Usefulness of Drug-induced Sleep Endoscopy to Diagnose Laryngeal Cause in Obstructive Sleep Apnea Patients

INTRODUCTION

Obstructive sleep apnea (OSA) is a sleep disorder characterized by repetitive episodes of cessation (apnea) or reduction (hypopnea) of airflow in the upper airway, due to its increased collapsibility occurring during sleep.¹ High rate of morbidity and mortality accompany this, due to cardiovascular outcome, the risk of occupational and automobile accidents, and poor quality of life, with neurocognitive impairment.^2,3 Hence, it is considered as a public health problem.

Numerous investigative modalities have been used to know the pathophysiology of upper airway obstruction in patients with OSA, including CT/MRI scanning and acoustic reflection. The gold standard investigation is considered to be polysomnography, which provides information about the OSA severity and degree of sleep fragmentation, but without giving any information regarding the level and degree of airway collapse.⁴

Determining the location of the upper airway obstruction during sleep is the main diagnostic challenge in patients with OSA.⁵ Flexiblescopy (FS) using Muller’s maneuver helps to assess the level and degree of upper airway during forced inspiration with patient’s mouth and nose closed, but it may not reflect the exact occurrence during sleep.⁶

To tackle this, drug-induced sleep endoscopy (DISE) was introduced to the diagnostic algorithm with its highlight being the ability to provide dynamic visualization of anatomic areas responsible for generation of noise and obstruction under condition mimicking sleep.⁷ The advantage of DISE is that upper airway collapse, which is not visible due to neuromuscular compensation in awake patients, can be observed during sleep and treatment advocated according to the location and degree of obstruction of the upper airway.^8,9 Laryngeal collapse, which is a cause of continuous positive airway pressure (CPAP) intolerance, often not visible in FS can be diagnosed during DISE. It helps in identifying CPAP intolerance in OSA.¹⁰ So, the approach of accurate diagnosis of the site and degree of upper airway obstruction and therapy targeted according to that would result in tremendous treatment outcome in patients with OSA.

The primary objective of this study is to compare the incidence of epiglottic fall as seen in routine FS vs DISE.

AIMS AND OBJECTIVES

To compare the incidence of epiglottic fall as seen in routine flexiblescopy vs DISE.

MATERIALS AND METHODS

Approval was obtained from the Institutional Ethics Committee for a prospective cross-sectional study among patients with OSA. The study was conducted in the Department of ENT of Amrita Institute of Medical Sciences, Kochi, with a duration of 2 years between August 2017 and August 2019. Informed consent was taken from all the patients.

RESULTS

Patient demographics are mentioned in Table 1.

The mean AHI and oxygen saturation in polysomnography is 39.88 ± 19.46 and 76.90 ± 12.53, respectively (Table 2).

The incidence of epiglottic collapse seen in FS was 6.7% (2 patients) and in DISE was 40% (12 patients). The comparison of epiglottic fall as seen in DISE and flexiblescopy is given in (Table 3). The difference in the frequency detected by the two methods found to be statistically significant as p value was 0.002. Kappa agreement was found to be 0.19, which shows only a slight agreement.

In FS, at the epiglottic level out of 30 patients, collapse was seen only in 2 cases (6.7%), which was of anteroposterior pattern. In DISE, of the 30 cases 12 cases (40%) had epiglottic collapse, which was of anteroposterior pattern with distribution and none of the cases had lateral pattern of collapse at the epiglottic level.

DISCUSSION

The ability to correctly identify severe collapse at each of the different levels of the upper airway has become essential in guiding the correct surgical management of patients with OSA. Furthermore, new multilevel approaches to OSA surgery have now resulted in improved outcomes compared with single level procedures.¹¹

Different levels and increase in the severity of obstruction in OSA can be assessed more precisely by doing DISE.^12,13 It is also reported that the initial management plan was changed in many OSA patient after DISE.^10,12

In our study, a statistically significant difference was noted (p value 0.002), while comparing the frequency of anteroposterior epiglottic collapse observed in flexiblescopy and DISE, and only a slight agreement was noted between these two methods. This was consistent with the study by Yegïn et al., which showed a lack of concordance in the frequency of anteroposterior epiglottic collapse detected by the two methods with only slight agreement (k = 0.107).¹³ As pathology of larynx was observed in 40% of patients, the role of larynx in OSA can be concluded to be significant and often underdiagnosed. The reason is that collapse of the epiglottis is usually not seen when the patient is awake.¹⁰ The significance of detecting laryngeal collapse by DISE and its role in CPAP failure and targeted therapy and successful treatment outcome was reported by Hybášková et al.^10,12,14,15

The most common type of epiglottis pathology in our study was collapsing of the epiglottis on the posterior wall of hypopharynx during inspiration. This type of collapse is termed the “closing door epiglottis”¹² (Fig. 1).

CONCLUSION

Evaluation of level of obstruction and degree of collapse in OSA during DISE is better than awake flexiblescopy. Laryngeal collapse in OSA is better diagnosed in DISE, which is often missed in awake endoscopy. Drug induced sleep endoscopy overcomes the drawbacks of awake endoscopy and provide more accurate evaluation of upper airway.

ETHICAL APPROVAL

Approval was obtained from the Institutional Ethics Committee. It is a part of dissertation study.

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