Intrapartum Fetal Oxygen Saturation Research Articles

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

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. 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. 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. CRD42023457368 (04/09/2023).

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 and Web of Science will be conducted following a detailed search strategy until August 2023. Three authors will independently review titles, abstracts and full text of articles. Two reviewers will independently extract data using pre-defined data extraction and assess the quality using the Risk of Bias tool for RCTs and Newcastle-Ottawa Scale for observational studies. 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 guidelines. PROSPERO registration: CRD42023457368 (04/09/2023)

Validation of a Novel Transabdominal Fetal Oximeter in a Hypoxic Fetal Lamb Model.

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 10min, 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.

Fetal Pulse Oximetry and Cesarean Delivery

ABSTRACT More than 5 years ago the Food and Drug Administration approved, conditionally, the OxiFirst Fetal Oxygen Saturation Monitoring System as an adjunct to electronic fetal monitoring. The goal of monitoring was to gain more knowledge of the condition of the fetus by continuously monitoring oxygen saturation when there is a nonreassuring fetal heart rate pattern. The sensor is inserted through the dilated cervix following membrane rupture, and positioned against the fetal face. This randomized trial, conducted at 14 university-based clinical centers, was designed as a means of learning whether adjunctive fetal oximetry lessens the need for cesarean delivery. Participants were nulliparous women with a singleton fetus in cephalic presentation at 36 or more weeks' gestation. The 5341 women in the study were randomized to either “open” fetal pulse oximetry with oxygen saturation values displayed to the clinician, or “masked” oximetry in which the results were hidden. Overall rates of cesarean delivery were 26.3% for the open group and 27.5% for masked monitoring, not a significant difference. The respective operative delivery rates were 7.1% and 7.9% for a nonreassuring fetal heart rate pattern; and 18.6% and 19.2% for dystocia, Findings were similar for the 2168 women in whom a nonreassuring fetal heart rate pattern was identified before randomization. There were no significant differences between the open and masked groups in the rates of forceps or vacuum-assisted delivery, even after excluding women who had labor induced. The relative risk of cesarean delivery associated with knowing the fetal oxygen saturation was 0.96 (95% confidence interval, 0.87–1.04). Neither maternal nor infant complications differed significantly in incidence between the study groups. The sensitivity, specificity, positive predictive value, and negative predictive value of a nonreassuring fetal heart rate pattern for low oxygen saturation (defined as less than 30% for 2 consecutive minutes) were, respectively, 87%, 19.5%, 35%, and 75%. One-fourth of fetuses with a normal heart rate pattern exhibited low oxygen saturation. This large-scale study failed to demonstrate that knowledge of intrapartum fetal oxygen saturation significantly lowers the rate of cesarean delivery or improves infant outcomes. The findings emphasize the need to rigorously evaluate new technologies.

Relationship between consistency of meconium-stained amniotic fluid and intrapartum fetal oxygen saturation in the first stage of labor

To determine whether pregnancies complicated by meconium-stained amniotic fluid (MSAF) have lower intrapartum fetal oxygen saturation (FSPO2) compared to those with clear amniotic fluid (AF) during the 1st stage of labor. This is a cohort study of women enrolled in a RCT of continuous intrapartum electronic fetal monitoring (EFM) combined with FSPO2 compared to EFM alone. FHR and FSPO2 were recorded from sensor insertion until delivery. Women with singleton pregnancies, gestational age (GA) ≥ 36 0/7 wks and cervical exam 2-6 cm were included. Exclusion criteria were non-vertex presentation, IUFD, and fetal structural/chromosomal defects. Maternal characteristics, FHR abnormalities, intrapartum and delivery outcomes, and FSPO2 were compared between women based on AF consistency (clear AF, thin MSAF, moderate MSAF, and thick MSAF). FSPO2 parameters analyzed were mean FSPO2 and the presence of 2 or more episodes of FSPO2 < 30% lasting at least 2 minutes. Linear and logistic regression analyses were performed to adjust for associated factors and determine the relationship between MSAF consistency and FSPO2. After controlling for maternal age, race, BMI, GA, chorioamnionitis, labor duration and BW < 2500 grams, there was no relationship between the presence of MSAF or MSAF consistency and mean FSPO2 (p > 0.05). However, there was an association between MSAF consistency and the presence of 2 or more episodes of FSPO2 < 30% lasting at least 2 minutes (p = 0.02) [see Table]. Meconium during the first stage of labor was associated with more frequent episodes of FSPO2 < 30%.Tabled 1FSPO2 DataClear AF (N = 1000)Thin MSAF (N = 118)Moderate MSAF (N = 115)Thick MSAF (N = 70)FSPO2 (mean % ± SD)50.4 ± 6.948.8 ± 7.349.6 ± 7.148.5 ± 7.4FSPO2 < 30% for ≥ 2 minutes137 (13.7%)24 (20.9%)27 (23.5%)18 (26.1%) Open table in a new tab

How well does reflectance pulse oximetry reflect intrapartum fetal acidosis?

