Newborn complications after intrapartum asphyxia with metabolic acidosis in the term fetus

An Assessment of the Relationships Between Umbilical Cord Blood Gas Analysis, APGAR (Appearance, Pulse, Grimace, Activity, and Respiration) Scores, and Neonatal Outcomes

Introduction Intrapartum hypoxic-ischemic injury is a condition that significantly affects neonatal health and, therefore, needs to be attended to urgently. Umbilical cord blood gas analysis (BGA) results and APGAR (appearance, pulse, grimace, activity, and respiration) scores are commonly used to assess birth asphyxia and the severity of neonatal acidemia. In this context, this study was conducted to investigate the correlations of BGA results and APGAR scores with neonatal outcomes to determine the combined value of BGA results and APGAR scores in neonatal health assessment. Methods The sample of this retrospective cohort study consisted of 593 consecutive-term newborns delivered in a tertiary referral center in Turkey between January 2020 and December 2022. All newborns' maternal, delivery, and neonatal characteristics, BGA results, and APGAR scores were analyzed to determine correlations with composite adverse neonatal outcomes. The study's primary outcome was defined as the rate of the composite adverse neonatal outcomes, whereas the secondary outcomes were determined as the impact of maternal and neonatal characteristics on composite neonatal morbidity and the correlation between the one- and five-minute APGAR scores and umbilical cord BGA parameters. Results Of the 593 infants included in the study, 191 (32.2%) infants experienced composite adverse neonatal outcomes, primarily mechanical ventilation (47.7%), followed by respiratory distress/syndrome (35.6%). Significant correlations were detected between composite adverse neonatal outcomes and advanced maternal age (p = 0.025), cesarean section history (p < 0.001), preterm delivery (p < 0.001), lower one- and five-minute APGAR scores (p < 0.001 for both cases), and acidemia severity (p = 0.007). However, the correlations between BGA parameters and APGAR scores were weak (r < 0.2). Conclusion This study investigated the correlations between neonatal mortality and morbidity and maternal factors, delivery characteristics, and fetal features, including one- and five-minute APGAR scores and BGA parameters. Nevertheless, weak correlations between BGA parameters and APGAR scores warrant further comprehensive prospective studies.

The Risk of Neonatal Morbidity in Umbilical Artery Hypercarbia and Respiratory Acidosis

OBJECTIVE

 To test the hypothesis that elevated umbilical artery (UA) partial pressure of carbon dioxide (pCO2) is associated with neonatal morbidity and to compare the risk of neonatal morbidity with different patterns of UA acidosis.

STUDY DESIGN

 This was a secondary analysis of a prospective cohort of term, singleton, nonanomalous deliveries with universal cord gas collection. The primary outcome was composite neonatal morbidity. Multivariable logistic regression was used to determine the relative risk (RR) for neonatal morbidity in patients with and without UA hypercarbia. A receiver operating characteristic curve determined the predictive value of pCO2 for neonatal morbidity. An additional multivariable logistic regression was used to evaluate the risk of neonatal morbidity in different patterns of UA acidosis.

RESULTS

 UA hypercarbia was associated with an increased risk of neonatal morbidity (RR: 2.56, 95% confidence interval [CI]: [2.07, 3.17]). After adjusting for UA acidemia, this association remained significant (adjusted RR: 1.39, 95% CI: [1.05, 1.83]). UA pCO2 was less predictive of neonatal morbidity than UA pH (area under the curve [AUC]: 0.65, 95% CI: [0.62, 0.68] vs. AUC: 0.72, 95% CI: [0.69, 0.75], p < 0.01). The odds ratios for neonatal morbidity for respiratory, mixed, and metabolic acidosis compared with normal cord gases were 1.48 (95% CI: [0.88, 2.49]), 6.41 (95% CI: [3.68, 11.17]), and 7.49 (95% CI: [5.76, 9.72]), respectively, p-trend < 0.01.

CONCLUSION

 UA hypercarbia is an independent predictor of neonatal morbidity, even in the setting of concomitant UA acidemia. UA mixed and metabolic acidosis carry significantly greater risk of neonatal morbidity compared with respiratory acidosis.

KEY POINTS

· UA pCO2 is associated with neonatal morbidity.. · UA respiratory acidosis is the UA cord gas pattern least associated with neonatal morbidity.. · UA pH is a superior predictor of neonatal morbidity compared with UA pCO2..

Is it time to end the use of base deficit for fetal well-being assessment?

Authors have expressed reservations regarding the use of base deficit measured in umbilical artery blood samples to assess fetal well-being during the course of labor and to predict neonatal neurologic morbidity. Despite its integration into clinical practice for more than 50 years, obstetricians and maternal-fetal medicine specialists may not realize that this marker has significant limitations in accurately identifying neonatal metabolic acidosis as a proxy for fetal well-being. In brief, there are 2 large families of base deficit, namely whole blood and extracellular fluid. Both rely on equations that use normal adult acid-base characteristics (pH 7.40 and partial CO2 pressure of 40 mm Hg) that overlook the specificity of the normal in utero acid-base status of pH 7.27 and partial CO2 pressure of 54 mm Hg. In addition, it ignores the unique characteristic of the in utero fetal response to acute hypoxia. The dependence on placental circulation for CO2 elimination may lead to extremely high values (up to 130 to 150 mm Hg) during hypoxic events, a phenomenon that is absent in adults with acute metabolic acidosis who can hyperventilate. The dispute over if to include a correction for high partial CO2 pressure in the bicarbonate estimation, as presented in the Great Trans-Atlantic Debates, remains unresolved. The key constants computed for adult acid-base physiology in the current base deficit algorithms, without accounting for the impact of high partial CO2 pressure or other fetal characteristics of buffering capacity (eg, differences in body water content composition, plasma protein, and hemoglobin attributes), may lead to an overestimation of metabolic acidosis, especially in newborns who are experiencing hypercarbia during the early stages of the hypoxic response. These unrecognized limitations impact the base deficit results and may mislead clinicians on fetal well-being assessments when discussing the management of fetal heart rate monitoring and neonatal outcomes. Based on our arguments, we believe that it is prudent to consider an alternative to base deficit for drawing conclusions regarding fetal well-being during the course of birth management. We propose a marker specifically related to the newborn acid-base physiology--the neonatal eucapnic pH correction. This marker can be added to arterial cord blood gas analysis, and we have described how to interpret it as a marker of neonatal metabolic acidosis.

Association between maternal short-term exposure to ambient air pollution and the risk of fetal distress: A matched case-control study

BACKGROUND

Ambient air pollution has been linked to gestational complications. However, the evidence on the relationship between air pollution and fetal distress is limited.

OBJECTIVES

To investigate the relationship between maternal short-term air pollution exposure and fetal distress, and to identify a potential susceptible population.

METHODS

This matched case-control study, involving 313 pregnancy women with fetal distress was conducted in Xi'an, the largest city in Northwest China from 2013 to 2016. Each woman with fetal distress was randomly matched with four women without fetal distress of the same age, same gestational week, and registration in the same period (n = 1252). Inverse distance-weighted (IDW) interpolation was applied to estimate maternal air pollution exposure based on the residential addresses. We employed conditional logistic regression model to evaluate the relationship between air pollutants and fetal distress. Distributed lag nonlinear model (DLNM) was performed to examine the exposure-response relationship between air pollutants and fetal distress.

RESULTS

Maternal short-term exposure to PM₁₀, PM_2.5-10 (PMc), SO₂, NO₂, and CO was associated with increased risk of fetal distress. Each 10 μg/m³ increment in PM₁₀, PMc, SO₂ at lag 014, and NO₂ at lag 010, the odds ratio (ORs) of fetal distress were 1.027 (95 % confidence interval (CI): 1.004, 1.050), 1.058 (95 % CI: 1.014, 1.105), 1.140 (95 % CI: 1.029, 1.264), and 1.158 (95 % CI: 1.046, 1.283), respectively. Similarly, with a 0.1 mg/m³ increment in CO at lag 014, the OR of fetal distress was 1.029 (95 % CI: 1.002, 1.058). Stratified analyses showed that the estimate associations of PM₁₀, PM_2.5 and CO appeared to be stronger, although not statistically significantly, among women with gestational complications.

CONCLUSION

Maternal short-term exposure to ambient air pollution may increase the risk of fetal distress. Understanding the detrimental role of air pollution in fetal distress can help us better develop preventative methods in reducing its' impact on maternal and fetal health.

Umbilical cord blood gases: probability of arterial or venous source in acidemia

OBJECTIVES

Umbilical cord blood gases (UBG) may be a critical element in the assessment of a depressed newborn infant but in some cases the arterial or venous UBG source is uncertain making clinical and/or medical-legal interpretation difficult. Objective: to estimate the probability of an arterial (ProbAS) or venous (ProbVS) UBG source depending on blood gas parameters in acidemic cases.

