Respiratory rate derived from principal component analysis of single lead electrocardiogram

We used principal component analysis to derive the respiratory rate from single lead ECGs. In this algorithm the respiratory induced beat-to-beat variability of the ECG is described by the coefficients of the principal components. Subjects were asked to breathe at different rates and naturally while respiration and ECG were recorded. Breathing rate, determined by Fourier analysis, was compared for the ECG derived respiration obtained by principal component analysis and the recorded respiratory signal. Across the different breathing patterns the mean absolute differences between reference respiratory rate and ECG respiratory rate were 0.2 breaths per minute (bpm) or less. In all cases the respiratory rate was accurately determined from respiratory surrogates derived from principal component analysis of the single lead ECGs.