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

Umbilical artery eucapnic pH to assess fetal well-being

BACKGROUND

Umbilical artery gas results help obstetricians assess fetal well-being during labor and guide screening decisions on eligibility for therapeutic hypothermia (ie, whole-body or head cooling). The accuracy of results, especially for the base deficit on arterial cord gas analysis, in predicting brain injury is questioned. A novel biomarker specifically calculated for fetal acid-base physiology and response to asphyxia-neonatal eucapnic pH as a marker of neonatal metabolic acidosis-has the potential to be an accurate predictor of hypoxic-ischemic encephalopathy.

OBJECTIVE

We aimed to compare false-negative rates of hypoxic-ischemic encephalopathy for umbilical artery pH, base deficit, and neonatal eucapnic pH in assessing fetal acid-base balance as a marker of fetal well-being and predicting acute brain injury.

STUDY DESIGN

This is a retrospective single-center cohort study of newborns ≥ 35 weeks of gestation diagnosed with hypoxic-ischemic encephalopathy. We compared false-negative rates for any grade of hypoxic-ischemic encephalopathy using unilateral paired chi-square statistical analysis based on cutoff values for umbilical artery pH ≤7.00, base deficit ≥16 mmol/L, base deficit ≥12 mmol/L and neonatal eucapnic pH ≤7.14. We performed an analysis of variance between umbilical artery pH, base deficit, and neonatal eucapnic pH for each hypoxic-ischemic encephalopathy grade.

RESULTS

We included 113 newborns. False-negative rate for hypoxic-ischemic encephalopathy was significantly higher for base deficit <16 mmol/L (n=78/113; 69.0%) than <12 mmol/L (n=46/113; 40.7%), pH >7.00 (n=41/113; 36.3%), or neonatal eucpanic pH >7.14 (n=35/113; 31.0%) (P<.0001). All true-positive cases were identified using only umbilical artery pH and neonatal eucapnic pH. Base deficit ≥16 or ≥12 mmol/L did not add any value in identifying newborns with hypoxic-ischemic encephalopathy when using umbilical artery pH and neonatal eucapnic pH. No association emerged between any marker and hypoxic-ischemic encephalopathy severity grading.

CONCLUSION

Our findings support the accuracy of neonatal eucapnic pH to assess fetal well-being during labor and to improve predictive performance for acute brain injury. Neonatal eucpanic pH, in addition to umbilical artery pH, may be a viable alternative in identifying newborns at risk for hypoxic-ischemic encephalopathy.

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.

Fetal brain response to worsening acidosis: an experimental study in a fetal sheep model of umbilical cord occlusions

Perinatal anoxia remains an important public health problem as it can lead to hypoxic-ischaemic encephalopathy (HIE) and cause significant neonatal mortality and morbidity. The mechanisms of the fetal brain's response to hypoxia are still unclear and current methods of in utero HIE prediction are not reliable. In this study, we directly analysed the brain response to hypoxia in fetal sheep using in utero EEG. Near-term fetal sheep were subjected to progressive hypoxia induced by repeated umbilical cord occlusions (UCO) at increasing frequency. EEG changes during and between UCO were analysed visually and quantitatively, and related with gasometric and haemodynamic data. EEG signal was suppressed during occlusions and progressively slowed between occlusions with the increasing severity of the occlusions. Per-occlusion EEG suppression correlated with per-occlusion bradycardia and increased blood pressure, whereas EEG slowing and amplitude decreases correlated with arterial hypotension and respiratory acidosis. The suppression of the EEG signal during cord occlusion, in parallel with cardiovascular adaptation could correspond to a rapid cerebral adaptation mechanism that may have a neuroprotective role. The progressive alteration of the signal with the severity of the occlusions would rather reflect the cerebral hypoperfusion due to the failure of the cardiovascular adaptation mechanisms.

Prevention of fetal brain injury in category II tracings

INTRODUCTION

With category II fetal heart rate tracings, the preferred timing of interventions to prevent fetal hypoxic brain damage while limiting operative interventions remains unclear. We aimed to estimate fetal extracellular base deficit (BDecf ) during labor with category II tracings to quantify the timing of potential interventions to prevent severe fetal metabolic acidemia.

