Update on intrapartum fetal pulse oximetry

Does the use of higher versus lower oxygen concentration improve neurodevelopmental outcomes at 18-24 months in very low birthweight infants?

BACKGROUND

Immediately after birth, the oxygen saturation is between 30 and 50%, which then increases to 85-95% within the first 10 min. Over the last 10 years, recommendations regarding the ideal level of the initial fraction of inspired oxygen (FiO2) for resuscitation in preterm infants have changed from 1.0, to room air to low levels of oxygen (< 0.3), up to moderate concentrations (0.3-0.65). This leaves clinicians in a challenging position, and a large multi-center international trial of sufficient sample size that is powered to look at safety outcomes such as mortality and adverse neurodevelopmental outcomes is required to provide the necessary evidence to guide clinical practice with confidence.

METHODS

An international cluster, cross-over randomized trial of initial FiO2 of 0.3 or 0.6 during neonatal resuscitation in preterm infants at birth to increase survival free of major neurodevelopmental outcomes at 18 and 24 months corrected age will be conducted. Preterm infants born between 230/7 and 286/7 weeks' gestation will be eligible. Each participating hospital will be randomized to either an initial FiO2 concentration of either 0.3 or 0.6 to recruit for up to 12 months' and then crossed over to the other concentration for up to 12 months. The intervention will be initial FiO2 of 0.6, and the comparator will be initial FiO2 of 0.3 during respiratory support in the delivery room. The sample size will be 1200 preterm infants. This will yield 80% power, assuming a type 1 error of 5% to detect a 25% reduction in relative risk of the primary outcome from 35 to 26.5%. The primary outcome will be a composite of all-cause mortality or the presence of a major neurodevelopmental outcome between 18 and 24 months corrected age. Secondary outcomes will include the components of the primary outcome (death, cerebral palsy, major developmental delay involving cognition, speech, visual, or hearing impairment) in addition to neonatal morbidities (severe brain injury, bronchopulmonary dysplasia; and severe retinopathy of prematurity).

DISCUSSION

The use of supplementary oxygen may be crucial but also potentially detrimental to preterm infants at birth. The HiLo trial is powered for the primary outcome and will address gaps in the evidence due to its pragmatic and inclusive design, targeting all extremely preterm infants. Should 60% initial oxygen concertation increase survival free of major neurodevelopmental outcomes at 18-24 months corrected age, without severe adverse effects, this readily available intervention could be introduced immediately into clinical practice.

TRIAL REGISTRATION

The trial was registered on January 31, 2019, at ClinicalTrials.gov with the Identifier: NCT03825835.

Association between intrapartum fetal pulse oximetry and adverse perinatal and long-term outcomes: a systematic review and meta-analysis protocol

Background

Current methods of intrapartum fetal monitoring based on heart rate, increase the rates of operative delivery but do not prevent or accurately detect fetal hypoxic brain injury. There is a need for more accurate methods of intrapartum fetal surveillance that will decrease the incidence of adverse perinatal and long-term neurodevelopmental outcomes while maintaining the lowest possible rate of obstetric intervention. Fetal pulse oximetry (FPO) is a technology that may contribute to improved intrapartum fetal wellbeing evaluation by providing a non-invasive measurement of fetal oxygenation status.

Objective

This systematic review and meta-analysis aims to synthesise the evidence examining the association between intrapartum fetal oxygen saturation levels and adverse perinatal and long-term outcomes in the offspring.

Methods

We will include randomised control trials (RCTs), cohort, cross-sectional and case-control studies which examine the use of FPO during labour as a means of measuring intrapartum fetal oxygen saturation and assess its effectiveness at detecting adverse perinatal and long-term outcomes compared to existing intrapartum surveillance methods. A detailed systematic search of PubMed, EMBASE, CINAHL, The Cochrane Library, Web of Science, ClinicalTrials.Gov and WHO ICTRP will be conducted following a detailed search strategy until February 2024. Three authors will independently review titles, abstracts and full text of articles. Two reviewers will independently extract data using a pre-defined data extraction form and assess the quality of included studies using the Risk of Bias tool for RCTs and Newcastle-Ottawa Scale for observational studies. The grading of recommendations, assessment, development, and evaluation (GRADE) approach will be used to evaluate the certainty of the evidence. We will use random-effects meta-analysis for each exposure-outcome association to calculate pooled estimates using the generic variance method. This systematic review will follow the Preferred Reporting Items for Systematic reviews and Meta-analyses and MOOSE guidelines.

PROSPERO registration

CRD42023457368 (04/09/2023).

