Metabolic effects of obstetric regional analgesia and of asphyxia in the newborn infant during the first two hours after birth. III. Adjustment of arterial blood gases and acid-base balance.

Effects of obstetric regional analgesia and of asphyxia on the arterial blood gases and acid-base balance in the first two hours after birth were investigated in 85 newborn infants divided into a control group, an asphyxia group and a continuous epidural, an intermittent epidural and a paracervical + pudendal block group. Lidocaine was the drug used in the analgesia groups. In the asphyxia group the metabolic acidosis decreased and pH was normalized to the level of the control group between 10 and 30 min after birth. During this period in the asphyxia group PaO2 was higher than and PaCO2 similar to the corresponding control values. Compared with the control group, in the regional analgesia groups the metabolic acidosis tended to be less extensive and PaO2 higher, whereas PaCO2 was similar. A lower packed red cell volume in the asphyxia and in the regional analgesia groups, probably due to differences in placental transfusion, may have had influence on the results. Within the regional analgesia groups infants with hyperglycemia showed signs of an increased metabolic acidosis while infants with hypoglycemia had low base deficit and lactate values supporting the assumption that neonatal blood glucose concentration may reflect perinatal distress.