Umbilical Artery Acid-base Status Research Articles

Predicting long-term neurodevelopmental outcomes in very preterm neonates by umbilical cord gas parameters

The predictive value of acidemia at birth on long-term neurodevelopmental outcomes remains poorly understood, especially in preterm neonates. This study aimed to assess the relationship between the umbilical artery acid-base status and major neurodevelopmental disability at an age of between 5 and 8 years among children born very prematurely. We performed a secondary analysis of the data from a follow-up study of a prospective cohort of 457 children aged between 23 weeks and 31 weeks and 6 days from 1996 to 2001. Arterial cord gas parameters that were <10th percentile in the original cohort of 457 neonates (ie, pH of <7.1, base deficit of <-8.6 mEq/L, and a partial pressure of CO2 of >77 mm Hg) were considered abnormal. Sensitivity analyses considered alternative definitions for abnormal cord gases including a pH of <7.0 or base deficit of <-12 mEq/L. The primary outcome was a composite of major neurodevelopmental disability, including an intelligence quotient score of <70, cerebral palsy, blindness, deafness, abnormal balance, impaired cognition, dystonia, and seizure disorder. A logistic regression analysis was used to adjust for race and caregiver intelligence quotient score and, in an additional analysis, for gestational age. A total of 259 of 261 maternal-infant dyads were evaluated at a mean child age of 6.8 years, with complete umbilical cord gas data for 228 of those. Infants with an abnormal pH and a base deficit (defined above) were over 4-fold more likely to have the composite disability and an intelligence quotient score of <70. These increased odds persisted after adjusting for age and caregiver intelligence quotient score, but when considering gestational age as well, none of the umbilical cord gas parameters significantly predicted the presence of the composite disability or an intelligence quotient score of <70. However, when using the stricter umbilical cord gas criteria (ie, pH of <7.0 and a base deficit of <-12 mEq/L), a base deficit of <-12 mEq/L was independently associated with both neurodevelopmental disability and an intelligence quotient score of <70. When defined more strictly, abnormal umbilical cord gases, specifically a base deficit of <-12 mEq/L, are associated with an increased risk for major long-term neurodevelopmental disability and an intelligence quotient score of <70 in children born very prematurely.

Comment on: ‘Is nuchal cord justified as a cause of obstetrician anxiety?’ by Narang et al.

Considering the literature about effects of nuchal cord on maternal and fetal morbidity, this article is of great importance to obstetricians so, we thank Narang et al. [1], for focusing on a quite frequent but undetermined subject. Most of the studies about this issue have reported conflicting results, mostly stressing on that, nuchal cord does not have an effect on perinatal outcomes [2]. But there are authors who correlated nuchal cord with some degree of hypoxia and even cerebral palsy [3, 4]. The current study seems to have some bias of design about patient selection which may lead to unintended outcomes regarding management of this patient population. The authors report that they have selected the patients with nuchal cord (single or multiple) who could give birth vaginally among 2,000 patients eligible for the study. They also claim that presence of nuchal cord had some statistically significant effects on umbilical artery acid–base status including pH and lactate but non-nuchal cord group had pathological range biochemical derangement [1] possibly regarding the pathologic cut-off for umbilical artery pH as 7.00 which is the most important parameter related with long-term outcomes. But the number of patients who were eligible for the study but delivered with cesarean section was not mentioned. Cesarean section incidence due to nuchal cord has been reported ranging between 11.1 and 35 % [5] and nuchal cord has been reported to be one of the four leading indications for cesarean delivery in the Chinese population [6]. Based on these reports, although nuchal cord is not an indication for cesarean section on its own, causal relationship with other factors such as decreased fetal heart rate variability or failure of descent may result with need of cesarean section. Although delivery is a complex process, the authors seem to eliminate any possible intervening factors which may interfere with the way of delivery and at this point, the number of patients who were referred to cesarean section gains importance as the only possible factor leading to cesarean might be ‘nuchal cord’ or the number of ‘nuchal cords’. This is why we suggest the authors to report about this aspect of the research. Only after then, it may be possible to claim that nuchal cord does not have a significance as a factor intervening with the process of delivery. In conclusion, retrospectively designed population studies up to now [2], reported about the effect of nuchal cord on acid base status of the umbilical artery to some extent, supporting the results of the current study but what we do not know yet is the significance of these effects in long-term for related subjects. This ‘unknown’ makes us reach more cautious conclusions regarding this issue.

