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About a third of babies are delivered by Cesarean section. There has been an increase in maternal deaths during labor due to complications with subsequent births after a C‐section. Therefore, there is a clinical motivation to reduce the C‐section rate. Current techniques are, however, inefficient at determining fetal distress leading to a high false positive rate for complications and ultimately a C‐section. For the current study, Monte Carlo simulations were used to calculate the amount of signal received on a model of a pregnant mother, as well as, the percent of the signal that comes from the fetal layer. Models with and without a 1 mm amniotic fluid were compared and showed differing trends. [ABSTRACT FROM AUTHOR]

Current intrapartum fetal oxygen saturation (SaO2) monitoring methodologies are limited, mostly consisting of fetal heart rate monitoring which is a poor predictor of fetal hypoxia. A newly developed transabdominal fetal oximeter (TFO) may be able to determine fetal SaO2 non-invasively. This study is to validate a novel TFO in determining fetal SaO2 in a hypoxic fetal lamb model. Fetal hypoxia was induced in at-term pregnant ewe by placing an aortic occlusion balloon infrarenally and inflating it in a stepwise fashion to decrease blood flow to the uterine artery. The inflation was held at each step for 10 min, and fetal arterial blood gases (ABGs) were intermittently recorded from the fetal carotid artery. The balloon catheter was deflated when fetal SaO2 fell below 15%, and the fetus was recovered. A total of three desaturation experiments were performed. The average fetal SpO2 reported by the TFO was derived at each hypoxic level and correlated with the ABG measures. Fetal SaO2 from the ABGs ranged from 10.5 to 66%. The TFO SpO2 correlated with the ABG fetal SaO2 (r-squared = 0.856) with no significant differences (p > 0.5). The fetal SpO2 measurements from TFO were significantly different than the maternal SpO2 (p < 0.01), which suggests that the transcutaneous measurements are penetrating through the maternal abdomen sufficiently and are expressing the underlying fetal tissue physiology. The recently developed TFO system was able to non-invasively report the fetal SpO2, which showed strong correlation with ABG measures and showed no significant differences. [ABSTRACT FROM AUTHOR]

The fetal oxygen saturation is an important parameter to determine the health status of a fetus, which is until now mostly acquired invasively. The transabdominal, fetal pulse oximetry is a promising approach to measure this non-invasively and continuously. The fetal pulse curve has to be extracted from the mixed signal of mother and fetus to determine its oxygen saturation. For this purpose efficient algorithms are necessary, which have to be evaluated under constant and reproducable test conditions. This paper presents the improved version of a phantom which can generate artificial pulse waves in a synthetic tissue phantom. The tissue phantom consists of several layers that mimic the different optical properties of the fetal and maternal tissue layers. Additionally an artificial vascular system and a dome, which mimics the bending of the belly of a pregnant woman, are incorporated. To obtain data on the pulse waves, several measurement methods are included, to help understand the behavior of the signals gained from the pulse waves. Besides pressure sensors and a transmissive method we integrated a capacitive approach, that makes use of the so called “Pin Oscillator” method. Apart from the enhancements in the tissue phantom and the measurements, we also improved the used blood substitute, which reproduces the different absorption characteristics of fetal and maternal blood. The results show that the phantom can generate pulse waves similar to the natural ones. Furthermore, the phantom represents a reference that can be used to evaluate the algorithms for transabdominal, fetal pulse oximetry.

Transabdominal fetal pulse oximetry is an approach to measure oxygen saturation of the unborn child non-invasively. The principle of pulse oximetry is applied to the abdomen of a pregnant woman, such that the measured signal includes both, the maternal and the fetal pulse curve. One of the major challenges is to extract the shape of the fetal pulse curve from the mixed signal for computation of the oxygen saturation. In this paper we analyze the principle kind of connection of the fetal and maternal pulse curves in the measured signal. A time varying finite element model is used to rebuild the basic measurement environment, including a bulk tissue and two independently pulsing arteries to model the fetal and maternal blood circuit. The distribution of the light fluence rate in the model is computed by applying diffusion equation. From the detectors we extracted the time dependent fluence rate and analyzed the signal regarding its components. The frequency spectra of the signals show peaks at the fetal and maternal basic frequencies. Additional signal components are visible in the spectra, indicating multiplicative coupling of the fetal and maternal pulse curves. We conclude that the underlying signal model of algorithms for robust extraction of the shape of the fetal pulse curve, have to consider additive and multiplicative signal coupling.

