Related Experiment Video
Updated: Jun 11, 2026
Continuous Venous-Arterial Doppler Ultrasound During a Preload Challenge
Published on: January 20, 2023
Pulse Pressure Variation During Passive Leg Raising to Assess Preload Responsiveness: Influence of Inspiratory Effort
Morgan Caplan1, Louis Pradignac1, Zoubir Djerada2
1Unité de Médecine Intensive et Réanimation Polyvalente, CHU Reims, Reims, France.
Objectives:
Passive leg raising (PLR) is reliable to assess preload responsiveness in spontaneously breathing patients, but it requires cardiac output (CO) measurements. Recent studies suggested that a decrease in pulse pressure variation (PPV) during PLR or an increase in pulse pressure (PP) during PLR could assess preload responsiveness, defined by a PLR-induced increase in CO. Our objective was to investigate whether PLR-induced changes in PPV and in PP assess preload responsiveness during pressure support ventilation (PSV).
Design:
Prospective study.
Setting:
Two ICUs of French university hospitals.
Patients:
Critically ill patients receiving PSV and requiring assessment of preload responsiveness.
Interventions:
Hemodynamic and transthoracic echocardiography variables were collected before and within 1 minute of PLR. PLR-induced changes in PPV and PP were calculated as the difference between PPV during PLR and PPV before PLR and the difference between PP during PLR and PP before PLR, respectively. Preload responsiveness was defined as an increase greater than or equal to 12% in the velocity-time integral of the subaortic flow during PLR. The population was subdivided according to the median value of airway occlusion pressure at 100 ms (P0.1), as an estimate of the inspiratory effort.
Measurements And Main Results:
Thirty-four patients were included. Their median Simplified Acute Physiology Score II was 52 (42-65). Fourteen (41%) were defined as preload responders. Unlike baseline PPV and PLR-induced change in PP, PLR-induced change in PPV was associated with preload responsiveness (area under the receiver operating characteristic curve [AUROC], 0.76; p = 0.026; cutoff value, -3%). In patients with lower inspiratory effort (P0.1 < 2.3 cm H2O), PLR-induced change in PPV had a greater ability to assess preload responsiveness (AUROC, 0.90; p = 0.050; cutoff value, -3%) than in patients with higher inspiratory effort (AUROC, 0.61; p = 0.480).
Conclusions:
During PSV, PLR-induced changes in PPV assess preload responsiveness, primarily in patients with lower inspiratory effort reflected by P0.1. This simple test can predict the CO response to fluid administration without requiring direct CO measurement.
Related Concept Videos
01:24Pulmonary Ventilation: Inhalation
Boyle's law becomes particularly pertinent when examining respiratory...
01:17Measurement of Blood Pressure
01:24Pressure Relationships in Thoracic Cavity
Breathing Mechanisms
Both intra-alveolar and intrapleural pressures rely on specific lung properties. The ability to breathe—allowing air to enter the lungs during...
01:21Sites for measuring blood pressure
The Brachial Artery: Primary Site for Blood Pressure Measurement
01:14Ventilatory Modes
There are three ventilatory modes: full support, partial support, and spontaneous. These are described below.
Full Support Modes
Full support modes include controlled mechanical ventilation, continuous mandatory...
01:28Special considerations while measuring blood pressure
Monitoring Both Arms:
Monitoring BP in both arms during the initial assessment is advisable, as the systolic value may differ by five to ten mm Hg between arms. For subsequent BP assessments, use the arm with the higher reading.