Nitrous oxide Succinylcholine

Warner LO, Bremer DL, Davidson PJ, Rogers GL, Beach TP. Effects of lidocaine, succinylcholine, and tracheal intubation on intraocular pressure in children anesthetized with halothane-nitrous oxide. Anesth Analg 1989 69(5) 687-90. 

The inhalational anaesthetics increase the effects of the neuromuscular blockers to differing extents, but nitrous oxide appears not to interact significantly. Ketamine has been reported to potentiate the effects of atracurium. Propofol does not appear to interact with mivacurium or vecuronium. Xenon is reported not to interact with mivacurium or rocuronium, and has less effect than sevoflurane on vecuronium neuromuscular blockade. Bradycardia has been seen in patients given vecuronium with eto-midate or thiopental. Propofol can cause serious bradycardia if it is given with suxamethonium (succinylcholine) without adequate antimuscarinic premedication, and asystole has been seen when fentanyl, propofol and suxamethonium were given sequentially. 

Although it is generally assumed that nitrous oxide does not affect the potency of neuromuscular blockers, one study found that the administration of nitrous oxide increased suxamethonium (succinylcholine) neuromuscular blockade. 

Szalados JE, Donati F, Bevan DR. Nitrous oxide potentiates succinylcholine neuromuscular blockade in humans. Anesh Analg (y99V) 72,18-21. 

A patient anaesthetised with fluroxene and nitrous oxide demonstrated 100% blockade with suxamethonium (succinylcholine) and tubocurar-ine. About 50 minutes later when twitch height had fully returned and tidal volume was 400 mL, she was given lidocaine 50 mg intravenously for premature ventricular contractions. She immediately stopped breathing and the twitch disappeared. About 45 minutes later the tidal volume was 450 mL. Later it was found that the patient had a dibucaine number (a measure of cholinesterase activity) of 23%. ... 

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