Pulmonary diffusing capacity in lambs during the early neonatal period.

A rebreathing method was used to make 53 measurements of pulmonary diffusing capacity (DLco) and functional residual capacity (FRC) in 17 newborn lambs during the first 2 days of life. DLco, FRC, and DLco/FRC all increased in studies made at 24--48 hr of age compared to those at 2--4 hr of age: DLco 0.86 +/- 0.18 to 1.52 +/- 0.09 ml/min/torr; FRC 37 +/- 10 to 60 +/- 8 ml and DLco/FRC 2.52 +/- 0.75 to 2.89 +/- 0.37 ml/min/torr/ml X 10(-2). DLco measured using 0.005% CO in the test gas was not different than that measured using 0.5% CO.