[Right-to-left shunt in the 1st month of life].

Pre- and post-ductal paO2-values of 116 newborn babies were measured under hyperoxic conditions (FiO2 = 1.0). Total and ductal right-to-left shunts were calculated according to Berggren (1942) and Gersony et al. (1972), respectively. Total shunt volumes amount to 17.4 +/- 5.9 (9--28)% of the aortic minute output in healthy term newborn babies, to 25.0 +/- 5.3 (19--36)% in healthy pre-term newborns and to 13.5 +/- 4.7 (4--19)% on the first day of life in healthy newborn babies from 4. to 28. day of life emphasising the significance of the decline of the arterial oxygen content during the neonatal adaptation period. This is still more evident in patients with disturbed adaptation such as asphyctic mature (28.0 +/- 7.5 (16--45)%) or hypoxic pre-term newborn babies (31.4 +/- 12 0 (12--56)%). As to be expected, the largest total shunt (up to 80% of aortic minute output) is found in newborn babies suffering from severe cyanotic cardiopathies, especially transposition of the great arteries. The incidence of a detectable ductal right-to-left shunt is low both in healthy and asphyctic infants.