Responses of the bronchial veins in a heart-lung-bronchial preparation.

•Almost all previous attempts to study the bronchial circulation have been limited to measurements of blood flow in the bronchial arteries and bronchopulmonary anastomoses. There have been two studies devoted to estimations of blood flow in the bronchial veins of the normal dog. In 1931, Berry and Daly perfused in dogs either the posterior bronchial artery of one lung or the entire aortic segment from which the bronchial arteries originate. Perfusion of the pulmonary artery was omitted temporarily to allow collection of outflow of blood into both atria. In each of four dogs, the allocations of the bronchial arterial blood were as follows: 12, 18, 30, and 39 per cent into the right atrium via the bronchial veins, and the remainder into the left atrium via the bronchopulmonary venous anastomoses. A second series of isolated right-lung preparations perfused simultaneously through the pulmonary artery and bronchial artery revealed that, in three dogs, 18, 20, and 87 per cent of bronchial arterial blood, respectively, drained into the right atrium via the bronchial veins. The considerable variation in distribution of bronchial arterial blood reported in both studies is probably because some of the bronchial arterial blood passes through adjacent medi-