For instance, in patients where acute circulatory failure and ARDS coexist, one should limit fluid administration even in cases of preload responsiveness because of the severity of lung injury [21], as assessed by increased lung water and by alteration of pulmonary vascular permeability [88].
In the case of low tidal volume, the small variations in intrathoracic pressure may not be sufficient to trigger significant preload variations, even in cases of preload responsiveness.
The aim of this study was to assess how mean systemic pressure (Psm) and resistance to venous return (Rvr) behave during passive leg raising (PLR) in cases of fluid responsiveness and fluid unresponsiveness.
Second, it may be hypothesized that, in patients with low lung compliance, the decreased transmission of alveolar pressure to the intrathoracic compartment could result in low ΔPP, even in cases of preload responsiveness.
In the present study conducted in patients with acute circulatory failure, we aimed to assess how Psm and Rvr behave during PLR in cases of fluid responsiveness and fluid unresponsiveness.
Estimating the MID is a special case of examining responsiveness to change [ 9] Responsiveness has been defined as the ability to detect changes that are meaningful or clinically important [ 10].
Therefore, after fluid loading and correction of left ventricular collapse the LV EF may not systematically increase even in the case of fluid responsiveness and increased inotropy.
By transferring a consistent amount of venous blood from the legs and the splanchnic compartment toward the intrathoracic compartment, it increases the mean systemic pressure [4], the cardiac preload and consequently cardiac output in the case of preload responsiveness of both ventricles [5].
In case of fluid responsiveness, PLR increased venous return by increasing Psm to a larger extent than CVP.
In the case of fluid responsiveness, PLR increased venous return by increasing Psm to a larger extent than CVP.
