Apnea detection from PPG and SpO2 using Hjörth parameters as inputs. MATLAB code for research and validation of the model. It includes classification models for binary (normal/abnormal respiration segments) and multiclass (normal/apneic/hypopneic respiration segments) decisions.
Cyclic Variation of the Heart Rate Index (CVHRI) is measured for each subject and the correlation with the Apnea-Hypopnea Index (AHI) is computed. CVHRI is defined as the sum of the frequencies of the spectrum peaks between 0 and 0.1 Hz divided by the total number of segments [1].
[1] D. Cajal, E. Gil, P. Laguna, C. Varon, D. Testelmans, B. Buyse, C. Jensen, R. Hoare, R. Bailón, J. Lázaro. "Sleep apnea severity stratification by an FFT-based PPG-derived index", presented at the 12th Conference of the European Study Group on Cardiovascular Oscillations (ESGCO), pp. 1-2. Oct. 2022.