METHODS

A total of 56,703 pairs of concomitant arterial and venous (CAV) UBG results assayed over an 8.8-year period were analyzed. Specimen pairs with preanalytical issues, duplicate source, or physiologically out-of-range or uninterpretable results were excluded. The 3,579 CAV-UBGs with an arterial and venous pH 6.70 to 7.25 were analyzed. Generalized additive model (gam)-based binomial logistic regressions were used to determine the ProbAS and ProbVS according to the blood gas parameters.

RESULTS

The relative differences between arterial and venous medians were: pO₂ ‒47%, pCO₂ 22%, pH -11%, and BD 4%. Below a median of 2.4 kPa, the lower the pO₂, the higher the ProbAS. Above this value, the higher the pO₂, the lower the ProbAS. An Excel worksheet is provided to calculate ProbAS and ProbVS from the regression model for different combinations of pH, pCO₂, and pO₂ values. Considering ProbAS and ProbVS above a cutoff 0.8, the model correctly identified the source in 56% of cases while 41% were indeterminant and 3% were erroneous.

CONCLUSIONS

The probability of an arterial or venous source of an umbilical blood gas can be estimated based on the pH, pCO₂, and pO₂ in most acidemic specimens.

Dietary embelin supplementation during mid-to-late gestation improves performance and maternal-fetal glucose metabolism of pigs

This study aimed to evaluate the effects of dietary embelin supplementation during late gestation (from days 60 to 110) on performance and maternal-fetal glucose metabolism of pigs. Sixty sows (Duroc × Yorkshire × Landrace; parity = 1.68 ± 0.03; N = 20) were randomly divided into three gestation (day 60 of pregnancy) treatments, Control pigs (CON) were fed a basal diet, and the other animals were fed a basal diet supplemented with 200 or 600 mg/kg embelin per kg of feed. The body weight, backfat thickness and litter size of the sows, and birth weight and mortality of piglets were recorded. Sows' blood and piglets' umbilical cord blood were collected for the measurements of hematological parameters and anti-oxidative and immune indexes, and maternal-fetal glucose metabolism parameters, respectively. The colostrum and milk and fecal samples of the sows were also collected for analysis of milk composition and apparent total tract nutrient digestibility. Dietary embelin had no effect on the BW and backfat thickness of the sows but significantly increased the birth weight of piglets (P < 0.05) and decreased the mortality (P < 0.05). Moreover, the white blood cell counts (day 90), neutrophil count and mean cell hemoglobin (day 110), total anti-oxidant capacity (T-AOC), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and catalase (CAT) content of the sows were increased significantly (P < 0.05) in the embelin groups than that in the CON group, whereas the malondialdehyde (MDA) content was decreased (P < 0.05). Embelin significantly increased immunoglobulin A (IgA) and immunoglobulin G (IgG) content in plasma of piglets as well as those in colostrum and milk of sows than the CON treatment (P < 0.05). In addition, dry matter, ash, and ether extract in the colostrum were similar between groups (P > 0.05), whereas the embelin significantly increased the crude protein in the milk. The apparent total tract nutrient digestibility was similar between treatments (P > 0.05). The embelin treatment significantly increased the glucose levels and lactate dehydrogenase B (LDHB) activity in sows plasma, and decreased the lactate levels in both sows and fetuses plasma (P < 0.05). Collectively, this study indicates that sows fed with embelin in mid-to-late gestation showed improved maternal health and anti-oxidative status, milk protein content, and maternal-fetal glucose metabolism, showing promise in natural plant extract nutrition for sows.

Optimal duration of cardiotocography assessment using the iPREFACE score to predict fetal acidemia

Cardiotocography (CTG) applicability to improve fetal outcomes remains controversial. This study aimed to determine the clinically optimal CTG assessment duration using the integrated score index to predict fetal acidemia by intrapartum fetal heart rate monitoring (iPREFACE score). This single-center, retrospective observational study included 325 normal full-term singleton vaginal deliveries at the Toho University Omori Medical Center, from September 2018 to March 2019. The iPREFACE(10), iPREFACE(30), and iPREFACE(60) scores were calculated at 10, 30, and 60 min immediately before delivery. The primary outcome was fetal acidemia (umbilical artery blood pH < 7.2). The secondary outcome was the correlation between all iPREFACE scores and the umbilical artery blood pH, base excess (BE), and lactate values. Patients without accurate CTG findings or with failure of umbilical artery blood sampling immediately after birth were excluded, leaving 145 patients in the final analysis. Of these, 16, three, and two had umbilical artery blood pH of < 7.2, < 7.1, and < 7.0, respectively. All iPREFACE scores significantly correlated with umbilical artery blood pH, BE, and lactate values. iPREFACE(30) had the highest predictive capacity for fetal acidemia, suggesting that 30 min immediately before delivery may be a useful scoring time in clinical practice.

The association of fetal acidemia with adverse neonatal outcomes at time of scheduled cesarean delivery

BACKGROUND

Fetal acidemia at the time of a scheduled cesarean delivery is generally unexpected. In the setting of reassuring preoperative monitoring, the duration of fetal acidemia in this scenario is presumably brief. The neonatal sequelae and risks associated with brief fetal acidemia in this setting are unknown.

OBJECTIVE

We aimed to assess whether fetal acidemia at the time of a scheduled prelabor cesarean delivery is associated with adverse neonatal outcomes.

STUDY DESIGN

This was a retrospective cohort study of singleton, term, nonanomalous, liveborn neonates delivered by scheduled cesarean delivery that was performed under regional anesthesia from 2004 to 2014 at a single tertiary care center with a universal umbilical cord gas policy. Neonates born to laboring gravidas and those whose cesarean delivery was performed for nonreassuring fetal status were excluded. All included patients had reassuring preoperative fetal monitoring. The primary outcome was a composite adverse neonatal outcome that included neonatal death, encephalopathy, therapeutic hypothermia, seizures, intubation, and respiratory distress. This outcome was compared between patients with and those without fetal acidemia (umbilical artery pH <7.2). A multivariable logistic regression was used to adjust for confounders. Cases of fetal acidemia were further characterized as respiratory, metabolic, or mixed acidemia based on additional umbilical cord gas values. Secondary analyses examining the association between the type of acidemia and neonatal outcomes were also performed.

RESULTS

Of 2081 neonates delivered via scheduled cesarean delivery, 252 (12.1%) had fetal acidemia at the time of delivery. Acidemia was more common in breech neonates and in neonates born to gravidas with obesity and gestational diabetes mellitus. Compared with fetuses with normal umbilical artery pH, those with fetal acidemia were at a significantly increased risk for adverse neonatal outcome (adjusted relative risk, 2.95; 95% confidence interval, 2.03-4.12). This increased risk was similar regardless of the type of acidemia.

CONCLUSION

Even a brief period of mild acidemia is associated with adverse neonatal outcomes at the time of a scheduled cesarean delivery despite reassuring preoperative monitoring. Addressing modifiable intraoperative factors that may contribute to fetal acidemia at the time of a scheduled cesarean delivery, such as maternal hypotension and prolonged operative time, is an important priority to potentially decrease neonatal morbidity in full-term gestations.

Predictive accuracy of admission cardiotocography as a screening tool for perinatal asphyxia in high-risk parturients in Northern Nigeria

OBJECTIVE

To determine the predictive accuracy of admission cardiotocography (CTG) as a screening test for perinatal asphyxia in high-risk parturients.

METHODS

A prospective study was done on a group of 180 high-risk parturients in the labor ward of Aminu Kano Teaching Hospital were subjected to a 30-min admission cardiotocography. Results were categorized based on the RCOG criteria. Those with normal results were allowed to progress in labor, while those with abnormal results had their delivery expedited. Umbilical artery blood gas analysis was done at delivery. Measured variables were expressed in descriptive statistics. Tests of association for categorical variables were done using the non-parametric chi-square test (P-value of ≤0.05). The Binary logistic regression model was used to control potential confounders.

RESULTS

After excluding five cord blood samples, 175 samples were analyzed. The CTG was reassuring in 149 (85.1%), non-reassuring in 15 (8.6%), and abnormal in 11 (6.3%) women. Fetal distress developed in 5 (3.4%) and 7 (46.7%) of reassuring and non-reassuring groups, respectively. The test had 91% sensitivity, specificity was 68.8%, and the predictive accuracy was 88.6% for asphyxia using base deficit.

CONCLUSION

The admission that cardiotocography is useful in detecting fetuses at risk of perinatal asphyxia in high-risk deliveries.

