Feasibility of a beat-by-beat finger photoplethysmograph device for estimating central (aortic) blood pressure waveform characteristics.

Abstract

Central blood pressure can be estimated non-invasively using radial applanation tonometry. However, the stability and accuracy of applanation tonometry signals is operator-dependent. We examined the concordance between finger and radial artery pressure waveforms captured using an automated, beat-by-beat, photoplethysmograph device (Finometer PRO) and radial applanation tonometry respectively, to estimate central pressure waveform characteristics including systolic (SP), diastolic (DP), augmented (AP), reservoir (RP), and excess (XSP) pressure at rest and during a period of elevated and sustained arterial blood pressure. The central pressure waveform characteristics were estimated from finger artery pressure waveforms captured by the Finometer, and were compared to those derived from radial artery pressure waveforms captured using applanation tonometry at baseline (Rest) and during a brief period of circulatory occlusion (OCC) immediately following an isometric handgrip exercise challenge (performed at 40% maximal voluntary contraction) in 24 healthy men (25 ± 5 years). Central pressure waveform parameters derived from the Finometer device were not different to those estimated from radial applanation tonometry: SP (Rest: 3 ± 2; OCC: 4 ± 2 mmHg), DP (Rest: 1 ± 1; OCC 1 ± 2 mmHg), AP (Rest:2 ± 3; OCC: 3 ± 3 mmHg), RP (Rest: 3 ± 4; OCC: 3 ± 5 mmHg), and XSP (Rest: 2 ± 2; OCC: 2 ± 3 mmHg) (all p > 0.05). Furthermore, intra-class correlation coefficients between methods were uniformly high for the estimated change from Rest-to-OCC in all parameters: SP (r = 0.97), DP (r = 0.96), AP (r = 0.94), RP (r = 0.95), and XSP (Rest: r = 0.98) (all p < 0.01). These findings demonstrate that the Finometer device may serve as an alternative automated device to radial applanation tonometry for capturing peripheral pressure waveforms that allow similar estimation of central pressure waveform characteristics.