Objective: The purpose of this study was to determine the sensitivity and specificity for acidosis of intrapartum fetal oxygen saturation measured by reflectance pulse oximetry. Study Design: Intrapartum fetal oxygen saturation values per labor stage were correlated with umbilical artery pH, base excess and PCO2 by regression analysis. Receiver operating characteristic curve analysis was performed with the use of historic umbilical arterial cutoff values; a fetal oxygen saturation cutoff range with optimal sensitivity and specificity was calculated. Results: Mean fetal oxygen saturation was 42.8%, over the mean 132 minutes of 107 recordings. Overall areas under the sensitivity and specificity curves were 0.77 for pH and PCO2, decreasing sharply toward birth; all areas for base excess were poor (approximately 0.5). Depending on stage and umbilical artery parameter, fetal oxygen saturation cutoffs were 33% to 36%, with sensitivities of 0.67 to 0.8 and specificities of 0.62 to 0.90. Conclusion: Fetal oxygen saturation sensitivities and specificities for acidosis do not yet justify the supplementation of cardiotocography with routine reflectance pulse oximetry. (Am J Obstet Gynecol 2002;186:1351-7.)

Abnormal fetal heart rate patterns during the active phase of labor: the value of fetal oxygen saturation

Objective: To determine the predictive value of intrapartum fetal oxygen saturation (SO2) for prediction of an umbilical artery pH less than 7.15 at birth in labors complicated by abnormalfetal heart rate traces.Study design: Eighty-five primigravidas in spontaneous labor complicated by abnormal fetal heart rate traces underwent fetal SO2 monitoring using the fetalpulse oximetry technique. Cases with an SO2 of < 30% were delivered by Cesarean section. Umbilical artery pH was measured at birth in all women.Results: With the value set of 30%as the cut-off point of fetal oxygen saturation, the positive predictive value for umbilical artery pH of < 7.15 was 61.5% and the negative predictive value was 95.8%, with a sensitivity of 72% and aspecificity of 93%.Conclusions: Fetal pulse oximetry is a promising technique for assessment of fetal well-being during labor and may decrease the number of unnecessary Cesarean sections.

Intrapartum fetal oxygen saturation monitoring in a busy labour ward

Objective: To measure the ease of use of a fetal pulse oximeter in a busy labour ward. Design: Descriptive study in the Labour Ward, National University Hospital, Singapore, involving 145 labouring women with singleton pregnancies, and fetuses in cephalic presentation, with cervical dilatation >2 cm and amniotic membranes ruptured. Results: Placement was comfortable. Oxygen saturation (S pO 2) readings were obtained in 127 women (87.5%). Adequate readings were obtained a median of 69% of the time the transducer was in situ. S pO 2 values in the last 10 min prior to delivery correlated poorly with parameters of neonatal outcome. Conclusion: The Nellcor N-400 fetal pulse oximeter and FS14 fetal sensor is a feasible method of intrapartum fetal monitoring in a busy labour ward and is acceptable to labouring women.

Intrapartum fetal oxygen saturation monitoring in congenital fetal heart block.

Conventional intrapartum electronic fetal heart rate monitoring is not informative in certain fetal conditions because the electronically-monitored fetal heart rate pattern is uninterpretable in terms of reflecting fetal normoxia. Such fetal conditions include various cardiac dysrrhythmias and some central nervous system abnormalities. Difficulties with intrapartum fetal welfare surveillance in such conditions often lead to operative delivery as a precautionary measure. We report 2 cases of intrapartum fetal oxygen saturation monitoring in the presence of congenital complete heart block (CCHB), using the Nellcor N400/FS14 oxygen saturation monitoring system. Mean intrapartum fetal oxygen saturation (FSpO2) was 32% (SEM +/- 1%) in the first case and 48% (SEM +/- 0.3%) in the second case. In both cases, vaginal delivery of otherwise healthy infants was achieved. Fetal pulse oximetry is a promising new technique which directly measures fetal oxygenation without reference to fetal heart rate patterns. It may assist in the intrapartum fetal welfare assessment in conditions such as complete heart block, thereby helping to avoid otherwise unnecessary operative delivery.

Prediction of umbilical artery base excess by intrapartum fetal oxygen saturation monitoring

OBJECTIVE: Our purpose was to evaluate the predictive value of intrapartum fetal oxygen saturation as monitored by reflectance pulse oximetry (Spo 2) for metabolic acidosis at birth. STUDY DESIGN: An observational study was carried out on intrapartum patients at ≥35 weeks' gestation having either a nonreassuring fetal heart rate pattern, intrauterine growth restriction, or thick meconium. Fetal oxygen saturation monitoring was performed with use of the Nellcor N-400 monitor and the FS-14 fetal oxygen sensor. Mean values of Spo 2 from the last 30 minutes of monitoring were correlated with umbilical artery base excess and pH at birth, with use of regression analysis, whereas the prediction of acidosis by Spo 2 at different thresholds was tested with use of receiver-operator characteristic curve calculations. RESULTS: Fifty-four patients met the criteria for data analysis, with a mean Spo 2 monitoring time of 150 ± 124 minutes (SD) and a mean signal loss of 30% ± 20%. Mean fetal Spo 2 for the last 30 minutes of monitoring averaged 42.1% ± 9.9% and, for individual patient studies, correlated significantly with calculated oxygen saturation in the umbilical vein ( r = 0.52, p < 0.001) and in the umbilical artery ( r = 0.34, p = 0.02) as measured at birth. However, the correlation with umbilical artery base excess values at birth was somewhat weaker ( r = 0.30, p < 0.05), as was the correlation with umbilical artery pH values ( r = 0.26, p = 0.05). Receiver-operator characteristic curve calculations were all nonsignificant when Spo 2 from the last 30 minutes of monitoring was used as a diagnostic test for predicting acidosis at birth. CONCLUSIONS: Intrapartum fetal Spo 2 as monitored in the current study was of limited use as a diagnostic test for predicting acidosis at birth, regardless of the Spo 2 cutoff value used. (Am J Obstet Gynecol 1997;177:775-9.)