Recovering fetal signals transabdominally through interferometric near-infrared spectroscopy (iNIRS)

Noninvasive transabdominal fetal pulse oximetry can provide clinicians critical assessment of fetal health and potentially contribute to improved management of childbirth. Conventional pulse oximetry through continuous wave (CW) light has challenges measuring the signals from deep tissue and separating the weak fetal signal from the strong maternal signal. Here, we propose a new approach for transabdominal fetal pulse oximetry through interferometric near-infrared spectroscopy (iNIRS). This approach provides pathlengths of photons traversing the tissue, which facilitates the extraction of fetal signals by rejecting the very strong maternal signal from superficial layers. We use a multimode fiber combined with a mode-field converter at the detection arm to boost the signal of iNIRS. Together, we can detect signals from deep tissue (>∼1.6 cm in sheep abdomen and in human forearm) at merely 1.1 cm distance from the source. Using a pregnant sheep model, we experimentally measured and extracted the fetal heartbeat signals originating from deep tissue. This validated a key step towards transabdominal fetal pulse oximetry through iNIRS and set a foundation for further development of this method to measure the fetal oxygen saturation.

Early postnatal metabolic profile in neonates with critical CHDs

BACKGROUND

Cyanotic CHD is a life-threatening condition that presents with low oxygen saturation in the newborn period. Hypoxemia might cause alterations in the metabolic pathways. In the present study, we aimed to evaluate the early postnatal amino acid and carnitine/acylcarnitine profiles of newborn infants with cyanotic CHD.

METHODS

A single centre case-control study was conducted. Twenty-seven patients with cyanotic CHD and 54 healthy newborn controls were enrolled. As part of the neonatal screening programme, results of amino acid and carnitine/acylcarnitine were recorded and compared between groups.

RESULTS

Twenty-seven neonates with cyanotic CHD and 54 healthy newborns as controls were enrolled in the study. Cyanotic CHD neonates had higher levels of alanine, phenylalanine, leucine/isoleucine, citrulline, ornithine, C5, C5-OH; but lower levels of C3, C10, C12, C14, C14:1, C16, C16.1, C18, C5-DC, C6-DC, C16-OH, C16:1-OH when compared with the healthy controls.

CONCLUSION

This study showed that there are differences between patients with cyanotic CHD and healthy controls in terms of postnatal amino acid and carnitine/acylcarnitine profiles.

Higher versus Lower Oxygen Concentration during Respiratory Support in the Delivery Room in Extremely Preterm Infants: A Pilot Feasibility Study

Background: Optimal starting oxygen concentration for delivery room resuscitation of extremely preterm infants (<29 weeks) remains unknown, with recommendations of 21–30% based on uncertain evidence. Individual patient randomized trials designed to answer this question have been hampered by poor enrolment. Hypothesis: It is feasible to compare 30% vs. 60% starting oxygen for delivery room resuscitation of extremely preterm infants using a change in local hospital policy and deferred consent approach. Study design: Prospective, single-center, feasibility study, with each starting oxygen concentration used for two months for all eligible infants. Population: Infants born at 23 + 0–28 + 6 weeks’ gestation who received delivery room resuscitation. Study interventions: Initial oxygen at 30% or 60%, increasing by 10–20% every minute for heart rate < 100 bpm, or increase to 100% for chest compressions. Primary outcome: Feasibility, defined by (i) achieving difference in cumulative supplied oxygen concentration between groups, and (ii) post-intervention rate consent >50%. Results: Thirty-four infants were born during a 4-month period; consent was obtained in 63%. Thirty (n = 12, 30% group; n = 18, 60% group) were analyzed, including limited data from eight who died or were transferred before parents could be approached. Median cumulative oxygen concentrations were significantly different between the two groups in the first 5 min. Conclusion: Randomized control trial of 30% or 60% oxygen at the initiation of resuscitation of extremely preterm neonates with deferred consent is feasible. Trial registration: Clinicaltrials.gov NCT03706586

Enhanced monitoring during neonatal resuscitation

Immediately after birth through spontaneous breaths, infants' clear lung liquid replacing it with air, and gradually establishing a functional residual capacity to achieve gas exchange. Most infants start breathing independently after birth and ~3% of infants who require positive pressure ventilation. When newborns fail to start breathing the current neonatal resuscitation guidelines recommend initiatingpositive pressure ventilationusing a face mask and a ventilation device. Adequate ventilation is the cornerstone of successful neonatal resuscitation; therefore, it is mandatory that anybody involved in neonatal resuscitation is trained in mask ventilation techniques. One of the main problems with mask ventilation is that it is very subjective with direct feedback lacking and not uncommonly, the resuscitator does not realise that their technique is unsatisfactory. Many studies have shown that monitoring tidal volume and leak around the mask or endotracheal tube enables the resuscitator to identify the problem and adjust their technique to reduce the leak and deliver and appropriate tidal volume. This chapter discusses the currently available monitoring devices used during stabilization/resuscitation in the delivery room.

