The effects of continuous positive pressure ventilation on pulmonary oedema, gas exchange and lung mechanics.

The effect of continuous positive pressure ventilation was studied in 23 dogs in whom pulmonary oedema was induced by rapid intravenous infusion of dextran 40. CPPV slowed but did not prevent the formation of oedema. CPPV prevented or reversed the formation of liver-like areas in the dependent lobes, maintaining the oedematous lung compliant and aerated. This led to a reduction of shunt and an increase in PaO2. The use of CPPV decreased cardiac output and body oxygen consumption. Mixed venous oxygen tension was higher in dogs ventilated by CPPV and these dogs tolerated fulminant frothy oedema without distress.