Mb Beatrijs van der Hout-van der Jagt

Insight into variable fetal heart rate decelerations from a mathematical model

During labor and delivery, variable decelerations in the fetal heart rate (FHR) are commonly seen on the cardiotocogram (CTG) that is used to monitor fetal welfare. These decelerations are often induced by umbilical cord compression from uterine contractions. Via changes in oxygenation and blood pressure, umbilical cord compression activates the chemo- and baroreceptor reflex, and thus affects FHR. Since the relation between the CTG and fetal oxygenation is complex, assessment of fetal welfare from the CTG is difficult. We investigated umbilical cord compression-induced variable decelerations with a mathematical model. For this purpose, we extended our model for decelerations originating from caput compression and reduced uterine blood flow with the possibility to induce umbilical venous, arterial and total cord occlusion. Model response during total occlusion is evaluated for varying contractions (duration and amplitude) and sensitivity of the umbilical resistance to the uterine pressure. A clinical scenario is used to simulate a labor CTG with variable decelerations. Simulation results show that fetal mean arterial pressure increases during umbilical cord occlusion, while fetal oxygenation drops. There is a clear relation between these signals and the resulting FHR. The extent of umbilical compression and thus FHR deceleration is positively related to increased contraction duration and amplitude, and increased sensitivity of the umbilical resistance to uterine pressure. No relation is found between contraction interval and FHR response, which can probably be ascribed to the lack of catecholamines in the model. The simulation model provides insight into the complex relation between uterine pressure, umbilical cord compression, fetal oxygenation, blood pressure and heart rate. The model can be used for individual learning, and incorporated in a simulation mannequin, be used to enhance obstetric team training.

A mathematical model to simulate the cardiotocogram during labor. Part A: Model setup and simulation of late decelerations

The cardiotocogram (CTG) is commonly used to monitor fetal well-being during labor and delivery. It shows the input (uterine contractions) and output (fetal heart rate, FHR) of a complex chain of events including hemodynamics, oxygenation and regulation. Previously we developed a mathematical model to obtain better understanding of the relation between CTG signals and vital, but clinically unavailable signals such as fetal blood pressure and oxygenation. The aim of this study is to improve this model by reducing complexity of submodels where parameter estimation is complicated (e.g. regulation) or where less detailed model output is sufficient (e.g. cardiac function), and by using a more realistic physical basis for the description of other submodels (e.g. vessel compression). Evaluation of the new model is performed by simulating the effect of uterine contractions on FHR as initiated by reduction of uterine blood flow, mediated by changes in oxygen and blood pressure, and effected by the chemoreflex and baroreflex. Furthermore the ability of the model to simulate uterine artery occlusion experiments in sheep is investigated. With the new model a more realistic FHR decrease is obtained during contraction-induced reduction of uterine blood flow, while the reduced complexity and improved physical basis facilitate interpretation of model results and thereby make the model more suitable for use as a research and educational tool.

A mathematical model to simulate the cardiotocogram during labor. Part B:parameter estimation and simulation of variable decelerations

During labor and delivery the cardiotocogram (CTG), the combined registration of fetal heart rate (FHR) and uterine contractions, is used to monitor fetal well-being. In part A of our study we introduced a new mathematical computer model for CTG simulation in order to gain insight into the complex relation between these signals. By reducing model complexity and by using physically more realistic descriptions, this model was improved with respect to our previous model. Aim of part B of this study is to gain insight into the cascade of events from uterine contractions causing combined uterine flow reduction and umbilical cord compression, resulting in blood and oxygen pressure variations, which lead to changes in FHR via the baro- and chemoreflex. In addition, we extensively describe and discuss the estimation of model parameter values. Simulation results are in good agreement with sheep data and show the ability of the model to describe variable decelerations. Despite reduced model complexity, parameter estimation still remains difficult due to limited clinical data.

Practice variation in the management of intrapartum fetal distress in The Netherlands and the Western world.

