Intrapartum fetal scalp lactate sampling for fetal assessment in the presence of a non-reassuring fetal heart rate trace

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Classification of Foetal Distress and Hypoxia Using Machine Learning Approaches

© 2018, Springer International Publishing AG, part of Springer Nature. Foetal distress and hypoxia (oxygen deprivation) is considered as a serious condition and one of the main factors for caesarean section in the obstetrics and Gynecology department. It is the third most common cause of death in new-born babies. Many foetuses that experienced some sort of hypoxic effects can develop series risks including damage to the cells of the central nervous system that may lead to life-long disability (cerebral palsy) or even death. Continuous labour monitoring is essential to observe the foetal well being. Foetal surveillance by monitoring the foetal heart rate with a cardiotocography is widely used. Despite the indication of normal results, these results are not reassuring, and a small proportion of these foetuses are actually hypoxic. In this paper, machine-learning algorithms are utilized to classify foetuses which are experiencing oxygen deprivation using PH value (a measure of hydrogen ion concentration of blood used to specify the acidity or alkalinity) and Base Deficit of extra cellular fluid level (a measure of the total concentration of blood buffer base that indicates the metabolic acidosis or compensated respiratory alkalosis) as indicators of respiratory and metabolic acidosis, respectively, using open source partum clinical data obtained from Physionet. Six well know machine learning classifier models are utilised in our experiments for the evaluation; each model was presented with a set of selected features derived from the clinical data. Classifier’s evaluation is performed using the receiver operating characteristic curve analysis, area under the curve plots, as well as the confusion matrix. Our simulation results indicate that machine-learning algorithms provide viable methods that could delivery improvements over conventional analysis

Maternal plasma levels of oxytocin during physiological childbirth - a systematic review with implications for uterine contractions and central actions of oxytocin

Oxytocin is a key hormone in childbirth, and synthetic oxytocin is widely administered to induce or speed labour. Due to lack of synthetized knowledge, we conducted a systematic review of maternal plasma levels of oxytocin during physiological childbirth, and in response to infusions of synthetic oxytocin, if reported in the included studies. An a priori protocol was designed and a systematic search was conducted in PubMed, CINAHL, and PsycINFO in October 2015. Search hits were screened on title and abstract after duplicates were removed (n = 4039), 69 articles were examined in full-text and 20 papers met inclusion criteria. As the articles differed in design and methodology used for analysis of oxytocin levels, a narrative synthesis was created and the material was categorised according to effects. Basal levels of oxytocin increased 3-4-fold during pregnancy. Pulses of oxytocin occurred with increasing frequency, duration, and amplitude, from late pregnancy through labour, reaching a maximum of 3 pulses/10 min towards the end of labour. There was a maximal 3- to 4-fold rise in oxytocin at birth. Oxytocin pulses also occurred in the third stage of labour associated with placental expulsion. Oxytocin peaks during labour did not correlate in time with individual uterine contractions, suggesting additional mechanisms in the control of contractions. Oxytocin levels were also raised in the cerebrospinal fluid during labour, indicating that oxytocin is released into the brain, as well as into the circulation. Oxytocin released into the brain induces beneficial adaptive effects during birth and postpartum. Oxytocin levels following infusion of synthetic oxytocin up to 10 mU/min were similar to oxytocin levels in physiological labour. Oxytocin levels doubled in response to doubling of the rate of infusion of synthetic oxytocin. Plasma oxytocin levels increase gradually during pregnancy, and during the first and second stages of labour, with increasing size and frequency of pulses of oxytocin. A large pulse of oxytocin occurs with birth. Oxytocin in the circulation stimulates uterine contractions and oxytocin released within the brain influences maternal physiology and behaviour during birth. Oxytocin given as an infusion does not cross into the mother's brain because of the blood brain barrier and does not influence brain function in the same way as oxytocin during normal labour does

