Improving the success rate of laryngeal mask airway insertion during etomidate induction by using fentanyl or succinylcholine

Abstract

Background: Smooth and successful insertion of a laryngeal mask airway (LMA) during etomidate induction requires a proper mouth opening and efforts to minimize airway reflexes such as gagging, coughing, or laryngospasm. We hypothesized that the concurrent use of fentanyl or succinylcholine with etomidate, the induction agent, could reduce the occurrence of airway reflexes and increase the success rate of LMA.

Methods: Sixty adult patients, ASA class I-II, scheduled for surgery under general anesthesia, were randomly allocated into three groups: group I in which patients were given etomidate 0.3 mg/kg alone; group 2 in which patients were given fentanyl 2 microg/kg and etomidate 0.3 mg/kg; groups 3 in which patients were give etomidate 0.3 mg/kg and succinylcholine 1 mg/kg. All patients were premedicated with atropine 0.01 mg/kg. When induction of anesthesia began we recorded the time from administering the designated regiminal agent or agents to the time of relaxation of jaw (the ease of mouth opening) and checked the patient for any excitatory movement after administering the induction agents. After inserting the LMA, we checked for signs of airway reflexes. Student's t test, Chi-square and Fisher's exact test were used to analyze the data. A value of P < 0.05 was considered significant.

Results: There were no significant differences in demographic data among the the three groups. The concurrent use of fentanyl or succinylcholine with etomidate during induction could significantly reduce the occurrence of excitatory movements and airway reflexes after LMA insertion, and increase the success rate of LMA insertion in comparison with using etomidate alone. Comparing the two adjutant agents, the concurrent use of succinylcholine could provide a significantly better jaw relaxation, shorten the time to insert the LMA and increase the success rate of LMA insertion.

Conclusions: As an induction agent to facilitate insertion of LMA, etomidate alone was far from perfect. The concurrent use of 2 microg/kg of fentanyl with etomidate might significantly reduce the occurrence of airway reflexes in response to LMA insertion and increase the success rate of insertion. However, concurrent use of 1 mg/kg succinylcholine with etomidate might provide better results in terms of shortened time for the LMA insertion, jaw relaxation, and the success rate of LMA insertion than that of fentanyl.