MATERIAL AND METHODS

A longitudinal study was conducted using the database of the Recurrence Prevention Committee, Japan Obstetric Compensation System for Cerebral Palsy, including infants with severe cerebral palsy born at ≥34 weeks' gestation between 2009 and 2014. Cases included those presumed to have an intrapartum onset of hypoxic-ischemic insult based on the fetal heart rate pattern evolution from reassuring to an abnormal pattern during delivery, in association with category II tracings marked by recurrent decelerations and an umbilical arterial BDecf  ≥ 12 mEq/L. BDecf changes during labor were estimated based on stages of labor and the frequency/severity of fetal heart rate decelerations using the algorithm of Ross and Gala. The times from the onset of recurrent decelerations to BDecf 8 and 12 mEq/L (Decels-to-BD8, Decels-to-BD12) and to delivery were determined. Cases were divided into two groups (rapid and slow progression) based upon the rate of progression of acidosis from onset of decelerations to BDecf 12 mEq/L, determined by a finite-mixture model.

RESULTS

The median Decels-to-BD8 (28 vs. 144 min, p < 0.01) and Decels-to-BD12 (46 vs. 177 min, p < 0.01) times were significantly shorter in the rapid vs slow progression. In rapid progression cases, physicians' decisions to deliver the fetus occurred at ~BDecf 8 mEq/L, whereas the "decisions" did not occur until BDecf reached 12 mEq/L in slow progression cases.

CONCLUSIONS

Fetal BDecf reached 12 mEq/L within 1 h of recurrent fetal heart rate decelerations in the rapid progression group and within 3 h in the slow progression group. These findings suggest that cases with category II tracings marked by recurrent decelerations (i.e., slow progression) may benefit from operative intervention if persisting for longer than 2 h. In contrast, cases with sudden bradycardia (i.e., rapid progression) represent a challenge to prevent severe acidosis and hypoxic brain injury due to the limited time opportunity for emergent delivery.

Umbilical Cord Blood Gas Pairs with Near-Identical Results: Probability of Arterial or Venous Source

OBJECTIVE

 In studies of concomitant arterial-venous umbilical cord blood gases (CAV-UBGs), approximately 10% of technically valid samples have very similar pH and/or pCO2 values and were probably drawn from the same type of blood vessel. Without a way to objectively determine the source in these cases, it has been argued that most of these same-source CAV-UBGs are venous because the vein is larger and more easily sampled than the artery. This study aimed to calculate the probability of an arterial (ProbAS) or venous source (ProbVS) of same-source CAV-UBGs in the clinically and medicolegally important pH range of 6.70 to 7.25 using a statistical predictive model based on the cord blood gas values.

STUDY DESIGN

 Starting with a dataset of 56,703 CAV-UBGs, the ProbAS, ProbVS, and respective 95% confidence intervals (CIs) were calculated for the 241 sample pairs with near-identical pH, pCO2, and pO2 values and a pH of 6.70 to 7.25. Using a previously validated generalized additive model, the source was categorized as: Probable Arterial or Highly Probable Arterial if the ProbAS and CIs were >0.5 or >0.8, respectively; Probable Venous or Highly Probable Venous if the ProbVS and CIs were >0.5 or >0.8, respectively; or Indeterminant if the CIs encompassed ProbAS/VS = 0.5.

RESULTS

 A total of 39% of the same-source CAV-UBGs were Probable Arterial, 56% were Probable Venous, and 5% were Indeterminant. However, considering samples with a pH ≤7.19, 80% were Probable Arterial and 16% were Probable Venous. Considering the Highly Probable categories, the more acidemic specimens were 9 times more likely to be arterial than venous. Similarly, CAV-UBGs with pCO2 > 8.2 kPa (62 mm Hg) or pO2 ≤ 1.9 kPa (14 mm Hg) were more likely to be in the arterial rather than the venous categories.

CONCLUSION

 Same-source CAV-UBGs in the more acidemic, hypercarbic, or hypoxemic ranges are more likely to be arterial than venous.

