Unilateral lung lavage: blood flow manipulation by ipsilateral pulmonary artery balloon inflation in dogs

The authors attempted to favorably manipulate the distribution of pulmonary blood flow during unilateral atelectasis and during unilateral lung lavage by nonocclusive inflation of an ipsilateral pulmonary artery catheter balloon (PAB). Six mongrel dogs were anesthetized, intubated with a double-lumen endotracheal tube, and following a thoracotomy, pulmonary artery and left lung blood flows (Qt and QLL/Qt, respectively) were measured electromagnetically; right lung blood flows (QRL/Qt) were derived by difference. A PAB was positioned in the right main pulmonary artery. The experimental sequence consisted of seven steps: 1) both lungs ventilated; 2) ventilation of the left lung (LL vent), right lung (RL) atelectatic, PAB deflated; 3) LL vent, RL atelectatic, PAB inflated; 4) LL vent, RL lavaged, PAB deflated; 5) LL vent, RL lavaged, PAB inflated; 6) LL vent, RL drained, PAB deflated; and 7) LL vent, RL drained, PAB inflated. At each step the shunt fraction (Qs/Qt) was determined. Inflation of the PAB during LL vent and RL atelectatic (step 3) caused QRL/Qt and Qs/Qt to decrease and QLL/Qt and PaO2 to increase significantly (compared to step 2). There were no significant differences in QRL/Qt, QLL/Qt, Qs/Qt, and PaO2 during RL lavage with the PAB deflated (step 4) compared to RL lavage with the PAB inflated (step 5). Inflation of the PAB during RL drainage (step 7) caused QRL/Qt to decreased and QLL/Qt to increase significantly compared to their values during periods of RL drainage with the PAB deflated (step 6). This resulted in a significant increase in PaO2 and decrease in Qs/Qt. These results demonstrate that the distribution of pulmonary blood flow in dogs can be favorably manipulated by nonocclusive ipsilateral PAB inflation and support a trial of use in selected patients during one-lung anesthesia and ventilation.