Mechanical Ventilation Redistributes Blood to Poorly Ventilated Areas in Experimental Lung Injury*

Objectives: Determine the intra-tidal regional gas and blood volume distributions at different levels of atelectasis in experimental lung injury. Test the hypotheses that pulmonary aeration and blood volume matching is reduced during inspiration in the setting of minimal tidal recruitment/derecruitment and that this mismatching is an important determinant of hypoxemia. Design: Preclinical study. Setting: Research laboratory. Subjects: Seven anesthetized pigs 28.7 kg (sd, 2.1 kg). Interventions: All animals received a saline-lavage surfactant depletion lung injury model. Positive end-expiratory pressure was varied between 0 and 20 cm H2O to induce different levels of atelectasis. Measurements and Main Results: Dynamic dual-energy CT images of a juxtadiaphragmatic slice were obtained, gas and blood volume fractions within three gravitational regions calculated and normalized to lung tissue mass (normalized gas volume and normalized blood volume, respectively). Ventilatory conditions were grouped based upon the fractional atelectatic mass in expiration (
Source: Critical Care Medicine - Category: Emergency Medicine Tags: Online Clinical Investigations Source Type: research