Fetal arrhythmias: Surveillance and management

Fetal arrhythmias warrant sophisticated surveillance and management, especially for the high-risk pregnancies. Clinically, fetal arrhythmias can be categorized into 3 types: premature contractions, tachyarrhythmias, and bradyarrhythmias. Fetal arrhythmias include electrocardiography, cardiotocography, echocardiography and magnetocardiography. Oxygen saturation monitoring can be an effective way of fetal surveillance for congenital complete AV block or SVT during labor. Genetic surveillance of fetal arrhythmias may facilitate the understanding of the mechanisms of the arrhythmias and provide theoretical basis for diagnosis and treatment. For fetal benign arrhythmias, usually no treatment but a close follow-up is need, while persistant fetal arrhythmias with congestive heart dysfunction or hydrops fetalis, intrauterine or postnatal treatments are required. The prognoses of fetal arrhythmias depend on the type and severity of fetal arrhythmias and the associated fetal conditions. Responses of fetal arrhythmias to individual treatments and clinical schemes are heterogeneous, and the prognoses are poor particularly under such circumstances.

Reducing Brain Injury of Preterm Infants in the Delivery Room

Cerebrovascular injury is one of the major detrimental consequences of preterm birth. Recent studies have focused their attention on factors that contribute to the development of brain lesions immediately after birth. Among those factors, hypothermia and lower cerebral oxygen saturation during delivery room resuscitation and high tidal volumes delivered during respiratory support are associated with increased risk of severe neurologic injury. In preterm infants, knowledge about causes and prevention of brain injury must be applied before and at birth. Preventive and therapeutic approaches, including correct timing of cord clamping, monitoring of physiological changes during delivery room resuscitation using pulse oximetry, respiratory function monitoring, near infrared spectroscopy, and alpha EEG, may minimize brain injury, Furthermore, postnatal administration of caffeine or other potential novel treatments (e.g., proangiogenic therapies, antioxidants, hormones, or stem cells) might improve long-term neurodevelopmental outcomes in preterm infants.

Fetal pulse oximetry for fetal assessment in labour

BACKGROUND

The use of conventional cardiotocographic (CTG) monitoring of fetal well-being during labour is associated with an increased caesarean section rate, compared with intermittent auscultation of the fetal heart rate, resulting in a reduction in neonatal seizures, although no differences in other neonatal outcomes. To improve the sensitivity of this test and therefore reduce the number of caesarean sections performed for nonreassuring fetal status, several additional measures of evaluating fetal well-being have been considered. These have demonstrated some effect on reducing caesarean section rates, for example, fetal scalp blood sampling for pH estimation/lactate measurement. The adaptation of pulse oximetry for use in the unborn fetus could potentially contribute to improved evaluation during labour and therefore lead to a reduction in caesarean sections for nonreassuring fetal status, without any change in neonatal outcomes.

OBJECTIVES

To compare the effectiveness and safety of fetal intrapartum pulse oximetry with other surveillance techniques.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (31 May 2014), contacted experts in the field and searched reference lists of retrieved studies. In previous versions of this review, we performed additional searches of MEDLINE, Embase and Current Contents. These searches were discontinued for this review update, as they consistently failed to identify any trials that were not shown in the Cochrane Pregnancy and Childbirth Group's Trials Register.

SELECTION CRITERIA

All published and unpublished randomised controlled trials that compared maternal and fetal outcomes when fetal pulse oximetry was used in labour, (i) with or without concurrent use of conventional fetal surveillance, that is, cardiotocography (CTG), compared with using CTG alone or (ii) with or without concurrent use of both CTG and other method(s) of fetal surveillance, such as fetal electrocardiography (ECG) plus CTG.

DATA COLLECTION AND ANALYSIS

At least two independent review authors performed data extraction. We sought additional information from the investigators of three of the reported trials.

MAIN RESULTS

We included seven published trials: six comparing fetal pulse oximetry and CTG with CTG alone (or when fetal pulse oximetry values were blinded) and one comparing fetal pulse oximetry plus CTG with fetal ECG plus CTG. The published trials, with some unpublished data, were at high risk of bias in terms of the impractical nature of blinding participants and clinicians, as well as high risk or unclear risk of bias for outcome assessor for all but one report. Selection bias, attrition bias, reporting bias and other sources of bias were of low or unclear risk. The trials reported on a total of 8013 pregnancies. Differing entry criteria necessitated separate analyses, rather than meta-analysis of all trials.Systematic review of four trials from 34 weeks not requiring fetal blood sampling (FBS) prior to study entry showed no evidence of differences in the overall caesarean section rate between those monitored with fetal oximetry and those not monitored with fetal pulse oximetry or for whom the fetal pulse oximetry results were masked (average risk ratio (RR) 0.99 using random-effects, 95% confidence intervals (CI) 0.86 to 1.13, n = 4008, I² = 45%). There was evidence of a higher risk of caesarean section in the group with fetal oximetry plus CTG than in the group with fetal ECG plus CTG (one study, n = 180, RR 1.56, 95% CI 1.06 to 2.29). Neonatal seizures and neonatal encephalopathy were rare in both groups. No studies reported details of long-term disability.There was evidence of a decrease in caesarean section for nonreassuring fetal status in the fetal pulse oximetry plus CTG group compared to the CTG group, gestation from 34 weeks (average RR (random-effects) 0.65, 95% CI 0.46 to 0.90, n = 4008, I² = 63%). There was no evidence of differences between groups in caesarean section for dystocia, although the overall incidence rates varied between the trials.

