GP1b - Drug-Induced Sleep Endoscopy Findings May Help Prognosticate Intubation Difficulty

Abstract: Individuals with obstructive sleep apnea (OSA) pose up to a fourfold greater risk of difficult intubation relative to those without OSA. Drug-induced sleep endoscopy (DISE) is a diagnostic procedure performed under deep sedation conditions that mimic natural sleep to help identify the locations, patterns, and severity of upper airway collapse for patients with OSA symptoms. Its findings are frequently documented using the VOTE system, which scores airway collapse at the level of the velum, oropharynx, tongue base, and epiglottis. However, it is unclear whether this data can help prognosticate intubation difficulty. The purpose of this study was to measure the association between DISE VOTE findings and Cormack-Lehane (CL) direct laryngoscopy view assessments.

A retrospective case control study was approved by the sponsoring university's institutional review board. An electronic medical record query using current procedural terminology (CPT) codes was performed to identify patients who underwent DISE by the Otolaryngology Service from 2017 to 2023. From this dataset, individuals who also underwent endotracheal intubation for elective surgery within 1 year of DISE were included. Patients with incomplete medical records and those who underwent awake fiberoptic intubation were excluded. The primary predictor variable was total VOTE score, an ordinal assessment from 0 to 14. The primary outcome variable was Cormack-Lehane (CL) direct laryngoscopy view. CL view was dichotomized into Category 1 (Grades 1 and 2a) and Category 2 (Grades 2b, 3, and 4), as category 2 assessments are associated with significantly higher risks of intubation difficulty. Secondary predictors included site-specific collapse at the velum, oropharynx, tongue base, and epiglottis. Covariates included age, sex, body mass index (BMI), apnea hypopnea index (AHI), Mallampati score, thyromental distance (TMD), and cervical range of motion.

Descriptive statistics were calculated. Continuous and ordinal data were assessed for normality using Shapiro-Wilk and Kolmogorov-Smirnov tests. Non-parametric Mann-Whitney U tests were conducted to compare the distributions of ordinal or continuous predictors versus the Cormack-Lehane direct laryngoscopy view. Categorical associations were examined using Pearson ?2 and Fisher's exact tests. Predictive modeling was performed using binary multiple logistic regression and PLUM ordinal regression to identify independent predictors and calculate the strength of their associations with airway outcomes. Model reliability and predictive capacity were evaluated using collinearity assessments.

Of the 2,004 patients who underwent DISE, 790 met intubation inclusion criteria. After excluding incomplete records, the study sample was composed of 544 subjects; 362 (66.5%) were male. Median age was 58 (17). Five hundred three (92.5%) subjects presented with Category 1 view; 41 (7.5%) presented with Category 2 view. Direct laryngoscopy view was not associated with total VOTE score (P = .79). However, when adjusting for confounders, higher CL view category was associated with shorter TMD (95% CI: 0.14 to 0.69, P < .01), epiglottis collapse (95% CI: 0.34 to 0.97, P = .04), and tongue base collapse (95% CI: 1.04 to 5.15, P = .04). Mallampati score, BMI, and AHI were not associated with laryngoscopy view.

Results suggest that total DISE VOTE score was not associated with direct laryngoscopy view. However, shorter thyromental distance and greater epiglottic and tongue base collapse may be associated with laryngoscopy view assessments. Anesthesia providers should review DISE findings, when available, as documentation of site-specific collapse severity may help alert them of potential view obstruction during direct laryngoscopy. Retrospective study design and class imbalance (only 7.5% Category 2 views) may have affected outcomes. Further prospective studies are planned.


References:


Leong, Siaw May et al. "Obstructive sleep apnea as a risk factor associated with difficult airway management - A narrative review." Journal of clinical anesthesia vol. 45 (2018): 63-68.


Seet, Edwin et al. "Airway Management in Surgical Patients With Obstructive Sleep Apnea." Anesthesia and analgesia vol. 132,5 (2021): 1321-1327.