KEY POINTS

· Umbilical cord arterial/venous gases (CAV-UBGs) with similar values are thought to be mainly venous.. · A validated statistical model was used to predict the probability an arterial or venous source.. · CAV-UBGs with very similar values and pH >  7.19 are likely venous; however, those with pH ≤ 7.19 and/or pCO2 >  8.2 kPa and/or pO2 ≤1.9 kPa are more likely arterial..

Neonatal serial creatinine levels as an adjunct biomarker in timing of fetal neurologic injury

Objective

To investigate the rise and clearance of newborn creatinine in perinatal asphyxia as an adjunct biomarker to support or refute allegations of acute intrapartum asphyxia.

Study design

In this retrospective chart review, newborns > 35 weeks gestational age were evaluated from closed medicolegal cases of confirmed perinatal asphyxia and reviewed for causation. Data collected included newborn demographic data, patterns of hypoxic ischemic encephalopathy, brain magnetic resonance imaging, Apgar scores, cord and initial newborn blood gases, and serial newborn creatinine levels during the first 96 h of life. Newborn serum creatinine values were collected at 0-12, 13-24, 25-48, and 49-96 h. Newborn brain magnetic resonance imaging was used to define 3 patterns of asphyxial injury: acute profound, partial prolonged, or Both.

Results

Two hundred and eleven cases of neonatal encephalopathy from multiple institutions were reviewed from 1987 to 2019 with only 76 cases having serial creatinine values during the first 96 h of life. A total of 187 creatinine values were collected. Partial prolonged and Both had significantly greater degree of metabolic acidosis in the first newborn arterial blood gas in comparison to acute profound. Acute profound and Both had significantly lower 5- and 10- minute Apgar scores in comparison to partial prolonged. Newborn creatinine values were stratified by asphyxial injury. Acute profound injury showed minimally elevated creatinine trends with rapid normalization. Partial prolonged and Both demonstrated higher creatinine trends with delayed normalization. Mean creatinine values were significantly different between the three types of asphyxial injuries within 13-24 h of life at the time when creatinine values peaked (p = 0.01).

Conclusion

Serial newborn serum creatinine levels taken within the first 96 h of life can provide objective data of timing and duration of perinatal asphyxia.

Infection Induced Fetal Inflammatory Response Syndrome (FIRS): State-of- the-Art and Medico-Legal Implications-A Narrative Review

Fetal inflammatory response syndrome (FIRS) represents the fetal inflammatory reaction to intrauterine infection or injury, potentially leading to multiorgan impairment, neonatal mortality, and morbidity. Infections induce FIRS after chorioamnionitis (CA), defined as acute maternal inflammatory response to amniotic fluid infection, acute funisitis and chorionic vasculitis. FIRS involves many molecules, i.e., cytokines and/or chemokines, able to directly or indirectly damage fetal organs. Therefore, due to FIRS being a condition with a complex etiopathogenesis and multiple organ dysfunction, especially brain injury, medical liability is frequently claimed. In medical malpractice, reconstruction of the pathological pathways is paramount. However, in cases of FIRS, ideal medical conduct is hard to delineate, due to uncertainty in diagnosis, treatment, and prognosis of this highly complex condition. This narrative review revises the current knowledge of FIRS caused by infections, maternal and neonatal diagnosis and treatments, the main consequences of the disease and their prognoses, and discusses the medico-legal implications.

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.

Association of labour duration in spontaneous deliveries with low neonatal Apgar scores and foetal acidosis: the Japan Environment and Children's Study

This study evaluated the association between labour duration (LD) and incidence of low neonatal Apgar scores and foetal acidosis. Data of 37,682 women with full-term singleton spontaneous vaginal deliveries from the Japan Environment and Children's Study were analysed. Women were classified according to the median LD as nulliparous (< 10 or ≥ 10 h) or multiparous (< 5 or ≥ 5 h) and further into five subcategories: nulliparous (< 10.0, 10.0-12.9, 13.0-15.9, 16.0-18.9, and ≥ 19 h) and multiparous (< 5.0, 5.0-7.9, 8.0-10.9, 11.0-13.9, and ≥ 14.0 h). Multiple logistic regression models were used to determine odds ratios (ORs) for outcomes in women with over-median LD. Over-median LD exhibited no statistically significant association with low neonatal Apgar scores. The adjusted ORs for both umbilical artery (UmA-pH) < 7.2 and < 7.1 were increased in nulliparous women with over-median LD, whereas only the adjusted OR for UmA-pH < 7.2 was increased in multiparous women with over-median LD. Moreover, this association manifested as a plateau in nulliparous women with LD ≥ 13 h and without dose-dependent association in multiparous women.