AUTHORS' CONCLUSIONS

The addition of fetal pulse oximetry does not reduce overall caesarean section rates. One study found a higher caesarean section rate in the group monitored with fetal pulse oximetry plus CTG, compared with fetal ECG plus CTG. The data provide limited support for the use of fetal pulse oximetry when used in the presence of a nonreassuring CTG, to reduce caesarean section for nonreassuring fetal status. A better method than pulse oximetry is required to enhance the overall evaluation of fetal well-being in labour.

Oxygen administration for the resuscitation of term and preterm infants

Oxygen has been widely used in neonatal resuscitation for about 300 years. In October 2010, the International Liaison Committee on Neonatal Resuscitation released new guidelines. Based on experimental studies and randomized clinical trials, the recommendations on evaluation and monitoring of oxygenation status and oxygen supplementation in the delivery room were revised in detail. They include: inaccuracy of oxygenation clinical assessment (colour), mandatory use of pulse oximeter, specific saturation targets and oxygen concentrations during positive pressure ventilation in preterm and term infants. In this review, we describe oxygen management in the delivery room in terms of clinical assessment, monitoring, treatment and the gap of knowledge.

Intrapartum fetal asphyxia: study of umbilical cord blood lactate in relation to fetal heart rate patterns

PURPOSES

To correlate between umbilical artery cord blood lactate and acid-base status with intrapartum fetal heart rate monitoring, and to measure the reliability of umbilical cord blood lactate for prediction of early neonatal outcome.

METHODS

Sixty-six participants with intrapartum abnormal fetal heart rate monitoring and 60 participants with normal intrapartum recordings were recruited. The abnormal recordings included late onset, atypical variable and simple variable decelerations. After delivery, the arterial cord blood lactate, pH, actual base excess (ABE), and Apgar score were measured in all participants.

RESULTS

There was significant inverse correlation between cord lactate and pH and ABE in all participants (correlation coefficient = -0.7, p < 0.0001). The cord lactate was significantly higher in the late onset and atypical variable decelerations groups compared to control (p < 0.0001). There was no significant correlation between the Apgar score and blood lactate in all groups; however, the sensitivity and specificity of cord lactate to predict low score at 5 min were higher in comparison to cord pH.

CONCLUSIONS

Umbilical cord blood lactate is a reliable marker for intrapartum fetal asphyxia compared to cord acid-base status with better prediction for newborns with low Apgar score.

Newborn piglet traits associated with survival and growth performance until weaning

Pre-weaning piglet mortality represents significant economic losses, and approximately half of this mortality occurs within the first 3 days after birth. Factors involved in postnatal mortality can also be associated with a poor growth performance until weaning. The aim of this study was to evaluate the effect of some variables measured right after birth on piglet survival during the first week of life and growth performance until weaning. Piglets included in the analysis (n=612) were born from 3 to 5 parity sows. Piglets were monitored for blood oxygen saturation (SatO2), heart rate (HR), blood glucose concentration, rectal temperature at birth (RT0 h) and at 24h after birth (RT24 h). Genetic line, birth following or not an obstetric intervention, birth order, sex, skin color, integrity of the umbilical cord, and time elapsed from birth until first attempts to stand were also recorded. Piglets were weighed at birth (BW), and at 7, 14 and 21 days after birth in order to evaluate their postnatal development. Cumulative mortality rates were 3.3%, 5.4% and 8.7% at 3, 7 and 21 days after birth, respectively. Body temperature at birth (RT0 h) did not affect (P>0.05) the survival nor the piglet growth performance. Piglets with cyanotic skin and those that took more than 5 min to stand showed higher chance of mortality (P<0.05) compared to normal skin piglets and to piglets which stood before 1 min, respectively. Piglets with broken umbilical cord had higher odds (P<0.05) of mortality up to 3 days after birth, respectively. Higher odds (P<0.05) of mortality up to 3 or 7 days were associated with later birth order (>9), low BW (<1275g), low (24-30 mg/dl) and high (45-162 mg/dl) blood glucose concentrations, or low RT24 h (<38.1°C). Piglets with BW<1545 g, low RT24 h (<38.6°C) and female piglets had higher odds of a low weight at weaning (P<0.05). Among the factors studied, cyanotic skin, delay for standing, broken umbilical cord, high birth order, low BW, low RT24 h, and both low and high blood glucose concentrations are indicators of a lower ability of piglets to survive during the first week after birth. The growth performance until weaning is compromised in piglets with a lower BW, a lower RT24 h and if they are female pigs.

