Safe removal of LMA in children - at what BIS?

Removal of an LMA without producing untoward complications has remained a matter of concern to all anesthesiologists; more so in pediatric practice where the margin of safety is narrow. Most work on LMA in adults supports its removal following return of airway reflexes. The situation regarding its removal in children is, however, less clear.

We conducted a randomized, prospective study to compare incidence of airway complications after removal of the LMA at deep or awake planes in 120 children, ASA I or II, aged 1-8 years and to objectively determine the most appropriate Bispectral index (BIS) to allow safe removal of an LMA in children. They were studied in two groups of 60 and depth of anesthesia (whether awake-Gp A or deep-Gp D) for LMA removal was decided by random distribution from sealed envelopes. BIS was recorded continuously for all the patients until 2 min after removal of LMA.

Mean SpO2 after removal of LMA was 93% Gp A and 98% in Gp D. The mean duration of surgery in Gp A was 53.9 +/- 10 and in Gp D 46.7 +/- 4 min. PESev at removal in Gp A was 0.20 +/- 0.16 and in Gp D was 0.59 +/- 0.1. BIS median in Gp A was 79 with a maximum of 86 and minimum of 66. In Gp D BIS, median was 60 with maximum of 76 and minimum of 58. The number of patients with airway complications in awake removal group was 21 (35%) and in deep removal group was 4 (6.6%).

Bispectral index scoring should prove a useful adjunct to the present monitoring and can be used to achieve smoother emergence conditions. We suggest that LMA removal should be attempted in children when a BIS value of approximately 60 is reached.