Medico-legal considerations in the context of neonatal encephalopathy and therapeutic hypothermia

Neonatal encephalopathy (NE) is a significant complication of the peripartum period. It can lead to lifelong neurologic disabilities, including cerebral palsy, cognitive impairments, developmental delays, and epilepsy. Induced hypothermia is the first therapy, which has shown promise in improving the outcomes for neonates with moderate to severe NE following a presumed intrapartum insult. NE is also a frequent source of medical malpractice litigation. In this paper, we will review salient features of the American Tort System as it pertains to medical malpractice. We will discuss the obstetric medico-legal implications of therapeutic hypothermia and suggest a five-step approach to analyzing neonatal cases for causation, etiology, timing of occurrence, responsibility, and liability. We will close with three illustrative clinical cases.

Ischemic hypoxic encephalopathy: The role of MRI of neonatal injury and medico-legal implication

Hypoxic ischemic encephalopathy is one of the major causes of neonatal death and neurological disability in the child, and represents the most common birth injury claim. Intrapartum asphyxia often leads to several long-term sequalae, such as cerebral palsy and/or developmental delay, epilepsy. Through the neuroimaging it's possible to identify and define the different lesioned pictures and provide useful elements to establish the moment in which the damage occurred; indeed, timing of injury is a key element in the legal arena. Magnetic resonance imaging (MRI) is emerging as one of the most important tools in identifying the etiologic of neonatal encephalopathy as well as in predicting long-term outcomes. The aim of this study is to evaluate all MRI tests performed in a group of infants and young patients with possible neonatal encephalopathy, in order to determine the role of MRI in perinatal hypoxic-ischemic damage and the specific patterns that can point towards a diagnosis of the time of the damage's onset. Another goal is to assess the role of MRI in cases subject to legal-medical ligation. Since the advent of hypothermic neuroprotection, new malpractice allegations have arisen, including the failure to initiate cooling in a timely manner. In all cases, documentation of the status of the baby at birth, including a thorough neurologic exam, can be extremely helpful to the later defence of a malpractice claim, which might occur years later.

Effects of acute tocolysis using ritodrine hydrochloride on foetal heart rate patterns in intrauterine foetal resuscitation: a retrospective, single-centre observational study

No consistent recommendations concerning the preferred tocolytic agents for intrauterine foetal resuscitation are available. We evaluated the effects of acute tocolysis (AT) using ritodrine hydrochloride on foetal heart rate (FHR) patterns and neonatal outcomes. We retrospectively analysed the data of patients undergoing emergency caesarean section because of non-reassuring foetal status indicated by foetal scalp electrodes. Patients were classified into AT (ritodrine hydrochloride approximately 500 µg/min) and control groups with 15 and 12 participants, respectively. FHR patterns, Apgar scores, umbilical arterial analysis, and neonatal admission were compared. All participants had FHR category II; decelerations disappeared in all foetuses in the AT group, with no significant difference in neonatal outcomes. The AT group had a higher baseline FHR and lower short-term FHR variability than the control group, indicating foetal autonomic responses. Further studies are needed to clarify the effects of AT on FHR patterns, neonatal outcomes, and foetal and neonatal autonomic responses.Impact statementWhat is already known on this subject? The usefulness of acute tocolysis using ritodrine hydrochloride has been well-documented in several studies; however, such an application often induces side effects, such as maternal tachycardia, palpitations, and tremors.What the results of this study add? The short-term administration of ritodrine hydrochloride eliminated decelerations, with no significant difference in neonatal outcomes in pregnant women with foetal heart rate category II. Meanwhile, there were higher foetal heart rate and lower short-term foetal heart rate variability in pregnant women administered with ritodrine hydrochloride, indicating foetal autonomic responses.What the implications are of these findings for clinical practice and/or further research? Ritodrine hydrochloride administration, even for short-term, appears to be associated with foetal autonomic responses. Further studies with stratification of patient groups based on the severity and aetiology of non-reassuring foetal status, including pregnant women with foetal category III, would elucidate the risk and benefit of acute tocolysis using ritodrine hydrochloride, based on foetal heart rate patterns, neonatal outcomes, and foetal and neonatal autonomic responses.

