The paradox of electronic fetal monitoring: more data may not enable us to predict or prevent infant neurologic morbidity

Intrapartum fetal monitoring and perinatal risk factors of neonatal hypoxic-ischemic encephalopathy

BACKGROUND

Neonatal hypoxic-ischemic encephalopathy (HIE) in term infants, is a major cause of neonatal mortality and severe neurologic disability.

OBJECTIVES

To identify in labor fetal monitoring characteristic patterns and perinatal factors associated with neonatal HIE.

STUDY DESIGN

Single-center retrospective case-control study between 2010 and 2017. Cases clinically diagnosed with neonatal HIE treated by therapeutic hypothermia according to strict criteria (HIE-TH) were compared to a group of neonates born in the same period, gestational age-matched diagnosed with fetal distress according to fetal monitoring interpretation that was followed by prompt delivery, without subsequent HIE or therapeutic hypothermia (No-HIE). The primary outcome of the study was the electronic fetal monitoring (EFM) pattern during 60 min prior to delivery; the secondary outcome was the identification of perinatal associated factors.

RESULTS

54 neonates with HIE were treated by therapeutic hypothermia. EFM parameters most predictive of HIE-TH were indeterminate baseline heart rate OR = 47.297, 95% (8.17-273.76) p < 0.001, bradycardia OR = 15.997 95% (4.18-61.18) p < 0.001, low variability OR = 10.224, 95% (2.71-38.45) p < 0.001, higher baseline of the fetal heart rate calculated for each increment of 1 BPM OR = 1.0547, 95% (1.001-1.116) p = 0.047. Rupture of a previous uterine cesarean scar and placental abruption were characteristic of the HIE-TH group 14.8% vs. 1% p < 0.05; and 16.7% vs. 6% p < 0.05, respectively. Adverse neonatal outcomes also differed significantly: HIE-TH had a higher rate of neonatal seizures 46.2% vs. 0% p < 0.001 and mortality 7.7% vs. 0% p < 0.001.

CONCLUSIONS

Characteristic fetal monitoring pattern prior to delivery together with acute obstetric emergency events are associated with neonatal HIE, neurological morbidity, and mortality.

Fetal Development: Voice Processing in Normotensive and Hypertensive Pregnancies

Recent observation of maternal voice recognition provides evidence of rudimentary memory and learning in healthy term fetuses. However, such higher order auditory processing has not been examined in the presence of maternal hypertension, which is associated with reduced and/or impaired uteroplacental blood flow. In this study, voice processing was examined in 40 fetuses (gestational ages of 33 to 41 weeks) of hypertensive and normotensive women. Fetuses received 2 min of no sound, 2 min of a tape-recorded story read by their mothers or by a female stranger, and 2 min of no sound while fetal heart rate was recorded. Results demonstrated that fetuses in the normotensive group had heart rate accelerations during the playing of their mother's voice, whereas the response occurred in the hypertensive group following maternal voice offset. Across all fetuses, a greater fetal heart rate change was observed when the amniotic fluid index was above compared to below the median (i.e., 150 mm), indicating that amniotic fluid volume may be an independent moderator of fetal auditory sensitivity. It was concluded that differential fetal responding to the mother's voice in pregnancies complicated by maternal hypertension may reflect functional elevation of sensorineural threshold or a delay in auditory system maturation, signifying functional differences during fetal life or subtle differences in the development of the central nervous system.

Fetal heart rate monitoring: from Doppler to computerized analysis

The monitoring of fetal heart rate (FHR) status is an important method to check well-being of the baby during labor. Since the electronic FHR monitoring was introduced 40 years ago, it has been expected to be an innovative screening test to detect fetuses who are becoming hypoxic and who may benefit from cesarean delivery or operative vaginal delivery. However, several randomized controlled trials have failed to prove that electronic FHR monitoring had any benefit of reducing the perinatal mortality and morbidity. Also it is now clear that the FHR monitoring had high intra- and interobserver disagreements and increased the rate of cesarean delivery. Despite such limitations, the FHR monitoring is still one of the most important obstetric procedures in clinical practice, and the cardiotocogram is the most-used equipment. To supplement cardiotocogram, new methods of computerized FHR analysis and electrocardiogram have been developed, and several clinical researches have been currently performed. Computerized equipment makes us to analyze beat-to-beat variability and short term heart rate patterns. Furthermore, researches about multiparameters of FHR variability will be ongoing.