Transabdominal fetal pulse oximetry is a method to monitor the oxygen supply of the unborn child non-invasively. Due to the measurement setup, the received signal of the detector is composed of photons coding purely maternal and photons coding mixed fetal-maternal information. To analyze the wellbeing of the fetus, the fetal signal is extracted from the mixed component. In this paper we assess source-detector configurations, such that the mixed fetal-maternal components of the acquired signals are maximized. Monte-Carlo method is used to simulate light propagation and photon distribution in tissue. We use a plane layer and a spherical layer geometry to model the abdomen of a pregnant woman. From the simulations we extracted the fluence at the detector side for several source-detector distances and analyzed the ratio of the mixed fluence component to total fluence. Our simulations showed that the power of the mixed component depends on the source-detector distance as expected. Further we were able to visualize hot spot areas in the spherical layer model where the mixed fluence ratio reaches the highest level. The results are of high importance for sensor design considering signal composition and quality for non-invasive fetal pulse oximetry.

Monitoring the oxygen saturation of an unborn child is an invasive procedure, so far. Transabdominal fetal pulse oximetry is a promising method under research, used to estimate the oxygen saturation of a fetus noninvasively. Due to the nature of the method, the fetal information needs to be extracted from a mixed signal. To properly evaluate signal processing algorithms, a phantom modeling fetal and maternal blood circuits and tissue layers is necessary. This paper presents an improved hardware concept for an artificial vascular system, utilizing an FPGA based CompactRIO System from National Instruments. The experimental model to simulate the maternal and fetal blood pressure curve consists of two identical hydraulic circuits. Each of these circuits consists of a pre-pressure system and an artificial vascular system. Pulse curves are generated by proportional valves, separating these two systems. The dilation of the fetal and maternal artificial vessels in tissue substitutes is measured by transmissive and reflective photoplethysmography. The measurement results from the pressure sensors and the transmissive optical sensors are visualized to show the functionality of the pulse generating systems. The trigger frequency for the maternal valve was set to 1 per second, the fetal valve was actuated at 0.7 per second for validation. The reflective curve, capturing pulsations of the fetal and maternal circuit, was obtained with a high power LED (905 nm) as light source. The results show that the system generates pulse curves, similar to its physiological equivalent. Further, the acquired reflective optical signal is modulated by the alternating diameter of the tubes of both circuits, allowing for tests of signal processing algorithms.

Aim: Although several studies reported the measurement of fetal oxygen saturation using fetal pulse oximetry (FPO) for evaluation of the fetal intrapartum condition, a systematic review of the seven randomized controlled trials (RCTs) provided no evidence to support FPO for intrapartum fetal monitoring. In the present review, we re‐evaluate an overview for the use of FPO and seven RCTs of FPO. Methods: We reviewed numerous previous reports on FPO and seven RCTs of intrapartum FPO. RCTs were conducted with the main outcome measure being a reduction in the cesarean section rate. Results: The largest trial with 5341 entries failed to show any reduction. The negative result from this RCT may be explained by the use of a different cutoff value for fetal oxygen saturation compared to the other RCT; in addition, there were differences in the indications for cesarean section due to dystocia and in the definition of non‐reassuring fetal status (NRFS). An abnormal FPO value, defined as the fetal oxygen saturation value <30% for at least 10 min, is useful for making a diagnosis of fetal acidosis. A newly developed device, an examiner's finger‐mounted tissue oximetry, accurately measures tissue oxygen saturation while overcoming the drawbacks of FPO, such as infection risk and slipping off of the sensor during descent of the fetal head. Conclusion: FPO (including the new device) with fetal heart rate monitoring in selected cases of NRFS may reduce the cesarean section rate. [ABSTRACT FROM AUTHOR]

Fetal heart rate monitoring by cardiotocography (CTG) detects heart rate abnormalities, which can reflect various degrees of hypoxia. The main purpose of intrapartum fetal monitoring is not so much to prevent brain involvement, which is rarely caused by intrapartum asphyxia and is strangely seen by many authors as the main reason for monitoring, as to prevent all types of early and late neonatal morbidity induced by hypoxia and acidemia. CTG during labor is associated with a reduction of neonatal seizures, but without significant differences for cerebral palsy, infant mortality or other standard neonatal well-being measures. CTG has been associated with an increase in the number of cesarean sections and instrumental vaginal deliveries. Thus, a second examination has become necessary, which is represented by new technologies such as measurement of fetal pH, fetal pulse oximetry, and ST analysis of the fetal electrocardiogram. Each of the fetal monitoring methods introduced so far into practice seems to correspond to certain clinical scenarios. However, the obtained information is limited and depends on the investigated pathophysiological mechanism. In the 21st century, CTG continues to be the main intrapartum fetal well-being assessment method. [ABSTRACT FROM AUTHOR]

Objective. Purpose of the study was to evaluate the diagnostic accuracy of fetal pulse oximetry (FPO) and STanalysis of the fetal ECG (STAN) in prediction of fetal acidemia at birth. Methods. A prospective clinical study was conducted at the Department of Obstetrics and Gynaecology, Jessenius Faculty of Medicine, Martin, Slovakia. In total, 63 out of 70 women with non-reassuring CTG patterns in labour were enrolled. Fetal surveillance during the labour continued with simultaneous CTG plus FPO and STAN monitoring. A receiver operating curve (ROC) analysis was performed to ascertain diagnostic accuracy of individual methods. Results. The study confirmed FPO has a significant ability to detect fetal acidemia at birth (UA-pH ≤ 7.2). The optimum diagnostic cut-off value of SpO2 was 33%, with FPO’s diagnostic sensitivity 60%, and specificity 85.2%. The diagnostic accuracies of STAN + CTG and CTG alone were inferior to that of FPO. Conclusions. FPO has an ability to predict fetal birth acidemia (UA-pH ≤ 7.2), and its diagnostic accuracy is superior to STAN + CTG, or CTG alone monitoring. Condensation.FPO has ability to predict fetal birth acidemia (UA - pH≤7.2), and its diagnostic accuracy is superior to STAN + CTG, or CTG alone monitoring.

