Umbilical Artery Base Excess Research Articles

Association of Prenatal Maternal Fever and Neonatal Umbilical Artery Blood-Gas Analysis: Evidence from a Tertiary Center at China

Background: Neonatal umbilical artery blood-gas analysis is a diagnostic procedure performed shortly after birth to assess the acid-base balance, oxygenation, and metabolic status of a newborn infant. This retrospective study aimed to investigate the association of prenatal maternal fever with neonatal umbilical artery blood-gas analysis. Methods: A retrospective analysis was conducted on data from 333 parturients and their newborns. Demographic characteristics, clinical information, and neonatal umbilical artery blood gas analysis data were analyzed to evaluate the association between prenatal maternal fever and neonatal blood-gas analysis. Pregnant women with fever (≥38.0 °C) during labor were compared with those without fever. Neonatal umbilical artery blood gas parameters were assessed in relation to the degree and duration of maternal fever. Results: The incidence of the adverse delivery outcome of parturients with high prenatal fever and long duration of fever was significantly higher than that of the low fever, short-term fever, and normal parturients (p < 0.05). The pH of neonatal umbilical veins in the high fever groups was reduced compared with the control group (p < 0.05). Lactic acid (Lac) of neonatal umbilical vein in the low fever and high fever groups was enhanced compared with the control group (p < 0.05). The pH of neonatal umbilical veins in the short-term fever and long-term fever groups was elevated compared with the control group (p < 0.05). The umbilical artery pH and base excess (BE) were positively correlated with maternal peak fever temperature (r = 0.20, r = 0.22, p < 0.05). The umbilical Lac was negatively correlated with maternal peak fever temperature (r = –0.22, p < 0.05). Moreover, the umbilical artery pH and BE were positively correlated with maternal duration of fever (r = 0.29, r = 0.21, p < 0.05). The umbilical artery Lac was negatively correlated with maternal duration of fever (r = –0.25, p < 0.05). Conclusions: The findings suggested that maternal fever during labor was associated with alterations in neonatal umbilical artery blood gas analysis. Understanding the influence of prenatal fever on delivery outcomes is crucial for optimizing maternal and neonatal health.

Case Report: Peripartum periventricular leukomalacia resulting in cerebral palsy associated with placenta previa in Japan

Intrapartum fetal heart rate monitoring abnormalities had been reported to correlate with decreased umbilical artery base excess associated with neonatal seizures. However, we present an infant born at 35 weeks of gestation diagnosed with cerebral palsy associated with periventricular leukomalacia (PVL) without fetal heart rate (FHR) monitoring abnormalities, According to the summary reports of PVL cases published on the home page of the Japan Obstetric Compensation System for Cerebral Palsy (JOCSC)), the percentage of placenta previa without FHR monitoring abnormalities in the cases of PVL was 5.7% (12/209), which seemed to be higher than the total percentage of placenta previa reported in Japan (0.3–0.5%).

A Comparison of Norepinephrine versus Phenylephrine to Prevent Hypotension after Spinal Anesthesia for Cesarean Section: Systematic Review and Meta-Analysis.

This systematic review and meta-analysis aimed to compare the effects of using phenylephrine or norepinephrine on the pH and base excess (BE) of the umbilical artery and vein in parturients undergoing cesarean section. The study protocol was registered in INPLASY. Independent researchers searched Ovid-Medline, Ovid-EMBASE, and Cochrane Central Register of Controlled Trials (CENTRAL) databases and Google Scholar for relevant randomized controlled trials (RCTs). The primary outcome of this study was the umbilical artery (UA) or umbilical vein (UV) pH as neonatal condition at birth, and the secondary outcome was the UA or UV BE as an additional prognostic value over the measurement of umbilical pH. There was no evidence of a difference between phenylephrine and norepinephrine for overall, UA, and UV pH (mean difference (MD) -0.001, 95% confidence interval (CI) -0.004 to 0.007; MD 0.000, 95%CI -0.004 to 0.004; and MD 0.002, 95%CI -0.013 to 0.017). There was also no evidence of a difference between phenylephrine and norepinephrine for overall, UA, and UV BE (MD 0.096, 95% CI -0.258 to 0.451; MD 0.076, 95%CI -0.141 to 0.294; and MD 0.121, 95%CI; -0.569 to 0.811). A meta-regression showed that factors such as umbilical artery or vein, infusion method, single or twin, and the number of parturients per study had no effect on the UA pH, UV pH, UA BE, or UV BE. No evidence of publication bias was detected. There was no evidence of a difference between phenylephrine and norepinephrine for umbilical pH and BE. A subgroup analysis and meta-regression also did not show evidence of differences.

