Effects of high-concentration oxygen inhalation during caesarean section with spinal anesthesia on lipid peroxidation, oxidant and antioxidant systems

Inhalation of O2 is performed routinely in order to prevent maternal desaturation and optimize fetal oxygenation during caesarean section with regional anesthesia. Inhalation of high-concentration O2 aims to improve fetal oxygenation but it may alse cause an increase at free radical activity and lipid peroxydation at both mother and baby.Findings from few number of studies exhibiting benefits and detriments of maternal oxygen application during elective caesarean section with regional anesthesia question necessity of additional O2 application during elective caesarean section under regional anesthesia.The aim of this study is to investigate how high-concentration O2 application during elective caesarean section with spinal anesthesia affects maternal and neonatal lipid peroxydation, Total Oxidant Status (TOS) and Total Antioxidant Status (TAS), and maternal and neonatal oxygenation.Our study was carried out with 50 subjects who were planned to have caesarean section and applied spinal anesthesia at Obstetrics and Gynecology Department during December 2009 - October 2012, with approval of Akdeniz University Medical School Ethical Committee and support of Scientific Research Projects Unit.Patients who didn?t receive premedication were divided into two equal groups following routine monitorization after being brought to operation table. Subjects at Group I (O2) had high-concentration (6 Lt/min) oxygen inhalation (FiO2 40-50%) via nasal cannula as soon as they lay on the operation table. Control subjects at Group II (K) didn?t have oxygen inhalation, they just had room air (FiO2 21%) inhalation.All subjects received 8-12 mg bupivacain solution intratecally by application of standard spinal anesthesia technique. At both groups, after the baby came out double clamps were placed on the umblical cord and it was cut before the baby took the first breath, venous sampling from umblical cord was performed in order to evaluate 8-isoprostan-which is a product of lipid peroxydation-, and also oxidative stress indicators TOS (Total Oxidant Status), TAS (Total Antioxidant Status) and OSI (Oxidation Stress Index). Five minutes after placenta was removed and oxytosin infusion was started, blood samples were taken from the mother for both maternal blood gas analysis and evaluation of maternal lipid peroxidation and oxidative stress indicators 8-isoprostan, TOS, TAS and OSI. Blood samples were centrifuged at 4400 rpm for 4 minutes and derived sera were frozen at -70°C for further evaluation of 8-isoprostan, TOS and TAS.Demographical data of the subjects were similar, at comparison of lipid peroxidation (8-isoprostan) and oxidative stress indicators (TOS, TAS, OSI) of both maternal blood and umblical cord, higher values were observed for high-concentration O2 group but there were no statistically significant differences between groups.Although there was no correlation between maternal and neonatal 8-isoprostan and TOS values, there was a positive correlation between TAS values.There was no significant difference between groups for SaO2 ve PaO2 values at umblical cord blood gas analysis. PaCO2 values were significantly higher at high-concentration oxygen group compare to control group, while pH values were lower.Conclusively, we believe that high concentration O2 application in order to improve fetal and maternal oxygenation at women with term pregnancy who are performed caesarean section under spinal anesthesia doesn?t result in lipid peroxidation and oxidative stress. But, we esteem that further studies are required in order to evaluate results at preterm and emergent cases and with different anesthetic techniques.