Comparison of ResMed AutoSet (version 3.03) with polysomnography in the diagnosis of the sleep apnoea/hypopnoea syndrome.

In patients with the sleep apnoea/hypopnoea syndrome (SAHS), accurate and timely diagnostic evaluation and initiation of effective treatment is important. Therefore, an increasing number of limited sleep studies are now performed nowadays diagnosing the SAHS in typical patients. It was the aim of the present study to evaluate the diagnostic accuracy of one such system, the updated ResMed Sullivan AutoSet, against polysomnography. Sixty seven patients underwent full overnight polysomnography and simultaneous data acquisition with the AutoSet. Up to now, the AutoSet was designed for apnoea detection only. The new AutoSet, with software version 3.03, detects apnoeas if ventilation drops to <25%, and apnoeas+hypopnoeas if ventilation drops to <50%, compared with the recent average (100 s), using two independent detectors. A two page report with graphically displayed information on oximetry, snoring and breathing parameters, and an apnoea+hypopnoea index (AHI) and an apnoea index (AI) are provided at the end of each study night. There was a correlation between the AHI assessed by the AutoSet (AHI-AutoSet) and by polysomnography (AHI-PSG; r=0.95). The mean difference between the AHI-AutoSet minus the AHI-PSG was 4.2 (SD 7.2) respiratory events x h(-1) (p<0.001). The AutoSet identified patients with an AHI-PSG >20 events x h(-1) (a level of respiratory disturbance that would warrant consideration for treatment in most centres for sleep disorders), with a sensitivity of 97% and a specificity of 77%. The AutoSet was superior to oximetry alone. As event counting was similar between the two methods, the AHI-AutoSet may provide a reasonable indicator of the respiratory disturbance at night, especially when taking the patients graphic study report into consideration. In conjunction with full clinical information on the patients under investigation, the AutoSet might become a useful device in diagnosing the sleep apnoea/hypopnoea syndrome.