[Is oxygen therapy truly useful and necessary during elective cesarean section under spinal anesthesia?]. The effect of maternal oxygen administration during the second stage of labor on umbilical cord blood gas values: a randomized controlled prospective trial. A double-blind randomised controlled trial of continuous oxygen therapy for compromised fetuses. Use of surfactant for prophylaxis versus rescue treatment of respiratory distress syndrome: experience from an Italian-Bulgarian trial. Influence of maternal oxygen administration on the term fetus before labor. Supplementary oxygen for elective Caesarean section under spinal anaesthesia: useful in prolonged uterine incision-to-delivery interval? Global report on preterm birth and stillbirth (3 of 7): evidence for effectiveness of interventions. Amnioinfusion for relief of recurrent severe and moderate variable decelerations in labor. Effects of maternal supplementary oxygen on the newborn for elective cesarean deliveries under spinal anesthesia.
To analyze maternal and fetal well-being with and without the application of oxygen therapy.
                Randomized trial of full-term parturients who had received prenatal care during pregnancy. The women were healthy and classified as ASA 1. They were scheduled for delivery by cesarean section under spinal anesthesia and randomized to 2 groups to breathe room air or air providing an inspired oxygen fraction of 40% through a face mask. We assessed the well-being of the neonate immediately after birth with the Apgar test and by measuring umbilical cord blood gases.
                One hundred thirty women were enrolled. Both groups were similar, with no differences in demographic or hemodynamic variables, time from uterine incision to fetal extraction, neonatal birth weight, presence of umbilical cord abnormalities, type of resuscitation required by the neonate, or Apgar score in the first or fifth minute. Oxygen saturation in maternal blood by pulse oximetry was higher after 10 minutes in the group of women who received supplemental oxygen through face masks. We also observed significant differences in umbilical cord arterial blood between the room air and supplemental oxygen groups, respectively, as follows: PaCO2, 51.14 mm Hg vs 54.33 mm Hg (P=.016); bicarbonate, 22.19 mEq L(-1) vs 23.23 mEq L(-1) (P=.012); lactate, 1.85 mmol L(-1) vs 1.64 mmol L(-1) (P=.038). The PO2 in venous blood also differed significantly: 25.53 mm Hg vs 28.13 mm Hg, respectively (P=033).
                Breathing supplemental oxygen or not during elective cesarean delivery of healthy parturients under spinal anesthesia does not have a significant effect on neonatal well-being. Our aim was to determine whether supplemental oxygen during the second stage of normal labor affects cord blood gas and cooximetry values.
                Patients at term pregnancy were prospectively randomized to the control or treatment group at the onset of the second stage of labor. The treatment group received 10 L/min oxygen by face mask, which result in a mean fractional inspired oxygen concentration of 0.81.
                There were 86 patients randomized into the study. In the oxygen group there were significantly more cord arterial pH values < 7.20 (9/41 vs 2/44, p < 0.05). The control group was compared with two subgroups of patients receiving oxygen: those receiving oxygen therapy for < or = 10 minutes and those receiving oxygen for > 10 minutes. Analysis of variance demonstrated significant differences (7.285 +/- 0.058, 7.312 +/- 0.056, 7.237 +/- 0.064; F test 8.3, p = 0.0005). Among several independent variables, regression analysis demonstrated that only duration of oxygen therapy had a significant inverse relation to cord arterial pH (F test = 15.6, p = 0.0002).
                Prolonged oxygen treatment during the second stage of normal labor resulted in a deterioration of cord blood gas values at birth. To investigate the effect of chronic oxygen therapy in fetuses with absent end diastolic flow in the umbilical artery assessed by doppler analysis at 24-30 weeks of gestation.
                A double-blind, randomised control trial was performed with patients blindly allocated to receive humidified oxygen or humidified air.
                A tertiary referral hospital in South Africa.
                Thirty-two women who presented between 24 and 30 weeks of gestation with a confirmed finding of absent end diastolic flow in the umbilical artery.
                After randomisation patients were allocated to receive a 40% mixture of humidified oxygen or humidified air from uniform coloured gas cylinders which were marked either 'a' or 'b' All women received betamethasone from 27 weeks of gestation on a weekly basis. Cardiotocographs were used from 28 weeks of gestation; after 28 weeks of gestation an amniocentesis was considered to confirm fetal maturity. Women were expected to breath the allocated gas continuously apart from meals and visits to the toilet.
                Survival of the fetus was the main outcome measure with secondary outcome measures documenting improvement in the fetal condition in utero.
                There were 16 women randomised to receive oxygen and 16 to receive air. There were nine survivors in the oxygen group (56.3%) and six in the air group (37.5%) (relative risk 1.5, 95% confidence interval 0.7-3.2). There was a nonsignificant increase in mean birthweight in the oxygen group (858.3 grammes vs 774.4 grammes) and a nonsignificant increase in mean duration of treatment in the oxygen group (12.8 days vs 10.4 days).
