Maternal Oxygen Therapy Research Articles

The impact of maternal hyper-oxygenation on foeto-placental blood flow

Objective: Maternal hyperoxygenation has been reported to increase foetal oxygen saturation, and is frequently employed during intra-partum episodes of foetal compromise as a component of in utero resuscitation. However, there has been little investigation of its influence on foetal haemodynamics, particularly in appropriately grown foetuses.Methods: This cohort study was undertaken between July 2013 and November 2013. All participants underwent an ultrasound scan prior to active labour (<4 cm dilated), during which foetal biometry, umbilical and middle cerebral artery Dopplers were recorded. Doppler measurements were then repeated after a 20-min period (to act as a control for subsequent measurements after oxygen therapy). Women were then asked to breathe 60% oxygen through Venturi valve masks for 20 min, after which the Doppler measurements were repeated.Results: Twenty women were recruited to the study. No significant change in the foetal cerebro-umbilical (CU) ratio was observed following maternal oxygen therapy. The degree of change in Doppler parameters after oxygen therapy was not related to the baseline value of the Doppler parameter.Conclusion: Maternal hyperoxygenation using 60% oxygen concentration over a 20-min period does not influence foetal umbilical or middle cerebral artery Doppler in appropriately grown foetuses. No adverse effects of maternal oxygen therapy were observed.

Circulation: Clinical Summaries.

Circulation: Clinical Summaries.

Reduced fetal cerebral oxygen consumption is associated with smaller brain size in fetuses with congenital heart disease.

Fetal hypoxia has been implicated in the abnormal brain development seen in newborns with congenital heart disease (CHD). New magnetic resonance imaging technology now offers the potential to investigate the relationship between fetal hemodynamics and brain dysmaturation. We measured fetal brain size, oxygen saturation, and blood flow in the major vessels of the fetal circulation in 30 late-gestation fetuses with CHD and 30 normal controls using phase-contrast magnetic resonance imaging and T2 mapping. Fetal hemodynamic parameters were calculated from a combination of magnetic resonance imaging flow and oximetry data and fetal hemoglobin concentrations estimated from population averages. In fetuses with CHD, reductions in umbilical vein oxygen content (P<0.001) and failure of the normal streaming of oxygenated blood from the placenta to the ascending aorta were associated with a mean reduction in ascending aortic saturation of 10% (P<0.001), whereas cerebral blood flow and cerebral oxygen extraction were no different from those in controls. This accounted for the mean 15% reduction in cerebral oxygen delivery (P=0.08) and 32% reduction cerebral Vo2 in CHD fetuses (P<0.001), which were associated with a 13% reduction in fetal brain volume (P<0.001). Fetal brain size correlated with ascending aortic oxygen saturation and cerebral Vo2 (r=0.37, P=0.004). This study supports a direct link between reduced cerebral oxygenation and impaired brain growth in fetuses with CHD and raises the possibility that in utero brain development could be improved with maternal oxygen therapy.

Whither oxygen for intrauterine resuscitation?

Oxygen is frequently administered to women in labor in the hope of improving fetal status. However, there is a paucity of outcome data to support this practice. Although maternal oxygen administration may make physiological sense, unwarranted faith in maternal oxygen therapy may delay the indicated intervention or result in continued labor stimulation when neither is in the best interests of the fetus. A properly designed clinical trial would help answer whether maternal oxygen supplementation in labor should be considered an indicated intervention for nonreassuring fetal status.

Maternal hyperoxygenation and foetal cardiac MRI in the assessment of the borderline left ventricle

Using phase-contrast MRI in a foetus with borderline left ventricular hypoplasia at 37 weeks' gestation we showed an increase in pulmonary blood flow during maternal hyperoxygenation. The associated increase in venous return to the left atrium, however, resulted in reversal of the atrial shunt, with no improvement in left ventricular output. The child initially underwent single ventricle palliation with a neonatal hybrid procedure, but following postnatal growth of the left ventricle tolerated conversion to a biventricular circulation at 5 months of age. We conclude that when there is significant restriction of filling or outflow obstruction across the left heart, neither prenatal nor postnatal acute pulmonary vasodilation can augment left ventricular output enough to support a biventricular circulation. Chronic pulmonary vasodilation may stimulate the growth of the left-sided structures allowing biventricular repair, raising the intriguing question of whether chronic maternal oxygen therapy might obviate the need for neonatal single ventricle pallation in the setting of borderline left ventricular hypoplasia.