IUGR management: new perspectives

AIM OF THE STUDY

Analyzing velocimetric (umbilical artery, UA; ductus venosus, DV; middle cerebral artery, MCA) and computerized cardiotocographic (cCTG) (fetal heart rate, FHR; short term variability, STV; approximate entropy, ApEn) parameters in intrauterine growth restriction, IUGR, in order to detect early signs of fetal compromise. POPULATION STUDY: 375 pregnant women assisted from the 28th week of amenorrhea to delivery and monitored through cCTG and Doppler ultrasound investigation. The patients were divided into three groups according to the age of gestation at the time of delivery, before the 34th week, from 34th to 37th week, and after the 37th week. Data were analyzed in relation to the days before delivery and according to the physiology or pathology of velocimetry. Statistical analysis was performed through the t-test, chi-square test, and Pearson correlation test (P < 0.05). Our results evidenced an earlier alteration of UA, DV, and MCA. The analysis between cCTG and velocimetric parameters (the last distinguished into physiological and pathological values) suggests a possible relation between cCTG alterations and Doppler ones. The present study emphasizes the need for an antenatal testing in IUGR fetuses using multiple surveillance modalities to enhance prediction of neonatal outcome.

Electronic fetal heart rate monitoring and its relationship to neonatal and infant mortality in the United States

OBJECTIVE

To examine the association between electronic fetal heart rate monitoring and neonatal and infant mortality, as well as neonatal morbidity.

STUDY DESIGN

We used the United States 2004 linked birth and infant death data. Multivariable log-binomial regression models were fitted to estimate risk ratio for association between electronic fetal heart rate monitoring and mortality, while adjusting for potential confounders.

RESULTS

In 2004, 89% of singleton pregnancies had electronic fetal heart rate monitoring. Electronic fetal heart rate monitoring was associated with significantly lower infant mortality (adjusted relative risk, 0.75); this was mainly driven by the lower risk of early neonatal mortality (adjusted relative risk, 0.50). In low-risk pregnancies, electronic fetal heart rate monitoring was associated with decreased risk for Apgar scores <4 at 5 minutes (relative risk, 0.54); in high-risk pregnancies, with decreased risk of neonatal seizures (relative risk, 0.65).

CONCLUSION

In the United States, the use of electronic fetal heart rate monitoring was associated with a substantial decrease in early neonatal mortality and morbidity that lowered infant mortality.

Umbilical cord blood gas analysis in augmented labour

Labour augmentation with oxytocin may produce an excessive increase in frequency, duration or strength in uterine contractions which may result in fetal stress. Umbilical cord acid-base assessment provides an objective parameter in evaluating the neonatal condition immediately after delivery. We evaluated the neonatal condition in 235 deliveries where oxytocin was used for labour augmentation. The umbilical cord blood acid-base status was correlated with intrapartum cardiotocographic findings and Apgar scores. In two cases we noted umbilical artery pH <7.05 but the BDecF was not higher than 11 mmol/l and the 5-minute Apgar score was 8 in all cases. Our results indicate that the use of oxytocin for labour augmentation had no adverse effects on neonatal condition.

Maternal Heart Rate Variability and Fetal Behavior in Hypertensive and Normotensive Pregnancies

The relation between maternal heart rate variability (HRV) and fetal behavior was examined in hypertensive and normotensive pregnant women. A total of 40 mother—fetal pairs (n = 20 normotensive mothers; n = 20 hypertensive mothers) at 33—41 weeks' gestation were observed using a standardized procedure lasting approximately 50 min. It included the following measurements: maternal beat-by-beat arterial blood pressure and HRV; spontaneous fetal heart rate (HR), body and breathing movements; and an estimate of amniotic fluid volume. The women in the hypertensive group had higher average body mass index (BMI) (33.7 vs. 28.8 kg/m2) than the normotensive group. In the normotensive group, there was no association between maternal HRV and fetal gestational age, HR, body or breathing movements. In the hypertensive group, maternal HRV measures of low-frequency, high-frequency, and total power were associated with fetal gestational age; also, there was an association between maternal autonomic modulation of HR and fetal spontaneous HR. These findings suggest that the maternal autonomic system influences fetal cardiac function in pregnancies complicated by hypertension.

Intrapartum fetal monitoring today

The literature on intrapartum fetal monitoring is reviewed emphasizing the pathophysiology, and current practice guidelines are discussed. FHR monitoring, ancillary tests, and investigational modalities are considered.

Developing a tool to appraise fetal monitoring guidelines for women at low obstetric risk

AIM

The aim of this paper is to report the development and use of a tool to appraise guidelines for fetal heart rate monitoring and discuss the findings generated in the appraisal process.

