Regulation of Regional Perfusion Distribution in the Lungs. Experimental Model and Effect of Alveolar Pressure

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Abstract
An experimental model for studying changes in regional perfusion distribution in the lungs of a dog was described. The right upper lobe was separated in vivo from the rest of the lungs by a balloon catheter and gas exchange of the lobe was artificially done asynchronously with the rest of the lungs by using a gas at a prescheduled alveolar pressure. 99mTc-albumin microsphere was the agent of choice for multiple sequential studies in 1 dog. Alveolar gas composition reached a plateau after the 4th inflation of the right upper lobe. The effect of alveolar pressure on regional perfusion distribution was studied by using N and air as exchange gases. Perfusion distribution in the right upper lobe was the least at the maximal alveolar pressure of 14-19 cm H2O, while it was the greatest at the tidal maximal alveolar pressure of 1 to -1 cm H2O with either gas. Alveolar hyperinflation in a localized lung region due to the increase in regional alveolar pressure reduced regional perfusion distribution.