Forensic Analysis of Umbilical and Newborn Blood Gas Values for Infants at Risk of Cerebral Palsy

Cerebral palsy litigation cases account for the highest claims involving obstetricians/gynecologists, a specialty that ranks among the highest liability medical professions. Although epidemiologic studies indicate that only a small proportion of cerebral palsy (10-20%) is due to birth asphyxia, negligent obstetrical care is often alleged to be the etiologic factor, resulting in contentious medical-legal conflicts. Defense and plaintiff expert opinions regarding the etiology and timing of injury are often polarized, as there is a lack of established methodology for analysis. The objective results provided by umbilical cord and newborn acid/base and blood gas values and the established association with the incidence of cerebral palsy provide a basis for the forensic assessment of both the mechanism and timing of fetal neurologic injury. Using established physiologic and biochemical principles, a series of case examples demonstrates how an unbiased expert assessment can aid in both conflict resolution and opportunities for clinical education.

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.

Training in the use of intrapartum electronic fetal monitoring with cardiotocography: systematic review and meta‐analysis

Background

Sub‐optimal classification, interpretation and response to intrapartum electronic fetal monitoring using cardiotocography are known problems. Training is often recommended as a solution, but there is lack of clarity about the effects of training and which type of training works best.

Objectives

Systematic review of the effects of training healthcare professionals in intrapartum cardiotocography (PROSPERO protocol: CRD42017064525).

Search strategy

CENTRAL, Cochrane Library, MEDLINE, EMBASE, PsycINFO, British Nursing Database, CINAHL, ERIC, Scopus, Web of Science, ProQuest, grey literature and ongoing clinical trials were searched.

Selection criteria

Primary studies that reported impact of training healthcare professionals in intrapartum cardiotocography. Title/abstract, full‐text screening and quality assessment were conducted in duplicate.

Data collection and analysis

Data were synthesised both narratively and using meta‐analysis. Risk of bias and overall quality were assessed with the Mixed Methods Appraisal Tool and GRADE.

Main results

Sixty‐four studies were included. Overall, training and reporting were heterogeneous, the outcomes evaluated varied widely and study quality was low. Five randomised controlled trials reported that training improved knowledge of maternity professionals compared with no training, but evidence was of low quality. Evidence for the impact of cardiotocography training on neonatal and maternal outcomes was limited, showed inconsistent effects, and was of low overall quality. Evidence for the optimal content and method of delivery of training was very limited.

Conclusions

Given the scale of harm and litigation claims associated with electronic fetal monitoring, the evidence‐base for training requires improvement. It should address intervention design, evaluation of clinical outcomes and system‐wide contexts of sub‐optimal practice.

Tweetable abstract

Training in fetal monitoring: systematic review finds little evidence of impact on neonatal outcomes.

Training in fetal monitoring: systematic review finds little evidence of impact on neonatal outcomes.

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.

Earlier and improved screening for impending fetal compromise

OBJECTIVE

The use of pH and base excess (FSSPHBE) from fetal scalp sampling (FSS) was abandoned when cardiotocography (CTG) was believed to be sufficiently accurate to direct patient management. We sought to understand the fetus' tolerance to stress in the 1st stage of labor and to develop a better and earlier screening test for its risk for developing acidosis. To do so, we investigated sequential changes in fetal pH and BE obtained from FSS in the 1st stage of labor as part of a research protocol from the 1970s. We then examined the utility of multiple of the median (MoM's) conversion of BE and pH values, and the capacity of Fetal Reserve Index (FRI) scores to be a proxy for such changes. We then sought to examine the predictive capacity of 1st stage FRI and its change over the course of the first stage of labor for the subsequent development of acidosis risk in the 2nd stage of labor.