BACKGROUND

Expert guidance on the appropriate method of monitoring the fetal heart in labour has been available for some time. However, practices not based on evidence were continuing routinely in the United Kingdom.

METHODS

We produced an 18-item tool for the appraisal of guidelines. Heads of Midwifery Services were asked to send the guideline currently in use. Twenty-four out of 28 responded, and sent 32 guidelines. Pairs of multidisciplinary reviewers appraised each guideline.

RESULTS

A prevalidated generic appraisal instrument was not found to be appropriate for intrapartum fetal monitoring guidelines. When using our own specifically-developed appraisal tool for assessing the quality of fetal monitoring guidelines, only 11 reviewer pairs showed 'good' or 'moderate' agreement in their scores.

CONCLUSIONS

Generically-validated guidelines may not be sufficiently discriminatory for specialized areas of practice such as intrapartum fetal monitoring.

Can Electronic Fetal Monitoring Identify Preterm Neonates With Cerebral White Matter Injury?

OBJECTIVE

Although preterm delivery occurs in only 10% of all births, these infants are at high risk for cerebral white matter injury and constitute a third of all cerebral palsy cases. Our objective was to estimate if electronic monitoring can identify preterm fetuses diagnosed with brain injury during the neonatal period.

METHODS

In this case-control study, 150 consecutive neonates with ultrasonography-diagnosed cerebral white matter injury were matched by gestational age within 7 days to 150 controls with normal head ultrasonograms. Tracings were retrieved for 125 cases (83%) and 121 controls (81%) and reviewed by 3 perinatologists blinded to outcome. Vaginal (64 cases, 72 controls) and cesarean deliveries (61 cases, 49 controls) were analyzed separately.

RESULTS

There was no difference in baseline heart rate, tachycardia, bradycardia, short-term variability, accelerations, reactivity, number or types of decelerations, or bradycardic episodes between cases and controls in either the vaginal or cesarean delivery groups. For the 6 neonates with metabolic acidosis severe enough to increase the risk for long-term neurologic morbidity, there was a significant increase in baseline amplitude range less than 5 beats per minute; however, its positive predictive value in predicting severe metabolic acidosis was only 7.7%. Increasing late decelerations were associated with decreasing umbilical arterial pH and base excess, but were not significantly different in the acidosis and control groups (1.0 +/- 1.8, 0.55 +/- 1.23 late decelerations per hour, P = .39).

CONCLUSION

Although decreased short-term variability and increased late decelerations are associated with decreasing umbilical arterial pH and base excess, electronic fetal monitoring is unable to identify preterm neonates with cerebral white matter injury.

Comparison of fetal behavior in low- and high-risk pregnancies

Meta-analyses were conducted on archival data of human fetal behavior to identify differential behavior among high-risk fetuses in pregnancies complicated by threatened preterm delivery, maternal hypertension or diabetes compared with low-risk fetuses in uneventful pregnancies, delivering as healthy, full-term infants. Data for a total of 493 fetuses (260 high risk, 233 low risk) from 23 weeks' gestation to term who participated in a study using a standardized protocol including observations of spontaneous and auditory-induced behavior were retrieved from our laboratory database. There were no differences in spontaneous behaviors when scored using clinical criteria for the nonstress test and biophysical profile; however, there were differences in the magnitude of the behaviors measured in the tests. Developmental differences were observed between those threatening to deliver early and the fetuses of hypertensive and diabetic mothers. The latter two groups differed little from one another but differed from low-risk fetuses in their response to auditory stimulation. We concluded that differences in behavior among high-risk groups suggest that atypical fetal behaviors may represent adaptation to condition specific insult rather than a generalized response to insult per se. The finding that high-risk fetuses showed atypical responses to auditory stimuli indicates a need to examine the relation between fetal auditory function and later language acquisition.

Challenge of conducting trials of neuroprotection in the asphyxiated term infant

There has been much progress in understanding the pathogenesis of hypoxic-ischemic brain injury in the near-term and term infant. Although gaps in our knowledge base persist, advances over the past two decades have led to the development of specific brain oriented therapies directed at critical events contributing to tissue damage. The primary goal of these interventions is to prevent or attenuate neurologic and developmental sequelae of brain injury. Examples of current potential treatments include modest reductions in brain temperature, receptor antagonists of excitatory neurotransmitters, reductions in O2 free radicals, blockade of inflammatory mediators, and inhibition of apoptotic pathways. At present, some of these treatments have sufficient animal data that demonstrate benefit, to justify moving experiments from the laboratory to the clinical arena. Modest hypothermia represents the neuroprotective intervention that has been investigated in the most complete fashion for the newborn, and there are multiple ongoing clinical trials testing its efficacy. This review will address specific challenges that are pertinent to the evaluation of any neuroprotective therapy implemented shortly after birth. Specific issues to be covered include the therapeutic window, establishing a diagnosis of hypoxic-ischemic encephalopathy, patient selection, characteristics of an effective therapy, safety considerations, appropriate outcome variables, and sample size considerations. Since clinical trials of brain hypothermia are in progress, many of these issues will be addressed from the perspective of this specific intervention.

