Effects of Different Oxygen Concentrations During General Anaesthesia for Elective Caesarean Section

Improved oxygen delivery to the fetus during cesarean section under sevoflurane anesthesia with 100% oxygen

“…The dialed 1.7% sevoflurane anesthesia with 100% oxygen (group G2) denoted higher PuvO 2 , PuaO 2 , and SuaO 2 than either spinal anesthesia or sevoflurane-nitrous oxide anesthesia (groups SP and G1). There was no ceiling in either PuvO 2 and PuaO 2 above PaO 2 of 300 mmHg, as described by Marx and Mateo [6]. However, in epidural anesthesia for elective cesarean section [14], an inspired oxygen concentration of 100% resulted in a slightly higher PuvO2 (47 mmHg) than the 43 Ϯ 9 mmHg with our sevoflurane anesthesia with 100% oxygen.…”

“…Such light anesthesia may accompany sympathetic stimulation, which induces uterine contraction and impairment of uteroplacental blood flow. Under the circumstances, an increase in maternal inspired oxygen concentration (F I o 2 above 0.5-0.6) or in Pao 2 above 300 mmHg failed to produce a corresponding increase in the umbilical venous partial pressure of oxygen (Puvo 2 ) [6]. Recently, the use of 100% oxygen supplemented with halothane, enflurane, or isoflurane at a delivered concentration of 1.5 MAC, reduced to 1 MAC after 5 min, was shown to result in higher PuvO 2 and improved fetal oxygen delivery [7].…”

Supplemental maternal oxygen therapy during caesarean section under epidural anaesthesia: a comparison of nasal prongs and facemask

“…Despite these adaptive changes, fetal oxygen reserves are quite limited at birth although clinically important increases may be registered by providing the mother with increased FIO2 . 2 The optimal level of fetal oxygen action before delivery during normal Caesarean section is not known. Increased fetal oxygen content may act as a reservoir permitting the fetus to withstand better the reduced placental perfusion that might result from aortocaval compression, decreased maternal blood pressure following induction of an epidural block or the decrease in uterine blood flow following uterine incision at Caesarean section.…”

Oxygen at Caesarean section: too much of a good thing?

“…She found not only higher umbilical venous and arterial oxygen content in the groups with high inspired oxygen concentration, but also more vigorous neonates, as determined by the mean time to sustained respiration, as well as Apgar scores. 14 However, Dr Marx's work was largely performed in elective cases under less stringent experimental conditions than those expected of today's clinical trials. Her work was neither randomised nor blinded, and while her results were interesting and certainly relevant, obstetric anaesthesia practice has changed somewhat since her time, with general anaesthesia now globally far less common for elective cases.…”