Objective. The aim of the study was to test the performance and safety of fetal pulse oximetry (FPO) in the management of non-reassuring CTG patterns in labour.

The vast majority of pregnant women are subjected to electronic fetal heart monitoring during labor. There is limited evidence to support its benefit compared with intermittent auscultation. In addition, there is significant variability in interpretation and its false-positive rate is high. The latter may have contributed to the rise in operative deliveries. In order to address the critical need for better approaches to intrapartum monitoring, the MFMU Network has completed two large multisite randomized trials, one to evaluate fetal pulse oximetry and the other to evaluate fetal ECG ST segment analysis (STAN). Both of these technologies had been approved for clinical use in the United States based on prior smaller trials. These technologies were evaluated in laboring women near term and their primary outcomes were overall cesarean delivery for the oximetry trial and a composite adverse neonatal outcome for STAN. Both the trials failed to show a benefit of the technology, neither in the rates of operative deliveries nor in the rates of adverse neonatal outcomes. The experience with these trials, summarized in this report, highlights the need for rigorous evidence before introduction of new technology into clinical practice and provides a blueprint for future trials to address the need for better intrapartum monitoring approaches. [ABSTRACT FROM AUTHOR]

Objetivo: estudar a correlação entre a saturação de oxigênio fetal medida pela oximetria de pulso durante o segundo período do parto e o pH da artéria umbilical ao nascimento. Pacientes e Métodos: a saturação de oxigênio fetal (FSpO2) foi monitorizada pela oximetria de pulso durante o segundo período do trabalho de parto em 64 gestações simples a termo com apresentação de vértice. O sangue dos vasos umbilicais foi obtido imediatamente após o nascimento para subseqüente medida dos gases e do pH venoso e arterial. Todos os fetos mantiveram a FSpO2 > ou = 30% durante o primeiro período do parto, até o início do segundo período. Resultados: a média da FSpO2 durante o segundo período do parto correlacionou-se significantemente com o pH da artéria umbilical ao nascimento (n = 64, r = 0,79, pPurpose: to study the correlation between fetal oxygen saturation measured by pulse oximetry during second stage of labor and umbilical artery pH at birth. Patients and Methods: fetal oxygen saturation (FSpO2) was monitored by pulse oximetry during the second stage of labor in 64 singleton pregnancies at term, with vertex presentation. Umbilical blood was sampled immediately after delivery for subsequent measurement of venous and arterial blood gases and pH. All fetuses maintained FSpO2 > or = 30% through the first stage of labor, until the start of second stage. Results: the mean FSpO2 at the second stage of labor correlated significantly with umbilical artery pH at birth (n = 64, r = 0.79, p

Objetivos: estudar os níveis de saturação de oxigênio fetal (SpO2) durante o trabalho de parto pela técnica da oximetria de pulso e sua relação com o pH da artéria umbilical (AU). Pacientes e Métodos: a SpO2 fetal foi medida durante o parto por meio da técnica da oximetria de pulso em 50 casos. Comparou-se a média dos valores de SpO2 entre os dois períodos do trabalho de parto, sendo o primeiro subdividido em fases, segundo a dilatação cervical ( ou = 7,20 e ou = 30,0%. Resultados: as médias da SpO2 fetal no primeiro período do parto foram de 53,0 ± 7,3% e 44,2 ± 6,8%, e no segundo 46,8 ± 7,7% e 38,4 ± 7,1% (pH da AU > ou = 7,20 e ou = 7,20) foram de 55,1 ± 5,1% (Purpose: to study fetal oxygen saturation (SpO2) levels during labor by continuous pulse oximetry tecnique, and its relation to umbilical artery (UA) pH. Patients and Methods: fetal SpO2 levels were measured during labor by the pulse oximetry technique in 50 subjects. Average values of SpO2 were compared between the first and second stage of labor, with the first stage further subdivided into phases, according to cervical dilatation of ( or = 7.20 and or = 30.0% was considered normal. Results: fetal SpO2 averages during the first stage were 53.0 ± 7.3% and 44.2 ± 6.8% (UA pH > or = 7.20 and or = 7.20) were 55.1 ± 5.1% (

