Effect of Maternal Hypocapnia V. Eucapnia on the Foetus During Caesarean Section

Use of umbilical cord blood gas analysis in the assessment of the newborn

“…However the changes in fetal pH associated with brief hyperventilation are small. Maternal hyperventilation lowers fetal P o 2 44 45…”

Hypocapnia

“…However, further lowering of the partial pressure of arterial carbon dioxide -even for a short duration, such as during anesthesia for cesarean section -may have serious adverse affects on the fetus (such as decreased fetal oxygen tension, increased base deficit, lower Apgar scores, and delayed onset of rhythmic neonatal breathing). 98 These effects may be prevented by administering inspired carbon dioxide. 98 Alkalosis associated with hypocapnia decreases placental perfusion, reduces umbilical-vein oxygen tension, 99 and causes reflex spasm of the umbilical vein.…”

“…98 These effects may be prevented by administering inspired carbon dioxide. 98 Alkalosis associated with hypocapnia decreases placental perfusion, reduces umbilical-vein oxygen tension, 99 and causes reflex spasm of the umbilical vein. 45 Because carbon dioxide increases fetal respiration, which may cause increased stretch and distention of the lung, 100 fetal hypocapnia may impair pulmonary maturation.…”

Management of Acute Respiratory Failure in Pregnancy

“…In one study, women undergoing cesarean delivery were subjected to mild hypocapnia (mean 23 mm Hg) or mild hypercapnia (39.3 mm Hg) by controlled ventilation, with or without additional exogenous carbon dioxide. 54 Hypocapnia produced a lower fetal PaO 2 (hypocapnia: 23 mm Hg; hypercapnia: 29 mm Hg), lower Apgar score, and delayed neonatal breathing. Another small study compared three groups of CO 2 level during delivery: (1) ventilated women delivered with mild hypercapnia (mean CO 2 57.6 mm Hg), (2) ventilated women with mild hypocapnia (mean CO 2 26.4 mm Hg), and (3) women managed with a local anesthesia block (mean CO 2 30.1 mm Hg).…”