Current status of the multicenter randomized clinical trial on fetal oxygen saturation monitoring in the United States

Current clinical methods of intrapartum fetal assessment are sensitive but poorly specific in detecting fetal compromise during labor. These limitations have substantially contributed to the escalating cesarean section rate which occurred in the US during the last several decades. Experimental and clinical research efforts directed towards application of the oxygen saturation monitor (pulse oximeter) to intrapartum fetal assessment have produced encouraging results. If this new method of fetal assessment is to enter the clinical arena, safety and efficacy issues must first be properly evaluated via randomized clinical trials. The purpose of this report is to describe the design of a multicenter randomized clinical trial of intrapartum fetal oxygen saturation monitoring recently begun in the US. Specific aspects of the trial, including purpose, study design, sample size estimates, control and test groups, inclusion and exclusion criteria, fetal heart rate classification, definition of normal fetal arterial oxygen saturation (Spo2), clinical management protocol, and assessment of maternal–fetal outcomes will be addressed.© 1997 Elsevier Science Ireland Ltd.

Prediction of umbilical artery base excess by intrapartum fetal oxygen saturation monitoring

Prediction of umbilical artery base excess by intrapartum fetal oxygen saturation monitoring

Intrapartum reflectance pulse oximetry: effects of sensor location and fixation duration on oxygen saturation readings.

To determine the effects of sensor location and suction fixation duration on measurements of intrapartum fetal oxygen saturation (SpO2) with a new reflectance pulse oximetry system. Fetal SpO2 values (n = 18) were determined in the first stage of labor before and after moving the sensor to another part of the fetal head. Mean fetal SpO2 values did not differ with sensor location (95% CI: -3.59 to 1.48). The duration of measurement period 1, before moving the sensor, was 104 +/- 44 (range 30-240) min. No time-dependent changes in SpO2 values were seen (r = 0.17). Suction is an effective and noninvasive method of securing the reflectance pulse oximetry sensor to the fetal head in the first stage of labor and does not interfere with reproducible SpO2 values over several hours.

The relationship between oxygen saturation and pH in umbilical blood: Implications for intrapartum fetal oxygen saturation monitoring

OBJECTIVE: Our purpose was to evaluate the relationship between umbilical arterial blood oxygen saturation determined by hemoximetry (Sao2) and umbilical arterial blood pH and base excess determined by blood gas analysis to establish a ″critical threshold” for fetal preductal arterial oxygen saturation determined by reflectance pulse oximetry (Spo2). STUDY DESIGN: Umbilical artery and vein blood specimens were obtained at delivery. Blood gas analysis and hemoximetry were performed. Polynomial regression analysis and receiver-operator characteristic curves were calculated for umbilical arterial blood Sao2 and theoretic preductal arterial blood Sao2 versus umbilical arterial blood pH and base excess. RESULTS: A total of 1101 paired umbilical artery and vein specimens were obtained. When the umbilical arterial blood Sao2 was ≥30%, umbilical arterial blood pH was ≥7.13 in 99.0% (388/392) of cases and <7.13 in 1.0% (4/392) of cases. When umbilical arterial blood Sao2 was <30%, umbilical arterial blood pH was ≥7.13 in 91.4% (648/709) of cases and <7.13 in 8.6% (61/709) of cases. CONCLUSIONS: From these analyses, it appears that an Spo2 cutoff value of 30% would be reasonable in clinical trials of intrapartum fetal pulse oximetry. (Am J Obstet Gynecol 1996;175:682-7.)

Intrapartum fetal pulse oximetry: Past, present, and future

Oxygen saturation monitoring (pulse oximetry) has markedly improved medical care in many fields, including anesthesiology, critical care, and newborn intensive care. In obstetrics, fetal heart rate monitoring remains the standard for intrapartum assessment of fetal well-being. Fetal heart rate monitoring is sensitive but nonspecific for detecting fetal compromise. Additional clinical information is needed to discern those fetuses not at risk for development of intrapartum acidosis to avoid unnecessary intervention. Fetal oxygen saturation monitoring is a new technique currently under development. This article reviews the evolution of intrapartum fetal oxygen saturation monitoring and proposes directions for future investigation. (Am J Obstet Gynecol 1996;175:1-9.)