Minimum effective dose of intrathecal hyperbaric bupivacaine for cesarean section with and without prophylactic norepinephrine infusion: Randomized triple-blinded trial.

Vasopressor usage can affect the rostral spread of intrathecal drug and, hence, its requirement during cesarean delivery. Although a decreased spread is evidenced with phenylephrine, there is no data for norepinephrine usage. The present study aimed to evaluate the minimum effective dose of intrathecal hyperbaric bupivacaine for cesarean section with and without prophylactic norepinephrine infusion. Patients scheduled for elective cesarean section under combined spinal-epidural block were randomized to receive intravenous infusion of norepinephrine (0.05 μg/kg/min) or normal saline (placebo), initiated immediately after intrathecal injection. Postspinal hypotension in either group (systolic arterial pressure ≤0.8 baseline) was treated with norepinephrine 4 μg rescue. Dose of intrathecal hyperbaric bupivacaine (0.5%) was decided for individual patients using up-and-down sequential allocation method. Primary outcome measure was the minimum effective dose of intrathecal hyperbaric bupivacaine (0.5%) defined as ED50, while secondary observations included spinal block characteristics and neonatal outcomes. Demographic parameters were statistically similar between both groups (P > 0.05). ED50 of intrathecal hyperbaric bupivacaine was 7.8 mg (95% confidence interval [CI]: 6.7-8.8) and 7.4 mg (95% CI: 6.1-8.7) for normal saline and norepinephrine group respectively (P = 0.810). Block characteristics were similar between both groups as was neonatal APGAR score, but umbilical artery base excess was greater for norepinephrine versus normal saline group (-4.4 ± 3.6 vs. -6.5 ± 2.4, P = 0.038). Use of prophylactic norepinephrine (0.05 μg/kg/min) during cesarean delivery does not require adjustment of intrathecal hyperbaric bupivacaine.

Complex umbilical cord entanglement: A case report

Background: Complex umbilical cord entanglement occurs less frequently and is associated with an increased risk of adverse perinatal outcomes. It is associated with umbilical artery pH and base excess levels that are significantly unfavorable, higher incidence of nonreassuring fetal heart rate, meconium-stained amniotic fluid, neonatal intensive care unit admissions, emergency cesarean section, and stillbirth. Case presentation: A 44-year-old para 2+0 gravida 3, with 2 previous cesarean delivery scars at 35 weeks presented with a history of reduced fetal movements for 24 hours. She had attended two antenatal care visits. Her blood group was A, rhesus negative, with hemoglobin levels of 11.2 g/dl, and normal platelets. Urinalysis and serology for HIV, hepatitis B, and Venereal Disease Research Laboratory test were nonreactive. She had received anti-D prophylaxis after her previous deliveries. An urgent obstetric ultrasound scan showed features consistent with intrauterine fetal death. Her coagulation profile was within the normal range. She was admitted for hysterotomy. Intraoperatively, a fresh stillborn baby boy was extracted with a cord around the neck tightly twice and entangled around the trunk. Conclusion: Complex umbilical cord entanglement occurs less frequently and associated with an increased risk of adverse perinatal outcomes. The risk of adverse perinatal outcomes increases with ≥3 loops of the umbilical cord. It is important to look out for cord entanglement antenatally by ultrasonography, particularly when assessing cases of decreased fetal movements.

Neonatal outcomes in pregnancies complicated by placenta accreta- a matched cohort study

PurposePregnancies complicated by placenta accreta spectrum (PAS) are associated with severe maternal morbidities. The aim of this study is to describe the neonatal outcomes in pregnancies complicated with PAS compared with pregnancies not complicated by PAS.MethodsA retrospective cohort study conducted at a single tertiary center between 03/2011 and 01/2022, comparing women with PAS who underwent cesarean delivery (CD) to a matched control group of women without PAS who underwent CD. We evaluated the following adverse neonatal outcomes: umbilical artery pH < 7.0, umbilical artery base excess ≤ − 12, APGAR score < 7 at 5 min, neonatal intensive care unit (NICU) admission, mechanical ventilation, hypoxic ischemic encephalopathy, seizures and neonatal death. We also evaluated a composite adverse neonatal outcome, defined as the occurrence of at least one of the adverse neonatal outcomes described above. Multivariable regression analysis was used to determine which adverse neonatal outcome were independently associated with the presence of PAS.Results265 women with PAS were included in the study group and were matched to 1382 controls. In the PAS group compared with controls, the rate of composite adverse neonatal outcomes was significantly higher (33.6% vs. 18.7%, respectively, p < 0.001). In a multivariable logistic regression analysis, Apgar score < 7 at 5 min, NICU admission and composite adverse neonatal outcome were independently associated with PAS.ConclusionNeonates in PAS pregnancies had higher rates of adverse outcomes. Apgar score < 7 at 5 min, NICU admission and composite adverse neonatal outcome were independently associated with PAS.

