Calcium, magnesium, and local anesthesia

The Effect of Intraoperative Magnesium Sulphate Infusion on Emergence Agitation after Ambulatory Ophthalmic Surgery in Children

This study investigated whether intraoperative infusion of magnesium sulphate reduces the incidence of emergence agitation (EA) in paediatric patients who undergo ambulatory ophthalmic surgery using the Paediatric Anaesthesia Emergence Delirium (PAED) scale. Ninety-two paediatric patients who were scheduled for elective ophthalmic surgery were randomly allocated to two groups: control or magnesium. In the magnesium group, patients received an initial intravenous loading dose of 30 mg/kg of 10% solution of magnesium sulphate over 10 min and then a continuous infusion of 10 mg/kg×h during the surgery. In the control group, an equal volume of 0.9% isotonic saline was administered in the same way as in the magnesium group. The PAED scale was assessed at 15-min intervals until the PAED score reached below 10 at the postanaesthetic care unit. EA was defined as a PAED score of 10 or higher. Of the 86 patients recruited, 44 and 42 were allocated to the control and magnesium groups, respectively. The incidence of EA was 77.3% in the control group and 57.1% in the magnesium group (odds ratio, 0.392; 95% confidence interval, 0.154 to 0.997; p = 0.046). The intraoperative infusion of magnesium sulphate significantly reduced the incidence of EA.

Facilitation of fiberoptic nasotracheal intubation with magnesium sulfate: A double-blind randomized study

Background:

A double-blinded, prospective, and randomized study was designed to determine the efficacy and tolerability of intravenous (IV) magnesium sulfate (MgSO₄) to facilitate fiberoptic bronchoscopic (FOB) nasotracheal intubations.

Patients and Methods:

A total of 120 patients scheduled to undergo elective awake fiberoptic nasotracheal intubation, while they were anesthetized for elective surgery were randomly allocated to one of three groups: The control Group S (n = 40) received 100 ml (50 ml 0.9% saline + 50 ml paracetamol) was infused in 10 min and direct IV 5 ml 0.9% normal saline, Group MD (n = 40): Received midazolam IV in a dose of 0.07 mg/kg in 5 ml 0.9% normal saline and 100 ml 0.9% was infused in 10 min and Group MS (n = 40): IV 45 mg/kg MgSO₄ 10 min in 100 ml of 0.9% normal saline through 10 min and direct IV 5 ml 0.9% normal saline.

Results:

Time required for nasotracheal intubation was significantly less in group Groups MD and MS, as compared with the control group, but not significant between the two groups. (Group MD: 9.05 + 1.95 min, Group MS 3.75 + 0.75 min and Group S 16.85 + 1.7 min). However, the number of fiberoptic intubation was significantly more in the MD and MS groups, as compared with the control group. Easy intubation (control group: 0, Group MD: 25 and Group MS: 35), moderate difficulty (control group: 5, Group MD: 12 and Group MS: 4) and difficult (control group: 35, Group MD: 3 and Group MS: 1). Procedure adverse events were significantly lower in Group MS. None of the patients in Group MS had procedure hypoxia, but it occurred in 10 patients of Group MD and 20 patients in Group S. Six patients in Group S and two in Group MD had procedure apnea whereas, none of the patients in the MS group experienced this. After medication and just before intubation heart rate and mean arterial pressure were significantly less in Groups MD and MS, as compared to the control group (Group MD: 77 + 7.7 beat/min, Group MS: 70 + 5.6 beat/min and Group S: 80 + 7.8 beat/min) (Group MD: 90 + 8.5 mmHg, Group MS: 80 + 8.1 mmHg and Group S: 105 + 10.5 mmHg). This difference however, significant between Group MD and Group MS.

Conclusion:

Intravenous MgSO₄ improved awaken FOB intubation without adverse hemodynamic or respiratory effects.

