CORD LACTATE, PH, AND BLOOD-GASES FROM HEALTHY NEONATES

Lactate, pH, pO(2), and pCO(2) were determined in arterial, venous, an d free flowing mixed umbilical cord blood obtained from deliveries of apparently healthy neonates. The goals of this study were to establish reference ranges for lactate and pH against which results in cases of high-risk labor and delivery could be compared, to see how the gases correlated with these values, and to determine whether easily accessib le mixed umbilical cord blood can serve as the sample in lieu of cord arterial or cord venous blood. Arterial and venous cord lactates were 2.98 mmol/1(+/- 1.40) and 2.80 mmol/1(+/- 1.35), respectively, from 85 cords obtained from vaginal and cesarean deliveries. Mixed cord blood lactate, obtained on 48 cords, was 2.72 mmol/1(+/- 1.28) versus 3.14 and 2.97 mmol/1 for the arterial and venous samples from those cords, respectively, and correlated quite well with lactate from the venous s pecimens (r = 0.97). Differences of>0.5 mmol/1 occurred between mixed and arterial cord bloods in 21 patients, and between mixed and venous cord bloods in 6 of the 48 patients, respectively. We conclude that (1 ) less than 2.5% of deliveries of apparently healthy neonates have art erial, venous, or mixed cord lactates greater than or equal to 7.0 mmo l/1 and pH less than or equal to 7.15, (2) neither cord venous pO(2) n or pCO(2) correlate well with cord venous lactate, and (3) readily ava ilable mixed cord blood is a satisfactory specimen for the measurement of venous cord latate.