Short-term morbidity and types of intrapartum hypoxia in the newborn with metabolic acidaemia: a retrospective cohort study

Objectives

To assess labour characteristics in relation to the occurrence of Composite Adverse neonatal Outcome (CAO) within a cohort of fetuses with metabolic acidaemia.

Design

Retrospective cohort study.

Setting

Three Italian tertiary maternity units.

Population

431 neonates born with acidaemia ≥36 weeks.

Methods

Intrapartum CTG traces were assigned to one of these four types of labour hypoxia: acute, subacute, gradually evolving and chronic hypoxia. The presence of CAO was defined by the occurrence of at least one of the following: Sarnat Score grade ≥2, seizures, hypothermia and death <7 days from birth.

Main outcome measures

To compare the type of hypoxia on the intrapartum CTG traces among the acidaemic neonates with and without CAO.

Results

The occurrence of a CAO was recorded in 15.1% of neonates. At logistic regression analysis, the duration of the hypoxia was the only parameter associated with CAO in the case of an acute or subacute pattern (odds ratio [OR] 1.3; 95% CI 1.02–1.6 and OR 1.04; 95% CI 1.0–1.1, respectively), whereas both the duration of the hypoxic insult and the time from PROM to delivery were associated with CAO in those with a gradually evolving pattern (OR 1.13; 95% CI 1.01–1.3 and OR 1.04; 95% CI 1.0–1.7, respectively). The incidence of CAO was higher in fetuses with chronic antepartum hypoxia than in those showing CTG features of intrapartum hypoxia (64.7 vs. 13.0%; P < 0.001).

Conclusions

The frequency of CAO seems related to the duration and the type of the hypoxic injury, being higher in fetuses showing CTG features of antepartum chronic hypoxia.

Tweetable abstract

This study demonstrates that in a large population of neonates with metabolic acidaemia at birth, the overall incidence of short‐term adverse outcome is around 15%. Such risk seems closely correlated to the duration and the type of hypoxic injury, being higher in fetuses admitted in labour with antepartum chronic hypoxia than those experiencing intrapartum hypoxia.

This study demonstrates that in a large population of neonates with metabolic acidaemia at birth, the overall incidence of short‐term adverse outcome is around 15%. Such risk seems closely correlated to the duration and the type of hypoxic injury, being higher in fetuses admitted in labour with antepartum chronic hypoxia than those experiencing intrapartum hypoxia.

Blood gas measures as predictors for neonatal encephalopathy severity

OBJECTIVE

To correlate arterial umbilical cord gas (aUCG) and infant blood gas with severity of neurological injury.

STUDY DESIGN

Retrospective single-site study of infants evaluated for therapeutic hypothermia. Clinical neurological examination and a validated MRI scoring system were used to assess injury severity.

RESULTS

Sixty-eight infants were included. aUCG base deficit (BD) and lactate correlated with infant blood gas counterparts (r = 0.43 and r = 0.56, respectively). aUCG and infant pH did not correlate. Infant blood gas lactate (R_ADJ² = 0.40), infant BD (R_ADJ² = 0.26), infant pH (R_ADJ² = 0.17), aUCG base deficit (R_ADJ² = 0.08), and aUCG lactate (R_ADJ² = 0.11) were associated with clinical neurological examination severity. aUCG and infant blood gas measures were not correlated with MRI score.

CONCLUSION

Metabolic measures from initial infant blood gases were most associated with the clinical neurological examination severity and can be used to evaluate hypoxic-ischemic cerebral injury risk.

Identification of the Fetus at Risk for Metabolic Acidemia Using Continuous Fetal Heart Rate Monitoring

The fetal heart rate can be used to assess the current metabolic state of the fetus and predict the risk of the evolution of metabolic acidemia through the course of labor. In this chapter, we will present the pathophysiology of the development of fetal acidemia and provide an organized approach to identifying the risk of worsening acidemia using changes noted in the fetal heart rate pattern to allow for interventions that might alter this course.

Maternal pre-pregnancy body mass index and foetal acidosis in vaginal and caesarean deliveries: The Japan Environment and Children's Study

A high maternal body mass index (BMI) is associated with increased risks of asphyxia-related neonatal morbidity. We evaluated the association between maternal pre-pregnancy BMI and foetal acidosis while accounting for the mode of delivery. Participants from the Japan Environment and Children's Study with singleton pregnancies after 22 weeks of gestation who gave birth during 2011-2014 were included. The participants (n = 71,799) were categorised into five groups according to the pre-pregnancy BMI: G1 (BMI < 18.5 kg/m2), G2 (18.5 to < 20.0 kg/m2), G3 (20.0 to < 23.0 kg/m2), G4 (23.0 to < 25.0 kg/m2), and G5 (≥ 25.0 kg/m2). Foetal acidosis was defined as umbilical artery pH (UmA-pH) < 7.20 or < 7.10. Multiple logistic regression analyses were used to evaluate the effect of pre-pregnancy BMI on foetal acidosis risk, accounting for the mode of delivery. In Japanese women, pre-pregnancy BMI ≥ 25.0 kg/m2 significantly increased the likelihood of foetal acidosis in newborns delivered vaginally. We found no association between pre-pregnancy BMI and foetal acidosis in newborns delivered via caesarean section. Counselling for body weight control before pregnancy and adequate management and selection of the mode of delivery in pregnant women with a high BMI who are in labour may be essential to avoid foetal acidosis.

Gestational weight gain and foetal acidosis in vaginal and caesarean deliveries: The Japan Environment and Children's Study

Inappropriate gestational weight gain (GWG), either above or below the recommended values, has been associated with an increased risk of adverse obstetric outcomes. To evaluate the risks of GWG for foetal acidosis according to pre-pregnancy body mass index (BMI) and mode of delivery, we analysed women with singleton pregnancies between 2011 and 2014 in the Japan Environment and Children’s Study. Participants (n = 71,799) were categorised according to pre-pregnancy BMI. GWG was categorised into insufficient, appropriate, or excessive. Foetal acidosis was defined as umbilical artery pH (UmA-pH) < 7.20 or < 7.10. Multiple logistic regressions were performed for each BMI category to identify the risks of GWG for foetal acidosis, accounting for the mode of delivery. Excessive GWG was significantly associated with increased foetal acidosis in overweight women and in women whose pre-pregnancy BMI was 23.0–25.0 kg/m² especially in those with vaginal deliveries. Conversely, excessive GWG was not significantly associated with increased foetal acidosis in obese women and in women whose pre-pregnancy BMI was  ≥ 25.0 kg/m².

Dietary supplementation with garcinol during late gestation and lactation facilitates acid-base balance and improves the performance of sows and newborn piglets1

The present study was conducted to evaluate the effects of dietary garcinol supplementation during late gestation (from the 90th day of pregnancy; day 90) and lactation on the acid-base balance of the umbilical cord blood and performance of sows and piglets. Sixty sows (Duroc × Yorkshire × Landrace; second- or third-parity; n = 20) were randomly divided into 3 gestation (day 90 of pregnancy) or lactation treatments, control diet (CON; basal diet), basal diet with 200 mg garcinol, and basal diet with 600 mg garcinol per kg of feed. The body weight (BW); backfat thickness and litter size of the sows; and birth weight, weaning weight, and mortality of piglets were recorded. Sows' blood and piglets' umbilical cord blood were collected for the measurements of hematological parameters and antioxidative and immune indexes, and acid-base balance parameters, respectively. The colostrum and milk and fecal samples of the sows were also collected for analysis of milk composition and apparent total tract nutrient digestibility. Garcinol had no effect on the BW and backfat thickness of the sows but significantly increased the birth weight and weaning weight of piglets (P < 0.05) and decreased the mortality (P < 0.05). Moreover, the white blood cell counts and neutrophil count, mean cell hemoglobin, superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and catalase (CAT) activity in the plasma of the sows were increased more significantly (P < 0.05) in the garcinol groups than that in the CON group, whereas the malondialdehyde (MDA) content was decreased (P < 0.05). The garcinol treatment significantly increased the pH, HCO3- and base excess values (P < 0.05), whereas it decreased the pCO2 and lactate content (P < 0.05) in the umbilical blood. Dry matter (DM), ash, and ether extract in the colostrum were similar between groups (P > 0.05), whereas the garcinol significantly increased the crude protein (CP) in the milk. In addition, the content of immunoglobulin A (IgA) and immunoglobulin G (IgG) in the plasma of piglets and in colostrum and milk of sows were increased more significantly (P < 0.05) in the garcinol groups than that in the CON group. The apparent total tract nutrient digestibility was similar between treatments. Collectively, this study indicates that sows fed with garcinol in late gestation and lactation showed improved maternal health and antioxidative status, milk protein content, acid-base balance in the umbilical cord blood, and growth performance in piglets, showing promise in natural plant extract nutrition for sows.

