WHEN OPEN GETS CLOSED: PHENOTYPIC CHARACTERISTICS OF SLEEP APNEA IN PATIENTS WITH NORMAL UPPER AIRWAY SIZE

Abstract

SESSION TITLE: Original Research in OSA SESSION TYPE: Original Investigations PRESENTED ON: 10/07/2018 07:30 AM - 08:30 AM PURPOSE: Obstructive sleep apnea is characterized by recurrent episodes of upper airway closure and has been typically associated with compromised upper airway space. However some adults with normal upper airway morphology also develop sleep apnea and this phenotype has not yet been adequately characterized. The aim of this study was to examine peculiarity of sleep apnea in a cohort of patients with normal upper airway morphology and size METHODS: This was a retrospective review from patients who underwent overnight diagnostic polysomnography. OSA was defined as AHI >5. Upper airway morphology was assessed by trained techs using Modified Friedman categorization and their classification was validated in an initial subset. Epworth scale ESS and other anthropometric variables such as neck circumference NC and BMI were also recorded. Respirattory arousal threshold ArTH was calculated from AHI, fraction of hypopneas and O2 nadir RESULTS: A total of 589 patients were included in the study 201 F and 388 M. 243 patients (41%) had a normal UA as defined as MF of 1 or 2. No age difference was seen between Normal UA and Small UA groups 55 +/- 13 vs 54 +/- 14. Gender and ethnicity distribution was not different– 45% of F and 39% of M had a normal UA (p >0.1) as did 43% of Hispanics & 38% of Caucasian. BMI was lower in the normal UA group 35 +/- 8 vs 37 +/- 7 p = 0.2 but NC was not different 16.9 +/- 4 vs 17.2 +/- 2; p= 0.2. ESS was not different between the two groups 10.4 +/- 6 vs 11.1 +/- 6. Sleep study showed lower AHI in normal UA group AHI 33 +/- 25 vs 39 +/- 28 in small UA group. REM AHI was the same in both groups 35 +/- 25 vs 35 +/- 26 & supine AHI was also lower in the normal UA group – 34 +/- 26 vs 40 +/- 29; p < 0..001. The normal UA group had less severe hypoxemia with O2 nadir 77 +/- 9 vs 75 +/- 11 and minutes spent below a sat 90% 37 +/- 47 vs 52 +/- 61 both being significantly lower p < 0.001. Patients with normal UA size had increased % of patients with low ArTH (ArTh >2) 47% vs 37%; p< 0.05. CPAP requirements were not different between normal UA and small UA 10.5 +/- 4 vs 11.2 +/- 4 CONCLUSIONS: Patients with OSA and normal upper airway size as assessed by MF scale have lower BMI, but similar neck size. There is no gender or ethnic bias. They have less severe sleep apnea with less supine AHI and less hypoxemia. They are more likely to have a low ArTH. Despite differences in airway size and AHI severity there was no difference in CPAP requirements in patient with normal UA size CLINICAL IMPLICATIONS: There is a significant percentage of patients with OSA who have normal upper airway assessment - identifying characteristics that place these patients at high risk for OSA will be useful in screening them appropriately. The significance of a low ArTH in this group is interesting and its physiologic basis needs to be explored as it may pave the way for more precision based therapeutic approaches in this group. DISCLOSURES: No relevant relationships by Akshar Aiyer, source=Web Response Speaker/Speaker's Bureau relationship with astra zeneca Please note: $5001 - $20000 Added 11/02/2017 by Shyamsunder Subramanian, source=Web Response, value=Consulting fee Speaker/Speaker's Bureau relationship with boehringer ingelheim Please note: $5001 - $20000 Added 11/02/2017 by Shyamsunder Subramanian, source=Web Response, value=Consulting fee Speaker/Speaker's Bureau relationship with genentech Please note: $5001 - $20000 Added 11/02/2017 by Shyamsunder Subramanian, source=Web Response, value=Consulting fee Speaker/Speaker's Bureau relationship with teva Please note: $5001 - $20000 Added 03/02/2018 by Shyamsunder Subramanian, source=Web Response, value=Consulting fee Speaker/Speaker's Bureau relationship with sunovion Please note: $1001 - $5000 Added 03/02/2018 by Shyamsunder Subramanian, source=Web Response, value=Consulting fee Speaker/Speaker's Bureau relationship with Sunovian Please note: $5001 - $20000 Added 11/20/2017 by Salim Surani, source=Web Response, value=Honoraria Advisory Committee Member relationship with Astra Zeneca Please note: $5001 - $20000 Added 11/20/2017 by Salim Surani, source=Web Response, value=Consulting fee No relevant relationships by Zoya Surani, source=Web Response No relevant relationships by Joseph Varon, source=Web Response