Central blood pressure estimation from radial artery in septic shock

Pulse Pressure (PP) increases progressively from the central arteries to the peripheral arteries, this well-established hemodynamic phenomenon is called pulse pressure amplification (PPA). Acute critically ill patients may be subject to profound alterations of cardiac and arterial properties. However, blood pressure (BP) is commonly monitored from one peripheral catheter only. The estimation of a central pressure is pivotal to investigate the PPA and thus to track changes in pulse wave propagation and to identify vascular dysfunctions. We analyzed the data from an animal experiment of polymicrobial septic shock to verify if the estimate of central BP from the radial artery BP waveform only permits the identification of the septic-induced alterations in pulse wave transmission. The method consists of an adaptive transfer function based on a model of wave transmission and reflection, and characterized by two parameters, the reflection coefficient Γ and the time delay T_d. The average root mean square error (RMSE) was assessed at each experimental time point, baseline: 3.5 (3.2, 3.9) mmHg, after septic shock development: 5.0 (3.6, 8.0) mmHg, after resuscitation: 12.3 (8.3, 16.7) mmHg, showing a good level of agreement with the measured waveforms.