Birth in the United States: an overview of trends past and present

The picture of birth in the United States today is complex and, as the data above indicates, difficult to describe in simplistic terms. Though many women today have come to believe that there are choices surrounding pregnancy and birth, the beliefs and practices of providers, insurers, and hospital administrators play a major role in either influencing those choices or dictating how they will be manifested. On one hand, technological advances have given women greater options with regard to the outcomes of pregnancy and birth. On the other hand, these very same technological advances place limits on the choices available to the individual. For example, increased efficiency in the placement and use of epidural anesthesia has made this a pain-control option for most of the childbearing women in the United States. The use of an epidural, however, puts limits on the choice of an institution at which to give birth and on the movements/activities of the woman during labor. Twentieth-century developments led to the almost complete demise of midwifery practice in the United States, thus taking birth away from the control of the individual woman and her close, matriarchal support system, and placing it in the hands of the patriarchal world of medicine and the institutions (i.e., hospitals) at which this approach to health care is practiced. Most births went from being normal, home-based events to becoming illness-oriented, hospital-based procedures. Just as some steps were being taken in the latter part of the twentieth century to return some of the control of birth back to pregnant women (e.g., childbirth education classes, the modern home-birth movement, increases in the number of midwifery-tended births), technological advances contributed to continued control by physicians and the hospitals of their practice (e.g., fetal monitoring, epidural anesthesia). Advances in technology have made birth possible for many individuals who otherwise would not have had the opportunity for this experience or a chance for a positive outcome (e.g., sufferers of infertility or the woman whose fetus has congenital yet repairable problems). But the widespread application of many of these advances to almost all pregnant and laboring women has raised questions as to just what is necessary for a healthy pregnancy, and are there limits to the role that technology should play in the course of what is viewed by many as a normal, nonmedical event. Just as the characters in 2001: A Space Odyssey recognized the incredible power of change that occurred in their lives as a result of the monolith being "born" into their world, so too do many women acknowledge the prodigious nature of giving birth in terms of the experience itself and the resulting effect on their lives [14]. But, as with the acknowledgment of Dr. Dave Bowman in 2001: A Space Odyssey that the technology of the fictitious future still could be wrong, thoughts of U.S. women giving birth today tend to be "in-between" a belief in the integrity of nature and a trust in the power of technology [14]. One can certainly conjecture that birth in the United States today, more than any other time in history, is at a crossroads, one in which the mostly natural, matriarchal community system of the sixteenth through nineteenth centuries is intersecting with the mostly technological, patriarchal system of the twentieth century. Will birth return to the home under the guidance of midwives, as was the case for most of America's past and as remains the case throughout much of the world? [32] Or will technology take birth to the other extreme, making it possible to eventually gestate outside the womb and rendering "delivery" a term not referring to passage through the birth canal, but to the dropping off a healthy term baby at the respective mother's doorstep? Certainly no one can predict what is to occur, but whatever that may be, hindsight will likely point to the start of the twenty-first century as the beginning of a new paradigm for birth in the United States. It should make for an interesting future.

An exploratory study of fetal behavior at 33 and 36 weeks gestational age in hypertensive women

The relationship between maternal blood pressure (BP) and fetal behaviors as well as differential spontaneous and vibroacoustic elicited fetal behaviors were examined in hypertensive (n = 21) compared to normotensive (n = 22) women at 33 and 36 weeks gestational age (GA). Maternal BP was negatively related to GA at birth and birth weight. On average, fetuses of hypertensive women were born 2 weeks earlier (38 weeks GA) and 340 g lighter. Maternal systolic BP was negatively related to the number of spontaneous body movements observed on ultrasound scan over 20 min and the magnitude of the fetal heart rate (FHR) acceleration elicited by a vibroacoustic stimulus. At 36 weeks GA, vibroacoustic stimulation elicited differential responding with fetuses in the hypertensive compared to the normotensive group having fewer body movements, a lower magnitude of FHR acceleration, and a lack of cardiac-body movement coupled responses. These findings suggest a relationship between maternal BP and fetal behaviors and differential functional development of sensory-motor response systems which need to be characterized in the subgroups of hypertensive disorders observed during pregnancy.

