Suxamethonium Propofol

Reduction of secretions and vagal reflexes Muscarinic antagonists, usually hyoscine, are used to prevent salivation and bronchial secretions and, more importantly, to proteci the heart from arrhythmias, particularly bradycardia caused by halothane, propofol, suxamethonium and neostigmine. Hyoscine is also iiniiemeiic and produces some amnesia. 

Baraka A. Severe bradycardia following propofol-suxamethonium sequence. BrJ Anaes (1988)61,482-3. 

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). 

Susceptibility factors and prophylaxis Although malignant hyperthermia is usually associated with the muscle relaxant suxamethonium, all inhalational anesthetics have been implicated and will be unsafe if risk factors for this condition are present, for example a family history or one of the congenital muscle disorders (76). This must be considered in patients at risk, as there are readily acceptable alternatives, such as propofol (77) and midazolam (78). 

There are several reports of pain during injection of rocuronium (5,6). Eight of 10 patients complained of severe pain, one complained of moderate pain, and another reported an unpleasant sensation (5). This suggests that rocuronium will almost invariably cause pain. The mechanism of this phenomenon is not clear, but there appear to be some similarities to propofol injection pain. Several authors have suggested that rocuronium should not be given to awake patients (5,6). On the other hand, small doses of rocuronium have been used, with some success, to prevent fasciculations and myalgia after suxamethonium (7-10). With regard to the severity of injection pain, rocuronium pretreatment in awake patients does not seem advisable. 

In addition, there was a reduced incidence and intensity of post-suxamethonium myalgia when anesthesia had been maintained by propofol infusion compared with iso-flurane (215). 

A 72-year-old woman with a symptomatic hiatus hernia, osteoarthritis, and Alzheimer s disease was taking fluoxetine 20mg/day, donepezil hydrochloride 10 mg/ day, nimesulide 12.5mg/day, and omeprazole 20 mg/ day (288). There still was no twitch response to peripheral nerve stimulation 20 minutes after rapid-sequence induction of anesthesia with propofol 2.5mg/kg and suxamethonium 1 mg/kg. She then gradually developed a weak twitch response, and 50 minutes after induction of anesthesia four twitches with a fade were elicited by train-of-four stimulation. No additional medication was given and after the end of the procedure 10 minutes later she was extubated uneventfully. She refused further blood testing and so her plasma cholinesterase activity at that time is not known. However, her anesthetic notes from a previous operation did not reveal any problems with prolonged paralysis after suxamethonium. 

Mirakhur RK, Shepherd WF, Darrah WC. Propofol or thiopentone effects on intraocular pressure associated with induction of anaesthesia and tracheal intubation (facilitated with suxamethonium). Br J Anaesth 1987 59(4) 431-6. 

Manataki AD, Arnaoutoglou HM, Tefa LK, Glatzounis GK, Papadopoulos GS. Continuous propofol administration for suxamethonium-induced postoperative myalgia. Anaesthesia 1999 54(5) 419-22. 

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. 

For reports of bradycardia occurring with atracurium or suxamethonium used with propofol and fentanyl, see Anaesthetics, general + Neuromuscular blockers , p.lOl. 

Body temperature Malignant hyperthermia occurred 3 hours after the start of an operation for esophageal resection in an 82-year-old man after anesthesia induced with propofol and suxamethonium and maintained with sevoflurane [6 ]. Masseter spasm was not a feature. End-tidal CO2 rose to 55 mmHg and body temperature exceeded 39.0°C. The patient responded promptly to dantrolene. Reports of malignant hyperthermia in patients over the age of 80 years are unusual. Both suxamethonium and sevofiur-ane are potent triggers. 

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