Redistribution of pulmonary blood flow impacts thermodilution-based extravascular lung water measurements in a model of acute lung injury.

Background: Studies using transthoracic thermodilution have demonstrated increased extravascular lung water (EVLW) measurements attributed to progression of edema and flooding during sepsis and acute lung injury. The authors hypothesized that redistribution of pulmonary blood flow can cause increased apparent EVLW secondary to increased perfusion of thermally silent tissue, not increased lung edema.

Methods: Anesthetized, mechanically ventilated canines were instrumented with PiCCO (Pulsion Medical, Munich, Germany) catheters and underwent lung injury by repetitive saline lavage.

Total and regional lung volume changes during high-frequency oscillatory ventilation (HFOV) of the normal lung.

The effect of high-frequency oscillatory ventilation (HFOV) settings on the distribution of lung volume (V(L)) with changes in mean airway pressure (Paw), frequency (f(R)) and tidal volume (V(T)) remains controversial. We used computer tomographic (CT) imaging to quantify the distribution of V(L) during HFOV compared to static continuous positive airway pressure (CPAP). In anesthetized, supine canines, CT imaging of the entire lung was performed during CPAP and HFOV at Paw of 5, 12.