Processing electrocardiograms towards respiratory signals

A report is presented on observations and preliminary experiments pertinent to the deduction of respiratory waveforms from electrocardiographic (EKG) traces by interpolating the values of the direction of cardiac electrical axis. Respiratory waveforms were deducted by considering the electrical axis of either the QRS-complex or the T-wave. The most significant result was obtained when, starting from an EKG trace, the authors were able to plot curves that were very close to the respiration curve obtained from a belt impedancemeter. This result indicates that the objective can be obtained. Other results concern difficulties in reconstruction. Among those are bradicardiac conditions, presence of misestimated samples, presence of rhythm disorders on EKG, and arrhythmias.<>