Devenir des enfants intoxiqués au monoxyde de carbone en période fœtale et traités par oxygénothérapie hyperbare — Étude d’une cohorte constituée sur 25 ans de 1983 à 2008

Carbon monoxide (CO) poisoning during pregnancy can be fatal for the fetus, or cause bone malformations or encephalopathy, depending on the stage of pregnancy at which the poisoning occurs. Fewer cases of death and encephalopathy have been reported since the adoption of maternal hyperbaric oxygen (HBO) therapy in this setting, but these children's long-term psychomotor development and growth remains to be documented. A prospective single-center cohort study spanning 25 years (1983 - 2008) included all pregnant women living in the Nord-Pas-de-Calais region of France who received HBO for CO poisoning and who gave birth to a living child. A descriptive analysis of the women and children was performed first. A control group of children was created by matching with anonymous files from local authorities. The results of the children's compulsory health & development assessments were used to compare the two groups. 406 women were included in the study, of whom 6 were expecting twins. The psychomotor development of 412 children was monitored, up to the day 8 assessments in 388 cases, the year 2 assessments in 276 cases, and the year 6 assessments in 232 cases. Sixty children have not yet reached the age of 6 years. No significant differences in psychomotor or height/weight criteria (p > 0.05 for both) were found between the exposed and unexposed children. No malformations were reported. These findings support the use of HBO therapy for all expectant mothers exposed to CO poisoning. No specific follow-up of the children is necessary if their neonatal status is normal.

Maternal oxygen administration for fetal distress

Maternal oxygen administration has been used in an attempt to lessen fetal distress by increasing the available oxygen from the mother. This has been used for suspected fetal distress during labour, and prophylactically during the second stage of labour on the assumption that the second stage is a time of high risk for fetal distress. The objective of this review was to assess the effects of maternal oxygenation for fetal distress during labour and to assess the effects of prophylactic oxygen therapy during the second stage of labour on perinatal outcome. We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (22 October 2012) and searched reference lists of retrieved studies. Randomized trials comparing maternal oxygen administration for fetal distress during labour and prophylactic oxygen administration during the second stage of labour with a control group (dummy or no oxygen therapy). Both review authors assessed eligibility and trial quality. Data were extracted, checked and entered into Review Manager software. For dichotomous data, we calculated relative risks (RR) and 95% confidence intervals (CI). For continuous data, we calculated weighted mean differences and 95% CI. We located no trials addressing maternal oxygen therapy for fetal distress. We included two trials which addressed prophylactic oxygen administration during labour. Abnormal cord blood pH values (less than 7.2) were recorded significantly more frequently in the oxygenation group than the control group (RR 3.51, 95% CI 1.34 to 9.19). There were no other statistically significant differences between the groups. There were conflicting conclusions on the effect of the duration of oxygen administration on umbilical artery pH values between the two trials. 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.

P37.10: Growth discordance and abnormal Doppler flow in a monochorionic triamniotic triplet pregnancy: A case report

