Cervical computed tomography in patients with obstructive sleep apnea: influence of head elevation on the assessment of upper airway volume

Abstract

Objective: Obstructive sleep apnea syndrome (OSAS) has a high prevalence and carries significant cardiovascular risks. It is important to study new therapeutic approaches to this disease. Positional therapy might be beneficial in reducing the apnea-hypopnea index (AHI). Imaging methods have been employed in order to facilitate the evaluation of the airways of OSAS patients and can be used in order to determine the effectiveness of certain treatments. This study was aimed at determining the influence that upper airway volume, as measured by cervical CT, has in patients diagnosed with OSAS. Methods: This was a quantitative, observational, cross-sectional study. We evaluated 10 patients who had been diagnosed with OSAS by polysomnography and on the basis of the clinical evaluation. All of the patients underwent conventional cervical CT in the supine position. Scans were obtained with the head of the patient in two positions (neutral and at a 44° upward inclination), and the upper airway volume was compared between the two. Results: The mean age, BMI, and neck circumference were 48.9 ± 14.4 years, 30.5 ± 3.5 kg/m2, and 40.3 ± 3.4 cm, respectively. The mean AHI was 13.7 ± 10.6 events/h (range, 6.0-41.6 events/h). The OSAS was classified as mild, moderate, and severe in 70%, 20%, and 10% of the patients, respectively. The mean upper airway volume was 7.9 cm3 greater when the head was at a 44° upward inclination than when it was in the neutral position, and that difference (17.5 ± 11.0%) was statistically significant (p = 0.002). Conclusions: Elevating the head appears to result in a significant increase in the caliber of the upper airways in OSAS patients.

Cervical computed tomography in patients with obstructive sleep apnea: influence of head elevation on the assessment of upper airway volume

“…In our study of cervical CT in patients with OSA, we found that airway volume increased by 7.9 cm 3 (17.5%) when a 44° upward inclination was compared with a neutral head position 1 . Our results are reliable and show statistically significant differences despite the small sample size 1 .…”

“…Our results are reliable and show statistically significant differences despite the small sample size 1 . The title states that the study involved cervical CT rather than CT with analysis of nasal airway volume.…”

“…We read with great interest the article by Souza et al 1 describing cervical CT in patients with obstructive sleep apnea (OSA) and the influence of head elevation on the assessment of upper airway volume. We congratulate the authors for choosing such a meaningful topic and using cone beam CT.…”

“…We congratulate the authors for choosing such a meaningful topic and using cone beam CT. In their study, 1 CT scans were obtained with the head of the patient in two positions (neutral and at a 44° upward inclination). Polysomnography was used for diagnosing the patients with OSA.…”

“…The title states that the study involved cervical CT rather than CT with analysis of nasal airway volume. In the studies of imaging evaluation of airway volume cited in the Discussion section of our study, airway volume was measured from the hard palate to the base of the epiglottis for analysis of interventions involving a mandibular advancement splint, maxillomandibular advancement surgery, and continuous positive airway pressure 1 . The clinical foundation for our study was provided by a previous study of OSA patients undergoing polysomnography; in that study, which was cited in our article, the apnea-hypopnea index was measured at baseline (i.e., during standard polysomnography) and after elevation of the head of the bed, the latter having resulted in a reduction in the apnea-hypopnea index 1 .…”