Upper Airway Areas, Volumes and Linear Measurements Determined on CT during Different Phases of Respiration Predict the Presence of Severe Obstructive Sleep Apnea

Publication date: Available online 9 December 2017
Source:Journal of Oral and Maxillofacial Surgery
Author(s): Khaisang Chousangsuntorn, Thongchai Bhongmakapat, Navarat Apirakkittikul, Witaya Sungkarat, Nucharin Supakul, Jiraporn Laothamatas
PurposeThe objective of this study was to analyze the potential of using low-dose, volumetric computed tomography (CT) during different phases of respiration for identifying patients likely to have severe obstructive sleep apnea (OSA) defined as having a respiratory disturbance index (RDI) of more than 30.Patients and MethodsA prospective study was undertaken at the Ramathibodi Hospital. Patients with diagnosed OSA (N = 82) were recruited and separated into two groups: Group 1 (RDI of ≤30, N = 36) and Group 2 (RDI of >30, N = 46). Both groups were scanned by low-dose volumetric CT while they were i) breathing quietly, ii) at the end of inspiration, and iii) at the end of expiration. Values for CT variables were obtained from linear measurements in lateral scout images during quiet breathing, and from upper airway area and volume measurements in axial cross-sections during different phases of respiration. All CT variables were compared between study groups. A logistic regression model was constructed to calculate an individual's likelihood of having an RDI of >30, and the predictive value of each variable and of the final model.ResultsThe minimum cross-sectional area (MCA) measured at the end of inspiration (cut-off point of ≤0.33 cm2) was the most predictive variable for identification of patients likely to have an RDI of >30 [adjusted odds ratio (OR) = 5.50, 95% confidence interval (CI) = 1.76–17.20] with sensitivity 74% and specificity 72%, followed by the MCA measured at the end of expiration (cut-off point of ≤0.21 cm2) [adjusted OR = 3.28, 95% CI = 1.05–10.24] with sensitivity 70% and specificity 68%.ConclusionCT scanning at the ends of both inspiration and expiration helped identify patients with RDI of >30 based on measurement of MCA. Low-dose volumetric CT can be a useful tool to help the clinician rapidly identify patients with severe OSA and decide upon the urgency to obtain a full-night PSG study and to start treatment.



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