Prevalence of spontaneous monochorionic triplet pregnancy is 1 in 7000 pregnancies with a 50–60% incidence of growth restriction. We report a case of 25 year old G1 P0 hospitalized at 24 6/7 weeks for one fetus with selective intrauterine growth restriction (IUGR) with absent or reversed end diastolic flow in the free loop of umbilical artery (FLUA). The estimated growths of the three fetuses were < 10%, 28% and 38%. There was no evidence of structural or functional cardiac abnormalities in any of the fetuses. There was no evidence of twin-twin transfusion syndrome. The patient was managed with bed rest, oxygen by nasal cannula, steroids and followed with daily biophysical profile and non-stress test, weekly Doppler and amniotic fluid evaluations. After eleven days, the IUGR fetus showed improvement in the ductus venosus and middle cerebral artery pulsatility index (PI) while FLUA showed mildly elevated PI. The plan was to prolong delivery of the triplets until after 32 weeks gestation, if possible. The antenatal course remained uneventful while on maternal oxygen therapy. At 32 weeks, the smaller fetus had grown to 37% percentile with all Doppler values within normal limits while on maternal oxygen and the delivery was conducted by scheduled cesarean section. The placental pathology showed a monochorionic placenta with one eccentric and two central insertions of the three vessel umbilical cords. The newborns weighed 1015 grams (g), 1350 g and 1530 g with normal Apgar score at 5 minutes. All of the triplets received continuous positive airway pressure and parenteral support in the newborn period. We conclude that oxygen therapy improved the Doppler flow pattern in the IUGR fetus of this triplet pregnancy and allowed for substantial growth in that fetus, thereby successfully prolonging the delivery date.

Intrauterine resuscitation during labor: Should maternal oxygen administration be a first-line measure?

Intrauterine resuscitation techniques are often used during labor when the fetal heart rate pattern is nonreassuring. These techniques have not been well studied; common practices are based on classic studies many years old. Models of intrauterine resuscitation using one (or more) technique as a first-line intervention and adding others in a specific series or clinical algorithm based on fetal response have not been tested. Maternal oxygen therapy is often used; however, recent evidence suggests potential risks to the mother and fetus or newborn. Even small increases in maternal and fetal pO(2) as a result of maternal oxygen administration can produce oxygen free radical activity in mothers and fetuses. The potential long-term effects are unknown. Caution should be exercised when considering maternal oxygen administration as a first-line intrauterine resuscitation measure until more data are available, reserving its use after other measures have been unsuccessful in resolving the nonreassuring fetal heart rate pattern.

Effect of maternal facial oxygen on neonatal behavioural scores during elective Caesarean section with spinal anaesthesia

Background and objective: For many, the administration of additional oxygen to the women receiving regional anaesthesia for Caesarean section is traditional, but for others it is controversial because of doubts about its efficacy. The aim of our study was to determine if beneficial effects of maternal oxygen therapy on the fetus could be revealed using a neonatal behavioural scoring system. Methods: Sixty women with a normal singleton pregnancy beyond 36 weeks gestation, undergoing elective Caesarean section under spinal anaesthesia were randomized into two groups: Group 1 received air and oxygen mixture through a Hudson style face mask (FiO2 of 0.21–0.25). Group 2 received FiO2 of 0.40–0.60 through an identical Hudson style face mask. Neurologic Adaptive Capacity Score on all the infants within 5 min of birth and between 10 and 24 h after the Caesarean delivery was performed. Apgar score, umbilical venous blood oxygen tension and umbilical artery standardized base excess were recorded. Results: Initial Neurologic Adaptive Capacity Scores at birth in Groups 1 and 2 were 32.6 (SD 4.6) and 31.3 (SD 4.3), respectively. Latter scores were 36.0 (SD 3.0) and 36.5 (SD 1.9), respectively. Neither were statistically significant. There were no significant differences between the groups for any of the recorded variables. Conclusions: Administering maternal oxygen using a standard commercial Hudson style face mask does not appear to significantly improve oxygen delivery to, nor does it influence acidosis or behavioural effects in, the normal neonate at elective Caesarean delivery with spinal anaesthesia.

Effect of maternal facial oxygen on neonatal behavioural scores during elective Caesarean section with spinal anaesthesia

