Correlation between bispectral index, end-tidal anaesthetic gas concentration and difference in inspired–end-tidal oxygen concentration as measures of anaesthetic depth in paediatric patients posted for short surgical procedures

Background and Aims: Measurement of end-tidal anaesthetic gas concentrations (ETAG) is currently a pragmatic indicator for monitoring anaesthetic depth. We aimed to assess the performance of ETAG for sevoflurane (ETAG-sevo) with bispectral index (BIS) and difference between inspired and end-tidal oxygen concentration (Fi−Et)O2% in measuring anaesthetic depth in toddlers and preschool children. Primary outcome was to correlate BIS with ETAG-sevo. Secondary outcome was to correlate (Fi−Et)O2% with ETAG-sevo and to derive cut-off value of (Fi−Et)O2%which corresponds with light planes of anaesthesia [minimum alveolar concentration (MAC 7 was obtained for (Fi−Et)O2% corresponding to MAC 7 corresponded with light planes of anaesthesia.