The physiology of intrapartum fetal compromise at term

Uterine contractions in labor result in a 60% reduction in uteroplacental perfusion, causing transient fetal and placental hypoxia. A healthy term fetus with a normally developed placenta is able to accommodate this transient hypoxia by activation of the peripheral chemoreflex, resulting in a reduction in oxygen consumption and a centralization of oxygenated blood to critical organs, namely the heart, brain, and adrenals. Providing there is adequate time for placental and fetal reperfusion between contractions, these fetuses will be able to withstand prolonged periods of intermittent hypoxia and avoid severe hypoxic injury. However, there exists a cohort of fetuses in whom abnormal placental development in the first half of pregnancy results in failure of endovascular invasion of the spiral arteries by the cytotrophoblastic cells and inadequate placental angiogenesis. This produces a high-resistance, low-flow circulation predisposing to hypoperfusion, hypoxia, reperfusion injury, and oxidative stress within the placenta. Furthermore, this renders the placenta susceptible to fluctuations and reduction in uteroplacental perfusion in response to external compression and stimuli (as occurs in labor), further reducing fetal capillary perfusion, placing the fetus at risk of inadequate gas/nutrient exchange. This placental dysfunction predisposes the fetus to intrapartum fetal compromise. In the absence of a rare catastrophic event, intrapartum fetal compromise occurs as a gradual process when there is an inability of the fetal heart to respond to the peripheral chemoreflex to maintain cardiac output. This may arise as a consequence of placental dysfunction reducing pre-labor myocardial glycogen stores necessary for anaerobic metabolism or due to an inadequate placental perfusion between contractions to restore fetal oxygen and nutrient exchange. If the hypoxic insult is severe enough and long enough, profound multiorgan injury and even death may occur. This review provides a detailed synopsis of the events that can result in placental dysfunction, how this may predispose to intrapartum fetal hypoxia, and what protective mechanisms are in place to avoid hypoxic injury.

Effects of Vasoactive Medications and Maternal Positioning During Cesarean Delivery on Maternal Hemodynamics and Neonatal Acid-Base Status

Maternal hemodynamics, positioning, and anesthesia technique for cesarean delivery influence neonatal acid-base balance; direct effects from drugs that cross the placenta also have an influence. Spinal anesthesia limits fetal exposure to depressant drugs and avoids maternal airway instrumentation, but is associated with hypotension. Hypotension may be prevented/treated with vasopressors and intravenous fluids. Current evidence supports phenylephrine as the first-line vasopressor. Fifteen degrees of lateral tilt during cesarean delivery has been advocated to relieve vena caval obstruction, but routine use may be unnecessary in healthy nonobese women having elective cesarean delivery if maternal blood pressure is maintained near baseline.

Use of automated fetal heart rate analysis to identify risk factors for umbilical cord acidosis at birth

OBJECTIVE

To identify clinical parameters and intrapartum fetal heart rate parameters associated with a risk of umbilical cord acidosis at birth, using an automated analysis method based on empirical mode decomposition.

METHODS

Our single-center study included 381 cases (arterial cord blood pH at birth pHa ≤7.15) and 1860 controls (pHa ≥7.25) extracted from a database comprising 8,383 full datasets for over-18 mothers after vaginal or caesarean non-twin, non-breech deliveries at term (>37 weeks of amenorrhea). The analysis of a 120-min period of the FHR recording (before maternal pushing or the decision to perform a caesarean section during labor) led to the extraction of morphological, frequency-related, and long- and short-term heart rate variability variables. After univariate analyses, sparse partial least square selection and logistic regression were applied.

RESULTS

Several clinical factors were predictive of fetal acidosis in a multivariate analysis: nulliparity (odds ratio (OR) 95% confidence interval (CI)]: 1.769 [1.362-2.300]), a male fetus (1.408 [1.097-1.811]), and the term of the pregnancy (1.333 [1.189-1.497]). The risk of acidosis increased with the time interval between the end of the FHR recording and the delivery (OR [95%CI] for a 1-min increment: 1.022 [1.012-1.031]). The risk factors related to the FHR signal were mainly the difference between the mean baseline and the mean FHR (OR [95%CI]: 1.292 [1.174-1.424]), the baseline range (1.027 [1.014-1.040]), fetal bradycardia (1.038 [1.003-1.075]) and the late deceleration area (1.002 [1.000-1.005]). The area under the curve for the multivariate model was 0.79 [0.76; 0.81].

CONCLUSION

In addition to clinical predictors, the automated FHR analysis highlighted other significant predictors, such as the baseline range, the instability of the FHR signal and the late deceleration area. This study further extends the routine application of automated FHR analysis during labor and, ultimately, contributes to the development of predictive scores for fetal acidosis.

Maternal exposure to fine particulate matter and the risk of fetal distress

Prenatal life exposure to fine particulate matter (aerodynamic diameter less than or equal to 2.5 µm, PM_2.5) has been linked with increased risk of adverse fetal development and birth outcomes in previous studies. However, to our knowledge, no study has investigated the association of maternal PM_2.5 with the risk of fetal distress, which is a harmful fetal status and may lead to fetal brain damage, even fetal death. Therefore, we conducted a study to determine the association between maternal PM_2.5 and fetal distress among 7835 mother-infant pairs from a birth cohort, in Wuhan, China, 2013-2015. The individual daily PM_2.5 level was assessed using land use regression model. We evaluated the association of maternal PM_2.5 level over the whole pregnancy with fetal distress by logistic regression model, and estimated the risk between PM_2.5 exposure in specific trimester and fetal distress using generalized estimating equations. We observed that per 10 µg/m³ change of maternal PM_2.5 level over the whole pregnancy was associated with 25% increased risk of fetal distress (95% confidence interval: 1.09-1.44). Further, we found PM_2.5 level in the 2nd trimester, but not in the 1st and 3rd trimesters, was associated with fetal distress. Stratified analyses indicated that the association was only significant among infants who were born in cold seasons. Our study suggested that PM_2.5 exposure during the whole pregnancy exhibited significant associations with the risk of fetal distress, and exposure in the 2nd trimester maybe the susceptible window. Further stratified analyses indicated that birth season is a possible modifier in the association.

Reliability of the point-of care analyzer "StatStrip® Xpress™" for measurement of fetal blood lactate

OBJECTIVES

Measurement of lactate in fetal blood is used to assess the degree of anaerobic metabolism. The technical difficulties in obtaining enough scalp blood for analysis by a bloodgas-analyzer advocates for the use of a point-of-care device. StatStrip®Xpress™ (SSX) has shown promising properties but needs further evaluation before implementation into fetal surveillance.

METHODS

Arterial/venous umbilical cord blood from 112 newborns were analyzed simultaneously with SSX and the reference method ABL800™. From 321 fetuses with abnormal heart rate scalp blood was sampled and analyzed repeatedly with SSX.

RESULTS

ABL800™ -lactate ranged from 1.9-13.3 mmol/L in arterial to 1.5-10.2 mmol/L in venous cord blood with excellent correlation to SSX (R² = 0.95). SSX-values were lower compared to the reference method ranging from -0.79 mmol/L for low values to -1.68 mmol/L for high values. The mean CV for SSX-values in cord respectively scalp blood was: lactate ≤3 mmol/L 7.1% respectively 8.4%; lactate >3 mmol/L 3.8% respectively 6.8%. Repeated measurements of the same sample with SSX where without significant difference in cord/scalp blood (p = 0.11).

CONCLUSION

SSX-lactate values were constantly lower but correlated excellent to the reference method. The reproducibility was good for cord and scalp blood. We suggest SSX as an attractive device for measurement of fetal lactate.

Threshold of metabolic acidosis associated with newborn cerebral palsy: medical legal implications

Obstetricians and gynecologists belong to 1 of the medical specialties with the highest rate of litigation claims. Among birth injury cases, those cases with cerebral palsy outcomes account for litigation settlements or judgments often in the millions of dollars. In cases of potential perinatal asphyxia, a threshold level of metabolic acidosis (base deficit ≥12 mmol/L) is necessary to attribute neonatal encephalopathy to an intrapartum hypoxic event. With increasing duration or severity of a hypoxic stress resulting in metabolic acidosis, newborn infant umbilical artery base deficit increases. It may be alleged that, as base deficit levels increase beyond 12 mmol/L, there is an increased likelihood and severity of cerebral palsy. As a corollary, it may be claimed that an earlier delivery (by minutes) would reduce the base deficit and prevent or reduce the severity of cerebral palsy. This issue is of relevance to obstetricians as defendants, because retrospective "expert" analysis of cases may suggest that optimal management decisions would have resulted in an earlier delivery. In addressing the association of metabolic acidosis and cerebral palsy, base deficit should be measured as the extracellular component (base deficit_{extracellular fluid}) rather than the commonly used base deficit_blood. Studies suggest that, beyond the base deficit threshold of 12 mmol/L, the incidence and severity of cerebral palsy does not significantly increase (until ≥20 mmol/L), although the risk of neonatal death rises markedly. Thus, among most infants with hypoxia-associated neonatal encephalopathy, the occurrence of cerebral palsy is unlikely to be impacted by delivery time variation of few minutes, and this argument should not serve as the basis for medical legal claims.

