Accuracy of oximetry with thermistor (oxiflow) for diagnosis of obstructive sleep apnea and hypopnea

• Published in: Sleep (New York, N.Y.) N.Y.), 2000-02, Vol.23 (1), p.61-69
• Main Authors: BALTZAN, M. A, VERSCHELDEN, P, AL-JAHDALI, H, OLHA, A. E, KIMOFF, R. J
• Format: Article
• Language: English
• Subjects: Adult; Aged; Ambulatory Care; Biological and medical sciences; Diagnosis, Computer-Assisted - instrumentation; Equipment Design; Female; Humans; Male; Medical sciences; Middle Aged; Non tumoral diseases; Otorhinolaryngology. Stomatology; Oximetry - instrumentation; Polysomnography - instrumentation; Predictive Value of Tests; Sleep Apnea, Obstructive - diagnosis; Upper respiratory tract, upper alimentary tract, paranasal sinuses, salivary glands: diseases, semeiology
• ISSN: 0161-8105; 1550-9109

To evaluate the diagnostic accuracy for obstructive sleep apnea and hypopnea (OSAH) of the OxiFlow (OF) device which combines oximetry with recording of thermistor airflow. Patients scheduled for overnight diagnostic polysomnography (PSG) were studied with OF either simultaneously during laboratory PSG (L-OF, n=86), at home on a separate night (H-OF, n=66), or both (n=55). 97 patients with suspected OSAH, of whom 40 had OSAH defined as an apnea-hypopnea index (AHI) of more than 15 events per hour of sleep on PSG. NA. The automated respiratory disturbance index (RDI) generated by the OF software considerably underestimated the AHI by PSG for both L-OF and H-OF. Altering the parameters for hypopnea identification by the software did not improve this. Visual inspection of the computerized OF tracings added considerable diagnostic information, but a manual count of RDI during visual review overestimated AHI. For the identification of cases vs. non-cases of OSAH, receiver operating characteristic area-under-the-curve statistics ranged from 0.77-0.90 for L-OF and from 0.71-0.77 for H-OF. Combining automated analysis with subsequent visual inspection of OF tracings yielded an overall sensitivity of 86% and specificity of 74% for the diagnosis of OSAH during H-OF recordings. Analysis of potential technician time saved indicated a benefit from the use of OF. OF has diagnostic utility for the identification of OSAH. However, because of hardware and software limitations, it is unclear whether this device is superior to oximetry alone.