Delivery of a Fetus with a Non-Reassuring Status Is Associated with Significant Maternal Morbidity

Objectives: When a labor process is complicated by non-reassuring fetal status (NRFS), obstetricians focus on delivery to optimize neonatal status. We explored maternal morbidity in the setting of NRFS. Our hypothesis is that delivery of a live newborn with NRFS is associated with significant maternal morbidity. Design, Participants, Setting, and Methods: A large retrospective cohort study of 27,886 women who delivered between January 2013 and December 2016 in a single health system was studied. Inclusion criteria included (1) women over the age of 18 at the time of admission; (2) singleton pregnancy; (3) live birth; and (4) gestational age greater than or equal to 37 weeks at the time of admission. NRFS was defined as umbilical cord pH less than or equal to 7.00, fetal bradycardia, late decelerations, and/or umbilical artery base excess ≤−12. Univariate and multivariate logistic regression and propensity score analyses were performed, and propensity score adjusted odds ratios (AORPS) were derived. p values <0.05 were considered statistically significant. Primary outcomes are maternal blood transfusion, maternal readmission, maternal intensive care unit (ICU) admission, and cesarean delivery in relation to umbilical artery pH, fetal bradycardia, and late decelerations. Results: Umbilical artery pH less than or equal to 7 was associated with maternal blood transfusion (AORPS 6.83 [95% CI 2.22–21.0, p < 0.001]), maternal readmission (AORPS 12.6 [95% CI 2.26–69.8, p = 0.0039]), and cesarean delivery (AORPS 5.76 [95% CI 3.63–9.15, p < 0.0001]). Fetal bradycardia was associated with transfusion (AORPS 2.13 [95% CI 1.26–3.59, p < 0.005]) and maternal ICU admission (AORPS 3.22 [95% CI 1.23–8.46, p < 0.017]). Late decelerations were associated with cesarean delivery (AORPS 1.65 [95% CI 1.55–1.76, p < 0.0001]), clinical chorioamnionitis (AORPS 2.88 [95% CI 2.46–3.37, p < 0.0001]), and maternal need for antibiotics (AORPS 1.89 [95% CI 1.66–2.15, p < 0.0001]). Umbilical artery base excess less than or equal to −12 was associated with readmission (AORPS 6.71 [95% CI 2.22–20.3, p = 0.0007]), clinical chorioamnionitis (AORPS 1.89 [95% CI 1.24–2.89, p = 0.0031]), and maternal need for antibiotics (AORPS 1.53 [95% CI 1.03–2.26, p = 0.0344]). Limitations: The retrospective design contributes to potential bias compared to the prospective design. However, by utilizing multivariate logistic regression analysis with a propensity score method, specifically inverse probability of treatment weighting, we attempted to minimize the impact of confounding variables. Additionally, only a portion of the data set had quantitative blood losses recorded, while the remainder had estimated blood losses. Conclusion: NRFS is associated with significant maternal complications, in the form of increased need for blood transfusions, ICU admissions, and increased infection and readmission rates. Strategies for minimizing maternal complications need to be proactively considered in the management of NRFS.

Hemodynamic maintenance with norepinephrine in caesarean section under spinal anesthesia and its fetal outcome: a systematic review

Background: Postspinal hypotension is a frequent maternal complication in caesarean delivery under neuraxial anesthesia. Anesthesiologists have been using different vasopressors to maintain hemodynamics. Recent studies suggested beneficial effects of norepinephrine on maternal blood pressure and cardiac output, but little evidence exist on the neonatal outcome. Objectives: This systematic review summarises recent evidence on neonatal outcome, such as umbilical arterial pH and base excess, after administration of norepinephrine during caesarean section. Methods: A literature search on PubMed from 2010 to 2022 was performed and every article was reviewed on neonatal outcome, as primary endpoint and on maternal hemodynamics, as secondary endpoint. A total of 15 randomised controlled trials were included. Results: Studies using a prophylactic infusion of norepinephrine show normal fetal blood gases. No evidence of fetal stress (pH &lt; 7,20, base excess &lt; -6) was assessed in the studies. Norepinephrine succeed in maintaining maternal hemodynamics. It is responsible for less bradycardia than phenylephrine and less tachycardia than ephedrine. Conclusion: Our study suggests that norepinephrine, preferably as prophylactic infusion, is a safe vasopressor to prevent postspinal hypotension in caesarean section. No signs of fetal acidosis could be demonstrated in the recent studies.

