Factors affecting bronchial collateral flow in the dog

Abstract

A preparation is described in which the pulmonary and systemic circulations were perfused separately. The only connection between the two circulations was by way of the bronchial collateral vessels. The volume of collateral flow could be measured by recording the rise and fall in the pulmonary drainage reservoir. A ‘forward’ bronchial collateral flow and a ‘reverse’ bronchial collateral flow is described and their existence has been confirmed by radioactive iodinated serum albumin studies. Increases in systemic arterial and venous pressures have been demonstrated to cause an increase in bronchial collateral flow. Independent increases of pulmonary arterial and left atrial pressures resulted in a decrease in bronchial collateral flow, and at suitable pressures a reversal of flow was demonstrable. The data suggest the presence of two bronchial circulations with drainage into the pulmonary arterial and venous systems separately.