Bispectral Index in Evaluating Effects of Sedation Depth on Drug-Induced Sleep Endoscopy

Abstract

Objective: To evaluate the effect of sedation depth on drug-induced sleep endoscopy (DISE).

Methods: Ninety patients with obstructive sleep apnea (OSA) and 18 snorers underwent polysomnography and DISE under bispectral index (BIS)-guided propofol infusion at two different sedation levels: BIS 65-75 (light sedation) and 50-60 (deep sedation).

Results: For the patients with OSA, the percentages of velopharynx, oropharynx, hypopharynx, and larynx obstructions under light sedation were 77.8%, 63.3%, 30%, and 33.3%, respectively. Sedation depth was associated with the severity of velopharynx and oropharynx obstruction, oropharynx obstruction pattern, tongue base obstruction, epiglottis anteroposterior prolapse and folding, and arytenoid prolapse. In comparison, OSA severity was associated with the severity of velopharynx obstruction, severity of oropharynx obstruction, and arytenoid prolapse (odds ratio (95% confidence interval); 14.3 (4.7-43.4), 11.7 (4.2-32.9), and 13.2 (2.8-62.3), respectively). A good agreement was noted between similar DISE findings at different times and different observers (kappa value 0.6 to 1, respectively). A high percentage of arytenoid prolapse (46.7% among the patients with OSA under light sedation) was noted.

Conclusions: Greater sedative depth increased upper airway collapsibility under DISE assessment. DISE under BIS-guided propofol infusion, and especially a level of 65-75, offers an objective and reproducible method to evaluate upper airway collapsibility. Some findings were induced by drug sedation and need careful interpretation. Specific arytenoid prolapse patterns were noted for which further investigations are warranted.

Clinical trials registration: http://www.clinicaltrials.gov, identifier: NCT01100554.

Commentary: A commentary on this article appears in this issue on page 965.

Keywords: bispectral index; drug-induced sleep endoscopy; laryngeal obstruction; obstructive sleep apnea.

© 2015 American Academy of Sleep Medicine.

Figures

Figure 1. Visual representations of the parameters recorded during drug-induced endoscopy

See Table 1 for a description of the parameters recorded during drug-induced endoscopy and the definitions.

Figure 2. Obstruction percentage of different drug-induced sleep endoscopy (DISE) parameters in four different disease severity groups (normal, mild, moderate, and severe obstructive sleep apnea).

The percentage of velopharynx obstruction (A) and oropharynx obstruction (B) of DISE under two different sedation depths. The existence of tongue base obstruction (C) and hypopharynx obstruction (D) under two DISE sedation depths. Tongue base obstruction was defined when cases had a tongue base drop that pushed the epiglottis backward. The percentage of larynx obstruction (E) and epiglottis prolapsed that touched the posterior pharyngeal wall (F) under two DISE sedation depths. The occurrence of epiglottis folding (G) and arytenoid prolapse (H) under different DISE sedation depths. p = the difference in obstruction percentages between different OSA severities; *p < 0.5, **p < 0.05, ***p < 0.01: the difference in obstruction percentages between different sedation depths in same OSA severity entity.

Figure 3. Demonstration of drug-induced sleep endoscopy patterns of a 45-year-old man who had mild obstructive sleep apnea (apnea-hypopnea index 8.5).

A1, Velopharynx when awake. A2, Oropharynx when awake. A3, Hypopharynx when awake. B1, Velopharynx at LS. B2, Oropharynx at LS. B3, Hypopharynx at LS. C1, Velopharynx at DS. C2, Oropharynx at DS. C3, Hypopharynx at DS.