Estimation of the aortic pressure waveform from a radial artery pressure waveform via an adaptive transfer function: Feasibility demonstration in swine

We previously proposed a new technique to estimate the physiologically and clinically more relevant central aortic pressure (AP) waveform from a conveniently and safely measured peripheral artery pressure (PAP) waveform distorted by wave reflections. In contrast to conventional generalized transfer function (GTF) techniques, the technique is able to adapt the transfer function relating PAP to AP to the inter-patient and temporal variability of the arterial tree by defining it through a tube model and invoking the fact that aortic flow is negligible during diastole to estimate the unknown model parameters. We conducted feasibility testing of this adaptive transfer function technique here with respect to radial artery pressure (RAP) waveforms, for the first time, as well as femoral artery pressure (FAP) waveforms from four swine instrumented with AP catheters during several hemodynamic conditions. Our results showed that the AP waveforms estimated by the technique from the RAP and FAP waveforms were in superior agreement to the measured AP waveforms (overall respective errors of 4.1 and 4.8 mmHg) than the two unprocessed PAP waveforms (9.1 and 8.1 mmHg) and a previous GTF technique trained on a subset of the same data (5.0 and 5.8 mmHg).