Comment in:

Am Rev Respir Dis. 1991 May;143(5 Pt 1):1198-200.

Adverse effects of large tidal volume and low PEEP in canine acid aspiration.

Section of Pulmonary and Critical Care Medicine, Michael Reese Hospital and Medical Center, Chicago, Illinois.

When normal lungs are ventilated with large tidal volumes (VT) and end-inspired pressures (Pei), surfactant is depleted and pulmonary edema develops. Both effects are diminished by positive end-expiratory pressure (PEEP). We reasoned that ventilatory with large VT-low PEEP would similarly increase edema following acute lung injury. To test this hypothesis, we ventilated dogs 1 h after hydrochloric acid (HCl) induced pulmonary edema with a large VT (30 ml/kg) and low PEEP (3 cm H2O) (large VT-low PEEP) and compared their results with dogs ventilated with a smaller VT (15 ml/kg) and 12 cm H2O PEEP (small VT-high PEEP). The small VT was the smallest that maintained eucapnia in our preparation; the large VT was chosen to match Pei and end-inspired lung volume. Pulmonary capillary wedge transmural pressure (Ppwtm) was kept at 8 mm Hg in both groups. Five hours after injury, the median lung wet weight to body weight ratio (WW/BW) was 25 g/kg higher in the large VT-low PEEP group than in the small VT-high PEEP group (p less than 0.05). Venous admixture (Qva/Qt) was similarly greater in the large VT-low PEEP group (49.8 versus 23.5%) (p less than 0.05). We conclude that small VT-high PEEP is a better mode of ventilating acute lung injury than large VT-low PEEP because edema accumulation is less and venous admixture is less. These advantages did not result from differences in Pei, end-inspiratory lung volume, or preload (Ppwtm).(ABSTRACT TRUNCATED AT 250 WORDS)

PMID: 2200314 [PubMed - indexed for MEDLINE]