Objective: To study respiratory arousals with and without obstructive sleep apnoea (OSA) in the same patient.
Design: Cross-sectional study, tertiary hospital based.
Duration: One year (2007 to 2008)
Observation and results: The study included 100 patients with suspected SDB who underwent split night sleep study. We came up with diagnosis in 97 cases. With calculation of arousal index with & without apnoea/hypopnoea, we were able to divide patients into OSA, combined (OSA+UARS) & Upper Airway Resistance Syndrome (UARS) groups. The outcome of study was as follows- 74 cases of OSA, 12 cases of combined(OSA+UARS), 5 cases of UARS, 3 cases of PLM, 3 cases of OSA+PLM and 3 normal studies. OSA was found to be most common SDB among men (83.1%) in age group 40-70 yrs with sedentary lifestyle and it is strongly associated with weight & BMI. UARS patients were non-obese with active lifestyle and had low threshold for arousals with prolonged nocturnal awakenings and SpO2 >91 % throughout study period.
Conclusions: UARS is not a distinct syndrome. It is merely a part of the disease spectrum of OSAHS. There exists a group that has characteristics of both OSA & UARS. The spectrum of disease is Primary snorers(PS)à UARS à combined (OSA+UARS) à OSA à OSAHS. UARS patients were mostly non-obese with active life style as compared to OSA patients. Also they displayed poor sleep efficiency with more prolonged awakenings compared to OSA patients.
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