Ramin, 1989a Riley, 1993b Kotaska, 201 Ob Kotaska, 2010e pH 7.28 (0.07) 7.27 (0.069) 7.26 (7.01n-7.39) 7.3 (7.05-7.39) Pco2 (mm Hg) 49.9 (14.2) 50.3(11n.1) 51 (30.9-85.8) 54 (37.5-79.5) HC03 -(mEq/L) 23.1 (2.8) 22.0 (3.6) Base excess (mEq/L) -3.6 (2.8) -2.7 (2.8) pH 7.34 (0.063) 7.31 (7.06-7.44) 7.34 (7.10-7.42) PC02 (mm Hg) 40.7 (7.9) 41 (24.9-70.9) 44 (29.1n-70.2) HC03 -(mEq/L) 21.4 (2.5) Base excess (mEq/L) -2.4 (2) aNewborns of selected women with uncomplicated vaginal deliveries. bNewborns of unselected women with vaginal deliveries.
(Data shown as mean (SO). dOata shown as range with 2.5 or 97.5 percentile. eCesarean delivery-labor not stated.
From Centers for Disease Control and Prevention, 201n2; Watson, 2006.
normal levels, and a base excess occurs when HC03 -values are above normal. Importantly, a mixed respiratory-metabolic acidemia with a large base deicit and a low HC03 -, for example 12 mmollL, is more often associated with a depressed neonate than is a mixed acidemia with a minimal base deficit and a more nearly normal HC03 -level.
The Newborn 61 3 inordinate proportions of neonatal deaths-8 percent, intensive care admissions-39 percent, intubations-14 percent, and seizures-13 percent (Goldaber, 1991). And, in a study from Oxford of more than 51,000 term newborns, the incidence of neonatal encephalopathy in those with a birth pH <7.0 was 3 percent (Yeh, 2012). Even those with who had normalrS-minute Apgar scores but an arterial cord pH values <7.0 had a significantly higher risk of morbidity that included respiratory distress, neonatal intensive care unit admission, and sepsis (Sabol, 2016). The speed of acidemia resolution after birth is associated with outcome (Casey, 2001a).
Acute interruption in placental gas exchange is accompanied by subsequent CO2 retention and respiratory acidemia. The most common antecedent factor is transient umbilical cord compres sion. Generally, respiratory acidemia is not harmful to the fetus (Low, 1994).
he degree to which pH is afected by pC02-the respira tory component of the acidosis-can be calculated. First, the upper normal neonatal pC02 of about 50 mm Hg is subtracted from the cord blood gas pC02 value. Each additional 10 mm