Screening of obstructive sleep apnoea: heart rate spectral analysis of nocturnal pulse oximetric recording

Using heart rate spectral analysis of nocturnal pulse oximetry, we prospect ively evaluated the utility of this methodology in patients clinically susp ected of having obstructive sleep apnoea (OSA). A hundred and ninety-seven outpatients referred with symptoms compatible with the diagnosis of OSA wer e studied. All participants had nocturnal pulse oximetry performed simultan eously with conventional polysomnography, Power density of heart rate obtai ned by nocturnal pulse oximetry was analysed using fast Fourier transformat ion of a Hamming-windowed signal. Recording test results were classified as abnormal (suspicion of OSA) in the presence of a peak in the periodogrann between period boundaries 30-70 sec. A normal test result was defined as th e absence of the 30-70 sec peak in the periodogram. The total area of the p eriodogram (S-TOT), the area enclosed in the periodogram between the period boundaries 30-70 sec (S30-70), the area enclosed in the period boundaries 30-70 sec with respect to the total area of the periodogram (S) and the pea k amplitude 30-70 sec (PA) were measured,The presence of a peak in the peri odogram has a sensitivity of 81.3%, a specificity of 91.5%, a positive pred ictive value of 69.1% and a negative predictive value of 85.1% for OSA diag nosis. The OSA patients were found to have higher values of S-TOT, S30-70, S and PA than the non-OSA patients. Receiver operating characteristics (ROC ) curve was constructed at different thresholds of STOT, S30-70 S and PA. F or a PA threshold of 10(%)(2), heart rate spectral analysis sensitivity for OSA was 58% and specificity was 92%. Furthermore, the positive and negativ e predictive values for diagnosis of OSA were 87 and 72% respectively Apnoe a-hypopnea index (AHI) correlated significantly with S-TOT (r = 0.44; P < 0 .001), S30-70 (r = 0.59; P < 0.001), S (r = 0.58; P < 0.001) and FA (r = 0. 58; P < 0.001). According to our results, heart rate spectral analysis obta ined by nocturnal pulse oximetry and identification of peak in the periodog rann between period boundaries 30-70 sec could be useful as a diagnostic te chnique for OSA patients. (C) 2001 Harcourt Publishers Ltd.