Effects of different ventilatory settings on alveolar and pulmonary microvessel dimensions in pigs

Mechanical ventilation with high tidal volume (TV) or positive end-expiratory pressure (PEEP) may induce lung overinflation and increased pulmonary vascular resistance to flow. In 8 healthy mechanically ventilated pigs, we evaluated whether incident dark field (IDF) vital microscopy, applied through a small thoracotomy, could be used to evaluate changes in alveolar and pulmonary microvessel dimensions under different ventilator settings. High TV (12 ml/kg) increased alveolar diameters (from 99 ± 13 to 114 ± 6 μm, p