                This study did not demonstrate that chronic oxygen therapy provides any benefits to compromised fetuses between 24 and 30 weeks of gestation. Larger studies with sufficient power are necessary to assess whether oxygen therapy can reduce perinatal mortality by a clinically useful amount in this group of patients. To show if surfactant applied in different social-sanitary realities as prophylaxis of respiratory distress syndrome (RDS) is equally useful and able to reduce mortality and incidence of 3-4 radiological grade RDS.
                Two neonatal intensive care units (NICU) in Italy, one NICU in Bulgaria and one NICU in Romania were involved in a randomized controlled clinical trial of prophylaxis vs rescue treatment of RDS. Babies with gestational age 26-30 wks were randomized before birth to prophylaxis in the delivery-room with 200 mg/kg of porcine surfactant (prophylaxis) or to routine assistance (control). Subsequently the babies developing RDS requiring mechanical ventilation and fraction of inspired oxygen (FiO2) > or = 0.4 to maintain PaO2 about 50 mmHg were allowed to be treated rescue with 200 mg/kg of the same surfactant. To reach end-points of reducing mortality by 40% and incidence of radiological grade 3-4 RDS a total number of 174 patients were required.
                Due to logistic, practical and social-political problems the study was interrupted after enrollment of 93 babies (61 in Italy and 32 in Bulgaria). The Romanian centre did not start the study because it was impossible in the scheduled times to equip it for mechanical ventilation of the newborn infants. Analysis done on an intention to treat basis did not show significant reductions of mortality and 3-4 radiological grade RDS, even if there was a trend towards a reduction in the babies given prophylaxis. A significantly lower number of babies given prophylaxis required a subsequent rescue treatment compared to controls (p < 0.001). There was no difference in other complications such as intraventricular haemorrhage, air-leak syndromes and infections between prophylaxis and control infants. As regards pulmonary gas exchange, the PaO2/FiO2 ratio was significantly improved in the babies given prophylaxis for the first 12 hours of life vs the controls.
                Even if the study was terminated before term, the analysis of the data shows that prophylaxis with surfactant is equally effective in different social-clinical conditions to improve pulmonary gas-exchange, especially in the first critical hours of life of premature babies. Thirty-two healthy pregnant women at term who were to undergo cesarean section following epidural anesthesia were randomly assigned to receive preoperatively, by face mask, room air or oxygen for more than 10 minutes. Patients were kept at a left lateral tilt position of 15 degrees and were unaware which gas was administered. Oxygenation significantly increased (p less than 0.05) maternal PO2 to 283 mm Hg (SD 67). The cord vein PO2 of the group receiving oxygen was 34 mm Hg (SD 6), significantly higher (p less than 0.01) than the value of 26 mm Hg (SD 7) in the group receiving room air. The cord artery PO2 of the oxygen group was also significantly higher (p less than 0.05) at 20 mm Hg (SD 6) versus 15 mm Hg (SD 6). No other cord gas values were significantly different. There was no significant difference in the cord vein-artery PO2 differential. There was no significant difference in the infants' hematocrits determined at 4 hours of age in the two groups. All infants were in excellent condition (1-minute Apgar score greater than or equal to 8). The benefit of administering supplementary oxygen during elective Caesarean section under regional anaesthesia is controversial. It has been hypothesized that its use would improve fetal oxygenation in the event of a prolonged uterine incision-to-delivery (U-D) interval. Our aim was to test this hypothesis in a prospective, randomized, double-blinded, controlled study.
                We allocated randomly 204 women having elective Caesarean section under spinal anaesthesia to breathe 21, 40 or 60% oxygen. We recorded the U-D interval, umbilical arterial (UA) and venous (UV) blood gases and oxygen content and Apgar scores. Subgroup analysis was performed according to whether the U-D interval was prolonged (>180 s) or not.
                The U-D interval was <180 s in 159 patients and >180 s in 45 patients. There were no differences in UV or UA blood gases, oxygen content or Apgar scores between cases with and without a prolonged U-D interval. In cases without a prolonged U-D interval, administering 60% oxygen increased UV PO(2) (mean 4.3 (SD 1.1) vs 3.7 (1.0) kPa, P=0.003) and oxygen content (14.4 (3.3) vs 12.9 (2.7) ml dl(-1), P=0.007) compared with air. In cases with a prolonged U-D interval, administering 60% oxygen increased UV PO(2) (4.6 (0.6) vs 3.9 (0.8) kPa, P=0.019) compared with air but there was no difference in UV oxygen content. There was no increase in the UV PO(2) or oxygen content when 40% oxygen was administered compared with air.