How well does reflectance pulse oximetry reflect intrapartum fetal acidosis?

OBJECTIVE

The purpose of this study was to determine the sensitivity and specificity for acidosis of intrapartum fetal oxygen saturation measured by reflectance pulse oximetry.

STUDY DESIGN

Intrapartum fetal oxygen saturation values per labor stage were correlated with umbilical artery pH, base excess and PCO(2) by regression analysis. Receiver operating characteristic curve analysis was performed with the use of historic umbilical arterial cutoff values; a fetal oxygen saturation cutoff range with optimal sensitivity and specificity was calculated.

RESULTS

Mean fetal oxygen saturation was 42.8%, over the mean 132 minutes of 107 recordings. Overall areas under the sensitivity and specificity curves were 0.77 for pH and PCO(2), decreasing sharply toward birth; all areas for base excess were poor (approximately 0.5). Depending on stage and umbilical artery parameter, fetal oxygen saturation cutoffs were 33% to 36%, with sensitivities of 0.67 to 0.8 and specificities of 0.62 to 0.90.

CONCLUSION

Fetal oxygen saturation sensitivities and specificities for acidosis do not yet justify the supplementation of cardiotocography with routine reflectance pulse oximetry.

Monitoring the fetus in labor: evidence to support the methods

Electronic fetal monitoring (EFM) was implemented across the United States in the 1970s. By 1998, it was used in 84% of all U.S. births, regardless of whether the primary caregiver was a physician or a midwife. Numerous randomized trials have agreed that continuous EFM in labor increases the operative delivery rate, without clear benefit to the baby. Intermittent auscultation (IA) is safe and effective in low-risk pregnancies and may play a role in helping birth remain normal. Clinicians and educators are encouraged to reconsider the use of IA in the care of healthy childbearing women.

The relationship between nucleated red blood cell counts and early-onset neonatal seizures

OBJECTIVE

This study was undertaken to better define the timing of neurologic insult in neonates with early-onset seizures through evaluation of neonatal nucleated red blood cell levels.

STUDY DESIGN

Medical records and the International Classification of Diseases, Ninth Revision codes were used to identify all term neonates with neonatal convulsions who were delivered at our institution (January 1, 1990-December 31, 1995). Each neonate with early-onset seizures was matched to the next 3 neonates who met the following criteria: gestational age > or =37 weeks, no early-onset seizures, birth weight > or =800 g, umbilical artery pH > or =7.25, and a 5-minute Apgar score >7. Demographic characteristics, clinical factors, and mean initial nucleated red blood cell counts were compared between groups.

RESULTS

During the 6-year study period, there were a total of 36, 490 singleton term deliveries of infants who were alive at birth. Forty-five (0.1%) of these neonates had early-onset seizures. Thirty neonates with early-onset seizures met the inclusion criteria. Mean nucleated red blood cell counts (number of nucleated red blood cells per 100 white blood cells) for neonates with early-onset seizures were significantly increased compared with those of control neonates (18.4 +/- 22.0 vs 4.6 +/- 4.5; P <.0008).

CONCLUSIONS

Our findings are suggestive of the hypothesis that neurologic injury leading to early-onset seizures often occurs before the intrapartum period.

Continuous intrapartum pH, pO2, pCO2, and SpO2 monitoring

The goal of intrapartum surveillance and its further development is better patient care for both the fetus and the gravida. A normal FHR pattern is usually associated with the delivery of a normal well-oxygenated infant; however, a nonreassuring FHR is not always associated with the delivery of a compromised infant. This situation has led to an increase in unnecessary obstetric interventions in the form of a rising cesarean section rate. Fetal scalp sampling was developed in an attempt to improve the predictive value of electronic FHR monitoring, but because this technique is not widely used, management decisions are frequently made using FHR patterns alone. Much research has been performed in the search for a continuous biochemical measurement of fetal status, including continuous pH, pO2, or pCO2 and various combinations of these methodologies. None of these measurements are used in current clinical practice, mainly owing to technical problems and difficulties associated with the continuous direct measurement of these parameters in fetal blood throughout labor. The promising new field of fetal pulse oximetry has the potential to provide reliable, meaningful, and reproducible data as shown in early cross-sectional studies and more recent longitudinal studies. By identifying developing hypoxia, this technology may reduce the uncertainty associated with electronic FHR monitoring. Fetal pulse oximetry may also provide critical information relating to the detection and management of the hypoxic fetus. Any new method of intrapartum fetal monitoring requires careful evaluation to assess its potential value before its introduction into clinical practice. The use of fetal SpO2 monitoring in the presence of a nonreassuring FHR pattern is being examined in a multicenter randomized controlled trial. This study will address the question of whether supplementary monitoring of fetal SpO2 levels can lead to a reduction in the cesarean section rate for fetal distress. The available data on fetal noninvasive pulse oximetry have been obtained from a combination of well-designed cohort studies (level II-2 evidence) or from earlier multiple time series (level II-3 evidence). The results from the US Multicenter Trial (level I evidence) should provide a significant addition to current evidence. A continuous fetal noninvasive monitor measuring fetal oxygenation directly could lead to an improvement in the sensitivity and specificity of fetal surveillance. This improvement could ultimately result in a reduction in unnecessary interventions by differentiating hypoxic fetuses from nonhypoxic fetuses and, more importantly, may lead to earlier intervention for fetuses in danger of serious compromise.

