Predicting fluid responsiveness in patients with spontaneous breathing.

Changes in pulse pressure during passive leg raising. 3. Effect of norepinephrine on pulse pressure

To evaluate whether the changes in arterial pulse pressure (PP) and/or pulse pressure variation (PPV) during passive leg raising (PLR) can be used to evaluate preload responsiveness in patients with spontaneous breathing activity.

Patients ventilated with pressure support mode or totally spontaneously breathing were prospectively included. The values of PP and PPV were recorded before and at the end of PLR. The changes in cardiac index (CI) or the velocity-time integral (VTI) of the left ventricular outflow tract during PLR were tracked by the pulse contour analysis or transthoracic echocardiography. Patients exhibiting an increase in CI ≥ 10% or VTI ≥ 12% during PLR were defined as preload responders.

Among 33 patients included, 28 (80%) received norepinephrine and 14 were preload responders. The increase in PP > 2 mmHg in absolute value (4% in percentage) during PLR (PLRPP) predicted preload responsiveness with an area under the receiver operating characteristic (AUROC) of 0.76 ± 0.09 (p = 0.003 vs. AUROC of 0.5). The changes in PPV during PLR, however, failed to predict preload responsiveness (p = 0.82 vs. AUROC of 0.5).

In patients with full spontaneous breathing activity, PLR-induced changes in PP had a fair ability to assess preload responsiveness even when norepinephrine was administered.

Registration number:ClinicalTrials.gov (NCT04369027).

Pulse pressure

Fluid responsiveness

Heart-lung interaction

Area under the receiver operating characteristic

Compliance of the respiratory system

Fraction of inspired oxygen

Intra-abdominal pressure

Pulse pressure variation

Receiver operating characteristic

Transthoracic echocardiography

Velocity-time integral

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