The use of minidose muscle relaxant to facilitate insertion of a laryngeal mask airway

Abstract

Background Laryngeal mask airway (LMA) has gained wide acceptance for airway management especially in day case surgery. Although propofol is known to blunt laryngeal reflexes, smooth and successful insertion of LMA requires a proper mouth opening to minimize airway reflexes such as gagging, coughing, and laryngospasm. The concurrent use of mini‐dose muscle relaxant with propofol could reduce the occurrence of airway reflexes and increase the success rate of LMA insertion. Aim of the study The aim of this study is to evaluate the effect of minidose atracurium and succinylcholine, to facilitate LMA insertion and which is better of them to achieve more satisfaction and less complications following induction of anesthesia with propofol, in day case surgery patients. Patients and methods This prospective, randomized, controlled, double-blind study was done on 90 healthy patients with American Society of Anesthesiologist physical status I or II, scheduled for elective surgery of less than 30 min under general anesthesia through LMA. These 90 patients were randomized by computer-generated and sealed opaque envelope method into three equal groups, according to the muscle relaxant given, with 30 patients (n = 30) each, after the induction of anesthesia with fentanyl. Atracurium group (group A) received a bolus of atracurium 0.15 mg/kg diluted in 2 ml of 0.9% sodium chloride intravenously before propofol injection and 2 ml of 0.9% sodium chloride after propofol injection. Succinylcholine group (group S) received 2 ml of 0.9% sodium chloride before propofol injection and a bolus of succinylcholine 0.25 mg/kg diluted in 2 ml of 0.9% sodium chloride intravenous after propofol injection. Control group (group C) received 2 ml of 0.9% sodium chloride before and after propofol injection. Two minutes after propofol injection, one disposable lubricated, semi-inflated classic LMA with appropriate size was inserted by an experienced anesthesiologist who was unaware of the drug used for injection and patient groups. Moreover, in the patient groups, a uniform general anesthesia technique was applied to all patients. The primary outcome was ease and reactions to LMA insertion and postoperative sore throat. The secondary outcome was hemodynamic changes, heart rate and mean arterial blood pressure before and after LMA insertion and postoperative myalgia. Results The result of this study reveals that the first attempt in LMA insertion was successful in up to 27 (90%) patients in group S, whereas in only 23 (83.3%) patients in group A and 16 (60.0%) patients in group C. The difference was statistically significant (P<0.001). Postoperative sore throat occurred in 11 (36.7%) of patients of control group, which was statistically significantly more than that in the studied groups. Postoperative myalgia was found in 12 (40%) patients in the succinylcholine group, which was statistically significant more than that in groups A and C (P=0.001). However, there was no difference in apnea times among all the groups. There was no significant difference in hemodynamic changes among all groups, although total propofol consumption was statistically highly significantly more in the control group (P<0.001). Conclusion The concurrent use of minidose muscle relaxant with propofol and fentanyl significantly reduces the occurrence of airway reflexes, increases the success rate of LMA insertion, and decreases the incidence of postoperative sore throat. However, minidose of succinylcholine has a far better effect than minidose of atracurium with significant postoperative myalgia.