OBJECTIVE Solid evidence on the effect of intrauterine resuscitation on neonatal outcome is limited, and superiority of one intervention over the others is not clear. We therefore surveyed the clinical practice variation in fetal monitoring and the management of fetal distress during labor, in Dutch labor wards. In addition, we have compared recommendations from international guidelines. STUDY DESIGN We conducted a survey among all 86 Dutch hospitals, using a questionnaire on fetal monitoring and management of fetal distress. In addition, we requested international guidelines of 28 Western countries to study international recommendations regarding labor management. RESULTS The response rate of the national survey was 100%. Labor wards of all hospitals use CTG for fetal monitoring, 98% use additional fetal scalp blood sampling, and 23% use ST-analysis. When fetal distress is suspected, oxytocin is discontinued and tocolytic drugs are applied in all hospitals. Nearly all hospitals (98%) use maternal reposition for fetal resuscitation, 33% use amnioinfusion, and 58% provide maternal hyperoxygenation. Management is mainly based on the Dutch national guideline (58%) or on local guidelines (26%). Eight international guidelines on fetal monitoring were obtained for analysis. Fetal scalp blood sampling facilities are recommended in all the obtained guidelines. Use of ST-analysis is recommended in three guidelines and advised against in three guidelines. Five guidelines also advised on intrauterine resuscitation: discontinuation of oxytocin and use of tocolytic drugs was advised in all guidelines, amnioinfusion was recommended in two guidelines and advised against in two guidelines, whereas maternal hyperoxygenation was recommended in two guidelines and advised against in one guideline. CONCLUSION Nationwide clinical practice, and recommendations from international guidelines agree on the use of fetal scalp blood sampling in addition to cardiotocography during labor. The opinion on the use of ST-analysis differs per clinic and per guideline. Discontinuation of oxytocin, administration of tocolytic drugs and maternal repositioning are rather uniform, on national and international level. However, there is a large variation in the use of amnioinfusion and maternal hyperoxygenation, which may be explained by the contradictory recommendations of the different guidelines.

Electrohysterography for uterine monitoring during term labour compared to external tocodynamometry and intra-uterine pressure catheter

OBJECTIVE Current uterine monitoring techniques have major drawbacks that could be avoided when using electrohysterography for uterine monitoring. Recently, a new electrohysterography method has been developed, providing a real-time tocogram on standard cardiotocography monitors. The diagnostic characteristics of this novel method need to be determined and compared to conventional methods We hypothesised that electrohysterography can perform better than external tocodynamometry due to the adhesive properties of the contact electrodes (less motion sensitive), and the improved signal acquisition through subcutaneous tissue (less obesity sensitive). STUDY DESIGN In this prospective diagnostic accuracy study, uterine contractions of labouring women were simultaneously monitored by three different monitoring techniques: electrohysterography, external tocodynamometry, and intra-uterine pressure catheter as method of reference. We performed a two-hour measurement during first and/or second stage of term labour. The contractions of each method were automatically detected by a computer-based algorithm. As the applied method had not been described in literature before, an interim analysis was performed to minimise exposure to the invasive pressure catheter. The main outcome parameter was the sensitivity of electrohysterography in comparison to external tocodynamometry for uterine contraction detection, tested by the Wilcoxon signed rank test. RESULTS Uterine contractions of 48 term labouring women were simultaneously monitored by electrohysterography, external tocodynamometry, and intra-uterine pressure catheter. The study was terminated after the interim analysis as the sensitivity of electrohysterography was significantly higher compared to external tocodynamometry: median 89.5% (interquartile range (IQR); 82-93) and 65.3% (IQR; 53-81) respectively, p<0.001. In a subgroup analysis of obese women (n=15), the sensitivity of electrohysterography was significantly higher than external tocodynamometry (median 88.4% (IQR; 79-95) and 45.8% (IQR; 38-61) respectively, p<0.001). Whereas in a subanalysis of second stage of labour (n=8), electrohysterography did not perform better than external tocodynamometry (median 72.8% (IQR; 61-87) and 66.4% (IQR; 46-75) respectively, p=0.225). Electrohysterography registered 0.4 more contractions per 10min than the intra-uterine pressure measurement (p<0.001) and 0.5 more contractions per 10min than external tocodynamometry (p<0.001). CONCLUSION Electrohysterography has a higher sensitivity for uterine contraction detection than external tocodynamometry during first stage of labour, in non-obese and obese women. Electrohysterography identifies more contractions than conventional techniques.