A retrospective observational study on a sample of 13,413 deliveries analysed the effect of a withdrawal of the CTG additional diagnostic methods of fetal hypoxia (fetal pulse oximetry and ST analysis of the fetal ECG) on operative delivery rates and frequency of the umbilical arterial pH < 7.15. Following the withdrawal, obstetricians are more likely to perform caesarean sections for fetal hypoxia (OR 2.23, 95% CI 1.94-2.55, p < 0.0001 ) and labour dystocia (OR 1.45, 95% CI 1.18-1.77, p = 0.0003), which increases the overall caesarean rate (OR 1.49, 95% CI 1.38-1.61, p < 0.0001 ), although decreases the incidence of birth umbilical arterial pH < 7.15 (OR 0.43, 95% CI 0.22-0.85, p = 0.015). This also leads to the significant decline in overall frequency of instrumental vaginal deliveries (OR 0.58, 95% CI 0.48-0.71). In order to decrease the overall caesarean rate, obstetricians need to be supported by more accurate and possibly automated diagnostic tools for intrapartum fetal hypoxia. [ABSTRACT FROM AUTHOR]

The goal of this review is to synthesize the available information regarding factors leading to the first cesarean, especially as it relates to the role of electronic fetal heart rate monitoring (EFM) in the prevention of the first cesarean. The widespread use of EFM did not reduce perinatal or neonatal adverse outcomes. Coupled with its inherent problems, such as poor sensitivity and reliability, this has led to a dramatic increase in cesarean delivery rates. To be realistic in any attempt to lower the current cesarean rate, we must address the inherent limitations in our current EFM methods. [Copyright &y& Elsevier]

Abstract: Objectives: To compare the effectiveness of pulse oximetry and fetal electrocardiography in the management of labor with nonreassuring fetal heart rate (NRFHR). Study design: This randomized experimental study consisted of two arms. In group 1 we used pulse oximetry and in group 2 we used STAN® technology. The participants in each group were 90 pregnant women with a full-term singleton fetus in cephalic presentation and cardiotocographic tracings compatible with NRFHR. We compared the following variables: rate of cesarean delivery, indications for operative delivery due to NRFHR, and repercussions on the newborn''s acid–base status. Results: The two groups differed significantly in the mode of delivery, with a cesarean delivery rate of 47.6% in group 1 vs. 30% in group 2 (p =0.032). The groups did not differ in the indications for ending labor due to NRFHR (62% vs. 61%, NS). In terms of neonatal outcomes, the 1-min Apgar score was 6 or lower in 17.8% of the group 1 neonates vs. 4.44% of the group 2 neonates (p <0.001). The groups also differed significantly in umbilical cord vein pH (7.23 vs. 7.27) and pCO2 (57.27 vs. 46.86) at birth. Conclusions: Fetal electrocardiography with the STAN® 21 system was more effective in detecting good fetal status and thus in identifying cases in which labor could proceed safely. Intrapartum surveillance with the STAN® 21 system reduced the rate of emergency cesarean delivery. [Copyright &y& Elsevier]

Abstract: Intrapartum fetal surveillance is mandatory in every labour. Continuous electronic fetal heart rate monitoring (CEFM) remains the main method used in high-risk clinical situations. Although the use of CEFM has been shown to reduce the incidence of neonatal seizures, it has not reduced the incidence of cerebral palsy or neonatal encephalopathy. CEFM is technically easy to introduce but interpretation is subjective. Inter-observer and intra-observer differences are well recognized in the interpretation of cardiotocograph (CTG) traces. Standardization of interpretation using guidelines and training of staff can improve reliability in interpretation. CEFM should be used as a screening test with the addition of fetal scalp blood sampling (FBS) to confirm fetal acid–base balance. Recent research has focussed on analysis of the ST segment of the fetal electrocardiograph as an adjunct to continuous electronic fetal monitoring. Fetal pulse oximetry techniques have also been considered. [ABSTRACT FROM AUTHOR]

Aims: To determine the predictive value of fetal pulse oximetry (FPO) for the development of fetal acidosis in cases of non-reassuring fetal heart rate (FHR). Methods: In a prospective observational study, pulse oximetry monitoring was examined in cases of non-reassuring FHR during singleton cephalic delivery at 36–42 weeks' gestation. The study examined whether fetal arterial oxygen saturation (FSpO2) values <30% for at least 10 min during the last 60 min before delivery increase the risk of fetal acidosis. The predictive reliability of this algorithm and the correlation to fetal acidosis [umbilical artery pH (UApH) <7.15] were analyzed. Results: We included 101 patients with non-reassuring FHR during delivery. The incidence of fetal acidosis was significantly higher when FSpO2 values <30% were recorded for at least 10 min (P=0.0). An UApH <7.15 was reliably excluded with a negative predictive value of 98.7% and detected with a sensitivity of 92.9%. Conclusions: A low pulse oximetry oxygen saturation <30% for at least 10 min correlates highly with fetal acidosis in cases of non-reassuring FHR. FPO reliably excludes moderate to advanced acidosis and can reduce the frequency of fetal blood analysis (FBA) in cases of non-reassuring cardiotocography (CTG). [ABSTRACT FROM AUTHOR]