Real-time imaging as visual biofeedback in active second stage of labor among nulliparas: a randomized controlled trial

A prolonged second stage of labor increases the risk of severe perineal laceration, postpartum hemorrhage, operative delivery, and poor Apgar score. The second stage is longer in nulliparas. Maternal pushing during the second stage of labor is an important contributor to the involuntary expulsive force developed by uterine contraction to deliver the fetus. Preliminary data indicate that visual biofeedback during the active second stage hastens birth. This study aimed to evaluate if visual feedback focusing on the perineum reduced the length of the active second stage of labor in comparison with the control. A randomized controlled trial was conducted in the University Malaya Medical Centre from December 2021 to August 2022. Nulliparous women about to commence the active second stage, at term, with singleton gestation, reassuring fetal status, and no contraindication for vaginal delivery were randomized to live viewing of the maternal introitus (intervention) or maternal face (sham/placebo control) as visual biofeedback during their pushing. A video camera Bluetooth-linked to a tablet computer display screen was used; in the intervention arm, the camera was focused on the introitus, and in the control arm, on the maternal face. Participants were instructed to watch the display screen during their pushing. The primary outcomes were the intervention-to-delivery interval and maternal satisfaction with the pushing experience assessed using a 0-to-10 visual numerical rating scale. Secondary outcomes included mode of delivery, perineal injury, delivery blood loss, birthweight, umbilical cord arterial blood pH and base excess at birth, Apgar score at 1 and 5 minutes, and neonatal intensive care unit admission. Data were analyzed with the t test, Mann-Whitney U test, chi-square test, and Fisher exact test, as appropriate. A total of 230 women were randomized (115 to intervention and 115 to control arm). The active second stage duration (intervention-to-delivery interval) was a median (interquartile range) of 16 (11-23) and 17 (12-31) minutes (P=.289), and maternal satisfaction with the pushing experience was 9 (8-10) and 7 (6-7) (P<.001) for the intervention and control arm, respectively. Women randomized to the intervention arm were more likely to agree to recommend their management to a friend (88/115 [76.5%] vs 39/115 [33.9%]; relative risk, 2.26 [95% confidence interval, 1.72-2.97]; P<.001) and more likely to have less severe perineal injury (P=.018). Real-time viewing of the maternal introitus as visual biofeedback during pushing resulted in higher maternal satisfaction compared with the sham control of viewing the maternal face; however, the time to delivery was not significantly shortened.

Rate of decline of fetal base excess after neuraxial anesthesia for scheduled cesarean delivery

In scheduled cesarean deliveries, the rate of decrease in the umbilical artery pH is related to the severity of maternal hypotension and the interval from spinal placement to delivery. Base excess values have greater use than umbilical artery pH values to time the duration of fetal acidemia because they demonstrate a linear rather than logarithmic correlation with the degree of acidosis. This study aimed to evaluate the rate of decline in the fetal base excess in scheduled cesarean deliveries that were converted to emergency cesarean delivery owing to fetal bradycardia following spinal anesthesia. All cases of scheduled cesarean deliveries in gestations at >34 weeks' gestation under spinal anesthesia that were converted to emergency cesarean deliveries owing to fetal bradycardia in the period May 2019 to May 2021 were reviewed. Included were those with (1) a preoperative reactive nonstress test and (2) fetal acidemia (umbilical artery pH <7.20). Excluded were those with anesthesia other than spinal and a birthweight below the 10th percentile for gestational age. Time intervals between the completion of spinal anesthesia and delivery were calculated and related to umbilical cord gas analytes. From a cohort of 1064 scheduled cesarean deliveries, 7 fulfilled the study criteria yielding 8 neonates. Mean ± standard error of the mean interval of spinal anesthesia to delivery was 15.0±1.9 minutes, and the decrease in mean blood pressure after spinal anesthesia was 39.1±3.0 mm Hg. Umbilical artery base excess ranged from -5.2 to -16.6 mmol/L (median, -8.0). Based on published normative data of prelabor fetal umbilical artery base excess (-2±0.6 mmol/L), the mean rate of base excess decrease was 0.38±0.25 mmol/minute. The rate of decrease in base excess when scheduled cesarean deliveries are converted to emergency cesarean deliveries owing to fetal bradycardia related to spinal anesthesia (1 mmol/2.6 min) matches the estimated rate of loss of base excess (1 mmol/2-3 minutes) reported in cases of severe bradycardia or sentinel events during labor.

Neonatal outcome of infants with umbilical cord arterial pH less than 7.