Intrapartum fetal heart rate monitoring: evaluation of a standardized system of interpretation for prediction of metabolic acidosis at delivery and neonatal neurological morbidity

Objective: To assess the ability of the intrapartum fetal heart rate interpretation system developed in 2008 by the National Institute of Child Health and Human Development (NICHD) to predict fetal metabolic acidosis at delivery and neonatal neurological morbidity.Methods: We analyzed the intrapartum fetal heart rate tracings of 314 singleton fetuses at ≥37 weeks using the NICHD three-tier system of interpretation: Category I (normal), Category II (indeterminate) and Category III (abnormal). Category II was further divided into Category IIA, with moderate fetal heart rate variability or accelerations, and Category IIB, with minimal/absent fetal heart rate variability and no accelerations. The presence and duration of the different patterns were compared with several clinical neonatal outcomes and with umbilical artery acid-base balance at birth.Results: The mean values of pH and base excess decreased proportionally as tracings worsened (p < 0.001). The duration of at least 30 min for Category III tracings was highly predictive of a pH <7.00 and a base excess ≤−12 mmol/L. The same was true for the duration of Category IIB tracings that lasted for at least 50 min.Conclusions: Our study demonstrates that the interpretation of fetal heart rate tracings based on a strictly standardized system is closely associated with umbilical artery acid-base status at delivery.

Effect of the umbilical cord blood acid‐base status and gas values on the yield of mononuclear cells and CD34+ cells

To investigate the influence of umbilical cord blood (CB) acid-base status and gas values on the yield of mononuclear cells and CD34⁺ cells, pH, pCO₂, pO₂, HCO₃⁻ and base excess were measured in arterial CB samples obtained from normal full-term deliveries. The relationship of these values with the yield of mononuclear cells and CD34⁺ cells detected in venous CB was analyzed. A total of 145 CB units were collected from full-term vaginal deliveries at a single hospital. Immediately after delivery, a segment of the umbilical cord was double clamped, and arterial CB was analyzed to determine the acid-base status and gases. Venous CB was collected in a sterile collection bag and processed for cell separation within 24 h of collection. The relationship between umbilical arterial acid-base status, each gas value, and the yield of mononuclear cells and CD34⁺ cells was analyzed. Statistically significant correlations were observed between the net weight of CB and the total mononuclear and CD34⁺ cell counts. In addition, there was a negative correlation between the mononuclear cell counts and pH, but a positive correlation between the mononuclear cell counts and pCO₂. However, no significant differences were observed between the primipara and multipara groups in terms of the net weight of CB, total mononuclear cell counts and total CD34⁺ cell counts. The findings of the present study show that the mononuclear cell counts are correlated with arterial CB pH and pCO₂, suggesting the involvement of fetal hypoxia on the yield of mononuclear cells.

Intrapartum Fetal Surveillance: Review of Three National Guidelines

Evidence-based guidelines regarding intrapartum fetal surveillance from three countries (United States, Canada, and Australia/New Zealand) were reviewed. The similarities in the three national guidelines (purported etiology, management of periodic changes, and intermittent auscultation for low-risk women) are understandable. Differences in recommendations (role of fetal admission test, amnioinfusion for variable decelerations, scalp pH, umbilical arterial acid-base status, and education in interpretation of fetal heart tracing) are not explained. The likelihood of recommendations being categorized as level A differed for the countries: United States, 41% (7/17); Canada, 18% (3/17); and Australia and New Zealand, 17% (2/12). Only one publication was cited by all three guidelines. To avoid confusion and possibly enhance their quality, national guidelines should acknowledge the presence of others on the same topic, and if there are differences then provide explanations for dissimilarities.

SP6-28 Effect of umbilical cord blood acid-base status and gas values on the yield of mononuclear cells and cd34 cells

PurposeTo investigate the influence of umbilical cord blood (CB) acid-base status and gas values on the yield of mononuclear cells and CD34 cells, pH, pCO2, pO2, HCO3− and base excess...

960 Complications in the Near Term and Term Infants with Severe Umbilical Artery Acidemia

Background and aims: Umbilical artery acidbase status is a useful marker of the fetal condition just before birth. The objective of our study was to determine the newborn complications in near term and term infants associated with umbilical artery acidemia of pH ≤ 7.10. Study design: We retrospectively reviewed the maternal and neonatal records of infant's ≥ 35 weeks, born between March 2007 and February 2010, with umbilical artery blood pH ≤ 7.10. Umbilical artery acidemia was classified as metabolic, respiratory and mixed. Results: 179 babies had an umbilical artery pH of ≤ 7.10, of which 59 had an umbilical artery pH < 7.00 and 120 had pH between 7.00 - 7.10. Overall 129 (72%) babies showed evidence of fetal distress; 82(45%) underwent emergency caesarean section, 41(22%) underwent instrumental vaginal delivery. Table below describes the neonatal complications in the two groups. Table Conclusion: The risk of moderate or severe hypoxic ischemic encephalopathy and neonatal seizures is high if umbilical artery pH is < 7.00 along with presence of mixed or metabolic acidosis. Hence these babies should have cerebral function monitoring at least for the first 24 hours.