Comparison of anesthetic efficacy between lidocaine with and without magnesium sulfate USP 50% for inferior alveolar nerve blocks in patients with symptomatic irreversible pulpitis

INTRODUCTION

The purpose of this prospective, randomized, double-blind, placebo-controlled study was to compare the anesthetic efficacy between lidocaine with and without magnesium sulfate USP 50% for inferior alveolar nerve (IAN) blocks in patients with symptomatic irreversible pulpitis.

METHODS

One hundred patients with symptomatic irreversible pulpitis of mandibular posterior teeth were selected for the study. The patients received 1 mL magnesium sulfate USP 50% or distilled water (placebo) 1 hour before administration of conventional IAN block. Endodontic access cavity preparation was initiated 15 minutes after the IAN block injection. Lip numbness was recorded for all the patients. Success of IAN block was defined as no or mild pain on the visual analogue scale during access cavity preparation and initial instrumentation.

RESULTS

The success rate for the IAN block was 58% for magnesium sulfate group and 32% for the placebo group, with statistically significant difference between the 2 groups (P = .016).

CONCLUSIONS

In mandibular posterior teeth diagnosed with symptomatic irreversible pulpitis, preoperative administration of 1 mL magnesium sulfate USP 50% resulted in statistically significant increase in success of IAN block compared with placebo.

The role of magnesium as an adjuvant during general anaesthesia

Magnesium sulphate is used extensively in the treatment of eclampsia, and is also used to treat refractory arrhythmias, asthma, myocardial ischaemia and acute respiratory failure. We studied the interaction between magnesium sulphate and the anaesthetic agents propofol, rocuronium bromide and fentanyl citrate. This randomised, double blind study was conducted in 50 patients. The magnesium group A (n = 25) received 30 mg x kg(-1) magnesium sulphate before induction of anaesthesia and 10 mg x kg(-1) continuously intra-operatively until the end of surgery. Group B (n = 25) received the same volume of isotonic saline. Propofol, rocuronium and fentanyl infusions were started and the patients lungs' were ventilated with 33% oxygen in nitrous oxide. Anaesthetic depth was maintained at a bispectral index value of between 40 and 60. Muscle relaxation was maintained at a train-of-four count of 1 throughout surgery using neuromuscular monitoring. The fentanyl infusion was titrated to haemodynamic variables: heart rate and blood pressure. We concluded that magnesium sulphate has anaesthetic, analgesic and muscle relaxation effects and significantly reduces the drug requirements of propofol, rocuronium and fentanyl during anaesthesia.

Evaluation of effects of magnesium sulphate in reducing intraoperative anaesthetic requirements

BACKGROUND

The present randomized, placebo-controlled, double-blind study was designed to assess the effect of peroperatively administered i.v. magnesium sulphate on anaesthetic and analgesic requirements during total i.v. anaesthesia.

METHODS

Eighty-one patients (36 women, 45 men) undergoing elective spinal surgery were included in one of two parallel groups. The magnesium group received magnesium sulphate 30 mg kg(-1) as a bolus before induction of anaesthesia and 10 mg kg(-1) h(-1) by continuous i.v. infusion during the operation period. The same volume of isotonic solution was administered to the control group. Anaesthesia was maintained with propofol (administered according to the bispectral index) and remifentanil (adjusted according to heart rate and arterial blood pressure) infusions.

RESULTS

A significant reduction in hourly propofol consumption was observed with magnesium administration. For example, the mean infusion rate of propofol in the second hour of the operation was 7.09 mg kg(-1) h(-1) in the control group vs 4.35 mg kg(-1) h(-1) in the magnesium group (P<0.001). The magnesium group required significantly less remifentanil (P<0.001) and vecuronium (P<0.001). No side-effects were observed with magnesium administration.

CONCLUSION

The administration of magnesium led to a significant reduction in the requirements for anaesthetic drugs during total i.v. anaesthesia with propofol, remifentanil and vecuronium.