                Supplementary oxygen did not increase fetal oxygenation in cases where the U-D interval was prolonged. Our data do not support the routine administration of supplementary oxygen during elective Caesarean section for this purpose. Interventions directed toward mothers before and during pregnancy and childbirth may help reduce preterm births and stillbirths. Survival of preterm newborns may also be improved with interventions given during these times or soon after birth. This comprehensive review assesses existing interventions for low- and middle-income countries (LMICs).
                Approximately 2,000 intervention studies were systematically evaluated through December 31, 2008. They addressed preterm birth or low birth weight; stillbirth or perinatal mortality; and management of preterm newborns. Out of 82 identified interventions, 49 were relevant to LMICs and had reasonable amounts of evidence, and therefore selected for in-depth reviews. Each was classified and assessed by the quality of available evidence and its potential to treat or prevent preterm birth and stillbirth. Impacts on other maternal, fetal, newborn or child health outcomes were also considered. Assessments were based on an adaptation of the Grades of Recommendation Assessment, Development and Evaluation criteria.
                Most interventions require additional research to improve the quality of evidence. Others had little evidence of benefit and should be discontinued. The following are supported by moderate- to high-quality evidence and strongly recommended for LMICs: Two interventions prevent preterm births--smoking cessation and progesterone. Eight interventions prevent stillbirths--balanced protein energy supplementation, screening and treatment of syphilis, intermittant presumptive treatment for malaria during pregnancy, insecticide-treated mosquito nets, birth preparedness, emergency obstetric care, cesarean section for breech presentation, and elective induction for post-term delivery. Eleven interventions improve survival of preterm newborns--prophylactic steroids in preterm labor, antibiotics for PROM, vitamin K supplementation at delivery, case management of neonatal sepsis and pneumonia, delayed cord clamping, room air (vs. 100% oxygen) for resuscitation, hospital-based kangaroo mother care, early breastfeeding, thermal care, and surfactant therapy and application of continued distending pressure to the lungs for respiratory distress syndrome
                The research paradigm for discovery science and intervention development must be balanced to address prevention as well as improve morbidity and mortality in all settings. This review also reveals significant gaps in current knowledge of interventions spanning the continuum of maternal and fetal outcomes, and the critical need to generate further high-quality evidence for promising interventions. To determine whether intrapartum amnioinfusion (AI) relieves recurrent moderate and severe variable decelerations in laboring women with clear or grade I meconium-stained amniotic fluid and reduces cesarean section rate for fetal distress.
                A randomized controlled trial was conducted in labor unit of Christian Medical College Hospital, Vellore, India, between October 2003 and September 2004. Women were randomized to receive AI (group I) and not to receive it (group II).
                A total of 150 women (75 in each group) were included in the study. There was significant relief of variable decelerations in group I and no difference in overall cesarean section rate but significant reduction in cesarean section rate for fetal distress in group I, and significant reduction in cesarean section rate for fetal distress in nulliparous women of group I. Neonatal acidemia was also significantly reduced in the nulliparous women receiving AI. The duration of maternal postpartum hospital stay was significantly reduced in group I. There were no adverse maternal or neonatal outcomes.
                AI was a beneficial therapeutic intervention in women patients showing fetal distress in first stage of labor, and it reduced cesarean section for fetal distress and neonatal acidemia. The aim of this investigation was to determine whether supplementary oxygen provided by either nasal cannula or face mask versus room air might affect fetal oxygenation during elective cesarean section under spinal anesthesia by assessing maternal and neonatal regional cerebral oxygenation (rSO(2)) with a cerebral oximeter.
                Ninety parturients were randomly allocated into three groups: two groups received 5 L/min oxygen by either nasal cannula (Group NC, n = 30) or face mask (Group FM, n = 30), respectively, and the third group was allowed to breathe room air (Group RA, n = 30). After maternal mean arterial pressure, heart rate and peripheral oxygen saturation had been monitored, rSO(2) was determined by cerebral oximeter. Umbilical artery (UA) and venous (UV) blood samples were collected for blood gas analysis. Neonatal rSO(2) and Apgar scores were recorded.
                The mean maternal rSO(2) which was recorded 3 and 5 min after administration of the spinal block in Group FM was lower than that of Group NC (p = 0.033 and 0.042, respectively). Neonatal rSO(2), UA pH, UV pH and UA base excess (BE) were lower in Group FM than in the other groups (p < 0.05). The Apgar score (1 min) in Group FM was lower than that of Group RA (p = 0.046).
                The effect of maternal supplementary oxygen on the newborn has been demonstrated by a cerebral oximeter monitor and supported by umbilical cord blood gas analysis and Apgar scores.
Implications for practice

There is not enough evidence to support the use of prophylactic oxygen therapy for women in labour, nor to evaluate its effectiveness for fetal distress.


Implications for research

In view of the widespread use of oxygen administration during labour and the possibility that it may be ineffective or harmful, there is an urgent need for randomized trials to assess its effects.