Dynamics of arterial pressure components in a sheep model of hemorrhage

There is a need for accurate monitors that can track blood loss and report a patient's current physiological response. We explored phase coherence between components of the arterial blood pressure waveform for this purpose. Adult conscious sheep underwent 25 mL/kg_body-Weight, hemorrhages over 15 minutes (14 total hemorrhage experiments) while continuous arterial blood pressure measurements were made. Phase coherence from a single arterial pressure monitor was assessed between all combinations of the pulse-pulse interval, systolic blood pressure, and pulse pressure sequences as a measure of the synchronization between the component dynamics. Phase coherence measures were compared during baseline, the peak compensatory response and a decompensation phase. Phase coherence in the range of 0.06-0. 15 Hz between the pulse-pulse interval and systolic blood pressure sequences as well as the systolic blood pressure and pulse pressure sequences was elevated during the peak compensation period. Analytical techniques to assess the relationship between signals recorded during hemorrhage can be explored for their potential predictive capabilities.