Extracting clinically relevant information from pulse oximetry traces
Cardiovascular assessment is necessary, yet unafordable for large population groups worlwide. Here we illustrate how signals obtained from standard oximeters can provide reliable estimates for transit time, a measure associated to vascular stiffness, as well as complexity measures derived from Recursive plot analysis. The salient features of our research were: 1) The possibility to use of photoplethysmographic (PPG) signals as a surrogate for transit time estimation; 2)The use of PPG signals for HRV analysis; 3)The possibility to use 2-min PPG recordings for cardiovascular estimation; 4)The proposal of a new vascular age estimator. An automated algorithm for estimating transit time from the PPG waveform yielded a strong association with age (r=0.80). All indices obtained from Recurrent Plot analysis of tachograms with PPG signals exhibited a high correlation with subject´s age. On the basis of the estimated indices a new estimator for cardiovascular age has been introduced, which exhibited a high correlation with age (r=0.97). Thus we concluded that PPG signals do retain information about cardiovascular age. This is evidenced from changes with age of different indices obtained from 2-min duration PPG traces. These result might be relevant for boosting cardiovascular diagnosis in settings with limited resources.
Pulse Oximetry, Heart Rate Variability, Transit Time Estimation, Recurrent Plot Analysis, Cardio Vascular Age.