Monitoring oxygen saturation and heart rate in the early neonatal period

Pulse oximetry is commonly used to assist clinicians in assessment and management of newly born infants in the delivery room (DR). In many DRs, pulse oximetry is now the standard of care for managing high risk infants, enabling immediate and dynamic assessment of oxygenation and heart rate. However, there is little evidence that using pulse oximetry in the DR improves short and long term outcomes. We review the current literature on using pulse oximetry to measure oxygen saturation and heart rate and how to apply current evidence to management in the DR.

Fetal pulse oximetry during labor: theory, clinical use and the future

Fetal pulse oximetry (FPO) has evolved through various phases of technical development and calibration. Clinical studies have addressed the issue of determining threshold action values and how well the technology is accepted by childbearing women and their caregivers. This article considers a variety of situations and factors that commonly occur during labor and that may influence fetal oximetry values. These include uterine contractions, supplemental oxygen and intravenous fluids administered to the mother, maternal position and epidural analgesia. The five randomized, controlled trials that compared the use of FPO in addition to fetal heart-rate monitoring with fetal heart-rate monitoring alone, have been systematically reviewed and subjected to meta-analysis where appropriate. Current clinical practice guidelines do not support the routine use of FPO; however, the recent emergence of robust multiwavelength oximeters may, in the future, offer further clinical applications for FPO.

Intrapartum oximetry of the fetus

Fetal monitoring during labor aims to identify fetal problems which, if uncorrected, may result in morbidity or death. A nonreassuring or abnormal fetal heart rate trace by cardiotocography (CTG) does not necessarily equate with fetal hypoxia and/or acidosis. However, in the absence of more objective data, the use of CTG often results in variable, but inappropriately high, operative delivery rates (forceps, vacuum, or cesarean delivery) for nonreassuring fetal status in many hospitals. The addition of fetal pulse oximetry (FPO) has the potential to improve the assessment of fetal well-being during labor. In this review we consider several aspects of FPO. Several factors, such as sensor to skin contact, uterine contractions, fetal hair, and caput succedaneum, influence the performance and use of FPO. Issues such as clinicians' perspectives of FPO sensor placement, maternal perspectives of FPO during labor, and an economic analysis have all favored FPO. Several randomized controlled trials (RCTs) of FPO reported a reduction in cesarean delivery for nonreassuring fetal status when FPO was added to conventional CTG monitoring, with no difference in overall cesarean delivery rates. One large RCT reported no difference in mode of birth for any indication. Several issues relevant to the future of FPO have been addressed by these RCTs, the major issue being that it makes no difference to cesarean rates. It may be argued that FPO has a valid clinical use in monitoring the fetus with congenital heart block. Additionally, in situations of nonreassuring fetal status and dystocia, FPO may provide the necessary reassurance until adequate resources for cesarean delivery are available.

Fetal pulse oximetry for fetal assessment in labour

BACKGROUND

Pulse oximetry could contribute to the evaluation of fetal well-being during labour.

OBJECTIVES

To compare the effectiveness and safety of fetal pulse oximetry with conventional surveillance techniques.

SEARCH STRATEGY

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (November 2006), MEDLINE (1994 to November 2006), EMBASE (1994 to November 2006) and Current Contents (1994 to November 2006).

SELECTION CRITERIA

All published and unpublished randomised controlled trials that compared maternal and fetal outcomes when fetal pulse oximetry was used in labour, with or without concurrent use of conventional fetal surveillance, compared with using cardiotocography (CTG) alone.

DATA COLLECTION AND ANALYSIS

At least two independent authors performed data extraction. Analyses were performed on an intention-to-treat basis. We sought additional information from the investigators of three of the reported trials.

MAIN RESULTS

Five published trials comparing fetal pulse oximetry and CTG with CTG alone (or when fetal pulse oximetry values were blinded) were included. The published trials, with some unpublished data, reported on a total of 7424 pregnancies. Differing entry criteria necessitated separate analyses, rather than meta-analysis of all trials. Four trials reported no significant differences in the overall caesarean section rate between those monitored with fetal oximetry and those not monitored with fetal pulse oximetry or for whom the fetal pulse oximetry results were masked. Neonatal seizures and hypoxic ischemic encephalopathy were rare. No studies reported details of assessment of long-term disability. There was a statistically significant decrease in caesarean section for nonreassuring fetal status in the fetal pulse oximetry plus CTG group compared to the CTG group in two analyses: (i) gestation from 36 weeks with fetal blood sample (fetal blood sampling) not required prior to study entry (relative risk (RR) 0.68, 95% confidence interval (CI) 0.47 to 0.99); and (ii) when fetal blood sampling was required prior to study entry (RR 0.03, 95% CI 0.00 to 0.44). There was no statistically significant difference in caesarean section for dystocia when fetal pulse oximetry (fetal pulse oximetry) was added to CTG monitoring, compared with CTG monitoring alone, although the incidence rates varied between the trials.