For many, the administration of additional oxygen to the women receiving regional anaesthesia for Caesarean section is traditional, but for others it is controversial because of doubts about its efficacy. The aim of our study was to determine if beneficial effects of maternal oxygen therapy on the fetus could be revealed using a neonatal behavioural scoring system. Sixty women with a normal singleton pregnancy beyond 36 weeks gestation, undergoing elective Caesarean section under spinal anaesthesia were randomized into two groups: Group 1 received air and oxygen mixture through a Hudson style face mask (FiO2 of 0.21-0.25). Group 2 received FiO2 of 0.40-0.60 through an identical Hudson style face mask. Neurologic Adaptive Capacity Score on all the infants within 5 min of birth and between 10 and 24 h after the Caesarean delivery was performed. Apgar score, umbilical venous blood oxygen tension and umbilical artery standardized base excess were recorded. Initial Neurologic Adaptive Capacity Scores at birth in Groups 1 and 2 were 32.6 (SD 4.6) and 31.3 (SD 4.3), respectively. Latter scores were 36.0 (SD 3.0) and 36.5 (SD 1.9), respectively. Neither were statistically significant. There were no significant differences between the groups for any of the recorded variables. Administering maternal oxygen using a standard commercial Hudson style face mask does not appear to significantly improve oxygen delivery to, nor does it influence acidosis or behavioural effects in, the normal neonate at elective Caesarean delivery with spinal anaesthesia.

Fetal effects of maternal supplementary oxygen during Caesarean section

This review summarises the current issues, knowledge and research on the effects of maternal supplementary oxygen therapy on the fetus during Caesarean section. This is a controversial subject since supplementary oxygen has the potential to confer both benefits and also harm to the fetus, depending on the circumstances. For elective Caesarean section, breathing room air under regional anaesthesia or 30% oxygen under general anaesthesia is not associated with either maternal or fetal hypoxia. A prolonged uterine-incision-to-delivery (U-D) interval of up to 310 s is not a major factor per se for development of fetal hypoxia or acidosis, and no benefits could be derived from breathing supplementary oxygen in this situation. Although it appears rational to provide supplementary oxygen in the presence of a hypoxic or compromised fetus, to achieve meaningful increases in fetal oxygenation, a very high inspired oxygen fraction (FiO2) is required. However, it still remains unclear whether this is beneficial for the fetus. The process of damage to the hypoxic fetus is one of oxidative stress mediated by free radicals generated during reperfusion (ischaemia-reperfusion injury). Independently, hyperoxia from breathing supplementary oxygen also induces formation of free radicals by direct mitochondrial electron transfer. Although hyperoxia could lessen the severity of fetal hypoxia, there is also a theoretical risk of an enhanced reperfusion injury. This issue has not been resolved in a clinical study, but an animal study reported enhanced formation of free radicals after an episode of fetal hypoxia in the group receiving supplementary oxygen. For elective Caesarean section, current evidence suggests that supplementary oxygen is unnecessary. For emergency Caesarean section, further data are required before a conclusion can be made for its beneficial and adverse effects. Improvement of fetal oxygenation should be the primary objective, and this is achievable in the short term by using a very high FiO2. Although there is also a possibility of an enhanced reperfusion injury, particularly in the preterm and non-labouring patients, further data are necessary before a conclusion can be made.

Maternal oxygen administration for fetal distress.

Maternal oxygen administration has been used in an attempt to lessen fetal distress by increasing the available oxygen from the mother. This has been used for suspected fetal distress during labour, and prophylactically during the second stage of labour on the assumption that the second stage is a time of high risk for fetal distress. The objective of this review was to assess the effects of maternal oxygenation for fetal distress during labour and to assess the effects of prophylactic oxygen therapy during the second stage of labour on perinatal outcome. We searched the Cochrane Pregnancy and Childbirth Group trials register (March 2003) and the Cochrane Central Register of Controlled Trials (The Cochrane Library, Issue 3, 2002). Randomised trials comparing maternal oxygen administration for fetal distress during labour and prophylactic oxygen administration during the second stage of labour with a control group (dummy or no oxygen therapy). Both reviewers assessed eligibility and trial quality. Data were extracted, checked and entered into RevMan software. For dichotomous data, relative risks (RR) and 95% confidence intervals (CI) were calculated. For continuous data, weighted mean differences and 95% CI were calculated. No trials addressing maternal oxygen therapy for fetal distress were located. Two trials which addressed prophylactic oxygen administration during labour were included. Abnormal cord blood pH values (less than 7.2) were recorded significantly more frequently in the oxygenation group than the control group (relative risk 3.51, 95% confidence interval 1.34 to 9.19). There were no other statistically significant differences between the groups. There were conflicting conclusions on the effect of the duration of oxygen administration on umbilical artery pH values between the two trials. Implications for practiceThere 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 researchIn 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 randomised trials to assess its effects.