Umbilical arterial pH of less than 7 is often used as the threshold below which the risks of neonatal death and adverse long-term neurological outcomes are considered to be higher. Yet within the group with pH <7, the risks have not been further stratified. Here, we aimed to investigate the predictors of adverse long-term outcomes of this group of infants. This was a retrospective study of 248 infants born after 34 weeks of gestation in a tertiary obstetric unit, between 2003 and 2017, with cord arterial pH <7 or base excess ≤-12 mmol/L at birth. The infants were categorized into two groups: (1) intact survivors, or (2) neonatal/infant deaths or cerebral palsy or developmental delay. The umbilical arterial pH and base excess levels, Apgar scores, mode of delivery, gestational age, small for gestational age, birth in the era before the implementation of neonatal hypothermic therapy, and the presence of a known sentinel event, were compared between the groups using univariate analysis followed by multivariate analysis. Among the 248 infants, there were 222 intact survivors (89.5%) and 26 infants with poor outcomes (10.5%), including eight deaths (3.2%) and 18 (7.3%) with cerebral palsy and/or developmental delay. Univariate analysis showed that infants with adverse outcomes had significantly lower cord arterial pH (6.85 vs 6.95, with p < 0.001), lower cord arterial base excess (-19.95 vs -15.90 mmol/L, p < 0.001), a higher proportion of having AS at 5min <7 (65.4% vs 13.1%, p < 0.001), and a higher proportion of having a sentinel event (34.6% vs 16.7%, p=0.034). Multivariate analysis confirmed cord arterial pH of <6.9 and an Apgar score at 5min <7 as independent prognostic factors (the adjusted odds ratios were 4.64 and 6.62, respectively). The risk of adverse outcome increased from 4.3% when the arterial pH was between 6.9 and <7, to 30% when the pH was <6.9. Infants born with umbilical artery pH <7 still have a high chance of 89.5% to become intact survivors. A cord arterial pH of <6.9 and an Apgar score at 5min <7 are independent prognostic factors for neonatal/infant death or adverse long-term neurological outcomes.

Case Report: Peripartum periventricular leukomalacia resulting in cerebral palsy associated with placenta previa in Japan

Intrapartum fetal heart rate monitoring abnormalities had been reported to correlate with decreased umbilical artery base excess associated with neonatal seizures. However, we present an infant born at 35 weeks of gestation diagnosed with cerebral palsy associated with periventricular leukomalacia (PVL) without fetal heart rate (FHR) monitoring abnormalities, According to the summary reports of PVL cases published on the home page of the Japan Obstetric Compensation System for Cerebral Palsy (JOCSC)), the percentage of placenta previa without FHR monitoring abnormalities in the cases of PVL was 5.7% (12/209), which seemed to be higher than the total percentage of placenta previa reported in Japan (0.3-0.5%).

Does acute funisitis predict worse neonatal outcomes among term newborns?

Acute funisitis-the histologic diagnosis of inflammation within the umbilical cord-represents a fetal inflammatory response to infection. Although acute funisitis has been associated with an increased risk of adverse outcomes among preterm neonates, there are limited and conflicting data with term deliveries. This study aimed to evaluate the association between acute funisitis and neonatal morbidity in neonates born at term to pregnant patients with a clinical diagnosis of intraamniotic infection. This was a retrospective cohort study of pregnant patients who had clinically diagnosed intraamniotic infection at term, delivered vaginally at a single tertiary institution from 2013 to 2019, and had histologic chorioamnionitis on placental pathology. Patients with intrauterine fetal demise or missing neonatal/placental pathology data were excluded. The primary outcome was a neonatal sepsis composite, defined as culture-positive bacteremia, neutropenia (absolute neutrophil count<3500/μL), or immature-to-total neutrophil ratio>0.2. The secondary outcomes included composite neonatal morbidity, defined as neonatal intensive care unit admission, 5-minute Apgar score <7, bacteremia, endotracheal intubation or need for continuous positive airway pressure, intraventricular hemorrhage (grade 3 or 4), necrotizing enterocolitis (stage 3 or 4), umbilical artery pH<7.1, umbilical artery base excess>12, and neonatal mortality. The components of these composites, neonatal intensive care unit length of stay, and Kaiser early-onset sepsis score were also measured. Neonates with acute funisitis on pathology were compared with those without acute funisitis using bivariate statistics. Regression was used to estimate the relative risk of outcomes. Of 184 neonates with deliveries complicated by intraamniotic infection, acute funisitis was present in 109 (59%) placental specimens. Composite neonatal sepsis was significantly higher among neonates with acute funisitis (relative risk, 1.85; 95% confidence interval, 1.13-3.03) than in those without acute funisitis. As a marker for sepsis, acute funisitis has a sensitivity of 39.4%, negative predictive value of 47.2%, specificity of 78.7%, and positive predictive value of 72.9%. An immature-to-total neutrophil ratio>0.2 (relative risk, 1.83; 95% confidence interval, 1.09-3.08) was also significantly associated with acute funisitis. Neonatal morbidity composite, intraventricular hemorrhage, necrotizing enterocolitis, neonatal intensive care unit admission, higher Kaiser early-onset sepsis scores, and other examined outcomes were not statistically associated with acute funisitis. In term deliveries complicated by intraamniotic infection, acute funisitis was associated with increased neonatal sepsis. Current approaches for estimating neonatal sepsis risk are limited by their reliance on indirect maternal factors such as maximum maternal temperature and intrapartum antibiotic use. This study suggests that acute funisitis may serve as a marker that could be utilized to augment risk stratification at birth if a protocol for evaluating the umbilical cord in real-time were widely adopted.

