Volume-pressure relationships of lungs and thorax in fetal, newborn, and adult goats

Abstract

The physical properties of the lungs and thorax in kids before and after the onset of respiration and in older goats demonstrate changes with age. The fetal goats' lungs contained a volume of fluid which made them approximately twice as heavy as those of animals which had lived a few hours. The intrapleural pressure in the fetus was atmospheric, and was more negative the larger the goat. The pressure-volume characteristics of the lungs and thorax measured in the paralyzed, anesthetized animals show the thorax of the kid to be more compliant and the lungs of the kid less compliant per gram of lung tissue than in the older animal. Studies on excised lungs from these animals show that the lungs of older animals contain a larger gas volume per unit lung weight at pressures over 5 cm H 2 O than lungs of younger animals. Submitted on July 19, 1961