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Volume 15 No. 01
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Accepted Papers

REM: A Publication for Residents and Fellows

Images: Drug-Induced Sleep Endoscopy: An Investigative Tool for Mechanisms of PAP Failure

Clara H. Lee, BS1; Everett G. Seay, BS, RPSGT2,3; Raj C. Dedhia, MD, MSCR2,3
1Emory University School of Medicine, Atlanta, Georgia; 2Department of Otolaryngology, Emory University School of Medicine, Atlanta, Georgia; 3Emory Sleep Center, Emory Healthcare, Atlanta, Georgia


This is a case report of a 60-year-old female with mild obstructive sleep apnea (OSA) who presented to CPAP Alternatives clinic following multiple failed attempts at positive airway pressure (PAP) therapy. She underwent drug-induced sleep endoscopy (DISE) with the concurrent application of PAP via two different mask types. Application of the oronasal mask at low pressures demonstrated soft palate collapse, while high pressures resulted in posterior tongue collapse. In contrast, application of the nasal mask eliminated palatal and tongue obstruction at low pressures, despite mask leak at higher pressures. She was recommended a trial of nasal autoPAP, which with the use of a chinstrap, resulted in both subjective and objective improvement of her OSA.


Lee CH, Seay EG, Dedhia RC. Drug-induced sleep endoscopy: an investigative tool for mechanisms of PAP failure. J Clin Sleep Med. 2019;15(1):171–172.


Drug-induced sleep endoscopy (DISE) utilizes flexible laryngoscopy to visualize the upper airway under various modes of pharmacologic sedation.1 Performed by otolaryngologists, DISE provides information about the sites and patterns of airway collapse seen in patients with obstructive sleep apnea (OSA). It is primarily used to identify treatment options for patients who seek alternatives to positive airway pressure (PAP), including oral appliances and sleep surgery.2 For example, the pattern of palatal collapse seen on DISE plays a role in determining eligibility for hypoglossal nerve stimulation.3 A recent development has been the concurrent application of PAP during DISE, which allows for direct observation of PAP's effect on the airway.4 We present a case of “PAP DISE” as an investigational tool for a patient who failed PAP.


A 60-year-old otherwise healthy Caucasian female was referred to the CPAP Alternatives Clinic by her sleep neurologist. She reported a 10-year history of OSA, which was initially treated with continuous PAP (CPAP), but had recently worsened. Her main complaints were daytime sleepiness and fatigue (Epworth Sleepiness Scale score 16). Prior to her visit, she had a home sleep apnea test, which revealed an apnea-hypopnea index (AHI) of 14 events/h and oxygen saturation nadir of 89%. She then had a PAP titration study, which showed persistent hypopneas despite a nasal CPAP of 15 cmH2O and oronasal bilevel PAP (BPAP) of 24/20 cmH2O. She underwent a trial of autotitrating BPAP, followed by a trial of autotitrating PAP (APAP), which resulted in residual AHI of 12.5 events/h and 16.3 events/h, respectively. During both trials, she wore an oronasal mask with minimal leak. Her body mass index was 28.8 kg/m2 and she had no abnormalities on HEENT exam. Given her unusual triad of high PAP requirements, low baseline AHI and benign physical examination, DISE was recommended to investigate the patient's poor response to PAP and determine possible alternative therapies.

The patient was taken to the endoscopy suite, where she was administered propofol to achieve a sleep-like state consisting of snoring and obstructive apneic events. She was first fitted with an oronasal mask attached to a bronchoscopy elbow (Respironics, Murrysville, Pennsylvania, United States) to allow passage of the laryngoscope (Figure 1). Her CPAP machine was programmed to a 5-minute ramp, from 5 to 20 cmH2O. As seen in Video 1, the initial source of obstruction was the soft palate, which became relieved around 12 cmH2O. As the pressures increased, the tongue base became displaced posteriorly, creating a new source of obstruction. Next, the patient was fitted with a nasal mask prepared in a similar manner (Figure 1). In contrast to the prior examination, the palatal obstruction was relieved at lower pressures without any tongue movement. As the pressures increased, the patient had an oral air leak, which was resolved by manual mouth closure.

Oronasal mask fitted with a bronchoscopy elbow (left). Nasal mask fitted with a bronchoscopy elbow (right).


