Search

Beat-to-beat variability has been suggested as a sensitive indication of fetal well-being. The suggestion originates from case reports of observed decrease in variability preceding clinical signs of fetal asphyxia and fetal death. Against this background a study was performed to evaluate possible changes in heart rate variability in relation to changes in fetal oxygenation. Chloralose-anesthetized sheep were used. Short-term hypoxia was produced without acidosis. The FECGs were recorded on magnetic tape and later analysed by scrutinizing each QRS complex prior to the trigger of a rate meter. The differential index (DI) described by Yeh and co-workers was chosen because it is easily computed and reflects the variability of coefficient of variation for two successive R-R intervals. In contrast to the generally held view of a progressive diminution of variability during the development of asphyxia, the variability was found to increase parallel with a decrease in fetal arterial PO2 determined on blood samples withdrawn at intervals and ranging between 26 and 10 mmHg. The correlation between variability and PO2 in the range below 8-10 mmHg is still to be determined. [ABSTRACT FROM AUTHOR]

Please cite this paper as: Kro G, Yli B, Rasmussen S, Norèn H, Amer-Wåhlin I, Didrik Saugstad O, Stray-Pedersen B, Rosén K. A new tool for the validation of umbilical cord acid-base data. BJOG 2010;117:1544-1552. Objective To identify the distribution of carbon dioxide tension (pCO2) relative to pH in validated umbilical cord acid-base data. Design Observational study. Setting European hospital labour wards. Population Data for 36 432 term newborns were obtained from three sources: two trials of fetal monitoring with electrocardiography (ECG; the Swedish randomised controlled trial and the European Union Fetal ECG trial) and data from Mölndal Hospital. Methods From the total study population, cases with missing values or obvious typing errors were excluded. The remaining data were validated based on specified criteria. Percentiles of arterial pCO2 by pH were calculated using multilevel regression modelling. Main outcome measures Umbilical cord pH, pCO2 and base deficit. Results Acid-base values were considered invalid in one out of seven cases. Percentiles for arterial pCO2 corresponding to specified values of arterial pH were developed from the validated data of 26 690 cases. Conclusions Percentiles for arterial pCO2 for a specified arterial pH can be used as a tool to identify cases with erroneously low pCO2 values, and thus avoid an incorrect interpretation of the newborn's acid-base status. [ABSTRACT FROM AUTHOR]

Objective To find whether low-to-high frequency (LF/HF) ratio of fetal heart rate (FHR) variability changes in relation to a significant ST-event during delivery, and if the change is predictive of metabolic acidosis of the newborn. Design A case–control study. Setting Data from a multicentre project. Subjects Acidotic and control fetuses with abnormal cardiotocography together with a ST-event in fetal electrocardiogram (ECG). Methods We studied intrapartum FHR variability with spectral analysis from 34 fetuses with a significant ST-event in the fetal ECG. LF/HF ratio of FHR variability was measured within a period of 1 hour before and 1 hour after a significant ST-event. Sensitivity and specificity of the change in LF/HF ratio of FHR variability in prediction of metabolic acidosis (pH ≤ 7.05 and base deficit value > 12.0 mmol/l) of the newborn were described by means of the receiver operating characteristic curve. Main outcome measures Change in LF/HF ratio of FHR in relation to a significant ST-event. Results We found that a relative change in LF/HF ratio greater than 30% in relation to a significant ST-event predicted cord arterial metabolic acidosis with a sensitivity of 89% (95% CI 68–100%) and specificity of 80% (95% CI 64–96%). Conclusions Relative changes in LF/HF ratio of FHR variability in relation to a significant ST-event are more pronounced in fetuses born with metabolic acidosis. [ABSTRACT FROM AUTHOR]

Objective. To monitor and analyze (audit) the introduction of the STAN methodology in a district hospital. Design. Retrospective study covering the total population of deliveries at term during 2004 and 2005. Material and methods. 1,875 out of 3,193 term pregnancies (59%) were monitored using the STAN® fetal heart monitor (Neoventa Medical, Moelndal, Sweden) and the associated clinical guidelines. Cord metabolic acidosis, neonatal outcome, and rates of operative deliveries for fetal distress were recorded. Results. The overall cesarean section rate was significantly reduced in the STAN group. Emergency (crash) cesarean sections were significantly reduced from 1.51% to 0.27% in the cardiotocography- and STAN-monitored groups, respectively (OR 0.18, 95% CI 0.07-0.49). When cesarean section was performed only because of non-reassuring cardiotocography, cord acid base was significantly higher, 7.26 versus 7.19 (p<0.01), as compared to when STAN guidelines were followed. Total population rates for operative deliveries for fetal distress and cesarean section rates were 6.7% and 3.5% respectively. The corresponding metabolic acidosis rate was 0.5%. Conclusion. High STAN usage in a busy labor ward setting provided an outcome equaling that noted previously in a larger academic unit, demonstrating the safe implementation of the STAN methodology in a nonacademic unit. [ABSTRACT FROM AUTHOR]

A letter to the editor is presented in response to the article on the comparison of intrapartum automated fetal electrocardiography and conventional cardiography.

Objective: To identify the distribution of carbon dioxide tension (pCO(2) ) relative to pH in validated umbilical cord acid-base data., Design: Observational study., Setting: European hospital labour wards., Population: Data for 36,432 term newborns were obtained from three sources: two trials of fetal monitoring with electrocardiography (ECG; the Swedish randomised controlled trial and the European Union Fetal ECG trial) and data from Mölndal Hospital., Methods: From the total study population, cases with missing values or obvious typing errors were excluded. The remaining data were validated based on specified criteria. Percentiles of arterial pCO(2) by pH were calculated using multilevel regression modelling., Main Outcome Measures: Umbilical cord pH, pCO(2) and base deficit., Results: Acid-base values were considered invalid in one out of seven cases. Percentiles for arterial pCO(2) corresponding to specified values of arterial pH were developed from the validated data of 26, 690 cases., Conclusions: Percentiles for arterial pCO(2) for a specified arterial pH can be used as a tool to identify cases with erroneously low pCO(2) values, and thus avoid an incorrect interpretation of the newborn's acid-base status., (© 2010 The Authors Journal compilation © RCOG 2010 BJOG An International Journal of Obstetrics and Gynaecology.)

Objective: To find whether low-to-high frequency (LF/HF) ratio of fetal heart rate (FHR) variability changes in relation to a significant ST-event during delivery, and if the change is predictive of metabolic acidosis of the newborn., Design: A case-control study., Setting: Data from a multicentre project., Subjects: Acidotic and control fetuses with abnormal cardiotocography together with a ST-event in fetal electrocardiogram (ECG)., Methods: We studied intrapartum FHR variability with spectral analysis from 34 fetuses with a significant ST-event in the fetal ECG. LF/HF ratio of FHR variability was measured within a period of 1 hour before and 1 hour after a significant ST-event. Sensitivity and specificity of the change in LF/HF ratio of FHR variability in prediction of metabolic acidosis (pH < or = 7.05 and base deficit value > 12.0 mmol/l) of the newborn were described by means of the receiver operating characteristic curve., Main Outcome Measures: Change in LF/HF ratio of FHR in relation to a significant ST-event., Results: We found that a relative change in LF/HF ratio greater than 30% in relation to a significant ST-event predicted cord arterial metabolic acidosis with a sensitivity of 89% (95% CI 68-100%) and specificity of 80% (95% CI 64-96%)., Conclusions: Relative changes in LF/HF ratio of FHR variability in relation to a significant ST-event are more pronounced in fetuses born with metabolic acidosis.