[Polycythemia in the newborn. III: blood volume in asphyxia and meconium].

Several authors had reported high blood volumes (BV) and Low placental residual blood volumes (PRBV) in hypoxic human newborns, and also in asphyxiated experimentally animals. Those findings could be explained by and exaggerated intrauterine placental transfusion, ante or intrapartum. The authors had observed high cord blood and 24-48 hs. hematocrits in meconium-stained amniotic fluid (MSAF) and/or low 1 minute Apgar score newborns (Nb), despite early cord clamping. Sometimes, by delaying cord clamping up to 1 minute, those hematocrits had a tendency to decrease, instead of increasing. In view of that, it was decided to measure BV in a small group of similar type of Nb's with Evans blue (T-1824) and to practice in some of them a delayed cord clamping, but elevating the infant above the introitus (DECC). The BV values obtained were a little higher than the ones from the literature, being the most elevated in Nb's with MSAF and the lowest from cesarean. Also, the early cord clamping babies had higher BV than the DECC. All the MSAF Nb's had low plasmatic BV. BV was positively related to Birth Weight and the Hematocrit, and inversely to the Apgar score and the cord blood pH. Unexpectedly, delayed cord clamping was only slightly related to Red Cell BV, not to BV. MSAF constitutes 10% of all deliveries and delayed cord clamping has to be re-evaluated, because it offers a good chance for those babies of developing a normal BV or Hct's.