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.

Association of umbilical cord blood gas values with mortality and severe neurologic injury in preterm neonates

Umbilical cord arterial and venous blood gas values reflect the acid-base balance status of a newborn at birth. Derangement in these values has been linked to poor neonatal outcomes in term and late preterm neonates; however, the utility of these values in preterm neonates of <29 weeks' gestation is unclear. This study aimed to determine the associations of umbilical cord arterial and venous blood gas values with neonatal mortality and severe neurologic injury in extremely preterm neonates and to identify the cutoff values associated with 2.5-fold increases or decreases in the posttest probabilities of outcomes. This was a retrospective cohort study of neonates who were born at 23+0 to 28+6 weeks' gestation between January 1, 2018 and December 31, 2019, and who were admitted to neonatal units in Canada. Various cut-offs of umbilical cord blood gas values and lactate values were studied. The main outcomes were mortality before discharge from the neonatal unit and severe neurologic injury defined as grade 3 or 4 periventricular or intraventricular hemorrhage or periventricular leukomalacia. The outcome rates were calculated for various cutoff values of umbilical cord blood gas parameters and were adjusted for birthweight, gestational age, sex, and multiple births. Likelihood ratios were calculated to derive posttest probabilities. A total of 1040 and 1217 neonates had analyzable umbilical cord arterial and venous blood gas values, respectively. In the cohort, the mean (standard deviation) gestational age was 26.5 (1.5) weeks, the mean birthweight was 936 (215) g, the prevalence of mortality was 10% (105/1040), and the prevalence of severe neurologic injury was 9% (92/1016). An umbilical cord arterial pH of ≤7.1 and base excess of ≤-12 mmol/L were associated with >2.5-fold higher posttest probability of mortality, and an umbilical cord arterial or venous lactate value of <3 was associated with a 2.5-fold lower posttest probability of mortality. An umbilical cord arterial lactate value of <3 was associated with a lower posttest probability of severe neurological injury. In preterm neonates of <29 weeks' gestation, low umbilical cord arterial pH and high umbilical cord arterial base excess values were associated with a clinically important increase in the posttest probability of mortality, whereas low umbilical cord arterial or venous lactate values were associated with a decrease in the posttest probability of mortality.

English

BACKGROUND Subarachnoid block has been widely used for caesarean sections and is found to be safe. Hypotension being the most common complication may adversely affect both the mother and foetus. Different measures used to treat this hypotension include preloading with crystalloids/colloids and treatment with vasopressors. The standard choice of vasopressor agents such as ephedrine and phenylephrine is still a controversial issue. It is therefore important to compare the efficacy of the two drugs in the prevention and treatment of maternal hypotension after subarachnoid block and particularly assess their effect on the foetus. The purpose of this study was to assess and compare the foetal acid-base status and APGAR score following administration of bolus dose of ephedrine or phenylephrine that was given intravenously for maintenance of arterial blood pressure during lower segment caesarean section (LSCS) under a subarachnoid block. METHODS 100 parturients (18 to 35 years) scheduled for elective caesarean section under subarachnoid block were selected and divided into two groups of 50 each. Group P received 50 mcg i.v bolus of phenylephrine and Group E received 6 mg of ephedrine IV bolus whenever the blood pressure dropped 20 % from baseline or systolic blood pressure ˂ 90 mmHg. Haemodynamic parameters were measured in all patients. APGAR scores at 1 and 5 minutes following delivery of baby were assessed and cord blood was obtained for acid-base status analysis immediately following delivery. RESULTS Hemodynamic parameters including heart rate, systolic blood pressure, diastolic blood pressure, and mean arterial pressure did not show any significant difference between the two groups, however, Group E showed higher heart rates. The difference in umbilical artery pH (P-value &lt; 0.001) and base excess (P-value = 0.004) was statistically significant with Group E showing lower pH and higher base excess values than Group P. There was no statistically significant difference in neonatal APGAR scores between the two groups. CONCLUSIONS Phenylephrine and ephedrine are equally efficient in managing hypotension during subarachnoid block for caesarean delivery. Thus, either vasopressor can be used although phenylephrine may be a better choice. KEY WORDS Caesarean Section, Phenylephrine, Ephedrine.