Abstract: Background: The purpose of this study was to compare fetal oxygen saturation by fetal pulse oximetry in parturients with and without epidural labor analgesia in a prospective case control study. Methods: Fetal oxygen saturation values were compared in term pregnant women who received epidural analgesia (epidural group) with those in women who did not (control group). Mode of delivery, Apgar score, fetal oxygen saturation, cord blood gas analysis and fetal outcomes were also compared. Results: A total of 150 pregnant women (75 in each group) gave written consent and were enrolled. The average fetal oxygen saturation during the first stage of labor (active phase) was 45.6 ± 8.1% for the epidural group and 45.9 ± 7.4% for the control group (NS); saturations for the second stage of labor were 44.9 ± 8.8% and 45.3 ± 6.7%, respectively (NS). In the epidural group, the duration of the first stage of labor was significantly longer (565 ± 217 min) than the control group (434 ± 222 min; P= 0.001). Cesarean delivery rates, neonatal cord blood gas analysis, Apgar scores, and neonatal outcomes were similar in the two groups. Conclusions: Fetal oxygen saturation values are similar in the first and second stage of labor in the presence or absence of epidural labor analgesia. [Copyright &y& Elsevier]

A new technique was validated in vivo in reflectance pulse oximetry for measuring low oxygen saturations. Two pairs of light emitter/detector diodes allow for estimation of light attenuation (LA) in tissue, which is assumed to be responsible for the inaccuracy of pulse oximetry at less than 70% arterial oxygen saturation. For validation, 17 newborn piglets were desaturated stepwise from 21% to 1.25% inspiratory oxygen concentration during general anesthesia, and arterial oxygen saturation was measured with the reflectance pulse oximeter adjusted for LA in tissue, with a standard transmission pulse oximeter and a hemoximeter. LA in tissue could be quantified and was different between snout and foreleg (probability level (p) < 0.05). At arterial oxygen saturations above 70%, the bias between the methods was at 0%-1% and the variability 4%-5%. From 2% to 100% arterial oxygen saturation, the reflectance pulse oximeter estimated oxyhemoglobin saturation more accurately than a conventional transmission pulse oximeter (p < 0.05). At low oxygen saturations below 70%, the bias and variability of the reflectance pulse oximeter calibration were closer to the hemoximeter measurements than the transmission pulse oximeter (p < 0.05). The variability of the reflectance pulse oximeter was slightly lower than the traditional oximeter by taking into account the LA in tissue (9% versus 11-15%, ns), and thus, the quality of the individual calibration lines improved (correlation coefficient, p < 0.05). [ABSTRACT FROM AUTHOR]

Aim: To determine how fetal pulse oximetry behaves in various cardiotocographic (CTG) tracings and correlates with neonatal outcome. Patients and Methods: Pregnant women undergoing active labor with singleton pregnancies of 32–42 weeks were enrolled. CTG recordings were reassuring or nonreassuring (namely variable or persisting late decelerations). Pulse oximetry values during labor and changing throughout deceleration and recovery phases, duration and frequency of pulse oximetry recordings <30%, and neonatal outcome were determined. One-wayanova, Tukey test, χ2-test and multiple logistic regression model were used for statistical analysis where appropriate. Results: A total of 156 pregnant subjects were divided into three groups: reassuring fetal heart rate (FHR) patterns (group 1, n = 78 [50%]), late decelerations (group 2, n = 16 [10.3%]) and variable decelerations (group 3, n = 62 [39.7%]). The initial and final pulse oximetry readings, pulse values in first stage of labor, the duration and the frequency of pulse oximetry recordings <30% were significantly different between groups ( P < 0.001, P < 0.001, P < 0.001, P = 0.001, P < 0.001). Fetal acidosis was significantly more frequent with late decelerations (23.1%, P = 0.004). A multiple logistic regression model demonstrated that the initial pulse oximetry value during active labor was the most predictive variable of neonatal well-being ( P < 0.001). Conclusion: Decreased fetal pulse oximetry values, especially prolonged and recurrent recordings <30% are well-correlated with abnormal FHR patterns, indicating an association with fetal compromise and metabolic acidosis. Going through active labor with a lower initial value of FSpO2 more frequently leads to an altered FHR pattern and subsequent adverse fetal outcome. [ABSTRACT FROM AUTHOR]

