Carbon monoxide diffusing capacity in newborn infants

In order to test the role of diffusing capacity in determining the arterial oxygen tension of newborn infants, pulmonary diffusing capacity for carbonmonoxide (DLCO) was measured in 21 healthy infants ranging in weight from 765 to 4,720 g. DLCO infants without respiratory distress correlated well with lung volume (r=0.76, P less than 0.001). A smaller correlation (r = 0.39, P less than 0.01) was obtained between DLCO and arterial oxygen tension. DLCO per unit volume of lung is similar when healthy premature infants, full term infants, and normal adults are compared. The wide range of normal values obtained in resting infants and the lack of correlation with arterial oxygen tensions are similar to observations made in adults.