METHODS

Using a retrospective research database evaluation, we evaluated FSSPHBE data from 475 high-risk parturients monitored in labor and their neonates for 1 h postpartum. We categorized specimens according to cervical dilatation (CxD) at the time of FSSPHBE and developed non-parametric, multiples of the median (MOMs) assessments. FRI scores and their change over time were used as predictors of FSSPHBE. Our main outcome measures were the changes in BE and pH at different cervical dilatations (CxD) and acidosis risk in the early 2nd stage of labor.

RESULTS

FSSPHBE worsens over the course of the 1st stage. The implications of any given BE are very different depending upon CxD. At 9 cm, -8 Mmol/L is 1.1 MOM; at 3 cm, it would be 2.0 MOM. The FRI level and its trajectory provide a 1st stage screening tool for acidosis risk in the second stage.

CONCLUSIONS

Fetal acid-base balance ("reserve") deteriorates beginning early in the 1st stage of labor, irrespective of whether the fetus reaches a critical threshold of concern for actual acidosis. The use of MoM's logic improves appreciation of such information. The FRI and its trajectory reasonably approximate the trajectory of the FSSPHBE and appears to be a suitable screening test for early deterioration and for earlier interventions to keep the fetus out of trouble rather than wait until high risk status develops.

FIRS: Neonatal considerations

Fetal Inflammatory Response Syndrome (FIRS) is the fetal counterpart of systemic inflammatory response syndrome (SIRS) described in adults. When the fetus is directly exposed to inflammation of the fetal membranes or the placental-fetal circulation, and organs are adversely affected, the disorder is known as FIRS. This syndrome can significantly affect multiple organs with significant short and long term implications for the newborn. In cases of neonatal encephalopathy when no obvious etiology is identified, FIRS needs to be considered. Based on the significant incidence of chorioamnionitis and its potential effects on the newborn, any evidence of maternal, fetal, or neonatal infection should mandate further evaluation of the placenta and membrane histopathology.

The most common patient safety issues resulting in legal action against neonatologists

Common patient safety issues may result in injuries to babies in the newborn period. A medical malpractice lawsuit is one way in which an injured patient can obtain compensation for the injuries they sustained as the result of an error. There are a number of common areas of malpractice risk for neonatologists including the delivery room, jaundice, hypoglycemia, and late preterm infants. A better understanding of the medical malpractice system and common patient safety issues in neonatology can lead to protective strategies to reduce risk for untoward events and subsequent litigation. Strategies including maintaining competency, following national guidelines, and proper communication and documentation can improve the care and treatment of neonatal patients and their families resulting in less malpractice exposure.

Umbilical artery base deficit/excess: sailing blindly in a thick fog

Assessing the wellbeing of newborns at birth with base deficit (BD)/base excess(BE) is well anchored in clinicians' practice. However, clinicians may not fully understand the concepts behind BD and the concerns regarding the validity of BD results provided by the hospital laboratory. These concerns are linked to the inconsistencies between the equations to calculate BD, and that these equations do not consider the aspects of acid-base physiology at birth. Additionally, the evidence-based supporting BD threshold in the literature to help physicians in making decisions is rather insufficient. These considerations support the need to review practice guidelines that use BD to guide decisions and bring to an end to clinicians to sail blindly in a thick fog.

Combined prenatal and postnatal prediction of early neonatal compromise risk

OBJECTIVE

Electronic fetal monitoring/cardiotocography (EFM) is nearly ubiquitous, but almost everyone acknowledges there is room for improvement. We have contextualized monitoring by breaking it down into quantifiable components and adding to that, other factors that have not been formally used: i.e. the assessment of uterine contractions, and the presence of maternal, fetal, and obstetrical risk factors. We have created an algorithm, the Fetal Reserve Index (FRI) that significantly improves the detection of at-risk cases. We hypothesized that extending our approach of monitoring to include the immediate newborn period could help us better understand the physiology and pathophysiology of the decrease in fetal reserve during labor and the transition from fetal to neonatal homeostasis, thereby further honing the prediction of outcomes. Such improved and earlier understanding could then potentiate earlier, and more targeted use of neuroprotective attempts during labor treating decreased fetal reserve and improving the fetus' transition from fetal to neonatal life minimizing risk of neurologic injury.