Relationship between Twin-to-twin Delivery Interval and Umbilical Artery Acid-base Status in the Second Twin

The purpose of this study was to determine the effect of twin-to-twin delivery interval on umbilical artery acid-base status of the second twin at birth. This was a retrospective cohort study of all live-born twins with measured acid-base status in umbilical arterial blood who were delivered after 34 weeks' gestation from June 2003 to February 2006. Twins with any maternal or fetal complications were excluded. Subjects were divided into two groups based on the mode of delivery of the first twin: normal cephalic vaginal deliveries (n=40) or cesarean deliveries (n=67). The inter-twin differences in umbilical arterial blood pH, PCO2, PO2, and base excess in twin newborns born vaginally were significantly greater than the corresponding differences in those born by cesarean section. A significant positive correlation was found between twin-to-twin delivery interval and inter-twin difference in umbilical arterial blood pH in twin newborns born vaginally. The umbilical arterial blood pH of the second twin was less than 7.0 in 14% (2/14) in cases delivered more than 20 min after the first twin. The umbilical arterial blood gas status of the second twin worsened with increasing twin-to-twin delivery interval, and pathologic fetal acidemia (pH < 7.0) might develop in the second twin when the twin-to-twin delivery interval was greater than 20 min.

The relationship between twin-to-twin delivery interval and umbilical artery acid-base status in the twin newborns

The relationship between twin-to-twin delivery interval and umbilical artery acid-base status in the twin newborns

Anaesthesia for Caesarean section and neonatal acid‐base status: a meta‐analysis*

Spinal anaesthesia is generally preferred for Caesarean section. Its superiority for the baby is often assumed. Umbilical artery acid-base status provides a valid index of fetal welfare. Twenty-seven studies reporting neonatal acid-base data with different types of anaesthesia were used to compare umbilical artery or vein pH and base deficit, using random-effect meta-analysis. Cord pH was significantly lower with spinal than with both general (difference: -0.015; 95% CI -0.029 to -0.001; 13 studies, 1272 subjects) and epidural anaesthesia (difference -0.013; 95% CI -0.024 to -0.002; 11 studies, 828 subjects). Larger doses of ephedrine contributed to the latter effect (p = 0.023). Sixteen studies reported a base deficit, which was significantly higher for spinal than for general (difference 1.109; 95% CI 0.434-1.784 mEq.l(-1); seven studies, 695 subject) and epidural anaesthesia (difference 0.910; 95% CI 0.222-1.598 mEq.l(-1); seven studies, 497 subjects). Spinal anaesthesia cannot be considered safer than epidural or general anaesthesia for the fetus.

The relationship between umbilical artery acid-base status and umbilical artery levels of total creatine kinase and creatine kinase isoenzymes. A preliminary study

The relationship between umbilical artery acid-base status and umbilical artery levels of total creatine kinase and creatine kinase isoenzymes. A preliminary study

The effect of labor on the normal values of umbilical blood acid-base status.