Figure 1

Oronasal mask fitted with a bronchoscopy elbow (left). Nasal mask fitted with a bronchoscopy elbow (right).

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We recommended a trial of nasal APAP with a range of 5 to 20 cmH2O. The patient was instructed to use a chinstrap if necessary to maintain mouth closure. One month later, we followed up with the patient via telephone. She reported subjective improvement, stating she felt more energized during the day. This motivated her to use her chinstrap, although she disliked it. In addition, her PAP download revealed objective improvement, with a median pressure of 8.2 cm H2O, residual AHI 0.8 events/h and usage 21 of 33 days.


Our case parallels a previous report by Schorr et al., in which a 67-year-old male with severe OSA had an unsuccessful PAP titration with an oronasal mask at all pressures, then achieved elimination of OSA with a nasal mask at 7 cmH2O. Like our patient, his PAP DISE revealed posterior displacement of the tongue with the oronasal mask at high pressures.5 Indeed, the benefits of nasal masks have been established. A recent meta-analysis by Andrade et al. found that oronasal masks have higher PAP requirements (+1.5 cmH2O), higher residual AHI (+2.8 events/h) and lower usage times (−48 min/night) compared to nasal masks.6

Several mechanisms may explain the inferiority of the oro-nasal mask. One hypothesis is that the tightening of the oro-nasal mask creates an artificial retrognathism, causing airway collapse.5,7 In this case, one would expect to see obstruction at all pressures with the oronasal mask; however, we only observed obstruction at higher pressures. A more likely possibility is that mouth opening creates an additional airstream, which neutralizes the nasal airstream and forces the tongue posteriorly, rendering PAP less effective and creating a new site of obstruction.7,8

It is interesting to note the discrepancy between the patient's titration study and most recent APAP trial. While she persisted to have hypopneic events at all pressures with nasal PAP during titration, she experienced resolution of her OSA with both nasal PAP DISE and APAP. Given that she had no major weight or craniofacial changes in the interim, we hypothesize this discrepancy is a result of sleep fragmentation and limited sleep sampling times, which may have overestimated the residual AHI on her titration study.

This case highlights the important role of mask selection in PAP success. Further research is required to determine why certain patients succeed with oronasal mask use, while others fail. In addition to identifying PAP alternatives, DISE may facilitate PAP use by determining optimal mask and pressure settings.


The authors have seen and approved the manuscript. The authors report no conflicts of interest.



Shteamer JW, Dedhia RC. Sedative choice in drug-induced sleep endoscopy: A neuropharmacology-based review. Laryngoscope. 2017;127(1):273–279. [PubMed]


De Vito A, Carrasco Llatas M, Ravensloot MJ, et al. European position paper on drug-induced sleep endoscopy (DISE): 2017 update. Clin Otolaryngol. 2018;43(6):1541–1552. [PubMed]


Vanderveken OM, Maurer JT, Hohenhorst W, et al. Evaluation of drug-induced sleep endoscopy as a patient selection tool for implanted upper airway stimulation for obstructive sleep apnea. J Clin Sleep Med. 2013;9(5):433–438. [PubMed Central][PubMed]


Civelek S, Emre IE, Dizdar D, et al. Comparison of conventional continuous positive airway pressure to continuous positive airway pressure titration performed with sleep endoscopy. Laryngoscope. 2012;122(3):691–695. [PubMed]


Schorr F, Genta PR, Gregorio MG, Danzi-Soares NJ, Lorenzi-Filho G. Continuous positive airway pressure delivered by oronasal mask may not be effective for obstructive sleep apnoea. Eur Respir J. 2012;40(2):503–505. [PubMed]


Andrade RGS, Viana FM, Nascimento JA, et al. Nasal vs oronasal CPAP for OSA treatment: a meta-analysis. Chest. 2018;153(3):665–674. [PubMed]


Deshpande S, Joosten S, Turton A, et al. Oronasal masks require a higher pressure than nasal and nasal pillow masks for the treatment of obstructive sleep apnea. J Clin Sleep Med. 2016;12(9):1263–1268. [PubMed Central][PubMed]


Smith PL, O'Donnell CP, Allan L, Schwartz AR. A physiologic comparison of nasal and oral positive airway pressure. Chest. 2003;123(3):689–694. [PubMed]

Supplemental Material

Video 1

(.mp4 | 35.18 MB)