Abstract: Objectives: The objective of this prospective study was to determine the reliability of fetal pulse oximetry (FPO) in cases of abnormal fetal heart rate (FHR) pattern and fetal oxygen saturation (FSpO2) below 30%. Study design: Three hundred and one deliveries complicated by abnormal FHR pattern were monitored with both CTG and FPO. Cases of FSpO2 values below 30% (n =52) formed the study group and those above 30% (n =249) were the control group. pH and base excess (BE) in the umbilical cord artery, 5-min Apgar score, and pH and BE in the newborn were measured and compared. Statistical analysis included the Epi info 2002 program, Chi-squared test, and linear regression. Results: FSpO2 values were consequently below 30% in 52 and above 30% in 249 cases. When FSpO2 values were below 30%, umbilical pH was significantly lower than in controls (P <0.01), while other parameters were not significantly different. If the time interval between the measurement of the first low (<30%) FSpO2 value and delivery did not exceed 32.4±2.5min, umbilical pH and Apgar scores did not show fetal acidosis. Conclusion: Our findings suggest that FPO is a reliable method of estimating fetal condition and may help reduce the number of cesarean sections performed due to abnormal FHR tracings. [Copyright &y& Elsevier]

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 ≥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. [ABSTRACT FROM AUTHOR]

Aim: Previous studies indicate that the addition of wavelet analysis of the fetal pulse oximetry tracings (FSPO2) and fetal heart rate (FHR) variability to cardiotocography (CTG), for intrapartum fetal monitoring, provides useful information on the fetal response to hypoxia. We applied the new procedure in non-reassuring CTG patterns, in which cesarean section was performed, and tested its accuracy in the diagnosis of the intrapartum fetal compromise. Methods: At the ‘Aretaieion’ University Hospital labor ward, 318 women with term fetuses in the cephalic presentation entered the trial during labor. They all were monitored with external CTG and fetal pulse oximetry. In the cases that cesarean section was applied, because of abnormal CTG tracings, we applied a method based on the multiresolution wavelet analysis and a self-organized map neural network on the first and second stage of labor. The main outcome parameter was the rate of cord metabolic acidosis at birth (pH < 7.05). Secondary outcomes included Apgar scores at 5 min, fetal transmission to neonatal intensive care unit (NICU) and neonatal encephalopathy. Results: Fifty out of 318 cases delivered operatively because of abnormal CTG patterns (rate 15.72%). In 30 cases, cord pH was >7.05, while in 11 Apgar scores at 5 min were <7, while none of those neonates were transferred to NICU. In the rest 20 cases cord pH was <7.05; in all of these cases Apgar scores at 5 min were <7, while four neonates were transferred to NICU. In one of them, neonatal encephalopathy was diagnosed. After the offline application of wavelet analysis and neural networks to the pulse oximetry and FHR variability readings of the 50 cases, statistics calculated that the system showed a sensitivity of 85% and a specificity of 93%, while false negative and false positive rates were 15% and 7%, respectively. Conclusion: Computerized FHR and FSPO2 monitoring shows an excellent efficacy and reliability in interpreting non-reassuring FHR recordings. [ABSTRACT FROM AUTHOR]

Aim: The aim was to investigate fetal peripheral blood flow using external cardiotocography (CTG), Doppler velocimetry, and pulse oximetry (PO) in normal labor compared with those complicated by hypoxia. Subjects: During labor, 35 term fetuses with oxygen saturation values (FSPO2) between 30 and 40%, and 25 term fetuses with FSPO2 values ⩽ 30% for a period of 20 s to 2 min were studied. Fetuses were assessed using simultaneous CTG, PO, and Doppler ultrasonography of the umbilical artery (UA). The pulsatility index (PI), resistance index (RI), and flow velocity integral (FVI) were recorded. Peripartum outcomes were compared with those of 30 fetuses with SPO2 values >40%. All groups presented abnormal CTG patterns and were comparable with regard to maternal age and parity. Setting: The Fetal Surveillance Unit of the 2nd Department of Obstetrics and Gynecology, ''Aretaieion'' Hospital, Athens University, Greece. Results: Umbilical artery Doppler revealed an initial increase in the RI and the PI in the presence of decreased oxygen saturation. The differences observed in Doppler velocity and impedance indices correlated with PO values. Fetal outcomes correlated with UA Doppler findings. Conclusions: Alterations in UA Doppler velocimetry indices were observed during labor-induced fetal hypoxia. PO readings of <40% provoked an increase in the RI and PI. When PO readings remained <30% for >2 min, both the PI and the RI were further increased in a more prominent way. UA velocimetry indices correlated with perinatal outcome. [ABSTRACT FROM AUTHOR]

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. Copyright © 2005 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Objective: We tested if fetal pulse oximetry in addition to electronic fetal monitoring (CTG) and scalp blood sampling improves the accuracy of fetal assessment and allows safe reduction of operative deliveries (-50%) and scalp blood sampling (-50%) performed because of nonreassuring fetal status. Study design: A randomized controlled trial was conducted in 146 patients with term pregnancies in active labor and abnormal fetal heart rate patterns: 73 had electronic fetal heart rate monitoring (CTG) and fetal scalp blood sampling (control group), 73 had CTG, fetal scalp blood sampling, and continuous fetal pulse oximetry (study group). Results: There was a reduction of -50% in operative deliveries and fetal scalp blood sampling performed because of nonreassuring fetal status in the study group: operative deliveries, study versus control 25/49 (P ≤ .001); fetal scalp sampling, study versus control 32/64 (P ≤ .001). An increase in cesarean sections because of dystocia in the study group did not change the net number of operative deliveries. There was no difference between the 2 groups in adverse maternal or neonatal outcomes, as well as for the end points of metabolic acidosis and need for resuscitation. Conclusion: There was a safe reduction in operative deliveries (-50%) and scalp blood sampling (-50%) performed because of nonreassuring fetal status. The increase in cesarean sections because of dystocia in the study group was a well-documented arrest of labor, but it did not change the total number of operative deliveries in this group. [ABSTRACT FROM AUTHOR]

