increased heart rate and blood pressure. Horses with pre-existing cardiovascular disease may develop hypotension. Atracurium... 

NMBAs are further differentiated by their duration of action during anesthesia. Succinylcholine and mivacurium are common ultra-short-acting competitive NMBAs (5-10 min). An intermediate duration of action (30-45 min) is maintained with the use of atracurium, cisatracurium, rocuronium and vecuronium. A long-lasting duration of action (90-100 min) is observed with d-tubocurarine, doxacurium, metocurine, pancuronium and pipecuronium. 

Vecuronium (Norcuron) Competes with ACh at nicotinic receptors. Does not activate receptor. Blockade can be overcome by high concentration of agonists. Adjunct to anesthesia muscle relaxant, eases intubation and ventilation, eases orthojDedic manipulation, controls respiration during chest surgery. Onset 3-5 min. Duration 25-40 min. 

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