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

T. C. Corbridge*, L. D H Wood, G. P. Crawford, M. J. Chudoba, J. Yanos, J. I. Sznajder

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

243 Scopus citations

Abstract

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 ventilation 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-spired 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 < 0.05). Venous admixture (Qva/Qt) was similarly greater in the large VT-low PEEP group (49.8 versus 23.5%) (p < 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). We speculate that in acute lung injury, PEEP protects against surfactant depletion and that large VT-low PEEP augments transfer of fluid from vessels to alveoli and thereby increase edema.

Original languageEnglish (US)
Pages (from-to)311-315
Number of pages5
JournalAmerican Review of Respiratory Disease
Volume142
Issue number2
DOIs
StatePublished - 1990

ASJC Scopus subject areas

  • Pulmonary and Respiratory Medicine

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