Effects of Anesthetic Depth Using the Bispectral Index During Sleep Endoscopy With PAP Titration

Airway collapsibility varies with the level of anesthetic depth during drug-induced sleep endoscopy (DISE). Bispectral index (BIS) monitoring uses EEG signals to quantify anesthetic depth. We conducted a prospective study to examine changes in VOTE scores and pharyngeal opening pressure (PhOP) during DISE with positive airway pressure (DISE-PAP), at light and deep sedation.

Anesthetic depth was monitored using BIS during DISE-PAP for 17 patients. We classified BIS ≥ 55 as light sedation and < 55 as deep sedation. The DISE exam was performed and subsequently PAP applied to assess PhOP at both light and deep sedation. We defined PhOP as the minimum pressure wherein all areas of the airway were opened. A blinded evaluation of the procedure video was performed by either one of two sleep surgery fellows or an attending sleep surgeon to create a VOTE score for the DISE exam and PhOP.

All n = 17 patients enrolled had OSA with a mean AHI of 30.5 and standard deviation 17.8. PhOP significantly correlated with BIS readings (rho = -0.45, p = 0.0328) but VOTE classification did not significantly correlate with BIS level (rho = 0.18, p = 0.189). The velum and epiglottis had opening pressures that correlated to BIS level (rho = -0.398; p = 0.044) and (rho = -0.426; p = 0.038), respectively.

Anesthetic depth measured by BIS correlates with airway resistance as measured by PhOP. PAP appears to be a useful tool during DISE as it gives a highly titratable and immediate measurement of pharyngeal collapsibility.