Intraoperative magnesium sulphate decreases agitation and pain in patients undergoing functional endoscopic surgery: A randomised double-blind study

Abstract

Background: Postoperative agitation is harmful for the patient as it may be associated with removal of catheters, nasal packs, oxygen masks and self-injury, and pose a danger to operating theatre staff.

Objective: The current study investigated the potential role of magnesium sulphate in treatment of postoperative agitation following functional endoscopic sinus surgery.

Design: A randomised, double-blinded, placebo-controlled trial.

Setting: ENT operating room, Menofia University Hospitals, Egypt.

Patients: A total of 312 adult patients (171 men and 141 women) were enrolled in the study. Eighteen patients (10 men and eight women) were excluded; data from 294 patients were analysed. Inclusion criteria were age between 20 and 60 years, American Society of Anesthesiologists' physical status 1 or 2 scheduled for functional endoscopic sinus surgery. Exclusion criteria were hypertension, cardiac ischaemia, cerebrovascular insufficiency, neuromuscular diseases, pregnancy, prolonged treatment with calcium-channel blockers, diabetic neuropathy or a known allergy to magnesium compounds.

Interventions: Patients were allocated randomly to either the magnesium group (a magnesium infusion of 30 mg kg in the first hour followed by 9 mg kg h until the end of the surgical procedure) or the control group (0.9% saline at the same volume and rate). Hypotensive anaesthesia was induced by nitroglycerine 5 to 20 μg kg min. In the postanaesthetic care unit (PACU), patients were assessed for agitation and pain using the Richmond agitation-sedation scale and numerical rating scale, respectively.

Primary outcome: The incidence and severity of agitation measured 5 min after admission to the PACU.

Results: Magnesium reduced postoperative agitation at time 0 (P = 0.009) and 5, 10, 15 and 30 min after PACU admission (P < 0.0001) as well as total agitation score [3 (0 to 6) versus 9 (0 to 12), P < 0.0001]. Magnesium also reduced pain [4.5 (4 to 5) versus 6 (5 to 6.25), P < 0.0001] and length of PACU stay (88 ± 23 versus 111 ± 31 min, P < 0.0001). The magnesium group consumed less pethidine in PACU compared with the control group (43 ± 15 and 59 ± 19 mg, respectively, P < 0.0001). The intraoperative end-tidal CO2 tension was comparable between groups (4.7 ± 0.7 versus 4.8 ± 1.2 kPa).

Conclusion: Intraoperative infusion of magnesium in patients undergoing endoscopic sinus surgery reduced postoperative agitation, pethidine consumption and pain assessed in the PACU. It also decreased the length of stay in PACU compared with the control group.

Trial registration: The current study was registered according to WHO and ICMJE standards on 7 January 2014, under registration number PACTR 201402000737691.