On Obstructions of the Branches of the Pulmonary Artery

OBSTRUCTIONS OF THE PULMONARY ARTERY.163 carefully detailed, are unconnected, and give a very imperfect account of the nature of the disease, and of the circumstances in which it occurs.I trust, therefore, that the following observations will be acceptable to the Society.From the arrangement of the pulmonary arteries, between which there is no anastomosis, except in their capillaries and smallest branches, it results that whenever the flow of blood through the capillaries of any part of a lung is prevented, there must also be a stagnation of the blood in all the branches from which those capillaries are derived; and in these circumstances, the blood coagulates in the vessels, and passes through various changes.Now, these conditions are present in several dis- eases :-First, in pulmonary apoplexy, especially in that form of it in which the blood collects in a de- fined and compact dark mass.At a meeting of the Society two years ago, I stated, what more recent examinations have confirmed, namely, that in all, or in the great majority of these cases, the branches of the pulmonary artery leading to the seat of effu- sion are blocked up by coagula, which present the distinguishing characters of those formed long pre- vious to death.In most cases, (perhaps in all those which depend only on disease of the heart,) the coagula are found in those branches alone in which the circulation is obstructed, but in some instances they extend further, the apoplectic effusion being inconsiderable in comparison with the size and num- M 2 * L. c. p. 17.