Is BIS monitoring cost-effective?

Effect of airway device and depth of anesthesia on intra-ocular pressure measurement during general anesthesia in children: A randomized controlled trial

Background and Aims:

Accurate measurement of intraocular pressure (IOP) under anaesthesia is essential for diagnosis and further management of pediatric glaucoma patients. However, depth of anaesthesia and use of airway device like laryngeal mask airway (LMA) or endotracheal tube can influence IOP values measured. We planned this study to compare change of IOP with facemask or LMA. Change of IOP at varying depth of anaesthesia was also assessed.

Material and Methods:

After Institutional ethical clearance and informed parental consent, 89 children of glaucoma aged 0-12 years were included in this prospective randomized controlled trial. The children were randomized to facemask (Group M) and LMA (Group L). Sevoflurane was the sole general anaesthetic used in both the groups and IOP were recorded after induction, at BIS 40-60, after LMA insertion (Group L), at BIS 60-80 and BIS more than 80.

Results:

The IOP values did not differ significantly between the groups at BIS 40-60 and at BIS 60-80. Moreover, pre and post LMA insertion IOP values were also comparable in Gr L (p = 0.11). However, significant increase in IOP values were observed with increasing BIS values within each group. The mean IOP in Group M at BIS 40-60 was 13.41 ± 4.04 as compared to 14.18 ± 3.64 at BIS 60-80 (p = 0.003). There was a similar pattern observed in Group L, where mean IOP at BIS 40-60 & BIS 60-80 was 14.13 ± 4.90 and 15.52 ± 4.57 respectively (p < 0.001).

Conclusion:

Either facemask or classic LMA can be safely used as per anaesthesiologist's preference without any significant effect on IOP. BIS monitoring may be used during IOP measurement in paediatric glaucoma suspects for accurate assessment of IOP.