Objective: The present study investigated whether respiratory variation in subclavian vein (SCV) diameters correlates with fluid responsiveness in mechanically ventilated patients. Design: Monocentric, prospective clinical study on fluid responsiveness.
Settings: The Intensive Care Unit at the Geneva University Hospitals.
Patients: Inclusion criteria were as follows: over 18 years of age, sedated, mechanically TM
ventilated, regular cardiac rhythm monitoring with the PiCCO
System, Germany), and requiring a fluid challenge (FC). Patients with active bleeding and/or those expected to survive less than 24 hours were excluded. Patients were recruited for a 1-year period. Responders were defined as patients in whom cardiac output (CO) was increased by ≥15% after FC.
Intervention: A 10-min fluid bolus of 500 mL of 0.9% saline was administered. CO and dynamic parameters (SVV and PPV) measured by PiCCOTM as well as classical hemodynamic parameters were recorded at baseline and after FC. Ultrasound measurements obtained in the subclavian long-axis view were used to calculate the SCVvariability index. A cut-off value for SCV variation for the prediction of fluid responsiveness was determined using receiver operating curve (ROC) analysis.
Measurements and Main Results: Thirteen out of 24 FCs (54%) induced an increase in CO of ≥ 15%. At baseline, the SCV variability (SCVvariability) index was greater in responders than in non-responders (38.7 ± 23 vs. 9.0 ± 5.5; p<0.05).
Diagnostic performance for the SCVvariability index revealed a cut-off value of 14 with a sensitivity of 100% [IC 95% (75 – 100)] and a specificity of 82% [IC 95% (48- 98)] for the prediction of fluid responsiveness. Other parameters, such as SVV and PPV, could not predict fluid responsiveness. The correlation coefficient between CO variation and the SCVvariability index was 0.73 (p<0.001).
Conclusions: The SCVvariability index was a reliable, non-invasive parameter for the prediction of fluid responsiveness at the bedside of mechanically ventilated, critically ill patients in this pilot study.

Sub-clavian vein variations to predict fluid responsiveness