Objectives: To determine the behavior of fetal oxygenation (FSpO2) in different patterns of fetal heart rate decelerations (FHR). Methods: A total of 787 decelerations were studied. Results: FSpO2 decreased significantly during decelerations, especially when the alteration was prolonged. Conclusions: Modifications in FHR occur simultaneously with alterations in FSpO2, although the latter do not persist in time. Different degrees of FSpO2 seen prior to deceleration are an expression of fetal respiratory status. [Copyright &y& Elsevier]

: Objective:We evaluated the feasibility of a new instrument for continuous fetal pulse oximetry during labor. The measuring sensor can be placed on the fetal back before or after rupture of membranes.: Methods:One hundred adult women who had completed 32 weeks of gestation and had an anticipated duration of labor greater than 30 minutes were included in the study. Patients with premature rupture of membranes for 24 hours or more, low placental localization, placenta previa or abruption, vaginal bleeding, acute infection, polyhydramnios, oligohydramnios, or uterine or congenital abnormalities were excluded.: Results:All sensors were placed successfully. The mean continuous recording time was 276 minutes. Peripheral oxygen saturation as measured by pulse oximeter values were obtained during a median of 64.05% of the recording time. No chorioamnionitis or endometritis was noted.: Conclusion:The new sensor instrumentation was safe for mother and fetus and was well accepted by parents and physicians. [Copyright &y& Elsevier]

Objectives: (1) To investigate fetal intracranial circulation, relative to peripheral blood flow, during labor with abnormal cardiotocographic (CTG) patterns, using three non-invasive methods. (2) To determine the utility of monitoring middle cerebral artery (MCA) Doppler during labor. Interventions: Fetuses were assessed using simultaneous CTG, pulse oximetry, and Doppler ultrasonography of both the MCA and umbilical artery (UA) to measure the pulsatility index (PI), resistance index (RI), and flow velocity integral (FVI). Study design: During labor 20 term fetuses with abnormal CTG patterns and oxygen saturation values >30%, and 24 term fetuses with abnormal CTG patterns and oxygen saturation values <30% were studied, and peripartum outcomes were compared. The groups were comparable with regard to maternal age and parity. Results were evaluated using the Student’s t-test and Fisher exact test. Results: MCA Doppler showed significantly lower PI and RI, and higher FVI in the presence of reduced oxygen saturation. Differences in fetal outcomes between the two groups correlated with MCA Doppler findings. Conclusions: In experienced hands, Doppler screening of fetal middle cerebral artery waveforms during labor can be useful in the evaluation of intrapartum hypoxia in complicated pregnancies. [Copyright &y& Elsevier]

Background: Fetal pulse oximetry measures arterial oxygen saturation during delivery. The fetal electrocardiogram STAN S21 analyzes the repolarisation segment of ECG (ST) waveform, which is altered by the intramyocardial potassium release resulting from metabolic acidemia. This study aimed to evaluate the feasibility of a simultaneous application of pulse oximetry and fetal electrocardiography and to estimate any agreement between both methods indicating fetal compromise.Methods: In an observational trial 35 fetuses were simultaneously monitored by pulse oximetry (OBS-500) and electrocardiography. The evaluation focused on signal output and on the coincidence of desaturation in fetal pulse oximetry and on ST events. Desaturation was defined as a drop of at least 20% of oxygen saturation from base line level occurring within 1 min (steep desaturation) or duration of time (s) with oxygen saturation below the threshold of 30%. Statistical analysis was performed with the Mann-Whitney U-test for continuous variables.Results: Signal output of the simultaneous application of both sensors was not significantly reduced in the electrocardiogram and in pulse oximetry (8% vs. 12% reduction). In 15 of the 35 fetuses, ST events indicating fetal hypoxia occurred. In these cases, pulse oximetry showed significantly more episodes of desaturation in comparison with fetuses without ST events. Median saturation during the ST events was significantly lower than in the recordings without ST events (60% vs. 74%, p < 0.05). In the umbilical artery these neonates showed significantly lower pH (7.19 vs. 7.33, p < 0.001), significantly higher lactate (5.1 vs. 3.4 mmol/l, p < 0.05) and significantly lower base deficit (-9.4mmol/l vs. -4.0 mmol/l, p < 0.001) levels.Conclusions: The combination of fetal pulse oximetry and fetal electrocardiography appears feasible and indicates signs of intermittent hypoxia. These findings may encourage the development of technology that combines these different methods of monitoring. [ABSTRACT FROM AUTHOR]

