High in comparison with low tidal volume ventilation aggravates oxidative stress-induced lung injury

AbstractVentilator settings influence the development and outcome of acute lung injury. This study investigates the influence of low versus high tidal volume (Vt) on oxidative stress-induced lung injury.Isolated rabbit lungs were subjected to one of three ventilation patterns (Vt–positive end-expiratory pressure, PEEP): LVZP (6 ml/kg–0 cm H2O), HVZP (12 ml/kg–0 cm H2O), LV5P (6 ml/kg–5 cm H2O). These ventilation patterns allowed a comparison between low and high Vt without dependence on peak inspiratory pressure (PIP). Infusion of hypochlorite (1000 nmol/min) or buffer (control) was started at t=0 min. Pulmonary artery pressure (PAP), PIP and weight were continuously recorded. Capillary filtration coefficient [Kf,c (10−4 ml s−1 cm H2O−1 g−1)] was gravimetrically determined (−15/30/60/90/120 min).PIP averaged 5.8±0.6/13.9±0.6/13.9±0.4 cm H2O in the LVZP, HVZP and LV5P groups. PIP, Kf,c or PAP did not change in control groups, indicating that none of the ventilation patterns caused lung injury by themselves. Hypochlorite-induced increase in Kf,c but not hypochlorite-induced increase in PAP, was significantly attenuated in the LVZP-/LV5P- versus the HVZP-group (Kf,c,max. 1.0±0.23/1.4±0.40 versus 3.2±1.0*). Experiments with hypochlorite were terminated due to excessive edema (>50 g) at 97±2.2/94.5±4.5 min in the LVZP-/LV5P-group versus 82±3.8* min in the HVZP-group (*: P