Spectral analysis of arterial blood pressure variability: assessing the accuracy of the Finometer device

In this study we appraised the accuracy of the Finometer in spectral analysis of systolic (SAP) and diastolic (DAP) arterial pressure. In 24 patients the blood pressure signal was simultaneously recorded invasively and by the Finometer and the power of SAP and DAP in the VLF (0.01÷0.04 Hz), LF (0.04÷0.15 Hz), and HF (0.15÷0.45 Hz) bands computed. To investigate the relationship between invasive and Finometer measurements, the percentage error was computed and bivariate spectral analysis performed. The error for SAP analysis, was (%): 139, 76, -32, 75 for respectively VLF, LF, HF and total power; DAP errors were much smaller. SAP variability is greatly enhanced by the Finometer, mainly due to the increase of power in the VLF and LF bands which overrides the reduction in the HF band. Noise and nonlinearities account for < 20% of the Finometer power changes, indicating that the differences are mainly due to amplification or attenuation effects.