Intrauterine resuscitation during the second stage of term labour by maternal hyperoxygenation versus conventional care: study protocol for a randomised controlled trial (INTEREST O2)

BackgroundPerinatal asphyxia is, even in developed countries, one the major causes of neonatal morbidity and mortality. Therefore, if foetal distress during labour is suspected, one should try to restore foetal oxygen levels or aim for immediate delivery. However, studies on the effect of intrauterine resuscitation during labour are scarce. We designed a randomised controlled trial to investigate the effect of maternal hyperoxygenation on the foetal condition. In this study, maternal hyperoxygenation is induced for the treatment of foetal distress during the second stage of term labour.Methods/designThis study is a single-centre randomised controlled trial being performed in a tertiary hospital in The Netherlands. From among cases of a suboptimal or abnormal foetal heart rate pattern during the second stage of term labour, a total of 116 patients will be randomised to the control group, where normal care is provided, or to the intervention group, where before normal care 100% oxygen is supplied to the mother by a non-rebreathing mask until delivery. The primary outcome is change in foetal heart rate pattern. Secondary outcomes are Apgar score, mode of delivery, admission to the neonatal intensive care unit and maternal side effects. In addition, blood gas values and malondialdehyde are determined in umbilical cord blood.DiscussionThis study will be the first randomised controlled trial to investigate the effect of maternal hyperoxygenation for foetal distress during labour. This intervention should be recommended only as a treatment for intrapartum foetal distress, when improvement of the foetal condition is likely and outweighs maternal and neonatal side effects.Trial registrationEudraCT, 2015-001654-15; registered on 3 April 2015. Dutch Trial Register, NTR5461; registered on 20 October 2015.

Could electrohysterography be the solution for external uterine monitoring in obese women

ObjectiveTo evaluate the influence of maternal obesity on the performance of external tocodynamometry and electrohysterography.Study designIn a 2-hour measurement during term labor, uterine contractions were simultaneously measured by electrohysterography, external tocodynamometry, and intra-uterine pressure catheter. The sensitivity was compared between groups based on obesity (non-obese/obese/morbidly obese) or uterine palpation (good/moderate/poor), and was correlated to maternal BMI and abdominal circumference.ResultWe included 14 morbidly obese, 18 obese, and 20 non-obese women. In morbidly obese women, the median sensitivity was 87.2% (IQR 74–93) by electrohysterography and 45.0% (IQR 36–66) by external tocodynamometry (p < 0.001). The sensitivity of electrohysterography appeared to be non-influenced by obesity category (p = 0.279) and uterine palpation (p = 0.451), while the sensitivity of tocodynamometry decreased significantly (p = 0.005 and p < 0.001, respectively). Furthermore, the sensitivity of both external methods was negatively correlated with obesity parameters, being non-significant for electrohysterography (range p-values 0.057–0.088) and significant for external tocodynamometry (all p-values < 0.001).ConclusionsElectrohysterography performs significantly better than external tocodynamometry in case of maternal obesity.