Intrapartum Fetal Surveillance. Is It Worthwhile?

Potentially significant intrapartum fetal asphyxia occurs in approximately 20 per 1000 births. Moderate and severe fetal asphyxia exposure with newborn morbidity occurs in 3 to 4 1000 births, with brain damage and subsequent disability in at least 1 per 1000 births. Although the prevalence of moderate and severe asphyxia is modest, prevention is important because of the serious implications of this complication to the child, family, and society. Because of the limited predictive value of clinical risk factors, the interpretation of patterns in a fetal heart rate record has become the primary screening test for intrapartum fetal asphyxia. Despite extensive clinic experience and numerous clinical trials, the benefits of EFM as a screening test have not been established, and harm may occur owing to unnecessary intervention. This observation raises serious ethical issues. When an intervention is initiated by the clinician rather than the patient, the clinician under greater obligation to ensure that the benefits outweigh the harm. Several factors complicate the demonstration of benefits of EFM as a screening test. There is no consensus regarding a protocol of fetal surveillance for low-risk patient who account for approximately 25% of intrapartum fetal asphyxia. Moderate and severe asphyxia cannot be prevented when asphyxial exposure has occurred before labor or before the onset of fetal surveillance. Prediction of intrapartum fetal asphyxia cannot occur when the quality of the record does not permit interpretation. Interpretation of predictive fetal heart rate patterns cannot occur unless the record is consistently and carefully scored. Prediction of most cases of intrapartum fetal asphyxia on the basis of fetal heart rate patterns is possible but difficult. Because the goal of intrapartum fetal surveillance is the prevention of moderate and severe fetal asphyxia, prediction must be achieved before fetal decompensation. Prediction must occur before absent baseline fetal heart rate variability evident in the record, which is uniformly associated with cerebral dysfunction and, in some cases, brain damage. The possibility of fetal asphyxia must be considered when, within a 1-hour window of recording, there are two or more cycles of minimal baseline fetal heart rate variability and two or more cycles of late or prolonged decelerations or both. Because approximately 9 of 10 predictive fetal heart rate patterns are false-positive, supplementary tests to confirm the diagnosis and to identify false-positives to prevent unnecessary intervention are essential. Until such time as additional fetal assessment tests are validated, blood gas and acid-base assessment of fetal blood can provide a definitive diagnosis and identify false-positive predictions.

Nurse versus machine: slaves or masters of technology?

As the millennium approaches nurses are challenged to reflect on the evolving role of technology on the profession. A preview of the technologies coming to the clinical arena in the not-so-distant future is provided. Eight guidelines for wise technology integration are offered to assist providers in appropriately using technology while preserving humanity in an increasingly high-technology world.

Fetal heart rate patterns in postasphyxiated fetal lambs with brain damage

OBJECTIVE

We previously showed that in asphyxiated fetal lambs the duration of hypotension correlated well with the severity of histologic damage to the brain, whereas the duration of bradycardia did not. This study compares fetal heart rate patterns with the degree of histologic damage to the brain.

STUDY DESIGN

Twelve chronically instrumented near-term fetal lambs were subjected to asphyxia by umbilical cord occlusion until fetal arterial pH was <6. 9 and base excess was <-20 mEq/L. An additional 4 fetuses served as sham-asphyxia controls. Fetal heart rate (from electrocardiogram), arterial blood pressure, fetal breathing movements, and electrocorticogram were continuously monitored before, during, and for 72 hours after asphyxia. Fetal brain histologic features were categorized as mild (group 1, n = 5), moderate (group 2, n = 4), and severe (group 3, n = 3). Long-term fetal heart rate variability expressed as amplitude range was assessed visually every 5 minutes from 30 minutes before asphyxia until 2 hours of recovery and at 6, 12, 24, 48, and 72 hours of recovery.

