PEDIATRIC LARYNGEAL MASK INSERTION

Abstract

S241 Introduction: We compared the ease of insertion of the laryngeal mask airway (LMA) using the standard method and two other commonly used techniques in children, assessing function using clinical and fiberoptic criteria. Methods: With IRB approval and written parental consent, 95 children (5-30 kg) undergoing general anesthesia with the LMA were randomized into 3 groups. Children weighing 5-10 kg had size 1.5 LMAs inserted, 10-20 kg size 2, and 20-30 kg size 2.5. Anesthesia was induced with inhalation of oxygen and 66% nitrous oxide with incremental sevoflurane up to 8%. Group 1 patients had the LMA inserted as described in the product manual [1]. In group 2, the LMA cuff was fully inflated (size 1.5 7ml, size 2 10ml and size 2.5 14ml air) and was inserted with the head and LMA as per the standard recommended position. Group 3 LMAs were inserted with the cuff at atmospheric pressure. The LMA was inserted upside down and rotated as it reached the posterior pharyngeal wall as part of one smooth insertion movement. All LMAs were lubricated with water based gel. LMA position was assessed by the ability to ventilate the patient and observing the capnograph tracing. Fiberoptic scoring was as follows; 4, only vocal cords (VC) seen; 3, VC plus posterior epiglottis; 2, VC plus anterior epiglottis; 1, VC not seen but function adequate; 0, no VC seen, inadequate function. The pressure at which a leak occurred against a closed expiratory valve was noted. Any presence of blood on LMA at extubation was also noted. Anesthesia duration and patient demographic data were also collected. Parametric data were analyzed using Student's t-test and categorical data using Chi squared. Results: There were no significant differences in the demographic data or anesthetic duration. This study showed a 93.8% 1st attempt successful placement. There was no difference between the three groups in fiberoptic confirmation of LMA placement or leak: (M=mean) (Table 1)Table 1Discussion: Although randomized to 3 different insertion techniques, we showed one of the highest successful first time LMA insertion in the pediatric literature [2,3]. Difficulty passing the LMA around the posterior pharyngeal wall is reported as the main problem with LMA insertion in children [4]. In this regard the alternative techniques offered no advantage over the standard technique. The deflated LMA is less likely to downfold the epiglottis than the inflated one (10% versus 50% in adults [5]), however this is probably not clinically important [6]. In our study, the epiglottis was folded over in approximately 30% of children in each group. The mean and distribution of fiberoptic scores were similar in all groups contrasting with an adult study where the standard technique was shown to be superior [5]. An advantage of the inflated technique is the decreased incidence of blood as reported in adults [6]. In conclusion, there were no differences in insertion success, clinical function or fiberoptic positioning between the 3 groups.