Supplementary Oxygen for Emergency C-Section Under Regional Anaesthesia
Background: Controversy still exists if the administration of supplementary oxygen to patients having emergency Caesarean section (CS) under regional anaesthesia is beneficial or potentially harmful. Therefore, in a prospective double-blinded study, we randomized patients having emergency CS under regional anaesthesia to receive either air or 60% oxygen until delivery and compared the effects on fetal oxygenation and lipid-peroxidation in the mother and baby.
Methods: We recruited 131 women having emergency CS under regional anaesthesia. Either 21% (air group) or 60% oxygen (oxygen group) was administered using a Venturi-type facemask until delivery. We compared the oxygen exposure duration, umbilical arterial (UA) and venous (UV) blood gases and oxygen content, and plasma concentration of 8-isoprostane. Subanalysis was performed according to whether or not fetal compromise was considered present.
Results: Data from 125 patients were analysed. For the oxygen group vs the air group, there were greater values for UA PO2 [mean 2.2 (SD 0.5) vs 1.9 (0.6) kPa, P=0.01], UA O2 content [6.6 (2.5) vs 4.9 (2.8) ml dl, P=0.006], UV PO2 [3.8 (0.8) vs 3.2 (0.8) kPa, P<0.0001], and UV O2 content [12.9 (3.5) vs 10.4 (3.8) ml dl, P=0.001]. There was no difference between the groups in maternal, UA, or UV 8-isoprostane concentration. Apgar scores and UA pH were similar between the groups. Similar changes were observed regardless of whether fetal compromise was considered present (n=37) or not (n=88).
Conclusions: Breathing 60% oxygen during emergency CS under regional anaesthesia increased fetal oxygenation with no associated increase in lipid-peroxidation in the mother or fetus.
Supplementary oxygen administration during elective Caesarean section (CS) under spinal anaesthesia increases oxygen transfer to the fetus, but causes a concomitant increase in lipid peroxidation in the mother and fetus, implying the potential for both benefit and harm. Moreover, in a subsequent study, we found that when the uterine incision-to-delivery interval was prolonged, administering supplementary oxygen did not improve fetal pH or oxygen indices. These findings question the need to administer supplementary oxygen during elective CS under regional anaesthesia.
Unfortunately, few data are available on the potential benefit and harm of administering oxygen to patients during emergency CS under regional anaesthesia. This is important because during emergency CS, the fetus is more likely to be compromised and administering supplementary oxygen to the mother may alleviate fetal hypoxia. Conversely, it has been suggested that administration of oxygen in this context may be harmful. Breathing supplementary oxygen generates free radicals which attack the lipid cell membrane (lipid peroxidation) to cause tissue damage. Thorp and colleagues reported a higher incidence of fetal acidosis when the mother breathed supplementary oxygen for more than 10 min during vaginal delivery, and Yamada and colleagues found an enhancement of lipid peroxidation in an animal study.
In the light of the above controversy, we designed this prospective stratified randomized double-blinded study in patients having emergency CS performed under regional anaesthesia. We aimed to compare fetal oxygenation and lipid peroxidation when 21% or 60% oxygen was administered to parturients until delivery, in both the presence and the absence of suspected fetal compromise.
Abstract and Introduction
Abstract
Background: Controversy still exists if the administration of supplementary oxygen to patients having emergency Caesarean section (CS) under regional anaesthesia is beneficial or potentially harmful. Therefore, in a prospective double-blinded study, we randomized patients having emergency CS under regional anaesthesia to receive either air or 60% oxygen until delivery and compared the effects on fetal oxygenation and lipid-peroxidation in the mother and baby.
Methods: We recruited 131 women having emergency CS under regional anaesthesia. Either 21% (air group) or 60% oxygen (oxygen group) was administered using a Venturi-type facemask until delivery. We compared the oxygen exposure duration, umbilical arterial (UA) and venous (UV) blood gases and oxygen content, and plasma concentration of 8-isoprostane. Subanalysis was performed according to whether or not fetal compromise was considered present.
Results: Data from 125 patients were analysed. For the oxygen group vs the air group, there were greater values for UA PO2 [mean 2.2 (SD 0.5) vs 1.9 (0.6) kPa, P=0.01], UA O2 content [6.6 (2.5) vs 4.9 (2.8) ml dl, P=0.006], UV PO2 [3.8 (0.8) vs 3.2 (0.8) kPa, P<0.0001], and UV O2 content [12.9 (3.5) vs 10.4 (3.8) ml dl, P=0.001]. There was no difference between the groups in maternal, UA, or UV 8-isoprostane concentration. Apgar scores and UA pH were similar between the groups. Similar changes were observed regardless of whether fetal compromise was considered present (n=37) or not (n=88).
Conclusions: Breathing 60% oxygen during emergency CS under regional anaesthesia increased fetal oxygenation with no associated increase in lipid-peroxidation in the mother or fetus.
Introduction
Supplementary oxygen administration during elective Caesarean section (CS) under spinal anaesthesia increases oxygen transfer to the fetus, but causes a concomitant increase in lipid peroxidation in the mother and fetus, implying the potential for both benefit and harm. Moreover, in a subsequent study, we found that when the uterine incision-to-delivery interval was prolonged, administering supplementary oxygen did not improve fetal pH or oxygen indices. These findings question the need to administer supplementary oxygen during elective CS under regional anaesthesia.
Unfortunately, few data are available on the potential benefit and harm of administering oxygen to patients during emergency CS under regional anaesthesia. This is important because during emergency CS, the fetus is more likely to be compromised and administering supplementary oxygen to the mother may alleviate fetal hypoxia. Conversely, it has been suggested that administration of oxygen in this context may be harmful. Breathing supplementary oxygen generates free radicals which attack the lipid cell membrane (lipid peroxidation) to cause tissue damage. Thorp and colleagues reported a higher incidence of fetal acidosis when the mother breathed supplementary oxygen for more than 10 min during vaginal delivery, and Yamada and colleagues found an enhancement of lipid peroxidation in an animal study.
In the light of the above controversy, we designed this prospective stratified randomized double-blinded study in patients having emergency CS performed under regional anaesthesia. We aimed to compare fetal oxygenation and lipid peroxidation when 21% or 60% oxygen was administered to parturients until delivery, in both the presence and the absence of suspected fetal compromise.
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