Detection of upper airway resistance syndrome using a nasal cannula/pressure transducer

Study objectives: To determine the diagnostic utility of a nasal cannula/pressure transducer (NC), in comparison to thermistor (TH), during routine, clinical nocturnal polysomnography (NPSG), Design: We analyzed the respiratory arousal index (RAI) using TH (RAI-TH) or NC (RAI-NC) in patients with suspected sleep-disordered breathing (SDB), Setting: Sleep disorders center of a university-affiliated teaching hospital. Patients: Fifty consecutive, nonselected patients referred for evaluation of suspected SDB. Measurements and results: Twenty patients were found to have obstructive sleep apnea/hypopnea syndrome (OSA), 25 had upper airway resistance syndrome (UARS), and 5 had primary snoring (PS), Mean RAI-NC was greater than the mean RAI-TH by 25%, 302%, and 500% in OSA, UARS and PS, respectively. RAI-NC was greater than or equal to 14 (mean, 25.2) in UARS and < 14 (mean, 9) in PS. Mean RAI-TH was 8.4 in UARS and 1.8 in PS, with significant overlap between the two groups. Conclusions: NC is more sensitive than TH in detecting respiratory events during NPSG and may represent a simple, objective means to identify UARS among patients with a range of SDB.