Objective: Fetal pulse oximetry is a minimally invasive, simple technique which continuously helps to reflect in utero well-being. The presence of meconium in the amniotic fluid may be a clinical sign of fetal hypoxaemia. Amnioinfusion has a beneficial effect on the incidence of meconium aspiration syndrome (MAS), and the presence of meconium below the level of the vocal cords.Study Design: We studied the impact of amnioinfusion combined with fetal pulse oximetry on the incidence of meconium aspiration syndrome and operative delivery.Results: The retrospective analysis revealed that the presence of meconium below the level of vocal cords was significantly reduced. The frequency of cesarean section is decreased, however, it did not reach statistical significance.Conclusion: Fetal pulse oximetry may be used in combination with amnioinfusion and cardiotocography (CTG) to reduce the risk of meconium aspiration syndrome and the number of instrumental deliveries and improve perinatal outcome. [ABSTRACT FROM AUTHOR]

Objectives: A retrospective analysis of short-term variability (STV), a cardiotocography (CTG) parameter, in relation to fetal blood saturation values (FSpO2) obtained by fetal pulse oximetry. Methods: The study included 26 healthy pregnant women monitored continuously during delivery with both cardiotocography and fetal pulse oximetry. Results: Lower FSpO2 values were observed in the group showing STV levels ≤6.0 ms in the 1st stage of labor (44.7±3.46% vs. 49.2±1.8%), but this result was not statistically significant. In the 2nd stage of labor, FSpO2 values in the group with STV levels ≤6.0 ms were significantly lower than those with STV levels >6.0 ms (34.4±2.9% vs. 43±7.2%; P<0.001). A positive correlation was found between STV levels ≤6.0 ms and mean FSpO2 values in the 2nd stage of labor. Conclusions: 1. A significant relationship was observed between short-term variability in the cardiotocographic records and fetal blood saturation levels in the 2nd stage of labor. 2. Fetal pulse oximetry can be valuable in assessing fetal wellbeing, especially when CTG records are abnormal. [Copyright &y& Elsevier]

Induction of labor under analgesia was planned for a 30-year-old-primiparous patient with hypertrophic obstructive cardiomyopathy (HOCM), as her fetal evaluation revealed intrauterine growth restriction at 38 weeks' gestation. However, regional analgesia during labor may present a potential risk for hemodynamic instability in patients with HOCM due to the possibility of a sympathetic block, as a result of vasodilation associated with the administration of local anesthesia. This case report demonstrates the successful management of the patient with analgesia provided by a continuous spinal catheter dosed with a continuous infusion of fentanyl and supplemental meperidine. Fetal surveillance monitoring included fetal pulse oximetry in addition to conventional cardiotocography, on the basis of which cesarean section was avoided. [ABSTRACT FROM AUTHOR]

Objective: Purpose of this presentation is to show the diagnostic power of fetal pulse oximetry in comparison to the other blood gas parameters from fetal blood samplings (FBS). The distribution of saturation readings in acidotic fetuses and normally oxygenated fetuses should be established. Study design: A fetal pulse oximetry system (N400, FS14) was evaluated in a strictly observational study design based on blinded saturation display and on continuous data storing. The investigation was performed on 170 fetuses with non-reassuring fetal heart rate (FHR)-tracings. Since pulse oximetry readings were not available for decision finding, the clinical management was based on electronic fetal monitoring and fetal blood samplings. The oxygen saturation from FBS or umbilical cord blood was measured by blood gas analysers with an integrated hemoximeter (Bayer 865; ABL 625, Radiometer) and biosensors measuring lactate as metabolic component. Out of the 170 cases 17 cases were defined as group of acidemia (pHumb. art. < 7.16 + BD<−9.4). The distribution of saturation readings and the duration of desaturation periods (in minutes and percentage of total monitoring time SPO2 below 30%) were determined. ROC curve analysis from FBS preceding delivery compared the diagnostic power of other blood gas parameters with oxygen saturation. The Wilcoxon test for uneven pairs was used. Results: The distribution of oxygen saturation in the normal group of fetuses differs significantly from the acidemic group. The correlation coefficient between both methods to determine oxygen saturation was r=0.66. A specific evaluation of the distribution of SPO2 shows an overestimation of pulse oximetry in the low range and an underestimation in the high range of saturation. ROC-curve analysis showed a good diagnostic power of lactate in comparison to the oxygen saturation measured by pulse oximetry or by hemoximetry. Conclusions: The advantage of continuous fetal pulse oximetry surveilling the fetus under suspicion of hypoxia appears limited by the poor diagnostic power of the respiratory parameter saturation itself and by the impairment of the precision of the technology. [Copyright &y& Elsevier]