AUTHORS' CONCLUSIONS

The data provide limited support for the use of fetal pulse oximetry when used in the presence of a nonreassuring CTG, to reduce caesarean section for nonreassuring fetal status. The addition of fetal pulse oximetry does not reduce overall caesarean section rates. A better method to evaluate fetal well-being in labour is required.

A cost-effectiveness analysis of the intrapartum fetal pulse oximetry multicentre randomised controlled trial (the FOREMOST trial)

OBJECTIVE

To report an economic analysis of the Australian intrapartum fetal pulse oximetry (FPO) multicentre randomised controlled trial (the FOREMOST trial), which examined whether adding FPO to conventional cardiotocographic (CTG) monitoring (intervention group) was cost-effective in reducing operative delivery rates for non-reassuring fetal status compared with the use of CTG alone (control group).

DESIGN

Cost-effectiveness analysis of the FOREMOST trial.

SETTING

Four Australian maternity hospitals, each with more than 4000 births/year.

POPULATION

Women in labour at > or =36 weeks of gestation, with a non-reassuring CTG.

METHODS

Costs were for treatment-related expenses, incorporating diagnosis-related grouping costs and direct costs (including fetal monitoring). Incremental cost-effectiveness ratio (ICER) and cost-effectiveness plane were calculated, and sensitivity analysis was conducted. The primary outcome was that of the clinical trial: operative delivery for non-reassuring fetal status avoided in the intervention group relative to that in the control group.

MAIN OUTCOME MEASURES

The ICER.

RESULTS

The ICER demonstrated a saving of $A813 for each operative birth for non-reassuring fetal status averted by the addition of FPO to CTG monitoring compared with the use of CTG monitoring alone.

CONCLUSION

The addition of FPO to CTG monitoring represented a less costly and more effective use of resources to reduce operative delivery rates for non-reassuring fetal status than the use of conventional CTG monitoring alone.

Clinicians' evaluations of fetal oximetry sensor placement in a multicentre randomised trial (the FOREMOST trial)

BACKGROUND

Fetal pulse oximetry (FPO) may improve the assessment of the fetal well-being in labour. Reports of health-care provider's evaluations of new technology are important in the overall evaluation of that technology.

AIMS

To determine doctors' and midwives' perceptions of their experience placing FPO sensors.

METHODS

We surveyed clinicians (midwives and doctors) following placement of a FPO sensor during the FOREMOST trial (multicentre randomised trial of fetal pulse oximetry). Clinicians rated ease of sensor placement (poor, fair, good and excellent). Potential influences on ease of sensor placement (staff category, prior experience in Birth Suite, prior experience in placing sensors, epidural analgesia, cervical dilatation and fetal station) were examined by ordinal regression.

RESULTS

There were 281 surveys returned for the 294 sensor placement attempts (response rate 96%). Sensors were placed by midwives (29%), research midwives (48%), registrars (22%) and obstetricians (1%). The majority of clinicians had 1 or more years' Birth Suite experience, had placed six or more sensors previously, and rated ease of sensor placement as good. Advancing fetal station (P < 0.001) and the presence of epidural analgesia prior to sensor placement (P = 0.029) predicted improved ease of sensor placement. Having a clinician placing a sensor for the first time predicted a lower rating for ease of sensor placement (P = 0.001), compared to having placed one or more sensors previously.

CONCLUSIONS

Clinicians with varying levels of Birth Suite experience successfully placed fetal oxygen saturation sensors, with the majority rating ease of sensor placement as good.

Women's evaluations of their experience in a multicenter randomized controlled trial of intrapartum fetal pulse oximetry (The FOREMOST Trial)

BACKGROUND

Fetal pulse oximetry improves the assessment of fetal well-being during labor. The objective of this study was to evaluate women's satisfaction with their experience with this additional technology.

METHODS

We surveyed women participating in the FOREMOST trial, a randomized controlled trial comparing the addition of fetal pulse oximetry (FPO) to conventional cardiotocograph (CTG) monitoring (intervention group), versus CTG-only (control group), in the presence of nonreassuring fetal status during labor. Our survey evaluated 3 aspects of women's experience: labor, fetal monitoring, and participation in the research. The survey was administered within a few days of giving birth and repeated 3 months later.

RESULTS

No differences were found between the intervention and control groups for women's evaluations of their labor, fetal monitoring, research, or overall experiences when surveyed on both occasions. Within each study group, a small but statistically significant decline occurred in women's scores for their experience of labor and overall experience from the initial survey close to the time of giving birth, to 3 months later. The magnitude of differences in responses over time was similar for the both groups. Women were more satisfied after a spontaneous or assisted vaginal birth than after cesarean section. Length of time the research midwife was present had a significant positive effect on women's ratings of their experience several days after giving birth (p = 0.006), but no effect at 3 months.

