Controlled sodium bicarbonate infusion and maternal acid--base balance during labor.

The effects of a controlled sodium bicarbonate (S.B.) infusion on the acid-base balance of primiparas in normal labor and delivery were studied and compared to a similar control group of primiparas without S.B. infusion. Beginning at 6 cm cervical dilatation. 2mEq of S.B./kg of total body weight were infused to patients in the study until full cervical dilatation. The dosage given to this group emerged from a study of base deficit dynamics and space distribution of S.B. in a control group of patients during labor and delivery. Significant variations in pH, base excess, and plasma bicarbonate were observed, beginning 44 +/- 19 minutes after the S.B. infusion. These variations in acid-base parameters persisted for 10 minutes following delivery. While no adverse effects were observed in our patients, this experimental design represents a preliminary approach toward correcting deleterious fetal acid-base variations during labor and delivery.