Lung extravascular volume during venovenous bypass with extracorporeal CO2-removal in dogs

Extracorporeal circulation can cause lung damage, which would be especially counterproductive during extracorporeal gas exchange for the treatment of acute respiratory failure. To test the hypothesis that partial venovenous bypass with extracorporeal CO2-removal combined with low-frequency positive pressure ventilation (ECCO2R-LFPPV) can adversely affect lung fluid balance, extravascular thermal lung volume (ETV) and hemodynamics were assessed before, during and after ECCO2R-LFPPV in normal closed chest dogs. In series I dogs (n = 6) subjected to 10 h of ECCO2R-LFPPV, ETV did not change significantly from control (7.1 ml/kg +/- 0.99 SE) during or after bypass. Gravimetric extravascular lung water and lung histology after bypass were found to be normal. In series II dogs (n = 5), subjected to shorter periods of ECCO2R-LFPPV, ETV also remained unchanged. In contrast to previous reports using sheep, pulmonary arterial hypertension during bypass was not observed. Thus, ECCO2R-LFPPV was not associated with increased lung water, pulmonary hypertension or morphological lung changes under the conditions studied and does not seem to cause lung damage in normal lungs.