Publications

Abstract : Background: A full polysomnography (PSG) is the gold standard for diagnosis of obstructive sleep apnea(OSA) and provides comprehensive data on the sleep stages, efficiency, apnea, hypopnea events, and overnight oximetry during supervised overnight sleep study.Aims: Overnight desaturation index (ODI) is a surrogate marker for diagnosis of OSA and can be easily recorded using portable standalone overnight oximetry devices which are considerably inexpensive when compared to the full PSG. There is limited data on comparisons between AHI amp; ODI. There is a need to find out if ODI is a reliable measure when compared to the AHI, to guide its use for first line screening in patients who attend the sleep service.Methods: The study was conducted in a tertiary care university hospital in South India. 250 consecutive patients who underwent 22-channel full PSG were included. All subjects were included after full clinical evaluation in a dedicated sleep clinic. Demographic data including comorbidities, AHI and ODI were compared.Results: Fifty four%(n=135)of subjects were obese with a mean AHI of 35.8 and 46%(n=115) were non obese with an AHI of 26.95 respectively. Underlying asthma was identified in 19.6%(n=49) and they had statistically higher AHI when compared to non asthmatics ( 42.1 vs 29.2, p0.005). There was a linear significant correlation between AHI amp; ODI (r 0.83, plt;0.001) and agreement between the two as determined by single measure intra class coefficient(ICC) 0.81(0.76-0.85, plt;0.001)Conclusion: Overnight oximetry based surrogates (ODI) have the potential for use as reliable first line screening tool in OSA