Functional hemodynamic monitoring

Abstract

Functional hemodynamic monitoring is the assessment of the dynamic interactions of hemodynamic variables in response to a defined perturbation. Recent interest in functional hemodynamic monitoring for the bedside assessment of cardiovascular insufficiency has heightened with the documentation of its accuracy in predicting volume responsiveness using a wide variety of monitoring devices, both invasive and noninvasive, and across multiple patient groups and clinical conditions. However, volume responsiveness, though important, reflects only part of the overall spectrum of functional physiologic variables that can be measured to define the physiologic state and monitor response to therapy.

Keywords: Dynamic tissue O(2) saturation; Functional hemodynamic monitoring; Positive-pressure ventilation; Stroke volume variation.

Copyright © 2015 Elsevier Inc. All rights reserved.

Figures

Figure 1

Stylized display of the raw tissue oxygen saturation (StO2) trand during a vascular occlusion test. The initial vertical line connotes the start of vascular occlusion whereas the second vertical line identified when StO2 starts to decrease. The rate of decrease in StO2 or deoxygenation rate (DeOx) is defined by the mean slope of the initial decrease in StO2 following vascular occlusion (blue arrow). The third vertical line defined the point when the vascular occluder is released and forearm blood flow is resumes. The wash out of deoxygenated blood causing reoxygenation (ReOx) is the second slope of the text (red arrow). Modified from Gomez et al. Intensive Care Med 2008, 34:1600-7.

Figure 2

Stylized display of two different Frank-Starling curves showing the relation between left ventricular (SV) stroke volume and LV end-diastolic volume. If positive pressure ventilation alters LV end-diastolic volume across a range of LV end-diastolic volumes, then LV stroke volume will also vary based on where on the Frank-Starling curve the subject is. Ay low levels of LV end-diastolic volume the LV stroke volume variability, quantified as stroke volume variation (SVV) will be greater than on the flatter portions of the curves. Thus, by assessing SVV for an appropriate degree of LV end-diastolic volume changes, one can reliably define where on the Frank-Starling relationship the patient is predicting subsequent LV stroke volume change sin response to increases in LV end-diastolic volume

Figure 3

A strip chart recording of airway pressure and arterial pressure over time. The ratio of the difference between the maximal (Δ) arterial pulse pressure (diastole to systole)(PPmax) and the minimal arterial pulse pressure (PPmin) to the mean pulse pressure (PPmean) defines pulse pressure variation (PPV).