GP1b - Are Drug Induced Sleep Endoscopy Findings Associated With Mask Ventilation Difficulty?

Abstract: Anesthesia providers may encounter difficulty in managing patients with obstructive sleep apnea (OSA) due to anatomic airway narrowing, tissue redundancy, and decreased muscle tone. Physical examination and laboratory data may alert clinicians to potential airway difficulty in this cohort. Drug-induced sleep endoscopy (DISE) is a diagnostic procedure that evaluates the severity and patterns of airway obstruction under conditions that mimic natural sleep. Findings are reported using the VOTE classification, which scores obstruction at the velum, oropharynx, tongue base, and epiglottis. However, controversy exists regarding the relationship between upper airway obstruction during DISE and mask ventilation difficulty under general anesthesia. The purpose of this study was to measure the association between DISE VOTE findings and mask ventilation difficulty (MVD).

A retrospective cohort study was approved by the institutional review board of the sponsoring institution. An electronic medical record query was performed to identify patients who underwent DISE by the Otolaryngology Department from 2017 to 2023. From this dataset, individuals who also underwent mask ventilation and endotracheal intubation for elective surgery within one year of DISE were included. Patients with incomplete medical records and those for whom ventilation was not attempted were excluded. The primary predictor variable was the total VOTE score, an ordinal assessment from 0 to 14. The primary outcome variable was mask ventilation difficulty assessment, which had two levels based on the Han scale. Easy mask difficulty was defined as Han grade 1 or 2 (easy ventilation with or without supraglottic airway). Difficult mask ventilation was defined as Han grade 3 (difficult, unsteady ventilation requiring help from another provider) or grade 4 (unable to ventilate). VOTE oropharynx and tongue base scores were secondary predictors. Covariates included age, sex, body mass index (BMI), apnea hypopnea index (AHI), Mallampati score, thyromental distance (TMD), and cervical range of motion (ROM).

Descriptive statistics were calculated. Shapiro-Wilk test was used to analyze sample normality. Mann-Whitney U and Chi Square tests were used to analyze relationships between predictor variables and the primary outcome variable. Collinearity was assessed; binary multiple logistic regression analysis was performed. P < .05 was statistically significant.

Of the 2004 patients who underwent DISE, 790 met intubation inclusion criteria. After excluding incomplete records, 500 subjects were included; 25 (5%) had difficult mask ventilation. Mask ventilation difficulty was not associated with total VOTE score (P = .66). However, subjects with difficult mask ventilation had higher median (IQR) oropharynx VOTE scores [2(2) vs 1(2) (P < .01)] and higher AHI scores [45.4(42.2) vs 27.7(25.6) (P < .01)] relative to subjects who did not. MVD was also associated with sex (P < .01). Binary multiple logistic regression revealed significant associations with difficult mask ventilation and male sex (95% CI [1.09, 21.8]; P = .04), AHI (95% CI [1.01, 1.05]; P < .01), oropharynx VOTE score (95% CI [1.03, 4.31]; P = .04), and total VOTE score (95% CI [0.43, 0.94]; P =.02). Other predictors like Mallampati, cervical ROM, and thyromental distance were not associated with mask ventilation difficulty.

Results suggest that while difficult mask ventilation was associated with increased oropharynx VOTE score, total VOTE score showed a negative association with difficult mask ventilation. Such seemingly conflicting findings may be influenced by the study’s small sample size and retrospective nature, both of which are weaknesses. Regardless, polysomnography and DISE data should be considered when formulating an airway assessment for OSA patients whenever possible. Future prospective studies may help to further elucidate the association between these findings.

Seet E, Nagappa M, Wong DT. Airway Management in Surgical Patients with Obstructive Sleep Apnea. Anesth Analg. 2021 May 1;132(5):1321-1327.

Kang TW, Wang JD, Tsai YS, Lin CR, Tseng CA. Intubation difficulty scale contributors and time delay in clinical practice. Medicine (Baltimore). 2022 Jan 28;101(4):e28724.