Limited value of end-expiratory inferior vena cava diameter to predict fluid responsiveness impact of intra-abdominal pressure.

Purpose: We sought to determine the diagnostic ability of the end-expiratory inferior vena cava diameter (IVC _EE ) to predict fluid responsiveness (FR) and the potential confounding effect of intra-abdominal pressure (IAP).
Methods: In this multicenter study, 540 consecutive ventilated patients with shock of various origins underwent an echocardiographic assessment by experts. The IVC _EE , velocity time integral (VTI) of the left ventricular outflow tract (LVOT) and intra-abdominal pressure (IAP) were measured. Passive leg raising (PLR) was then systematically used to perform a reversible central blood volume expansion. FR was defined by an increase in LVOT VTI ≥ 10% after 1 min of PLR.
Results: Since IVC _EE was not obtained in 117 patients (22%), 423 were studied (septic shock: 56%), 129 of them (30%) having elevated IAP (≥ 12 mmHg) and 172 of them (41%) exhibiting FR. IVC _EE  ≤ 13 mm predicted FR with a specificity of at least 80% in 62 patients (15%), while IVC _EE  ≥ 25 mm predicted the absence of FR with a specificity of at least 80% in 61 patients (14%). In the remaining 300 patients (71%), the intermediate value of IVC _EE did not allow predicting FR. An adjusted relationship between IVC _EE and FR was observed while this relationship was less pronounced in patients with IAP ≥ 12 mmHg.
Conclusions: Measurement of IVC _EE in ventilated patients is moderately feasible and poorly predicts FR, with IAP acting as a confounding factor. IVC _EE might add some value to guide fluid therapy but should not be used alone for fluid prediction purposes.