Neonatal outcomes following prophylactic administration of phenylephrine or noradrenaline in women undergoing scheduled caesarean delivery: A randomised clinical trial.

There is limited evidence to support the use of noradrenaline over phenylephrine during elective caesarean section with regards to its impact on foetal acidosis. Concerns regarding a deleterious effect of noradrenaline on foetal blood gas analysis because of its β-mimetic activity cannot currently be ruled out by data from randomised controlled trials. We hypothesised that noradrenaline would be associated with higher umbilical artery base excess values and less foetal acidosis compared with phenylephrine. This study aimed to observe the effect of prophylactic infusions of phenylephrine or noradrenaline in low-risk elective caesarean delivery on umbilical artery blood gas analysis. A prospective, randomised, double-blind trial. Labour room operating theatre of tertiary care hospital in Northern India from April 2020 to November 2020. Full-term, nonlabouring pregnant women, scheduled for elective caesarean delivery under spinal anaesthesia. Equipotent prophylactic infusions of either phenylephrine 100 μg min-1 or noradrenaline 5 μg min-1 were administered to maintain maternal SBP between 90 and 110% of baseline using a predefined algorithm. The primary outcome was umbilical artery base excess in noradrenaline versus the phenylephrine group. The incidence of foetal acidosis defined as umbilical artery base excess less than -6 mmol l-1 was also assessed for noradrenaline versus phenylephrine. Median [IQR] umbilical artery base excess was significantly higher in the noradrenaline group: -5.4 [-6.6 to -4.03] versus -6.95 [-9.02 to -4.53] in the phenylephrine group (P = 0.014). No significant difference in the incidence of foetal acidosis was observed between noradrenaline and phenylephrine groups: 36 versus 54% (P 0.07); difference 18% (95% CI, -1.4 to 35.6%). Prophylactic noradrenaline 5 μg min-1 infusion resulted in higher base excess values compared with phenylephrine 100 μg min-1 infusion. A comparable incidence of foetal acidosis was observed in women receiving either noradrenaline or phenylephrine. Maternal bradycardia was more pronounced with phenylephrine while targeting blood pressure goals. CTRI/2020/03/023986.

670 Neonatal outcomes after cesarean for non-reassuring fetal status in the first stage of labor

Non-reassuring fetal status (NRFS) is the second most common indication for cesarean delivery (CD) accounting for 1 in 4 cesareans. We sought to evaluate neonatal outcomes following CD for NRFS. This was a secondary analysis of a prospective cohort study. We included singleton term pregnancies admitted for labor or induction of labor between 2010-2014. The primary outcome was fetal acidemia defined as umbilical artery (UA) pH < 7.1. Secondary outcomes were UA base excess, lactate, and neonatal composite morbidity (hypoxic-ischemic encephalopathy, meconium aspiration syndrome, hypothermia treatment, intubation, mechanical ventilation, neonatal seizure, death). The exposure was first stage CD for any indication that included NRFS and the control group was all other deliveries. Multivariable logistic regression and the Zhang method was used to estimate relative risk and adjust for confounders. We also performed a sensitivity analysis of patients who underwent CD for the sole indication of NRFS. Of the 8580 patients in the cohort, 721 (8.4%) had a first stage CD for NRFS. Among these, 476 (66.0%) were for the sole indication of NRFS. The risk of fetal acidemia was 5 times higher among patients undergoing CD for NRFS compared to all other deliveries (7.3% vs 1.2%, aRR 5.45[95% CI 3.35-8.68]). UA base excess and lactate were higher among patients with CD for NRFS. CD for NRFS was associated with an increased risk of composite neonatal morbidity (4.0% vs 1.0%, aRR 2.52 [95% CI 1.30-4.78]). After restricting the analysis to patients who had CD for the sole indication of NRFS, the risk of fetal acidemia and neonatal morbidity remained significantly higher in the CD for NRFS group than control deliveries. CD for NRFS is associated with an increased risk of fetal acidemia and composite neonatal morbidity. Although the vast majority of infants delivered for NRFS have normal outcomes, these results suggest that the diagnosis of NRFS using continuous fetal monitoring in labor is predictive of adverse outcomes.

