Measurement of regional bronchial arterial blood flow and bronchovascular resistance in dogs

Abstract

Little is known about normal variations and control of bronchial blood flow and bronchovascular resistance. We have used the reference-flow technique and 15-microns-diameter microspheres to measure bronchial blood flow under physiological conditions. Dogs (n = 13) were anesthetized and ventilated, and their chests were opened. A ligature was placed loosely around the left main pulmonary artery, and the left atrium was cannulated. In six dogs three sets of microspheres were injected simultaneously into the left atrium, and in another seven dogs the three sets of microspheres were injected sequentially at 0.5-h intervals. Prior to each injection measurements of pulmonary arterial, left atrial, and aortic pressures, cardiac output, and blood gases were made. Five seconds after injection the left main pulmonary artery was transiently occluded to prevent recirculation. After the final injection, dogs were killed, the lungs were removed, and the parenchyma was stripped off the large and small airways of the left lung. Knowing the radioactivity in the trachea, bronchi, parenchyma, and in the reference flow blood and also the aortic and left atrial pressures, we calculated bronchial blood flow (ml X min-1 X g dry lung-1) and bronchovascular resistance (cmH2O X ml-1 X min X 100 g dry lung). Results showed that there were no significant differences between the three measurements of bronchial blood flow when microspheres were injected simultaneously or sequentially. Bronchial blood flow to the left lung was 0.4% of cardiac output; 55% of the total flow went to lung parenchyma and 45% to trachea and bronchi. Expressed as flow/g dry lung the greatest flow was to the airways.

Nimodipine‐induced changes in the distribution of carotid blood flow and cardiac output in pentobarbitone‐anaesthetized pigs

“…In the case of left atrial injection, the lungs receive microspheres via both peripheral AVAs and bronchial arteries; however, the contribution via the latter route appears to be only about 1% (Baile et al, 1982). Thus, even in this case, the values for 'lung blood flow' can be used as an index of peripheral AVA flow (i.e.…”

Airway blood flow and bronchovascular congestion in sheep

“…The radioactivity of the samples was counted and correction made for gamma spectrum overlap, background counts and radioactive decay. Tracheal mucosal and right lung blood flow were calculated, as described previously [16].…”

Circulatory heat sources for canine respiratory heat exchange.

“…We, too, reasoned that although the bronchial circulation is well positioned to influence airway wall temperature (14), the small magnitude ofthis blood supply ( 1% ofthe cardiac output [ 15]) might render its physiological role in affecting airway wall temperature insignificant. In contrast, the relatively large flow of blood (100% of the cardiac output) within the pulmonary arteries, which remain adjacent to the bronchi as they branch, might act as a more effective heat source for airway wall warming.…”