Gaseous Interchange Between Adjacent Lung Lobules

It is desired to make a preliminary report of certain experimental evidence that respiratory and other gases may enter one lobule from another in the lung without resort to known anatomical passageways. This was found in vivo and in vitro in work with dogs. In vitro observations. A single lung lobe, freshly secured, was prepared by dissection at the hilus and isolation of the stem bronchus and origin of the first side branch, with care to avoid damage to the parenchyma. A cannula was tied into the lumen of the branch bronchus. The corresponding lung lobule was then inflated by blowing into the cannula, and immediately air was found to escape from the open stem bronchus. The stem bronchus was now ligated, the blowing continued, and the remainder of the lung became inflated. The pattern of dissemination of the air is depicted in Fig. i. Here an atelectatic lung lobe was employed and serial rontgenographs were made during inflation. The relative density of the atelectatic tissues served to indicate the paths taken by the air. The amount of pressure required to effect this passage of air from the cannulated lobule to the adjacent parts was estimated, as follows: A specimen hitherto unused was placed in an airtight chamber, and the stem bronchus and its first branch were separately connected to the outside with tubes. By gradually withdrawing air from the chamber the lung was expanded to a degree just sufficient to aerate all parts. Now, the tip of one bronchial tube was submerged in water, while a current of air with manometric control was run into the other tube. When the pressure had mounted to I.O cm. H20, there was bubbling from the submerged tube. Repeated trials gave the same minimum value and without regard for variations in the degree of lung expansion, except when complete collapse was allowed. Then, 6.o cm. H20 pressure was required to initiate air passage and 2.0 cm. H20 pressure to maintain it. These two types of experiment have been repeated many times and with the same results.