Anesthesiology
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Pulmonary capillary blood volume is a major determinant of lung gas transport efficiency, and also potentially related to ventilator-induced lung injury. Yet, knowledge on how lung expansion influences pulmonary blood volume in injured lungs is scant. We hypothesize that lung expansion produced by positive end-expiratory pressure (PEEP) modulates the global and regional spatial distribution of pulmonary blood volume. ⋯ During low-volume mechanical ventilation and systemic endotoxemia, lung blood volume is markedly heterogeneously distributed, and modulated by PEEP. Nondependent regions are susceptible to low blood volume and capillary closure. Recruitment of pulmonary vascular blood volume with gas volume is nonlinear, limited at intermediate PEEP indicating its advantage to spatial distribution of blood volume.