0467 A Combination Index of Low Frequency Cardio-Pulmonary-Coupling and Oxygen Desaturation has a Strong Correlation with the Apnea Hypopnea Index

Abstract

Introduction: Deriving an AHI from limited measurements enables simple sleep apnea diagnosis. Cardiopulmonary coupling (CPC) is an ECG-based analysis incorporating cyclic variation in heart rate (CVHR) typical of apnea, and ECG-derived respiration, to generate sleep apnea metrics. Elevated Low Frequency Coupling (e-LFC) is a CPC pattern that has been associated with fragmented sleep. Narrow spectral band e-LFC (e-LFC-NB) associates with sustained central apnea, classic periodic breathing, and high loop gain obstructive sleep apnea OSA). Broad spectral band e-LFC (e-LFC-BB) associates with OSA. Methods: We combined e-LFC with oxygen desaturations to generate a SleepImage-AHI (SAHI) index and examined its correlation with the conventional 3%/arousal AHI using polysomnograms in 38 subjects. CPC analysis was done on the ECG from the PSG, generating a narrow-band index (NBI) and broad-band index (BBI). The PSG pulse oximeter trace was processed to calculate the Oxygen Desaturation Index (ODI) defined as events lasting 10 seconds or longer of 3% or more within each CPC LFC periods. The SAHI-Adult = (NBI + ODI), and the SAHI-Pediatric = (BBI + NBI + ODI), per hour of sleep. Pearson coefficient was calculated to estimate correlation between SAHI and 3% AHI, and Bland- Altman (BA) for agreement between the two methods. Results: There were 20 adults age 42-90 (median: 69.5, SD 14.5). There were 18 children age 5-10 years. Females were 52.6%. Pearson coefficient was 0.7649. One adult PSG had short cycle non-hypoxic periodic breathing events without desaturations which were not scored leading to AHI of 13.1 vs. SAHI of 76.2. Removal of this outlier study resulted in a correlation coefficient 0.92. The BA analysis mean difference = -2.28 (CI -6.25 to 1.70) for the whole set and -0.637 (CI -2.87 to 1.59) with the outlier remove, 0.599 (CI -1.23 to 2.43) for the pediatric, -4.87 (CI -12.38 to 2.64) for adults with, and -1.81 (CI -5.94 to 2.32) with the outlier removed. Conclusion: Combining CPC and ODI yields a metric comparable to AHI3%/arousal on PSGs.