The respiratory variation in inferior vena cava diameter as a guide to fluid therapy.

Abstract

To investigate whether the respiratory variation in inferior vena cava diameter (DeltaD(IVC)) could be related to fluid responsiveness in mechanically ventilated patients. Prospective clinical study. Medical ICU of a non-university hospital. Mechanically ventilated patients with septic shock (n=39). Volume loading with 8 mL/kg of 6% hydroxyethylstarch over 20 min. Cardiac output and DeltaD(IVC) were assessed by echography before and immediately after the standardized volume load. Volume loading induced an increase in cardiac output from 5.7+/-2.0 to 6.4+/-1.9 L/min (P<0.001) and a decrease in DeltaD(IVC) from 13.8+/-13.6 vs 5.2+/-5.8% (P<0.001). Sixteen patients responded to volume loading by an increase in cardiac output > or =15% (responders). Before volume loading, the DeltaD(IVC) was greater in responders than in non-responders (25+/-15 vs 6+/-4%, P<0.001), closely correlated with the increase in cardiac output (r=0.82, P<0.001), and a 12% DeltaD(IVC) cut-off value allowed identification of responders with positive and negative predictive values of 93% and 92%, respectively. Analysis of DeltaD(IVC) is a simple and non-invasive method to detect fluid responsiveness in mechanically ventilated patients with septic shock.