Although several investigators have attempted to define the normal values of umbilical cord blood pH and gases, there is considerable controversy about the optimal cutoff values to diagnosis intrauterine asphyxia. A possible reason for this might be that several studies have included data from fetuses born after different duration of labor. To determine the effect of labor and the duration of second stage on labor on umbilical arterial acid-base status at birth in healthy term infants. Umbilical artery acid-base status was determined in patients (n = 356) who met the following criteria: 1) singleton term pregnancy with no significant medical, obstetric, or neonatal complications; 2) vertex presentation if delivered vaginally; 3) neither regional nor general anesthesia applied if delivered vaginally; 4) no use of oxytocin; 5) normal fetal heart rate patterns; 6) clear amniotic fluid; 7) Apgar scores at 1 and 5 min > or = 7; 8) appropriate fetal weight for gestational age. Patients were divided into three groups. A-patients delivered by cesarean section (CS) in the absence of labor (n = 135); B-patients delivered by CS during first stage of labor (n = 62); C-patients with vaginal birth (n = 159). A Kruskal-Wallis ANOVA with post-hoc procedures and stepwise multiple regression analysis were performed. 1) There were significant differences in cord arterial acid-base values between study groups (pH: no labor CS, 7.27 +/- 0.05 vs labor CS, 7.26 +/- 0.05 vs vaginal birth, 7.24 +/- 0.07, p < 0.00001). 2) There was a significant fall in cord arterial pH and bicarbonate concentrations with increased duration of second stage of labor in newborns born vaginally (pH: duration of second stage, 1-30 min, 7.25 +/- 0.07 vs 31-60 min, 7.22 +/- 0.06 vs > 61 min, 7.21 +/- 0.07, p < 0.05). 3) Analysis of confounding variables which could influence the cord pH such as parity, use of vacuum, gestational age, maternal age, and birth weight by stepwise multiple regression analysis indicated that only the duration of second stage of labor pain had a significant relationship with cord blood pH. There is a significant fall in umbilical artery pH and bicarbonate with the presence of labor and increased duration of second stage of labor in healthy term neonates. This should be taken into consideration in evaluating neonatal well-being by cord blood pH and acid-base measurements.

Relationship between fetal cardiac and extra-cardiac Doppler flow velocity waveforms and neonatal outcome in intrauterine growth retardation

In a total of 42 consecutive pregnancies with intrauterine growth retardation (IUGR), Doppler velocimetry was related to neonatal outcome as determined by Apgar score at 1 min, umbilical artery acid-base status and Po 2, number of nucleated red blood cells (NRBC), duration of ventilatory support, and sonographic appearance of cerebral leukomalacia. Doppler flow velocity waveforms were obtained from the ascending aorta (AO), pulmonary artery (PA), internal carotid artery (ICA) and umbilical artery (UA) at 2–3 day intervals until delivery. At cardiac level the peak systolic velocity (PSV) and time-averaged velocity (AV), and at peripheral level the pulsatility index (PI) was determined. As all Doppler parameters were significantly related to gestational age at birth, gestational age was taken into account in the analysis. There was no relationship between Apgar score, acid-base status and Doppler parameters. Low AVAO was related to a low umbilical artery Po 2. Significant correlations were established between PSVPA, AVPA and PIUA, and the duration of neonatal ventilatory support. Infants who died within 22 days after admission to the neonatal intensive care unit ( n = 7) displayed a significantly higher PIUA than those who remained alive. The PIUA was also related to the absolute and relative number of NRBCs. No relationship existed between the Doppler parameters and degree of leukomalacia. The present study demonstrates that from all Doppler parameters, the PIUA is most clearly related to neonatal outcome in IUGR. intrauterine growth retardation; fetal cardiac outflow tract; Doppler ultrasonography; neonatal outcome

Epidural Versus General Anaesthesia for Elective Caesarean Section Effect on Apgar Score and Acid-Base Status of the Newborn

Summary Elective Caesarean section deliveries over a 5-year period were studied to compare the effect of epidural block with general anaesthesia on the condition of the infant at birth. The Apgar score and umbilical arterial acid-base status were used as determinants of the latter. Epidural block was used in 139 (22.8%) mothers while 471 (77.2%) were performed under general anaesthesia. No babies in the epidural group were severely depressed (Apgar < 4), compared with 6.2% in the general anaesthesia group. Only 4.3% of the epidural sections were moderately depressed (Apgar 4–6), compared with 15.4% of the others. These differences remained highly significant when infants of less than 2500 g were excluded, and when matched groups were compared. Mean umbilical arterial pH was similar within the two groups (pH 7.28), and was not consistent with asphyxia in almost 90% of the depressed infants. The findings suggest that general anaesthesia, rather than asphyxia or aortocaval compression, is responsible for most of the depressed infants born by elective Caesarean section. This may involve over 20% of babies delivered in this manner, so greater use of epidural block for elective Caesarean section is recommended. Further investigations are required to improve results with general anaesthesia.

Umbilical arterial acid-base status at birth in term infants and outcome at age four and a half years : Ann Johnson, J. Dennis, L. Mutch, P. Yudkin and P. Johnson, Department of Obstetrics, John Radcliffe Hospital, University of Oxford, U.K.

Umbilical arterial acid-base status at birth in term infants and outcome at age four and a half years : Ann Johnson, J. Dennis, L. Mutch, P. Yudkin and P. Johnson, Department of Obstetrics, John Radcliffe Hospital, University of Oxford, U.K.