CONCLUSIONS

The addition of fetal pulse oximetry for the assessment of fetal well-being during labor did not affect childbearing women's perceptions of fetal monitoring or their labor. Women evaluated their experience in the research process positively overall. Small changes occurred in women's perception of their satisfaction over time.

The effect of intrapartum fetal pulse oximetry, in the presence of a nonreassuring fetal heart rate pattern, on operative delivery rates: a multicenter, randomized, controlled trial (the FOREMOST trial)

OBJECTIVE

The objective of the study was to compare operative delivery rates for nonreassuring fetal status between 2 groups of laboring women: those having conventional cardiotocograph monitoring and those having cardiotocograph monitoring plus fetal pulse oximetry.

STUDY DESIGN

The intrapartum fetal oximetry prospective, multicenter, randomized, controlled trial (the FOREMOST trial) was conducted in 4 Australian maternity hospitals. The primary outcome was operative birth rates for nonreassuring fetal status.

RESULTS

There was a statistically significant 23% relative risk reduction in operative delivery for nonreassuring fetal status in the fetal pulse oximetry + cardiotocograph group (n = 75 of 305, 25%), compared with those in the cardiotocograph-only group (n = 95/295, 32%) (relative risk 0.77, 95% confidence interval 0.599, 0.999, P = .048). There were no significant between-group differences in overall operative births (fetal pulse oximetry + cardiotocograph group 73%, cardiotocograph-only group 71%, relative risk 1.04, 95% confidence interval 0.94, 1.15, P = .478) or neonatal outcomes.

CONCLUSION

The use of fetal pulse oximetry to augment fetal well-being assessment during labor resulted in a statistically significant reduction in the operative intervention for nonreassuring fetal status, compared with the use of conventional cardiotocograph monitoring alone. This reduction was achieved with no significant difference in neonatal outcomes.

Vibroacoustic stimulation for fetal assessment in labour in the presence of a nonreassuring fetal heart rate trace

BACKGROUND

Fetal vibroacoustic stimulation is a simple, non-invasive technique where a device is placed on the maternal abdomen over the region of the fetal head and sound is emitted at a predetermined level for several seconds. It is hypothesized that the resultant startle reflex in the fetus and subsequent fetal heart rate acceleration or transient tachycardia following vibroacoustic stimulation provide reassurance of fetal well-being. This technique has been proposed as a tool to assess fetal well-being in the presence of a non-reassuring cardiotocographic trace during the first and second stages of labour.

OBJECTIVES

To evaluate the clinical effectiveness and safety of vibroacoustic stimulation in the assessment of fetal well-being during labour, compared with mock or no stimulation for women with a singleton pregnancy exhibiting a non-reassuring fetal heart rate pattern.

SEARCH STRATEGY

We searched the Cochrane Pregnancy and Childbirth Group Trials Register (30 September 2004), the Cochrane Central Register of Controlled Trials (The Cochrane Library, Issue 1, 2004), MEDLINE (January 1966 to January 2005), EMBASE (January 1966 to January 2005) and reference lists of all retrieved articles. We sought unpublished trials and abstracts submitted to major international congresses and contacted expert informants.

SELECTION CRITERIA

All published and unpublished randomised trials that compared maternal and fetal/neonatal/infant outcomes when vibroacoustic stimulation was used to evaluate fetal status in the presence of a non-reassuring cardiotocographic trace during labour, compared with mock or no stimulation.

DATA COLLECTION AND ANALYSIS

Two independent review authors identified potential studies from the literature search and assessed them for methodological quality and appropriateness of inclusion, using a data extraction form. Attempts to contact study authors for additional information were unsuccessful.

MAIN RESULTS

The search strategies yielded six studies for consideration of inclusion. However, none of these studies fulfilled the requirements for inclusion in this review.

AUTHORS' CONCLUSIONS

There are currently no randomised controlled trials that address the safety and efficacy of vibroacoustic stimulation used to assess fetal well-being in labour in the presence of a non-reassuring cardiotocographic trace. Although vibroacoustic stimulation has been proposed as a simple, non-invasive tool for assessment of fetal well-being, there is insufficient evidence from randomised trials on which to base recommendations for use of vibroacoustic stimulation in the evaluation of fetal well-being in labour in the presence of a non-reassuring cardiotocographic trace.

Severe Variable Decelerations and Fetal Pulse Oximetry during the Second Stage of Labor

OBJECTIVES

The aim of the study was to investigate the usefulness of fetal pulse oximetry in cases of severe variable decelerations in the second stage of labor.

METHODS

It is a prospective study including 58 patients. Thirty-eight patients (group A) had a normal uncomplicated labor and 20 patients (group B) developed severe variable decelerations during the second stage of labor. All patients were primiparous with normal pregnancies and had electronic fetal monitoring of labor in conjunction with fetal pulse oximetry. An estimation of fetal pH and base deficit was performed at delivery in all patients.

