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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.

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

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.

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 v...

1Financial disclosure: Nellcor Puritan Bennett, Pleasanton, CA provided the technical equipmentBackground. The goal of this investigation was to evaluate the agreement of fetal pulse oximetry to saturation readings from hemoximetry at low oxygen saturation. Methods. Fetal oxygen saturation measurements obtained by pulse oximetry were compared with those obtained by hemoximetry in fetal scalp blood samplings. The prospective observational trial included fetuses with non-reassuring fetal heart rate tracings suggestive of hypoxia and requiring fetal scalp blood samplings. Arterial oxygen saturation was determined by a blinded pulse oximeter (N400, FS14; Nellcor Puritan Bennett, Pleasanton, CA, USA) and continuously stored on a notebook computer. Saturation from fetal scalp blood samples was measured by hemoximetry (Bayer Diagnostics 865; ABL 625, Radiometer). Data analysis focussed on the absolute and relative difference between hemoximetry and pulse oximetry of fetuses, showing the most distinct difference ...

Pulse oximetry is widely used to monitor the patient's well-being in anesthetic and neonatal practice. As a result of recent technologic and theoretical advances, it has emerged as a clinical tool in intrapartum fetal monitoring. Oximeters record both pulse rate and arterial oxygen saturation of the fetus and they may be adapted to derive an estimate of peripheral perfusion. Reflectance oximetry is more accurate than transmission oximetry in intrapartum fetal management. This method uses the pulsatile changes of red and infrared light reflected from tissue to estimate arterial oxygenation. Pulse oximetry is cheap, non-invasive, simple to operate, relatively accurate and has a fast response time. Factors adversely affecting the accuracy of the pulse oximeter output include transducer displacement, peripheral vasoconstriction, hypotension, anemia, presence of intravascular dyes, meconium staining, fetal hair and scalp edema. Fetal pulse oximetry is limited by a wide normal range and inadequate calibration. The amniochorionic membranes however do not affect oximetry readings so that this method may be applied before rupture of the membranes, i.e. before labor. Once successfully developed, fetal pulse oximetry could potentially be used in combination with other monitoring techniques to reduce instrumental and operative interventions during labor and improve perinatal outcome.

Continuous fetal monitoring was achieved with a fetal scalp pulse oximetry sensor in 86 labours. The average recorded fetal oxygen saturation in early labour (cervical dilatation less than 5 cm) was 68% (SD 13%). At the end of labour (cervical dilatation greater than or equal to 9 cm) the recorded mean oxygen saturation was 58% (SD 17%). The largest range of readings during a single labour was 81%-11% but this drop was associated with cord compression. The average SD during 1 h of normal labour was 10%. A second group of 40 fetuses was monitored during induction of labour before and after elective amniotomy. Oxygen saturation did not appear to change after amniotomy (mean change -0.4%, SD 1.2%) and there was no difference between mean antenatal or early intrapartum readings. We excluded the amniochorionic membranes as a possible source of data corruption by measuring their in vitro absorption spectra and confirming that they do not preferentially absorb light of either 660 or 940 nm wavelength. Non-invasive pulse oximetry can be used to monitor the fetus before and during labour.

Objective To observe fetal arteriolar oxygen saturation during maternal epidural analgesia. Design An observation study of 27 epidural top-ups. Setting Labour ward, St James's University Hospital and Leeds General Infirmary, Leeds University, UK. Sample Seventeen fetuses in uncomplicated labour monitored with a N400 fetal pulse oximeter. Outcome measure A change in fetal pulse oximetry reading following epidural analgesia. Results There is no change in fetal oxygen saturation following an uncomplicated epidural top-up (F = 0.93 ; df 35 and 784). Conclusion An uneventful maternal epidural has no measurable effect on fetal oxygen saturation measured with a N400 pulse oximeter.