Mechanics of the respiratory system in healthy newborn calves using impulse oscillometry.

Arterial blood gases, acid-base balance and respiratory function tests using impulse oscillometry (IOS) were performed on 40 clinically healthy newborn calves during the first 24 hours of life to evaluate their respiratory adaptation to extrauterine life. Gas exchange efficiency of the lung was significantly improved with time and was accompanied by the correction of the mixed acidosis observed at birth and by significant changes in respiratory mechanics. Major changes were detected within the first 6 hours. The significant decrease in resistance (R) and the increase in reactance (X) with time, demonstrate the improvement in respiratory mechanics of both upper and lower airways, and reflect the increase in lung volume, the improved lung tissue elasticity and/or distribution of the ventilation. Respiratory mechanical, arterial blood gases and acid-base balance data provided in this study describe a successful respiratory adaptation to extrauterine life in healthy newborn calves.