RESULTS

There was no statistically significant difference in relation to maternal age and gestational age between the two groups. Group A patients did not delivered neonates with metabolic acidosis. Six out of 20 (group B) patients delivered neonates with a pH <7.10 despite a fetal pulse oximetry reading of >30%.

CONCLUSIONS

It appears that fetal pulse oximetry is not capable of detecting pre-acidotic or acidotic fetuses during the second stage of labor in patients with severe variable decelerations and the management of such patients should be supported by fetal scalp pH when indicated or otherwise the obstetrician should expedite delivery either with assisted operative delivery or cesarean section. Fetal heart rate monitoring was introduced into clinical practice over 30 years ago. It continues to be the predominant method of intrapartum fetal surveillance despite worries about its accuracy and efficacy.

Fetal pulse oximetry for fetal assessment in labour

BACKGROUND

Fetal pulse oximetry (FPO) may contribute to the evaluation of fetal well-being during labour.

OBJECTIVES

To compare the effectiveness and safety of FPO with conventional surveillance techniques, using the results of randomised controlled trials.

SEARCH STRATEGY

We searched the Cochrane Pregnancy and Childbirth Group trials register (31 July 2004) and conducted a systematic literature search of MEDLINE (1994 to July 2004), EMBASE (1994 to July 2004) and Current Contents (1994 to July 2004).

SELECTION CRITERIA

All published and unpublished randomised controlled trials (RCTs) that compared maternal and fetal/neonatal/infant outcomes when FPO was used in labour, with or without concurrent use of conventional fetal surveillance, compared with using cardiotocography (CTG) alone.

DATA COLLECTION AND ANALYSIS

Two independent reviewers performed data extraction. Analyses were performed on an intention-to-treat basis. We sought additional information from the investigators of the one reported trial.

MAIN RESULTS

One published RCT (comparing FPO and CTG with CTG alone) was included; and two ongoing RCTs were identified. The single included RCT reported on 1010 cases. Unpublished pilot data were available for some outcomes to give a total of 1190 cases. There was no difference in the overall caesarean section rate between the two groups (relative risk (RR) 1.12, 95% confidence interval (CI) 0.91 to 1.37). There were less caesarean sections for nonreassuring fetal status in the FPO plus CTG group compared with the CTG only group (RR 0.45, 95% CI 0.28 to 0.72). The only reported neonatal seizure occurred in the CTG only group (RR 0.29 95% CI 0.01 to 7.08). Use of FPO with CTG decreased operative delivery (caesarean section, forceps, vacuum) for nonreassuring fetal status (RR 0.71, 95% CI 0.55 to 0.93) compared with CTG alone. No differences were seen for overall operative deliveries, endometritis, intrapartum or postpartum haemorrhage, uterine rupture, low Apgar scores, umbilical arterial pH or base excess, admission to the neonatal intensive care unit or fetal/neonatal death.

REVIEWERS' CONCLUSIONS

The one published RCT reported that FPO decreased the caesarean section rate and operative delivery rates for nonreassuring fetal status, without adversely affecting maternal or fetal/neonatal outcomes. However, no difference was seen in the overall caesarean section (CS) or operative delivery rates because more CS were performed for dystocia in the FPO group. Further RCTs may address dystocia in labours monitored with FPO, maternal satisfaction with fetal monitoring and labour, long-term neurodevelopmental outcome of infants who exhibited nonreassuring fetal status in labour and costs of FPO.

Effects on the fetus and newborn of maternal analgesia and anesthesia: a review

PURPOSE

To review the effects of maternal anesthesia and analgesia on the fetus and newborn.

METHODS

An on-line computerized search of Medline, Embase, and the Cochrane Collaboration via PubMed was conducted. English language articles were selected. The bibliographies of relevant articles and additional material from other published sources were retrieved and reviewed.

PRINCIPAL FINDINGS

No one test clearly separates the effects on the fetus/newborn, if any, of maternally administered medication during labour and delivery, or during surgery for non-obstetric indications. Supposition in this regard is limited in part by methodology previously used to study the transplacental passage of various drugs. This work needs to be repeated using a human model. Routine maternal supplemental oxygen administration is being questioned in light of research showing that free radical generation and oxidative stress are implicated as the underlying mechanisms in several neonatal conditions. Maternal hypotension is associated with neonatal acidemia and base excess correlates with neonatal outcome. Common postpartum analgesics transfer minimally into breast milk. Maternal or fetal surgery conducted during pregnancy necessitates modification of both anesthetic and surgical approaches. The key to resuscitation of the fetus is resuscitation of the mother: intra-uterine maneuvers, including perimortem Cesarean section, aim to reverse treatable causes of fetal asphyxia, restore fetal oxygenation, and correct fetal acidosis.

CONCLUSIONS

The well-being of the infant is a major criterion for evaluating the anesthetic management of pregnant women. Many tools exist to assist with this determination for the fetus, whereas few are available to evaluate the newborn.