RESULTS

Long-term fetal heart rate variability amplitude decreased from 32 +/- 17 beats/min (mean +/- SEM) preocclusion to 4 +/- 13 beats/min at the end of occlusion (P <.001) without significant differences among the 3 groups. During 10 to 45 minutes of recovery, the long-term variability of group 1 was significantly greater than that of groups 2 and 3. At 24 to 72 hours of recovery, the long-term variability of groups 1 and 2 was significantly higher than that of group 3, which was almost 0. The "checkmark" and sinusoidal fetal heart rate patterns were observed during the recovery period in groups 2 and 3.

CONCLUSIONS

Decreased long-term fetal heart rate variability and the "checkmark" and sinusoidal fetal heart rate patterns were indicators of the severity of asphyxial histologic damage in the fetal brain.

The art of midwifery: lost to technology?

This paper looks at how the art of midwifery is affected by the increasing availability and use of sophisticated technology. The use of the cardiotocograph is an example of how overuse of such technology can have detrimental affects, not only for the midwife but also for the woman in labour. While this technology has made a great impact in obstetric nursing, the effects on the low-risk pregnancy need to be evaluated. Midwives need to be research-based in their clinical practice and question the overuse of technology, such as the cardiotocograph, in cases where it is not warranted.

The intrapartum CTG prior to neonatal encephalopathy at term: a case-control study

OBJECTIVE

To compare cardiotocograph (CTG) records during labour in cases of neonatal encephalopathy and matched controls.

DESIGN

Case-control study.

SETTING

Metropolitan area of Perth, Western Australia.

SUBJECTS

Term deliveries complicated by neonatal encephalopathy and controls matched for sex, hospital, time of birth, day of week of birth and maternal health insurance.

MAIN OUTCOME MEASURES

Low fetal heart rate (FHR) variability, FHR accelerations, late decelerations, total Kreb's score and FIGO classification of CTG records.

RESULTS

The neonatal encephalopathy group had significantly more abnormal CTG records (89%) classified according to FIGO, although 52% of control CTG records were also abnormal. CTG records from cases developed significant differences in terms of absence of FHR accelerations and low FHR variability, but not late decelerations, prior to delivery.

CONCLUSION

Given the low incidence of neonatal encephalopathy in this study (7 per 1000) the predictive value of an abnormal CTG record is clinically unhelpful. However, the changes in the FHR in such cases suggest a greater disturbance of fetal (rest-activity) behaviour during labour.

Historical perspectives: forgotten past, unpredictable future

Intrapartum surveillance has in recent years become a matter of debate. Following its earlier development, first in auscultation and then 40 years ago in electronic monitoring, obstetricians accepted its use with great, perhaps too great, enthusiasm. Years later, attempts to evaluate the actual consequences of this use led to disappointment: although its benefit on perinatal mortality is acknowledged, two observations lead one to reconsider the legitimacy of its use. First the apparent lack of beneficial influence on neonatal long-term morbidity, and second the definite increase in the rate of caesarean section. Furthermore, recent comparative studies, despite some discrepancies, seem to indicate that clinical monitoring by auscultation leads to results as good as those from electronical monitoring, particularly with respect to fetal mortality and infant morbidity. These observations obviously merit careful consideration; some explanations may be put forward to explain these apparently surprising results. From a practical point of view, this discussion leads to two opposite choices for obstetric policy: either to 'go back' to auscultation or to try to identify indicators more specific to fetal asphyxia and increased risk of cerebral palsy, leading to more precise and fewer indications for caesarean section. This chapter on historical perspectives may be useful in pointing out what were the goals of the obstetric pioneers involved in electronic monitoring: definitely not to build theoretical considerations on the pathophysiology of fetal distress, but to gather continuous information about the fetal heart rate in the hope of detecting changes announcing fetal asphyxia before it becomes irremediable, and hence preventing fetal death. These promises have been fulfilled. It follows that continuous clinical monitoring, which provides the same kind of information, is quite likely to lead to similar clinical results. It also follows that this relatively cumbersome method has really nothing to do with the 'classical' clinical surveillance in use before the widespread acceptance of electronical monitoring. It may be beneficial to experiment with this specific type of clinical surveillance; it would be dangerous, however, to 'go back' to the type of monitoring practised 40 years ago.