Neurophysiological development of newborn pigs: effect of the sow

The objective of the present study was to determine the effect of sow parity on neonatal piglet health and vitality at birth. We evaluated 1505 neonate piglets, which were born of York–Landrace sows with the following parity distribution: primiparous (n = 202), second (n = 207), third (n = 211), fourth (n = 222), fifth (n = 225), sixth (n = 218) and seventh parity (n = 220). Piglets born to primiparous and seventh-parity sows had the lowest and highest birthweights respectively, and showed the most marked imbalances in blood gas exchanges, acid–base balance and energy profiles, as well as the highest percentage of severe meconium staining of the skin and the lowest vitality scores (P &lt; 0.05). In contrast, the neonates from the fourth-parity sows had the highest vitality scores, required less time to reach the mother’s teat, and had the highest percentage of adhered umbilical cords and newborns with dyspnoea, apnoea and abnormal heartbeat (P &lt; 0.05). The results of this study suggest that during eutocic farrowings, the sow’s parity number has the following effects on newborn piglets: reduced vigour and longer latencies to begin breathing, stand and take the teat. These effects are due to the presence of imbalances in gas exchanges, the acid–base balance and energy profiles that occurred when the mother was a primiparous or older sow. These signs indicate that the newborn piglet survived a process of intrapartum asphyxia.

Neurological impairments in hypoxic neonates and lactate levels

INTRODUCTION

Metabolic acidosis with increasing lactate concentration develops due to the lack of oxygen in the tissues.

OBJECTIVES

The effect of lactic acidosis on neurological development in the first year of life.

MATERIALS AND METHODS

Our study included 50 newborns with perinatal hypoxia requiring oxygen therapy and 50 healthy newborns. pH, pCO2, pO2, base excess (BE) and lactates from arterialized capillary blood were determined in both groups of newborns, in the first and second hours after birth, and neurological development in the first year of life was estimated.

RESULTS

pH, pCO2, pO2, BE and lactates differed significantly between the groups in the first and second hours after birth p < 0.01. Hypotonia was recorded in 20/50 cases and hypertonia was recorded in 10/50 cases in the first year of life.

CONCLUSION

Lactate concentration may be an indicator of neurological damage in neonates with perinatal hypoxia.

A Comprehensive Evaluation of the Predictive Abilities of Fetal Electrocardiogram-Derived Parameters during Labor in Newborn Acidemia: Our Institutional Experience

This study aimed to identify cardiotocography patterns that discriminate fetal acidemia newborns by comprehensively evaluating the parameters obtained from Holter monitoring during delivery. Between June 1, 2015, and August 1, 2016, a prospective observational study of 85 patients was conducted using fetal Holter monitoring at the Beijing Obstetrics and Gynecology Hospital, Capital Medical University, China. Umbilical cord blood was sampled immediately after delivery and fetal acidemia was defined as umbilical cord arterial blood pH < 7.20. Fetal electrocardiogram- (FECG-) derived parameters, including basal fetal heart rate (BFHR), short-term variation (STV), large acceleration (LA), deceleration capacity (DC), acceleration capacity (AC), proportion of episodes of high variation (PEHV), and proportion of episodes of low variation (PELV), were compared between 16 fetuses with acidemia and 47 without. The areas under the curve (AUC) of receiver operating characteristics (ROC) were calculated. Although all the computerized parameters showed predictive values for acidemia (all AUC > 0.50), STV (AUC = 0.84, P < 0.001), DC (AUC = 0.84, P < 0.001), AC (AUC = 0.80, P < 0.001), and PELV (AUC = 0.71, P = 0.012) were more strongly associated with fetal acidemia. Our institutional experience suggests that FECG-derived parameters from Holter monitoring are beneficial in reducing the incidence of neonatal acidemia.

The limits of electronic fetal heart rate monitoring in the prevention of neonatal metabolic acidemia

BACKGROUND

Despite intensive efforts directed at initial training in fetal heart rate interpretation, continuing medical education, board certification/recertification, team training, and the development of specific protocols for the management of abnormal fetal heart rate patterns, the goals of consistently preventing hypoxia-induced fetal metabolic acidemia and neurologic injury remain elusive.

OBJECTIVE

The purpose of this study was to validate a recently published algorithm for the management of category II fetal heart rate tracings, to examine reasons for the birth of infants with significant metabolic acidemia despite the use of electronic fetal heart rate monitoring, and to examine critically the limits of electronic fetal heart rate monitoring in the prevention of neonatal metabolic acidemia.

STUDY DESIGN

The potential performance of electronic fetal heart rate monitoring under ideal circumstances was evaluated in an outcomes-blinded examination fetal heart rate tracing of infants with metabolic acidemia at birth (base deficit, >12) and matched control infants (base deficit, <8) under the following conditions: (1) expert primary interpretation, (2) use of a published algorithm that was developed and endorsed by a large group of national experts, (3) assumption of a 30-minute period of evaluation for noncritical category II fetal heart rate tracings, followed by delivery within 30 minutes, (4) evaluation without the need to provide patient care simultaneously, and (5) comparison of results under these circumstances with those achieved in actual clinical practice.

RESULTS

During the study period, 120 infants were identified with an arterial cord blood base deficit of >12 mM/L. Matched control infants were not demographically different from subjects. In actual practice, operative intervention on the basis of an abnormal fetal heart rate tracings occurred in 36 of 120 fetuses (30.0%) with metabolic acidemia. Based on expert, algorithm-assisted reviews, 55 of 120 patients with acidemia (45.8%) were judged to need operative intervention for abnormal fetal heart rate tracings. This difference was significant (P=.016). In infants who were born with a base deficit of >12 mM/L in which blinded, algorithm-assisted expert review indicated the need for operative delivery, the decision for delivery would have been made an average of 131 minutes before the actual delivery. The rate of expert intervention for fetal heart rate concerns in the nonacidemic control group (22/120; 18.3%) was similar to the actual intervention rate (23/120; 19.2%; P=1.0) Expert review did not mandate earlier delivery in 65 of 120 patients with metabolic acidemia. The primary features of these 65 cases included the occurrence of sentinel events with prolonged deceleration just before delivery, the rapid deterioration of nonemergent category II fetal heart rate tracings before realistic time frames for recognition and intervention, and the failure of recognized fetal heart rate patterns such as variability to identify metabolic acidemia.

CONCLUSIONS

Expert, algorithm-assisted fetal heart rate interpretation has the potential to improve standard clinical performance by facilitating significantly earlier recognition of some tracings that are associated with metabolic acidemia without increasing the rate of operative intervention. However, this improvement is modest. Of infants who are born with metabolic acidemia, only approximately one-half potentially could be identified and have delivery expedited even under ideal circumstances, which are probably not realistic in current US practice. This represents the limits of electronic fetal heart rate monitoring performance. Additional technologies will be necessary if the goal of the prevention of neonatal metabolic acidemia is to be realized.

Urinary Uric Acid/Creatinine Ratio - A Marker For Perinatal Asphyxia

BACKGROUND

Perinatal hypoxia is one of the leading causes of perinatal mortality in developing countries. Both apgar score and arterial blood pH predict the neonatal mortality in asphyxia. Apgar score alone does not predict neurologic outcome and as it is influenced by various factors. This study was conducted to evaluate the utility and sensitivity of urinary uric acid to creatinine ratio (UA/Cr ratio) in asphyxia diagnosis, compared to invasive Arterial Blood Gas (ABG) analysis.

AIM

To assess the urinary uric acid/creatinine ratio as an additional marker for perinatal asphyxia compared with ABG analysis in apgar score monitoring.

MATERIALS AND METHODS

The present case control study was conducted at a teaching hospital in Central Gujarat. Data of 40 healthy newborns and 40 asphyxiated newborns were collected. In absence of regional estimates, a sample of size 39 was required to attain a power of 80% at 5% alpha (type I error) considering a moderate effect size of 0.65. (UA/Cr) ratio was measured from the spot urine sample collected during 24-72 hours of birth. Statistical analysis was performed by Independent t-test, Pearson's correlation coefficient (r) and Receiver Operating Characteristic (ROC) plots.