STUDY DESIGN

We have analyzed a 45-year-old research database of closely monitored labors, deliveries, and an additional hour of continuous neonatal surveillance. We applied the FRI prenatally and created a new metric, the INCHON index that combines the last FRI with umbilical cord blood and 4-minute umbilical artery blood parameters to predict later neonatal acid/base balance. Using the last FRI scores, we created 3 neonatal groups. Umbilical cord and catheterized umbilical artery bloods at 4, 8, 16, 32, and 64 minutes were measured for base excess, pH, and PO₂. Continuous neonatal heart rate was scored for rate, variability, and reactivity.

RESULTS

Neonates commonly do not make a smooth transition from fetal to postnatal physiology. Even in low risk babies, 85% exhibited worsening pH and base excess during the first 4 minutes; 34% of neonates reached levels considered at high risk for metabolic acidosis (≤-12 mmol/L) and neurologic injury. Neonatal heart rate commonly exhibited sustained, significant tachycardia with loss of reactivity and variability. One quarter of all cases would be considered Category III if part of the fetal tracing. Our developed metrics (FRI and INCHON) clearly discriminated and predicted low, medium, and high-risk neonatal physiology.

CONCLUSIONS

The immediate neonatal period often imposes generally unrecognized risks for the newborn. INCHON improves identification of decreased fetal reserve and babies at risk, thereby permitting earlier intervention during labor (intrauterine resuscitation) or potentially postnatally (brain cooling) to prevent neurologic injury. We believe that perinatal management would be improved by routine, continuous neonatal monitoring - at least until heart rate reactivity is restored. FRI and INCHON can help identify problems much earlier and more accurately than currently and keep fetuses and babies in better metabolic shape.

Cumulative deceleration area: a simplified predictor of metabolic acidemia

OBJECTIVE

Fetal monitoring, ubiquitous in obstetrics is used to predict and prevent intrapartum fetal injury. Despite decades of education and nomenclature revision, clinicians show low agreement on key elements, including the types of deceleration and hence their presumed etiology. Cumulative deceleration area is not dependent on deceleration type and could potentially mitigate this problem. Although deceleration area has shown promise as a marker of acidemia, no reports have shown how deceleration area evolves in late labor. Advances in computerization allow for direct measurement of deceleration area and standard fetal heart rate (FHR) patterns. The objective of this study was to compare the evolution and discrimination performance of deceleration area and other FHR patterns in late labor in term neonates with metabolic acidemia (MA) and in those with normal cord gases.

METHODS

This retrospective cohort study included women with a term singleton (≥37 weeks) in cephalic presentation with cord gas data and FHR tracings available for analysis. MA included neonates with an umbilical artery base deficit >12 mmol/L (n = 132). Controls included those with normal cord gases (base deficit <8 mmol/L) and a 5-minute Apgar score of >6 (n = 1498). Deceleration area and other FHR patterns were summarized and compared in 30-minute segments over the last five hours. Receiver-operating characteristic curves were constructed and AUCs compared.

RESULTS

Deceleration area had the highest AUC (0.702, 95% CI 0.655-0.749) and was a superior marker of MA compared to baseline (AUC 0.588, 95% CI 0.530-0.645), baseline variability (AUC 0.611, 95% CI 0.558-0.663), and number of late decelerations (AUC 0.582, 95% CI 0.527-0.637).

CONCLUSION

Cumulative deceleration area reduces the necessity to determine deceleration type. In a single number, it objectively quantifies three important aspects of decelerations; frequency, depth and duration and was a superior marker of MA compared to baseline level, baseline variability and number of late decelerations. The acidemia group had higher deceleration area over the last two hours prior to delivery. This result indicates that the cumulative area and persistence of repetitive decelerations is important clinically.