1067 Electronic FHR monitoring, pH and newborn outcomes – this is as good as it gets

To examine the relationship between umbilical artery (UA) cord gas values and fetal tolerance of labor and/or delivery. We hypothesized the existence of wide biologic variability in fetal tolerance of metabolic acidemia which, if present, would weaken a fundamental assumption underlying the use of EFHRM. A retrospective cohort study of term, singleton fetuses delivered between 2012 and 2020. Universal cord gases were collected. Umbilical cord gas values and Apgar scores were extracted. We calculated Spearman correlation coefficients (CC) and constructed ROC curves for UA pH and base excess (BE) as predictors of Apgar score. Our cohort included cord gas and Apgar scores from 29,787 deliveries. The statistical correlation between UA pH and BE and both 1 and 5 minute Apgar scores was weak or non-existent in both the group as a whole and in all pH range sub-groups (Table 1). ROC curve analysis of pH as a predictor of 5 minute Apgar >=7 showed only an acceptable discrimination (AUC= 0.75 95%CI 0.71-0.79, p< 0.01)) with a similar story for base excess (AUC=0.745 95%CI 0.708-0.782, p< 0.01). Subgroup analysis of deliveries with pH >7.2 or BE >-4 showed even poorer predictive ability (Figure 1). Of 8 newborns who underwent cooling for HIE, 3 (38%) had UA pH > 7.15. The use of EFHRM is predicated upon a documented correlation between certain FHR patterns and UA pH, and an arbitrary, presumed correlation between pH and fetal tolerance of labor/delivery, as reflected in newborn condition. To the extent that the latter relationship is invalid, the former correlation is irrelevant. Our data demonstrate a weak to absent correlation between metabolic acidemia and even short term fetal condition, confirming wide biologic variability in fetal tolerance of the hypoxic stress of labor and significantly weakening this latter assumption. No amount of future tweaking of FHR pattern interpretation is likely to result in improved newborn outcomes given this flaw in one fundamental assumption upon which FHRM is based.View Large Image Figure ViewerDownload Hi-res image Download (PPT)

Maternal Oxygen Supplementation Compared With Room Air for Intrauterine Resuscitation

Supplemental oxygen is commonly administered to pregnant women at the time of delivery to prevent fetal hypoxia and acidemia. There is mixed evidence on the utility of this practice. To compare the association of peripartum maternal oxygen administration with room air on umbilical artery (UA) gas measures and neonatal outcomes. Ovid MEDLINE, Embase, Scopus, ClinicalTrials.gov, and Cochrane Central Register of Controlled Trials were searched from February 18 to April 3, 2020. Search terms included labor or obstetric delivery and oxygen therapy and fetal blood or blood gas or acid-base imbalance. Studies were included if they were randomized clinical trials comparing oxygen with room air at the time of scheduled cesarean delivery or labor in patients with singleton, nonanomalous pregnancies. Studies that did not collect paired umbilical cord gas samples or did not report either UA pH or UA Pao2 results were excluded. Data were extracted by 2 independent reviewers. The analysis was stratified by the presence or absence of labor at the time of randomization. Data were pooled using random-effects models. The primary outcome for this review was UA pH. Secondary outcomes included UA pH less than 7.2, UA Pao2, UA base excess, 1- and 5-minute Apgar scores, and neonatal intensive care unit admission. The meta-analysis included 16 randomized clinical trials (n = 1078 oxygen group and n = 974 room air group). There was significant heterogeneity among the studies (I2 = 49.88%; P = .03). Overall, oxygen administration was associated with no significant difference in UA pH (weighted mean difference, 0.00; 95% CI, -0.01 to 0.01). Oxygen use was associated with an increase in UA Pao2 (weighted mean difference, 2.57 mm Hg; 95% CI, 0.80-4.34 mm Hg) but no significant difference in UA base excess, UA pH less than 7.2, Apgar scores, or neonatal intensive care unit admissions. Umbilical artery pH values remained similar between groups after accounting for the risk of bias, type of oxygen delivery device, and fraction of inspired oxygen. After stratifying by the presence or absence of labor, oxygen administration in women undergoing scheduled cesarean delivery was associated with increased UA Pao2 (weighted mean difference, 2.12 mm Hg; 95% CI, 0.09-4.15 mm Hg) and a reduction in the incidence of UA pH less than 7.2 (relative risk, 0.63; 95% CI, 0.43-0.90), but these changes were not noted among those in labor (Pao2: weighted mean difference, 3.60 mm Hg; 95% CI, -0.30 to 7.49 mm Hg; UA pH<7.2: relative risk, 1.34; 95% CI, 0.58-3.11). This systematic review and meta-analysis suggests that studies to date showed no association between maternal oxygen and a clinically relevant improvement in UA pH or other neonatal outcomes.