RESULTS

The mean (UA/Cr ratio) (2.75±0.18 vs 1.78±0.23) is significantly higher in asphyxiated group than in the control group (p<0.0001). Urinary UA/Cr ratio had negative correlation with blood pH (r= -0.27, p=0.18), which was not significant (p>0.05). Urinary UA/Cr ratio with criterion of >2.3 had 100% sensitivity, 100% specificity with AUC of 1 (p<0.0001) had a better predictive value.

CONCLUSIONS

Apgar score is usually reduced in neonates with congenital anomalies and premature neonates. Hence, it is preferable that the clinical diagnosis of asphyxia by apgar scores be supported by other investigations so that early decision can be taken about the level of care the baby needs. pH, lactates and base deficits change with establishment of respiration following resuscitation. However, pH, lactate, base deficit estimations are invasive and need rapid estimations. Non-invasive urinary UA/Cr ratio may be an answer to these issues as it easy, economical and equally efficient.

Cardiac output changes with phenylephrine and ephedrine infusions during spinal anesthesia for cesarean section: A randomized, double-blind trial

Hypotension is a common side effect of spinal anesthesia. Phenylephrine and ephedrine are the two most frequently used vasopressors to treat spinal hypotension during cesarean delivery. In this randomized double-blind study, we aimed to evaluate cardiac output (CO) changes with phenylephrine or ephedrine infusions titrated to maintain baseline systolic blood pressure (bSBP) during spinal anesthesia. Women (n = 40) scheduled for elective cesarean delivery received either phenylephrine 100 μg/min or ephedrine 5 mg/min infusions. Baseline hemodynamics (cardiac output, heart rate, systolic blood pressure) were recorded in the left lateral tilt position before fluid preload, and recorded every minute after spinal anesthesia until delivery. Umbilical cord blood gases were analyzed within 5 minutes of delivery. Good systolic blood pressure control was attained in both groups with minimal periods of hypotension (SBP <80% of bSBP) or hypertension (SBP >120% of bSBP). Cardiac output and heart rate increased over time with ephedrine, but decreased with phenylephrine. The maximum increase in CO from the baseline was 12%, in the ephedrine group, and this occurred 20 minutes after spinal injection. Cardiac output fell by more than 17% in the phenylephrine group, maximal at 10 minutes following spinal injection. Despite good systolic blood pressure control and increased cardiac output with ephedrine, administration of ephedrine was associated with significantly more fetal acidosis [Median (Interquartile range, IQR) UApH - phenylephrine = 7.33 (7.31-7.34) and ephedrine = 7.22 (7.16-7.27), P < .05].

Acidemia in neonates with a 5-minute Apgar score of 7 or greater - What are the outcomes?

BACKGROUND

The Apgar score is universally used for fetal assessment at the time of birth, whereas, the collection of fetal cord blood gases is performed commonly in high-risk situations or in the setting of Apgar scores of <7, which is a less standardized approach. It has been well-established that neonatal acidemia at the time of delivery can result in significant neonatal morbidity and death. Because of this association, knowledge of the fetal acid-base status and detection of acidemia at the time of delivery can serve as a sensitive and useful component in the assessment of a neonate's risk. Umbilical cord blood gas analysis is an accurate and validated tool for the assessment of neonatal acidemia at the time of delivery. Because the collection of fetal cord blood gases is not a standardized practice, it is possible that, with such a varied approach, some cases of neonatal acidemia are not detected, particularly in the setting of reassuring Apgar scores.

OBJECTIVE

In a setting of universally obtained cord blood gases, we sought to identify the rates of acidemia and associated factors in neonates with 5-minute Apgar scores of ≥7.

STUDY DESIGN

This retrospective cohort study identified all term, singleton, nonanomolous neonates with 5-minute Apgar scores of ≥7. The incidence of umbilical artery pH ≤7.0 or ≤7.1 and base excess ≤-12 mmol/L or ≤-10 mmol/L were examined overall and in association with obstetric complications and adverse neonatal outcomes. Chi-squared tests were used to compare proportions, and multivariable logistic regression was used to control for potential confounders.

RESULTS

In this cohort, the incidence of an umbilical artery pH of ≤7.0 was 0.5%, of a pH ≤7.1 was 3.4%, of a base excess ≤-12 mmol/L was 1.4%, and of ≤-10 mmol/L was 4.0%. Rates of neonatal acidemia were greater in the setting of meconium (4.3% vs 3.2%; P<.001), placental abruption (13.2% vs 3.4%; P<.001), and cesarean deliveries (5.8% vs 2.8%; P<.001), despite normal 5-minute Apgar scores. Additionally, umbilical artery pH ≤7.0 was associated with an increased risk of respiratory distress syndrome (adjusted odds ratio, 6.5; 95% confidence interval, 2.9-14.3) and neonatal intensive care unit admission (adjusted odds ratio, 10.8; 95% confidence interval, 6.8-17.4). Base excess of ≤-12 mmol/L was also associated with an increased risk of neonatal sepsis (adjusted odds ratio, 4.7; 95% confidence interval, 1.9-12.1). Finally, when examined together, neonates with both a pH of ≤7.0 and base excess of ≤-12 mmol/L continued to demonstrate an increased risk of neonatal intensive care unit admission and respiratory distress syndrome, with adjusted odds ratios of 9.6 and 6.0, respectively. This risk persisted in neonates with a pH of ≤7.1 and base excess of ≤-10 mmol/L as well, with adjusted odds ratios of 4.5 and 1.1, respectively.

CONCLUSION

Because neonates with reassuring Apgar scores have a residual risk of neonatal acidemia that is associated with higher rates of adverse outcomes, the potential utility of obtaining universal cord blood gases should be further investigated.

Umbilical Cord Venous Lactate for Predicting Arterial Lactic Acidemia and Neonatal Morbidity at Term

OBJECTIVE

To estimate the utility of umbilical venous lactate, more readily available than umbilical cord arterial lactate, for predicting arterial lactic acidemia and neonatal outcomes at term.

METHODS

This was a prospective cohort study of consecutive, nonanomalous, singleton, term births after labor in a large academic medical center (2009-2014). Umbilical arterial and venous lactate were measured immediately after delivery, before knowledge of neonatal outcomes. The outcome measures were arterial lactic acidemia (greater than 3.9 mmol/L) and a composite neonatal outcome consisting of neonatal death and any of a number of neonatal morbidities including intubation, mechanical ventilation, meconium aspiration syndrome, hypoxic-ischemic encephalopathy, and therapeutic hypothermia. Predictive ability of venous lactate was estimated using the area under the receiver operating characteristic curve.

RESULTS

Among 7,741 births, venous lactate was strongly predictive of arterial lactic acidemia (area under the curve 0.958). The "optimal" cut point of venous lactate for predicting both arterial lactic acidemia and the composite neonatal outcome was 3.4 mmol/L. This predicted arterial lactic acidemia with sensitivity of 87.0% and specificity of 91.3%. Positive and negative predictive values were 79.9% and 94.7%, respectively. The composite neonatal outcome occurred in 104 neonates (1.3%). Compared with arterial lactate, venous lactate predicted the composite neonatal outcome with comparable sensitivity (75.0% compared with 74.0%, P>.99) but slightly lower specificity (69.7% compared with 72.2%, P<.01).

CONCLUSION

Umbilical venous lactate strongly predicts arterial lactic acidemia and is comparable with arterial lactate for predicting neonatal morbidity at term. It could be used as a measure of neonatal morbidity when arterial blood is not available.

Preliminary case control study to establish the correlation between novel peroxidation biomarkers in cord serum and the severity of hypoxic ischemic encephalopathy

BACKGROUND

Hypoxic-ischemic encephalopathy (HIE) has deleterious neurological consequences. To identify patients at risk of neuronal damage deserving implementation of neuroprotective strategies clinicians have relied on prenatal sentinel events, postnatal clinical assessment (Apgar score), and blood gas analysis. This feasibility study aimed to assess if lipid peroxidation byproducts associated with neuronal damage correlated with cord blood metabolic acidemia in patients with HIE.

POPULATION AND METHODS

This is a case/control study in which cases were newborn infants with severe acidemia (pH<7.00; base excess ≥12mmol/L) while control babies exhibited normal gases (pH=7.20-7.40; base excess=-4 to +4mmol/L) in the first cord blood analysis performed immediately after birth. Concomitantly, lipid peroxidation byproducts were determined using ultra performance liquid chromatography coupled to mass spectrometry in the same cord blood sample.

