Obstructive sleep apnea in a referral population in India.

There are few published studies of obstructive sleep apnea in the Asian subcontinent. The objectives were to describe the syndrome and evaluate the utility of computed tomography (CT) cephalometry in patients found to have obstructive sleep apnea (OSA) by polysomnography. This article reports on a retrospective case series in a referral population. A total of 880 patients (560 males and 320 females) were seen in a referral center in Hyderabad, South India, during the last 7 years. All patients with suspected obstructive sleep apnea were evaluated with 16-channel polysomnogram by overnight sleep study; 600 subjects (68%; 480 males and 120 females) underwent evaluation with CT cephalometry. Mean age was 51.4 +/- 9.5 years (standard deviation). The mean apnea-hypopnea index (AHI) was 27.93 +/- 3.8. The majority of patients had more than 10 AHI; mean percentage of sleep efficiency was 80.62 +/- 15.38; mean percentage of rapid eye movement (REM) sleep was 13.79 +/- 7.89; mean awake arterial oxygen saturation (SaO2) was 90%; mean sleep SaO2 was 84% +/- 4.4%; mean Epworth Sleepiness Scale (ESS) score was 12.3 +/- 2.8. The tongue base area (TBA) was found to be significantly associated with obstructive sleep apnea (OSA), with mean TBA 1032.8 +/- 427 mm2 compared with normal controls at 561.1 +/- 197.6 mm2 (p < 0.001). Mean gonion-gnathion-hyoid angle (Go-Gn-H) was 28.5 +/- 10.5 in OSA and 16 +/- 16.7 in controls; uvula area was 452.5 +/- 145.8 mm2 in OSA and 221.4 +/- 49.85 mm2 in controls; uvula diameter was 13.8 +/- 2.74 mm in OSA and 10.1 +/- 1.72 mm in controls. A total of 704 patients with OSA (80%) were found to be hypertensive, with daytime mean blood pressure of 160/100 +/- 8.5/4.8 mm Hg. Mean duration of reported hypertension was 2 years. The present study showed moderate to severe OSA in a majority of suspected cases referred for polysomnogram. Mild disease was seen in 20.45% of patients (n = 180). On CT cephalometry, the TBA correlated significantly with OSA; hypertension is common in patients with OSA.