Please click here to obtain permission to reproduce this image.
Click on image to view larger version.
Figure 4 Relationship between beat-to-beat single-beat Mw (SBMw) (top panel) maximum power divided by the square of the end-diastolic volume (PWRmax/EDV2) (middle panel) or single-beat elastance (SBEes) (bottom panel) and end-diastolic volume during the same vena caval occlusion runs performed before (control) and during aortic constriction. End-diastolic volumes are normalized to the value of the first steady-state beat recorded. Values of the three single-beat indexes are normalized to the control steady-state value. Single-beat Mw estimates are insensitive to both preload and afterload. PWRmax/EDV2 is significantly preload sensitive ( p < 0.05) but is significantly afterload sensitive only for EDVs less than 65% of baseline (*p < 0.05). Single-beat Ees is highly variable from beat to beat.
|