RESULTS

A total of 19 controls and 20 cases were recruited. No differences in gestational characteristics were present. However, cases exhibited profound metabolic alterations as compared to controls (Cases vs.

CONTROL

pH=6.90±0.1 vs. 7.33±0.03; base excess=-15±3 vs. -1±2mmol/L), 85% were admitted to the NICU, and 50% developed symptoms of HIE. 8-iso-15(R)-PGF2α (P=0.01) and total isoprostanes (P=0.045) presented statistically significant differences between cases and control groups and correlated with level of HIE.

CONCLUSIONS

The 8-iso-15(R)-PGF2α and isoprostanes reflecting oxidative damage are significantly increased in severe postnatal acidemia. Follow up studies with adequate power are necessary to confirm if these biomarkers measured in cord blood serum could be predictive of neonatal encephalopathy.

Fetal scalp blood lactate during second stage of labor: determination of reference values and impact of obstetrical interventions

OBJECTIVE

To determine the reference interval of fetal scalp blood lactate during second stage of labor.

MATERIAL

Two hundred and fifty-three women in first stage of labor with a reassuring CTG were asked for permission to sample fetal scalp blood during second stage.

RESULTS

In cases with reassuring CTG and five minute Apgar score ≥9, the mean lactate value (±2 SD) was 2.5 mmol/L (lower limit 1.1, higher limit 5.2). The lactate concentration was significantly higher among nulliparous and in cases with use of epidural or oxytocin (p <0.001). There was a moderate positive correlation between scalp lactate values and active pushing time. When parity, epidural, oxytocin and active pushing time were analyzed together, they had equal influence on lactate values (p <0.001). Higher lactate values were associated with intermediate/pathological CTG compared to normal CTG (p <0.001). There was no correlation to gestational age or birthweight (p = 0.72, respectively 0.43).

CONCLUSIONS

The reference interval of fetal scalp lactate during second stage is 1.1-5.2 mmol/L. Parity, use of epidural or oxytocin and the duration of pushing are associated to increased lactate concentration; however, we could not demonstrate any correlation to advancing gestational age or birthweight.

The significance of base deficit in acidemic term neonates

OBJECTIVE

Much emphasis is placed on the metabolic component of umbilical cord acidemia at birth, with an importance attached to an arterial level of <7.00 accompanied by a base deficit of 12 mmol/L. We hypothesized that in acidemic neonates, the level of arterial base deficit provides no prognostic information beyond that provided by the level of arterial pH.

STUDY DESIGN

This is a cohort study using a database of deliveries from a major teaching hospital, with additional information from neonatal records. A total of 8797 term, singleton, nonanomalous neonates were identified who had paired and validated cord blood gas analysis. Of these, 520 were acidemic (pH <7.1) and 84 were severely acidemic (pH <7.0). Outcomes examined were encephalopathy grade 2/3 and/or death, Apgar <7 at 5 minutes, neonatal unit admission, and composite outcomes of neurological and systemic involvement. Hierarchical logistic regressions were done using IBM SPSS Statistics 20.0 (Armonk, NY) to assess the predictive value of arterial pH and arterial base deficit.

RESULTS

For each outcome the median pH and base deficit of those neonates affected by the adverse outcome was significantly lower than for those who were unaffected. Hierarchical logistic regressions showed that pH is a significant predictor of all adverse outcomes studied (P < .001 for all outcomes). When base deficit, and then the cross-product, are added to the model, neither add predictive value.

CONCLUSION

In acidemic neonates, the metabolic component does not predict those at risk of adverse outcomes once pH is taken into account. The apparently worse outcomes with greater base deficit simply reflect a greater degree of acidemia. The prognostic significance attached to the base deficit among acidemic neonates is questionable.

Umbilical cord arterial lactate compared with pH for predicting neonatal morbidity at term

OBJECTIVE

To test the hypothesis that umbilical cord arterial lactate is superior to pH for predicting short-term neonatal morbidity at term.

METHODS

We conducted a prospective cohort study of all consecutive, non-anomalous, singleton, vertex, term births from 2009 to 2012 at Washington University Medical Center. Umbilical arterial lactate and pH were measured immediately after delivery, before knowledge of neonatal outcomes. The primary outcome was a composite neonatal morbidity consisting of neonatal death, intubation, mechanical ventilation, meconium aspiration syndrome, hypoxic encephalopathy, and need for hypothermic therapy. The predictive ability of lactate and pH were compared using receiver operating characteristic curves. Optimal cutoff values of lactate and pH were estimated based on the maximal Youden index.

RESULTS

Of 4,997 term deliveries during the study period, 4,910 met inclusion criteria. The composite neonatal morbidity occurred in 56 neonates (1.1%). The mean lactate level was nearly twofold higher in neonates with the composite morbidity (6.49 compared with 3.26 mmol/L, P<.001), whereas mean pH values were less distinct (7.19 compared with 7.29, P<.001). Lactate was significantly more predictive of neonatal morbidity than pH (receiver operating characteristic curve area: 0.84 compared with 0.78, P=.03). The optimal cutoff value for predicting neonatal morbidity was 3.90 mmol/L for lactate and 7.25 for pH. Corresponding sensitivities and specificities were also higher for lactate (83.9% and 74.1% compared with 75.0% and 70.6%, respectively).

CONCLUSION

Results of this large prospective cohort study show that umbilical cord arterial lactate is a more discriminating measure of neonatal morbidity at term than pH.

LEVEL OF EVIDENCE

: II.

The effects on Apgar scores and neonatal outcomes of switching from a combination of phenylephrine and ephedrine to phenylephrine alone as a prophylactic vasopressor during spinal anesthesia for cesarean section

Background

Ephedrine, unlike phenylephrine, has a dose-related propensity to depress fetal pH during spinal anesthesia during cesarean section. A low arterial umbilical cord pH has a strong association with neonatal mortality and morbidity. The purpose of this retrospective study was to investigate influences of vasopressor change on Apgar scores and adverse neonatal outcomes in cesarean section.

Methods

In obstetric anesthesia, we changed the prophylactic vasopressor from a combination of phenylephrine and ephedrine to phenylephrine alone in 2000. We evaluated the impact of vasopressor change on Apgar scores (1 and 5 min), incidence of Apgar score < 7 (1 and 5 min), neonatal seizure, continuous positive airway pressure (CPAP), intermittent positive pressure ventilation (IPPV), intraventricular hemorrhage (IVH), periventricular leucomalacia (PVL), and hypoxic ischemic encephalopathy (HIE) in low-risk elective cesarean sections during a period when the combination of phenylephrine and ephedrine was used (2008-2009, two years) and the period of phenylephrine use alone (2011-2012, two years).

Results

There were no differences in Apgar scores (1 and 5 min), the incidence of 5 min Apgar score < 7, neonatal seizure, CPAP, IPPV, IVH, PVL, and HIE between the two time periods. However, the incidence of 1 min Apgar < 7 was decreased during the period of phenylephrine use compared with the period of phenylephrine and ephedrine use (P = 0.002).

Conclusions

Conversion from a combination of phenylephrine and ephedrine to phenylephrine alone as a prophylactic anti-hypotensive drug during spinal anesthesia for cesarean section in low-risk pregnancy may be associated with a significant decrease in the incidence of 1 min Apgar < 7.

Maternal and fetal Acid-base chemistry: a major determinant of perinatal outcome

Very small changes in pH may significantly affect the function of various fetal organ systems, such as the central nervous system, and the cardiovascular system with associated fetal distress and poor Apgar score. Review of existing data on maternal-fetal acid-base balance in pregnancy highlight the factors that are associated with derangements of the acid-base status and the impact of the derangements on fetal outcome. Extensive search of electronic databases and manual search of journals for relevant literature on maternal and fetal acid chemistry, clinical studies and case studies were undertaken. There is a substantial reduction in the partial pressure of carbon dioxide (pCO2) in pregnancy. Adequate buffering prevents significant changes in maternal arterial pH. Normal fetal metabolism results in the production of acids which are buffered to maintain extracellular pH within a critical range. Fetal hypoxia can occur when maternal oxygenation is compromised, maternal perfusion of the placenta is reduced, or delivery of oxygenated blood from the placenta to the fetus is impeded. When adequate fetal oxygenation does not occur, metabolisms proceed along with an anaerobic pathway with production of organic acids, such as lactic acid. Accumulation of lactic acid can deplete the buffer system and result in metabolic acidosis with associated low fetal pH, fetal distress and poor Apgar score. There is a significant reduction in pCO2 in pregnancy. This change, however, does not result in a corresponding significant reduction in maternal arterial pH, because of adequate buffering. Very small changes in pH may cause significant derangement in fetal function and outcome.