Lactate determination in ante- and intrapartum surveillance

Lactate concentration is reported to be high in amniotic fluid (AF). Prelabour rupture of membranes (PROM) occur in about 20% of all pregnancies. The condition is associated with fetal and maternal complications, and might be a marker of imminent delivery. Therefore among women with suspected prelabour rupture of the membranes (PROM), it is of great importance to accurately confirm the diagnosis. In our studies we wanted to assess whether lactate determination in vaginal/amniotic fluid could be used as a diagnostic test for prelabour rupture of membranes, and could predict onset of labour in women with suspected PROM. We selected women with a history of suspect PROM after 34 weeks gestation for determination of lactate concentrations in vaginal fluid. A lactate concentration > 4.5 mmol/l was found to be the best cut-off value for a positive ‘Lactest’ and showed a sensitivity of 86% and specificity 92%.The median time interval between examination and spontaneous onset of labour among the women with `high´ lactate (> 4.5 mmol/l) were 8.4 hours and for those with `low´ lactate concentration (< 4.5 mmol/l) 54 hours. Among women with `high´ lactate concentration 88% started in labour within 24 hours, as compared with 21% for those with `low´ lactate concentration. Labour dystocia is clinically defined as slow or arrest of progress during labour and is a common obstetrical problem worldwide. In our study we looked for an association between high lactate concentration in amniotic fluid and labour dystocia. We selected women in active labour attending labour ward, and performed at least two consecutive measurements of lactate concentration in amniotic fluid during labour. Among women with spontaneous vaginal deliveries (n=23) the mean lactate concentration in AF during labour was 8.9 mmol/l and among women with labour dystocia (n=31) the corresponding value was 10.9 mmol/l (p 10.1 mmol/l) in at least two consecutive measures, 86% were delivered instrumentally/operatively due to dystocia. Using this definition of a positive test gives a sensitivity of 81% a specificity of 82%, a positive predictive value of 86%, and a negative predictive value of 76%. Fetal surveillance during labor is often based on fetal heart rate monitoring using the cardiotocograph (CTG). A normal CTG is reassuring for a well oxygenated fetus. However, a non-reassuring trace occurs in up to 50% of all recordings, but only a small proportion of these fetuses are at risk of hypoxia. In a multicentre trial we wanted to compare pH vs. lactate analysis, regarding prevention of acidemia at birth. 2992 women in labour were randomised to pH (n=1,496) or lactate analysis (n=1,496). Protocol violations were significantly less frequent in women randomised to lactate compared with women randomised to pH analysis, 11.0% vs. 1.5%. There were no significant differences between the groups in the rate of metabolic acidemia (RR 0.96) or pH <7.00 (RR 0.88) in cord artery blood at birth. We have with this thesis shown the usefulness of determination of lactate in AF and fetal blood sampling. Lactate in AF can be used in the diagnosis of suspected PROM, in the prediction of spontaneous onset of labour for women with suspected PROM, and also in the diagnosis of labour dystocia. We have shown lactate analysis of fetal scalp blood to be at least as good as pH analysis in the management of intrapartum fetal distress

Ante partum determination of lactate in amniotic fluid

Background: The present studies were conducted to investigate whether lactate determination in vaginal fluids, 'Lac-test', could be used as a diagnostic test for prelabour rupture of membranes (PROM). To derive the best cut-off value for a positive test and to asses weather lactate determination in vaginal fluid was associated with, and could predict, onset of labour for woman with suspect PROM. Lactate concentration was measured with the commercially available Lactate ProTM an electrochemical test strip method which needs only 5ul of fluid to analyze the lactate concentration. The test was carried out bedside and the result was available after 60 seconds. The studies were made as prospective observational studies in labour ward at Söder hospital Stockholm years 2002-2003. Paper I. Two hundred women with a history of suspect PROM after 34 weeks gestation were selected for determination of lactate concentrations in vaginal fluid. In 100 of these cases, actim PROM testTM were also analyzed. Sensitivity, specificity, positive and negative predictive values and Kappa indices were calculated. Results: A lactate concentration > 4.5 mmol/l was found to be the best cut-off value for a positive test. 'Lac-test' had a sensitivity of 86% (95% C.I. 77-96%), specificity 92% (95% C.I 84-99%), positive and negative predictive values of 92% and 87%, respectively. Likelihood ratio (LR) for a positive Lac-test was 10.75 and for a negative test 0. 15. The Kappa index for the 'Lactest' was 78%. Paper II. One hundred and seventy nine women attending labour ward at Söder hospital with suspect PROM after 34 weeks gestation were selected for determination of lactate concentrations in vaginal fluid. Association between time to spontaneous onset of labour within 24 hours and 48 hours and lactate concentration in vaginal fluid was analyzed Results: The median time interval between examination and spontaneous onset of labour was 8.4 hours for those with "high" lactate (> 4.5 mmol/l) and 54 hours for those with "low" lactate concentrations (< 4.5 mmol/l). Among women with "high" lactate concentrations 76 (88%) started in labour within 24 hours, as compared with 20 (21%) for those with "low" lactate concentration, giving an Odds Ratio (OR) of 27.7; 95% C.I. 12-63.3. Conclusion: Lactate determination is a valid test in cases with a history of suspects PROM. High lactate concentration (> 4.5 mmol/l) in vaginal fluid is strongly associated with, and can predict, woman with suspect PROM spontaneous onset of labour within 24 hours and 48 hours