Comparison of the psychological and physiological effects on students of a video-assisted or text introduction to a simulated task

Introduction The use of different methods for introducing the scenario in simulation-based medical education has not been investigated before and may be a useful element to optimise the effectiveness of learning. The aim of this study was to compare an immersive video-assisted introduction to a minimal text-based one, with regard to emotional assessment of the situation. Methods In this pilot study, 39 students participated in a medical simulated scenario. The students were randomly assigned to an experimental group (video-assisted introduction) or a control group (minimal textual introduction) and both were followed by performing surgery on LapSim (Surgical Science, Gothenburg, Sweden). The emotional assessment of the situation, cognitive appraisal, was defined as the ratio of the demands placed by an individual’s environment (primary appraisal) to that person’s resources to meet the demands (secondary appraisal). Secondary outcomes were anxiety (State-Trait Anxiety Inventory), physiological parameters (heart rate, heart rate variability, skin conductance, salivary cortisol), engagement (Game Engagement Questionnaire), motivation (Intrinsic Motivation Inventory) and performance (mean score in percentage calculated by LapSim of predefined levels). Results Participants in the immersive video group (n=17) were overloaded in terms of their perceived demands (a ratio of 1.17, IQR 0.30) compared with those in the control group (a ratio of 1.00, IQR 0.42, n=22) (P=0.01). No significant differences were found between the groups in secondary outcomes. Both groups showed an increase of anxiety after the introduction method. In the experimental group, this score increased from 9.0 to 11.0, and in the textual group from 7.5 to 10.5, both P<0.01. Discussion This study shows that the method of introducing a simulated scenario may influence the emotional assessment of the situation. It may be possible to make your simulation introduction too immersive or stimulating, which may interfere with learning. Further research will be necessary to investigate the impact and usefulness of these findings on learning in simulation-based medical education.

An empirical model for educational simulation of cervical dilation in first-stage labor

BackgroundSeveral models for educational simulation of labor and delivery were published in the literature and incorporated into a commercially available training simulator (CAE Healthcare Lucina). However, the engine of this simulator does not include a model for the clinically relevant indicators: uterine contraction amplitude and frequency, and cervical dilation. In this paper, such a model is presented for the primigravida in normal labor.MethodsThe conceptual and mathematical models represent oxytocin release by the hypothalamus, oxytocin pharmacokinetics, and oxytocin effect on uterine contractions, cervical dilation, and (positive) feedback from cervical dilation to oxytocin release by the hypothalamus.ResultsSimulation results for cervical dilation are presented, together with target data for a normal primigravida. Corresponding oxytocin concentrations and amplitude and frequency of uterine contractions are also presented.ConclusionAn original empirical model for educational simulation of oxytocin concentration, uterine contractions, and cervical dilation in first-stage labor is presented. Simulation results for cervical dilation match target data for a normal patient. The model forms a basis for taking into account more independent variables and patient profiles and can thereby considerably expand the range of training scenarios that can be simulated.

Assessment tool for the instructional design of simulation-based team training courses: the ID-SIM

Introduction To achieve an expert performance of care teams, adequate simulation-based team training courses with an effective instructional design are essential. As the importance of the instructional design becomes ever more clear, an objective assessment tool would be valuable for educators and researchers. Therefore, we aimed to develop an evidence-based and objective assessment tool for the evaluation of the instructional design of simulation-based team training courses. Methods A validation study in which we developed an assessment tool containing an evidence-based questionnaire with Visual Analogue Scale (VAS) and a visual chart directly translating the results of the questionnaire. Psychometric properties of the assessment tool were tested using five descriptions of simulation-based team training courses. An expert-opinion-based ranking from poor to excellent was obtained. Ten independent raters assessed the five training courses twice, by using the developed questionnaire with an interval of 2 weeks. Validity and reliability analyses were performed by using the scores from the raters and comparing them with the expert’s ranking. Usability was assessed by an 11-item survey. Results A 42-item questionnaire, using VAS, and a propeller chart were developed. The correlation between the expert-opinion-based ranking and the evaluators’ scores (Spearman correlation) was 0.95, and the variance due to subjectivity of raters was 3.5% (VTraining*Rater). The G-coefficient was 0.96. The inter-rater reliability (intraclass correlation coefficient (ICC)) was 0.91 (95% CI 0.77 to 0.99), and intra-rater reliability for the overall score (ICC) was ranging from 0.91 to 0.99. Conclusions We developed an evidence-based and reliable assessment tool for the evaluation of the instructional design of a simulation-based team training: the ID-SIM. The ID-SIM is available as a free mobile application.