Maternal oxygen administration for suspected impaired fetal growth.

Fetal hypoxaemia is often a feature of fetal growth impairment. It has been suggested that perinatal outcome after suspected impaired fetal growth might be improved by giving mothers continuous oxygen until delivery. The objective was to assess the effects of maternal oxygen therapy in suspected impaired fetal growth on fetal growth and perinatal outcome. We searched the Cochrane Pregnancy and Childbirth Group trials register and the Cochrane Controlled Trials Register. Acceptably controlled trials comparing maternal oxygen therapy with no oxygen therapy in suspected impaired fetal growth. Eligibility and trial quality was assessed. Two studies involving 62 women were included. Oxygenation compared with no oxygenation was associated with a lower perinatal mortality rate (relative risk 0.41, 95% confidence interval 0.21 to 0.78). However higher gestational age in the oxygenation groups may have accounted for the difference in mortality rates. There is not enough evidence to evaluate the benefits and risks of maternal oxygen therapy for suspected impaired fetal growth.

Effect of maternal oxygen therapy on placental calcium transport in intrauterine growth retarded rats.

We tested the hypothesis that continuous maternal oxygen (O2) therapy leads to an increase in fetal survival, improvement in fetal growth, and correction of decreased placental calcium (Ca) transport, in pregnant rats who underwent uterine artery ligation. We measured on Day 21 of pregnancy, the unidirectional maternofetal clearance of 45Ca (Kmf45Ca) and 51Cr-EDTA (Kmf51Cr-EDTA) across in-situ perfused placentas of rats randomized on Day 17 to a modified Wigglesworth (bilateral uterine artery ligation) procedure (group WW, n = 8), to modified Wigglesworth and supplemental maternal O2 treatment (FiO2 0.40) (group WWO2, n = 8), or to a sham operation (group Sh, n = 8). Kmf51Cr-EDTA provides a measure of placental "porosity" or passive permeability. Maternal O2 therapy did not improve fetal survival, fetal growth, or placental Ca transport. CONCLUSION AND SPECULATION: Bilateral uterine ligation in the pregnant rat leads to IUGR and decreased placental Ca transport which cannot be corrected by maternal O2 therapy.

Supplemental Maternal Oxygen Therapy During Cesarean Section Under Epidural Anesthesia

Supplemental Maternal Oxygen Therapy During Cesarean Section Under Epidural Anesthesia

Improvement of Fetal Umbilical and Aortic Doppler Waveforms with Persistent Placental Disease

Doppler acquired velocity waveforms of fetal and maternal vessels have been analyzed as both a predictor and an index of fetal health. Increases in downstream impedance reflected by a decrease in placental tertiary villi arterioles or an obliterative angiopathy of the placenta are thought to be responsible for the increased impedance and hence the abnormal waveforms identified. We present a case of improvement of abnormal fetal velocity waveforms (including reversed diastolic flow in the fetal abdominal aorta). Despite improvement of umbilical and aortic waveforms there was evidence of placental disease with a decrease in the number of placental tertiary villi arterioles. The recovery of fetal waveforms was associated with maternal bed rest and oxygen therapy.

Maternal oxygen therapy for intrauterine growth retardation.

Humidified oxygen (55%) was administered continuously through a face mask to 5 patients whose pregnancies (4 singleton and 1 twin) were all complicated by severe intrauterine growth retardation, oligohydramnios, high blood-flow impedance in the fetal aorta and umbilical artery, and low mean blood-velocity in the fetal thoracic aorta. All the fetuses were hypoxic and 2 were acidotic. After maternal hyperoxygenation, the fetal pO2 increased to within or near the normal range, and resulted in a sustained increase in the mean blood-velocity in the fetal thoracic aorta. 5 fetuses survived with minimum neonatal morbidity. The effect of maternal hyperoxygenation on the fetal pO2 in such cases may prove to be a useful method of assessing placental function and guiding management.