clinicaltrials.gov Identifier: NCT00403806.

These trials do not provide convincing evidence that perioperative magnesium may have favorable effects on postoperative pain intensity and analgesic requirements. Perioperative magnesium supplementation prevents postoperative hypomagnesemia and decreases the incidence of postoperative shivering. It may be worthwhile to further study the role of magnesium as a supplement to postoperative analgesia, since this relatively harmless molecule is inexpensive, and the biological basis for its potential antinociceptive effect is promising.

Background: A previously published study suggested that pre-treatment with magnesium sulphate (MgSO 4 ) had no impact on the speed of onset of rocuroniuminduced neuromuscular block. We set out to verify this assumption. Methods: Eighty patients (18-60 years) were randomly allocated to MgSO 4 60 mg/kg or placebo (saline). Study drugs were given intravenously for 15 min before induction of anaesthesia with propofol, sufentanil and rocuronium 0.6 mg/kg. Anaesthesia was maintained with a target-controlled propofol infusion. Neuromuscular transmission was measured using train-of-four (TOF)-Watch SX s acceleromyography. M AGNESIUM is widely used in peri-operative medicine, for instance, to treat arrhythmia in cardiac patients or to control blood pressure and to prevent seizures in parturients with pre-eclampsia.Magnesium has an impact on neuromuscular transmission. It reduces the amount of acetylcholine that is released at the motor nerve terminal 1,2 by decreasing the calcium conductance of presynaptic voltage-dependent calcium channels. 3 After pre-treatment with magnesium sulphate (MgSO 4 ), an increased speed of onset and a prolongation of the recovery period of neuromuscular blockade have been observed with atracurium and vecuronium. 4,5 However, in a similar study, rapid administration of an intravenous bolus of MgSO 4 , 60 mg/kg, injected immediately before rocuronium, significantly prolonged recovery of the neuromuscular block but curiously had no influence on the speed of onset. 6 The authors of that MgSO 4 -rocuronium interaction study speculated that differences in the efficacy of magnesium pretreatment in reducing the onset time of different non-depolarising neuromuscular blocking agents (NMBA) reflected differences in the pharmacodynamic properties of the NMBAs; the shorter the baseline onset time of the NMBA (as with rocuronium), the less effect MgSO 4 pre-treatment would have. However, it may be assumed that the effect of the magnesium ion on the neuromuscular endplate is both concentration and time dependent. Therefore, an alternative hypothesis would be that, after a rapid bolus injection immediately before the administration of rocuronium, the magnesium ions have no scope to reach the motor nerve These data were presented in part at the annual scientific meeting of the Swiss Society of Anaesthesiology and Resuscitation, Fribourg, Switzerland, November 2008. 299 Acta Anaesthesiol Scand 2010; 54: 299-306 : 10.1111/j.1399-6576.2009.02160.x terminal in a concentration that is high enough to interfere with rocuronium. In an in vitro study on mammalian motor nerve endings, 4-6 min were necessary to establish a new frequency of miniature end-plate potentials after administration of increasing magnesium concentrations. 7 Consequently, a magnesium infusion, rather than a bolus injection immediately before the injection of the NMBA, should have an impact on neuromuscular blockade. In theory, MgSO 4 pre-treatment should reduce the onset time of a rocuronium-induced block to an extent that makes it an ...

Approximately 60% of perioperative anaphylactic reactions are thought to be immunoglobulin IgE mediated, whereas 40% are thought to be non-IgE mediated hypersensitivity reactions (both considered non-dose-related type B adverse drug reactions). In both cases, symptoms are elicited by mast cell degranulation. Also, pharmacological reactions to drugs (type A, dose-related) may sometimes mimic symptoms triggered by mast cell degranulation. In case of hypotension, bronchospasm, or urticarial rash due to mast cell degranulation, identification of the responsible mechanism is complicated. However, determination of the type of the underlying adverse drug reaction is of paramount interest for the decision of whether the culprit drug may be re-administered. Neuromuscular blocking agents (NMBA) are among the most frequent cause of perioperative anaphylaxis. Recently, it has been shown that NMBA may activate mast cells independently from IgE antibodies via the human Mas-related G-protein-coupled receptor member X2 (MRGPRX2). In light of this new insight into the patho-mechanism of pseudo-allergic adverse drug reactions, in which as drug-receptor interaction results in anaphylaxis like symptoms, we critically reviewed the literature on NMBA-induced perioperative anaphylaxis. We challenge the dogma that NMBA mainly cause IgE-mediated anaphylaxis via an IgE-mediated mechanism, which is based on studies that consider positive skin test to be specific for IgE-mediated hypersensitivity. Finally, we discuss the question whether MRGPRX2 mediated pseudo-allergic reactions should be re-classified as type A adverse reactions.