Optimal Maternal Ventilation During Laparotomy With General Anesthesia in Pregnancy in the Ovine Model

( Anesth Analg . 2025;140(1):175–184. doi: 10.1213/ANE.0000000000006872) General anesthesia is required in pregnant women for various types of surgery, including both obstetric and nonobstetric procedures. During pregnancy, progesterone increases maternal minute ventilation, leading to mild respiratory alkalosis. This change reduces maternal carbon dioxide (partial pressure of carbon dioxide in arterial blood or p a CO 2 levels and alters blood gas values when compared with nonpregnant individuals. Clinical guidelines recommend maintaining maternal p a CO 2 around 30 mm Hg during general anesthesia in pregnancy. However, the impact of this target on fetal outcomes is not well understood. It is known that both high and low p a CO 2 levels can affect fetal health in different ways. High maternal p a CO 2 can increase uterine blood flow and facilitate oxygen release to tissues, however, it may also lead to fetal acidosis. Conversely, low maternal p a CO 2 can enhance fetal CO 2 elimination, however, might reduce uterine blood flow and oxygen delivery to the fetus. Thus, determining the optimal maternal p a CO 2 level during general anesthesia is critical for balancing fetal oxygenation and avoiding adverse effects.