ECG-derived respiration: Comparison and new measures for respiratory variability

During ECG recording, several methods can be applied to derive a respiratory signal from the ECG (EDR signal). In this paper 4 EDR methods, including ECG filtering, R and RS amplitude based techniques and QRS areas, are examined. Comparison of these methods with a simultaneously recorded respiratory signal lead to the conclusion that the R and RS amplitude based techniques generate the best respiratory signals (respectively MSE = 0.63 and MSE = 0.72) and have the advantage over ECG filtering (MSE = 1.53) and QRS areas (MSE = 2.15) that even sighs can be detected. Based on the respiratory signal, new measures (rMSSD, SDSD, pBB1 and pBB2) that reflect the respiratory variability (RV) are defined. Those RV measures have proven their use by the ability to distinguish between periods of rest and stress during mental stress testing (5 alternating periods of rest and mental stress). Moreover, most RV measures are able to differentiate between the first resting period and the periods following mental stress.