Vetrabutine clorhydrate use in dystocic farrowings minimizes hemodynamic sequels in piglets

The objective was to measure the effects of VC (a uterotonic drug with vasodilator effects) in eutocic and dystocic sows, on the acid-base balance and some vitality traits of piglets at birth. Farrowing was induced with prostaglandin F2α. Four groups of sows (20 sows/group) were monitored; Groups 1 and 2 were eutocic sows, whereas Groups 3 and 4 were dam-fetal dystocic sows. Groups 1 and 3 (control) were given saline, whereas Groups 2 and 4 were given VC im (1.66 mg/kg of body weight) after the first piglet was born. Piglets' physio-metabolic performance was monitored peripartum. Treatment with VC reduced (P<0.0001) the percentage of intrapartum stillbirths in sows either with eutocic (5.2 vs. 10.0%) and dystocic (7.6 vs. 16.7%) farrowings and increased (P<0.0001) the number of pigs born alive without any evidence of AFS (89.9 vs. 79.9%, eutocic and 81.6 vs. 65.2%, dystocic). In addition, for the group of pigs with no acute fetal suffering (AFS), VC treatment enhanced survival responses with a half point grater vitality score in Group 4; it also reduced the latency to first teat contact by 6 min (P<0.05) in both treated groups compared to controls; and it improved the condition of the pigs' umbilical cord, with more adhered (98 vs. 86% in eutocic and 88 vs. 80% in dystocic; P<0.05) and less ruptured cords. Moreover, VC reduced the severity of adverse physio-metabolic indicators and the acid-base balance of piglets with AFS at birth by lowering blood lactate (89.8 vs. 93.5 mmol/L in eutocic groups and 94.6 vs. 100.2 mmol/L in dystocic groups; P<0.05), PaCO2 and Ca2+, and by increasing blood pH, HCO3 and PaO2 levels (P<0.05).

Maternal carbon dioxide level during labor and its possible effect on fetal cerebral oxygenation: mini review

During pregnancy, and especially during labor, the maternal carbon dioxide level declines considerably. Maternal carbon dioxide levels show a close relation with fetal carbon dioxide levels. The latter affects fetal cerebral oxygenation by regulating cerebral blood flow and shifting the oxyhemoglobin dissociation curve. In addition, maternal hypocapnia appears to impair placental oxygen transfer. Thus, maternal hyperventilation may interfere with optimal fetal cerebral oxygenation. Here, we provide a brief overview of the literature relevant to this issue.

Developmental outcome at 6.5 years after acidosis in term newborns: a population-based study

OBJECTIVES

Infants who develop encephalopathy after perinatal asphyxia have an increased risk of death and adverse neurologic outcome. Conflicting results exist concerning outcome in healthy infants with metabolic acidosis at birth. The aim of the current study was to evaluate whether metabolic acidosis at birth in term infants who appear healthy is associated with long-term developmental abnormalities.

METHODS

From a population-based cohort (14,687 deliveries), 78 infants were prospectively identified as having metabolic acidosis (umbilical artery pH < 7.05 and base deficit in the extracellular fluid >12.0 mmol/L). Two matched controls per case were selected. The child health and school health care records were scrutinized for developmental abnormalities.

RESULTS

Outcome measures at 6.5 years of age for 227 of 234 children (97%) were obtained. No differences were found concerning neurologic or behavioral problems in need of referral action or neurodevelopmental diagnosis in comparison of control children with acidotic children who had appeared healthy at birth, ie, had not required special neonatal care or had no signs of encephalopathy.

CONCLUSIONS

Infants born with cord metabolic acidosis and who appear well do not have an increased risk for neurologic or behavioral problems in need of referral actions or special teaching approaches at the age of 6.5 years.

Comparison of two point-of-care testing (POCT) devices for fetal lactate during labor

BACKGROUND

Point-of-care testing (POCT) of fetal scalp blood lactate is used as an alternative for pH analysis. Lactate measurements have not been standardized and values vary with each device used. The aim of this study was to evaluate the performance of two POCT lactate meters for intrapartum use.

METHODS

Analytical performance of StatStrip Lactate (Nova Biomedical) and Lactate Pro (Arkray) was evaluated using CLSI EP10. Both POCT meters were compared with our lactate reference method (RapidLab 860; Siemens Healthcare Diagnostics) using fetal scalp and neonatal cord blood. Deming regression analysis was performed.

RESULTS

StatStrip Lactate coefficients of variation (CVs) were 5.1%, 5.0% and 2.6% at 0.9, 7.5 and 14.1 mmol/L lactate, respectively. CVs for Lactate Pro were 10.7%, 5.2% and 5.7% at 1.7, 4.1 and 6.4 mmol/L lactate, respectively. Consecutive lactate measurements in 37 fetal scalp and 122 cord blood samples revealed different test characteristics for the two POCT devices. In fetal scalp blood: StatStrip Lactate=1.13*RapidLab-0.39 (R(2)=0.907) and Lactate Pro=0.95*RapidLab-0.03 (R(2)=0.823). In cord artery blood: StatStrip Lactate=1.08*RapidLab-0.09 (R(2)=0.810) and Lactate Pro=0.72*RapidLab+0.59 (R(2)=0.807).

CONCLUSIONS

Overall performance of both Lactate Pro and StatStrip Lactate was good, with StatStrip Lactate having smallest CVs and closest correlation to our reference method. Both StatStrip Lactate and Lactate Pro can be used as a lactate POCT device for obstetric use.

Early Cerebral Hemodynamic, Metabolic, and Histological Changes in Hypoxic-Ischemic Fetal Lambs during Postnatal Life

The hemodynamic, metabolic, and biochemical changes produced during the transition from fetal to neonatal life may be aggravated if an episode of asphyxia occurs during fetal life. The aim of the study was to examine regional cerebral blood flow (RCBF), histological changes, and cerebral brain metabolism in preterm lambs, and to analyze the role of oxidative stress in the first hours of postnatal life following severe fetal asphyxia. Eighteen chronically instrumented newborn lambs were randomly assigned to either a control group or the hypoxic-ischemic (HI) group, in which case fetal asphyxia was induced just before delivery. All the animals were maintained on intermittent positive pressure ventilation for 3 h after delivery. During the HI insult, the injured group developed acidosis, hypoxia, hypercapnia, lactic acidosis, and tachycardia (relative to the control group), without hypotension. The intermittent positive pressure ventilation transiently improved gas exchange and cardiovascular parameters. After HI injury and during ventilatory support, there continued to be an increased RCBF in inner regions among the HI group, but no significant differences were detected in cortical flow compared to the control group. Also, the magnitude of the increase in TUNEL positive cells (apoptosis) and antioxidant enzymes, and decrease of ATP reserves was significantly greater in the brain regions where the RCBF was not higher. In conclusion, our findings identify early metabolic, histological, and hemodynamic changes involved in brain damage in premature asphyxiated lambs. Such changes have been described in human neonates, so our model could be useful to test the safety and the effectiveness of different neuroprotective or ventilation strategies applied in the first hours after fetal HI injury.

Cost-effectiveness of cardiotocography plus ST analysis of the fetal electrocardiogram compared with cardiotocography only

OBJECTIVE

To assess the cost-effectiveness of addition of ST analysis of the fetal electrocardiogram (ECG; STAN) to cardiotocography (CTG) for fetal surveillance during labor compared with CTG only.

DESIGN

Cost-effectiveness analysis based on a randomized clinical trial on ST analysis of the fetal ECG.

SETTING

Obstetric departments of three academic and six general hospitals in The Netherlands. Population. Laboring women with a singleton high-risk pregnancy, a fetus in cephalic presentation, a gestational age >36 weeks and an indication for internal electronic fetal monitoring.

METHODS

A trial-based cost-effectiveness analysis was performed from a health-care provider perspective.

MAIN OUTCOME MEASURES

Primary health outcome was the incidence of metabolic acidosis measured in the umbilical artery. Direct medical costs were estimated from start of labor to childbirth. Cost-effectiveness was expressed as costs to prevent one case of metabolic acidosis.

RESULTS

The incidence of metabolic acidosis was 0.7% in the ST-analysis group and 1.0% in the CTG-only group (relative risk 0.70; 95% confidence interval 0.38-1.28). Per delivery, the mean costs per patient of CTG plus ST analysis (n= 2 827) were €1,345 vs. €1,316 for CTG only (n= 2 840), with a mean difference of €29 (95% confidence interval -€9 to €77) until childbirth. The incremental costs of ST analysis to prevent one case of metabolic acidosis were €9 667.

CONCLUSIONS

The additional costs of monitoring by ST analysis of the fetal ECG are very limited when compared with monitoring by CTG only and very low compared with the total costs of delivery.