On intrapartum fetal monitoring

The currently advised conduct for intrapartum surveillance of the fetus is either intermittent auscultation of continuous electronic monitoring, depending on the physician's preference. This applies to all, normal or high-risk, conditions. The bases for this recommendation, a number of controlled studies comparing the two methods, showed no better neonatal outcomes and increased cesarean section rates with electronic fetal monitoring. A review of the works pertaining to fetal development of cardiovascular and central nervous systems and their response to various pathophysiologic conditions (in animals and humans) was carried out in an effort to find an explanation for this apparently uncongruous position. It was found that fetal responses to seemingly comparable conditions are radically different depending on age of gestation. Many authors have pointed this out for the human fetus. However, for interpretation of electronic fetal monitoring in labor, various standard, nondescriptive, confusing words are used to imply the need for rapid intervention. The complete lack of uniform interpretation has been shown in studies comparing interobserver and intraobserver variations. This may be the consequence of poor or superficial teaching of a tool that requires much study and hard work for useful application. The inescapable conclusion is unpleasant but inevitable: to use electronic fetal monitoring properly it is necessary to start a new learning of the physiology of the fetus, its changing evolution as pregnancy advances, its different responses under stress or distress, and the various ways these are represented in electronic fetal monitoring tracings. These efforts take dedication and time spent in labor suites collating tracings with neonatal condition. Only by doing this will it be possible to assist the laboring patients with a useful tool that, so far, has not been adequately applied because of insufficient understanding.

Why has conventional intrapartum cardiotocography not given the expected results?

It is probable that conventional electronic fetal monitoring (EFM) has reduced the intrapartum death rate, but the expected dramatic reduction in neurological handicap has not occurred. There are two reasons for this: the majority of infants, who develop neurological problems have been harmed before the onset of labor, and the method of EFM has been more difficult to use in daily routine than expected. However, EFM is the best method we have to monitor high risk cases and the results can be improved by better training of the staff.

Continuous fetal monitoring of HbO2 with pulse oximetry

Pulse oximetry is well established in anesthesia and intensive care medicine. Application for fetal monitoring would be desirable, but significant modifications are necessary. We report our first promising clinical experience with a self-developed probe, hard- and software system. We hope by the positive results which we have observed that this new technology--oxicardiotocography (OCTG) will improve the safety of fetal monitoring.

Benefits and risks of episiotomy: a review of the English-language literature since 1980. Part II

Mediolateral and, to a lesser degree, midline episiotomies substantially increase the amount of blood loss at delivery; in fact, simple avoidance of episiotomy may be the most powerful means the delivery attendant has to prevent excessive intrapartum hemorrhage. The long-term morbidity of the anal sphincter damage induced by episiotomy, particularly midline, has generally been underestimated in both its frequency and severity. Other potential fetal and maternal complications of episiotomies, although rare, are numerous and serious. The overall degree of risk that accompanies this procedure could only be justified by a clear and overriding benefit, which, as discussed under "Benefits" earlier in this review, does not appear to exist.

Benefits and risks of episiotomy: a review of the English-language literature since 1980. Part I

The professional literature on the benefits and risks of episiotomy was last reviewed critically in 1983, encompassing material published through 1980. This paper reviews the evidence accumulated since then. (Part II follows in this issue.) It is concluded that episiotomies prevent anterior perineal lacerations (which carry minimal morbidity), but fail to accomplish any of the other maternal or fetal benefits traditionally ascribed, including prevention of perineal damage and its sequelae, prevention of pelvic floor relaxation and its sequelae, and protection of the newborn from either intracranial hemorrhage or intrapartum asphyxia. In the process of affording this one small advantage, the incision substantially increases maternal blood loss, the average depth of posterior perineal injury, the risk of anal sphincter damage and its attendant long-term morbidity (at least for midline episiotomy), the risk of improper perineal wound healing, and the amount of pain in the first several postpartum days.

How useful is intrapartum electronic fetal heart rate monitoring?

It is essential for an obstetric anesthesiologist to be aware of the fetal status before undertaking care of the laboring mother. In the last 20 years electronic fetal monitoring has been the most widely used technique of evaluating the fetus in labor. Recently however, the ability to predict or improve fetal outcome using traditional interpretation has been questioned. This review presents a summary of the current technology and interpretation of intrapartum electronic fetal monitoring, as well as a discussion of its limitations and some of the developments in this field which may help improve the accuracy of fetal assessment. The new developments in fetal monitoring discussed in this article are computerized assessment of fetal heart tracings, heart rate variability analysis, fetal electrocardiogram waveform analysis, abdominal detection of fetal ECG, fetal scalp oxygen saturation, fetal pH sampling and transcutaneous oxygen and carbon dioxide measurement.