Fibreoptic Assessment of Paediatric Sized Laryngeal Mask Airways

Abstract

Laryngeal mask airways (LMA) are commonly used in paediatric anaesthesia. A well-placed LMA should provide a direct view of the vocal cords facilitating bronchoscopy or fibreoptic intubation. The aim of this audit was to assess the bronchoscopie view of the glottis obtained through an LMA with regard to its size. We prospectively assessed the position of LMAs in relation to the glottic aperture in 350 children (zero to seven years) undergoing elective fibreoptic examination of the upper and/or lower airways. Following induction of anaesthesia and positioning of the LMA, a fibreoptic evaluation of the view of the glottis was performed (complete, partial or no visualisation). Chest movement on manual ventilation was judged as good in the majority of patients and adequate for the remainder. No overt signs of airway obstruction were noted in any patient. However, a complete view of the glottic aperture was present in only 50% of size 1 LMAs, 57.5% of size 1.5, 72.7% of size 2 and 77.8% of size 2.5. The epiglottis impinged on the LMA opening, partially obstructing the view of the glottis in 36.3% of size 1 LMAs, 31.5% of size 1.5, 21% of size 2 and 17.8% of size 2.5. In 13.7% of size 1 LMAs, 11% of size 1.5, 6.3% of size 2 and 4.4% of size 2.5, the epiglottis was completely downfolded, obstructing the view of the glottic aperture. The findings indicate that even if ventilation is judged as adequate, smaller paediatric LMAs are more commonly associated with suboptimal anatomical positioning with partial obstruction of the glottic aperture than larger LMAs, and therefore may require repositioning more often.

A randomized crossover comparison between the Laryngeal Mask Airway‐Unique™ and the air‐Q Intubating Laryngeal Airway in children*

“…Fiberoptic views with the LMA‐U in this study are consistent with other studies using the size two LMA (14,15). Even with complete epiglottic downfolding, both devices provided adequate ventilation parameters without evidence of airway obstruction, which is consistent with previous literature (4,18–22). The lower rates of epiglottic downfolding seen with the ILA in this study may highlight a potential advantage when considering fiberoptic‐guided tracheal intubations, especially when cuffed tracheal tubes are desired (4).…”

A prospective randomized trial comparing supraglottic airways for flexible bronchoscopy in children

“…Any new product should also perform at least as well as a recognized ‘gold standard’. Complication rates increase with sizes 1 and 1.5 cLMA™s in the under 10 ‐kg group (12,19–21), and our results are consistent with these findings. The results of this study have anesthetic implications for diagnostic flexible bronchoscopy procedures, and fiberoptic and blind endotracheal intubation procedures (22,23) if SGAs are utilized.…”

“…(11) found 17% of patients had partial airway obstruction based on fiberoptic examination, and 2% had clinically severe airway obstruction. In a study of 350 children, von Ungern‐Sternberg (12) found good or adequate ventilation conditions in all patients, but an incomplete view of the glottis through a flexible bronchoscope occurred in up to 50% of cases with smaller single‐use SGAs being associated with poorer views. In our study, 5.5% of SGA insertions were associated with clinically severe airway obstruction that required readjustment of the SGA.…”

Initial experience of the i-gel supraglottic airway by the residents in pediatric patients

“…Clinically, all patients had unobstructed airways. Von Ungern-Sternberg [7] showed that complete downfolding of the epiglottis over the laryngeal inlet occurred in 11% and partial downfolding in 32% of patients using a size 1.5 LMA. It appears that the use of the size 1.5 i-gel airway should be handled especially carefully because this size covers a wide body weight range, from 5 to 12 kg, which coincides with 6-month-old to 2-year-old children.…”