A Technique for Serial Sampling of Umbilical Artery Blood at Birth

Time of Onset of Effective Ventilation at Birth

“…Their 2-to 5-min values showed a respiratory acidosis and a hypoxia more severe than one would ordinarily expect even in umbilical artery blood at birth [1,3], At 10 min the PO, values were fairly high but a respiratory acidosis was still in evidence, and in fact the PC 02 and pH values did not approxi mate even expected birth values until 20 min of age. Since O liver et al did not report any values between birth and 2-5 min, it cannot be determined whether their infants had an initial improvement in blood gas values, fol lowed by a secondary reversal of trend and so a second period of increasing asphyxia, or whether their 2-to 5-min values did in fact represent the end point of an unbroken trend from normal birth values to more severe asphyxia 2-5 min.…”

“…17 infants were studied by the technique described previously [1], For these infants, the first sample (Cl) was obtained 11-41 sec after birth and the second sample (C2) was obtained 22-59 sec after birth. From 1 to 6 breaths occurred between birth and C l, and from 1 to 6 breaths occurred between Cl and C2.…”

“…A technique for serial sampling of umbilical artery blood at birth was described in a prior report [1], A second study utilizing this technique showed that the first 4-5 breaths appear not to be effective ventilations, and that blood gas values consistently become more asphyxial over the first 20 sec after birth [8], In the present study, serial samples were obtained at a later point in time, such that, for some infants, improvement occurred in the arterial blood gas values from the first to the second sampling. The data reported in the present study suggest that the fifth breath is the approximate point at which there is reversal of the trend toward increasing asphyxia following birth and the beginning of a trend toward improvement in the infant's blood gas values.…”

Changes in Umbilical Artery Blood Gas Values with the Onset of Respiration

“…The technique of serial sampling of umbilical artery blood has been described in another report [1]. Utilizing this technique, serial determinations were carried out in the perinatal period for an additional group of 21 infants.…”

“…Oxygen saturation was determined, rather than Po2, because after analysis of the prior results [1], it appeared that oxygen saturation was more likely than Po2 to show substantial changes over the time interval studied. The reason that only small changes in Po, would be expected is discussed in the prior paper [1]. The pH, Pco.,, and BD were determined using a Radiometer AME-1 micro-blood gas apparatus and the oxygen saturation was determined using an American Optical Company oximeter.…”