SLEEP-DISORDERED BREATHING Predictive value of automated oxygen saturation analysis for the diagnosis and treatment of obstructive sleep apnoea in a home-based setting

Background: A portable monitor for the automated analysis of episodic nocturnal oxygen saturation or SpO2 (the Remmers Sleep Recorder, RSR) has been proposed for the diagnosis of obstructive sleep apnoeahypopnoea (OSAH). A study was undertaken to compare the diagnostic performance of automated analysis with the manual scoring of polygraphic data by a more comprehensive respiratory monitor (the Suzanne recorder) used simultaneously in their intended home environment. Methods: The respiratory disturbance indexes of the two monitors were compared in 94 consecutive adult patients suspected of having OSAH and who were deemed eligible for home-based investigation. Results: The RSR overestimated the number of respiratory events associated with a >4% fall in SpO2 by 13% (p,0.005) but underestimated the number of apnoeas and hypopnoeas defined on the basis of respiratory variables alone or their association with a >4% fall in SpO2 or autonomic arousals by 38–48% (p,0.0001). In addition to these significant biases, the limits of agreement in all instances were wide, indicating a poor concurrence between the two monitors. Conclusion: The automated analysis of SpO2 with the RSR cannot be substituted for the manual scoring of polygraphic data with the more comprehensive respiratory monitor in the diagnosis of OSAH in an ambulatory home-based setting.