Comparison of the effects of high peak (45 cm H
O) positive inspiratory pressure plus high tidal-volume ventilation (HiP-HiV) with the effects of negative inspiratory airway pressure plus high tidal-volume ventilation (iron lung ventilation = LoP-HiV) and of high peak (45 cm H
O) positive inspiratory pressure plus low tidal-volume ventilation (thoracoabdominal strapping = HiP-LoV). Pulmonary edema was assessed by the determination of extravascular lung water content (Qwl/BW) and permeability alterations by the determination of bloodless dry-lung weight (DLW/BW) and of the distribution space in the lungs of 125I-labeled albumin (Alb. Sp.). Dotted lines represent the upper 95 percent confidence limit for control values. Permeability edema occurred in both groups receiving high tidal-volume ventilation. Animals ventilated with a high peak-pressure and a normal tidal volume had no edema. Used with permission. From Dreyfuss et al. .