Passive leg raising and microvascular skin blood flow to predict peripheral tissue perfusion fluid responsiveness

To assess whether skin blood flow (SBF) monitoring combined with passive leg raising (PLR) can predict microvascular fluid responsiveness in septic patients.

Prospective observational study.

Single-center, 18-bed medical ICU in a tertiary university hospital in Paris, France.

Adult patients with sepsis requiring intravenous fluid administration.

Patients underwent a standardized PLR maneuver followed by a 500 mL saline fluid administration. Peripheral SBF was continuously monitored by fingertip laser Doppler flowmetry.

Of 37 patients included, 27 (73%) were classified as fluid responders, defined by a > 15% increase in SBF after volume expansion (ΔSBF-VE). In responders, SBF increased significantly during PLR (ΔSBF-PLR 40% [21-105]), while no significant changes were observed in non-responders. SBF variations induced by PLR (ΔSBF-PLR) strongly predicted fluid responsiveness with an AUROC of 0.95 [0.86-1.00] (P < 0.001). A ΔSBF-PLR threshold of > 6% identified responders with an 96 [80-100] % sensitivity and 90 [59-100] % specificity. Positive predictive value was 96 [80-100] % and negative predictive value was 91 [59-100]. Changes in SBF did not correlate with changes in cardiac output after volume expansion (R² =0.04, P = 0.28).

In septic patients, PLR-induced changes in SBF reliably predict peripheral microvascular responsiveness to a subsequent volume expansion. This simple, non-invasive approach may facilitate personalized fluid strategies aimed at optimizing microvascular tissue perfusion.