Isis Amer-Wåhlin

Cardiotocography only versus cardiotocography plus ST analysis of fetal electrocardiogram for intrapartum fetal monitoring: a Swedish randomised controlled trial

BACKGROUND Previous studies indicate that analysis of the ST waveform of the fetal electrocardiogram provides information on the fetal response to hypoxia. We did a multicentre randomised controlled trial to test the hypothesis that intrapartum monitoring with cardiotocography combined with automatic ST-waveform analysis results in an improved perinatal outcome compared with cardiotocography alone. METHODS At three Swedish labour wards, 4966 women with term fetuses in the cephalic presentation entered the trial during labour after a clinical decision had been made to apply a fetal scalp electrode for internal cardiotocography. They were randomly assigned monitoring with cardiotocography plus ST analysis (CTG+ST group) or cardiotocography only (CTG group). The main outcome measure was rate of umbilical-artery metabolic acidosis (pH <7.05 and base deficit >12 mmol/L). Secondary outcomes included operative delivery for fetal distress. Results were first analysed according to intention to treat, and secondly after exclusion of cases with severe malformations or with inadequate monitoring. FINDINGS The CTG+ST group showed significantly lower rates of umbilical-artery metabolic acidosis than the cardiotocography group (15 of 2159 [0.7%] vs 31 of 2079 [2%], relative risk 0.47 [95% CI 0.25-0.86], p=0.02) and of operative delivery for fetal distress (193 of 2519 [8%] vs 227 of 2447 [9%], 0.83 [0.69-0.99], p=0.047) when all cases were included according to intention to treat. The differences were more pronounced after exclusion of 291 in the CTG+ST group and 283 in the CTG group with malformations or inadequate recording. INTERPRETATION Intrapartum monitoring with cardiotocography combined with automatic ST-waveform analysis increases the ability of obstetricians to identify fetal hypoxia and to intervene more appropriately, resulting in an improved perinatal outcome.

Fetal electrocardiogram: ST waveform analysis in intrapartum surveillance

ST waveform analysis of fetal electrocardiogram (ECG) for intrapartum surveillance (STAN) is a newly introduced method for fetal surveillance. The purpose of this commentary is to assist in the proper use of fetal ECG in combination with cardiotocography (CTG) during labour. Guidelines and recommendations concerning CTG and ST waveform interpretation and classification are stated that were agreed on by the European experts on ST waveform analysis for intrapartum surveillance during a meeting in Utretcht, the Netherlands in January 2007.

S100 protein in serum as a prognostic marker for cerebral injury in term newborn infants with hypoxic ischemic encephalopathy

The astroglial protein S100 is an established biochemical marker for CNS injury in the adult. The aim was to investigate whether S100 in serum is a prognostic marker of cerebral injury in term newborn infants with hypoxic ischemic encephalopathy (HIE) after perinatal asphyxia. Serum S100 was measured on postnatal days 1-4 in 62 term infants with birth asphyxia. The infants were classified for HIE and had follow-up for at least 18 mo.Infants with moderate and severe HIE had significantly higher S100 levels on postnatal day 1 (p = 0.031) and day 2 (p = 0.008) than infants with mild or no HIE. The levels of S100 decreased on days 2 and 3 in all infants with HIE. The median S100 level on postnatal day 1 was higher in nine infants who died neonatally and in 10 infants who developed cerebral palsy (CP), compared with 43 infants with no signs of impairment at follow up, 14.0 (0.5-60.0) μg/L, 20.7 (0.2-64.0) μg/L and 5.5 (0.7-120.0) μg/L, respectively. A level of S100 above 12 μg/L the first day of life was significantly more frequent in infants who died or developed CP than in infants with no impairment at follow up (p = 0.02). Increased S100 levels were significantly inversely correlated with perinatal pH in the infants and associated with abnormal CTG at admission to the labor ward. Early determination of serum S100 may reflect the extent of brain damage in infants with HIE after asphyxia.

Outcome in obstetric care related to oxytocin use. A population-based study.

Background. The purpose of this study was to investigate the delivery outcome in relation to oxytocin use in labor. Methods. We studied 106,755 deliveries from 1995 to 2002 in the Perinatal Revision South, a population‐based register comprising information from 10 hospitals in southern Sweden. Results. Oxytocin use in labor increased from 27.6% in 1995/96 to 33.2% in 2001/02 (p<0.000006). Oxytocin was administered to 47.7% of the nulliparas and 18.5% of the multiparas. There were large differences between hospitals (range among nulliparas: 32.6–60.4%; among multiparas: 13.9–27.0%). After exclusion of deliveries with induction of labor and deliveries lasting >12 h, there was a significant association between oxytocin use and Apgar score < 7 at 5 min (OR 2.3; 95% CI 1.8–2.9), need for neonatal intensive care (OR 1.6; 95% CI 1.5–1.7), and operative delivery (OR 4.0; 95% CI 3.7–4.2). Conclusions. In deliveries with relatively short duration (≤12 h), a significant association was seen between oxytocin use and adverse outcome. Even though the results are difficult to interpret, the significant difference between the use of oxytocin in different hospitals, as well as the increase of oxytocin use over time, calls for a randomized controlled study to elucidate the advantages and disadvantages of oxytocin use during labor and delivery.

Cerebral Inflammatory Response After Fetal Asphyxia and Hyperoxic Resuscitation in Newborn Sheep

Resuscitation with pure oxygen at birth after fetal asphyxia may aggravate brain damage by inducing pro-inflammation. The toll-like receptors (TLRs) may serve a pro-inflammatory role in hyperoxemia during ischemia-reperfusion. Sixteen near-term fetal sheep (132-136 d) were subjected to 10 min of cord occlusion, delivery and mechanical ventilation with 100% O2 (n = 8), or 21% O2 (n = 8) for 30 min followed by normoxemia for 90 min. Eight sheep fetuses were delivered immediately with inspired O2 targeted at normoxemia for 120 min (controls). Levels and distributions of mRNAs for IL-1β, TNF-α, IL-12p40, IL-18, IL-6, IL-10, IFN-γ, TLR-2, -3 and -4 in cerebral tissue at 2 h after birth were evaluated with real-time polymerase chain reaction (PCR) and in situ hybridization. Expressions of IL-1β, IL-12p40, TLR-2, and TLR-4 were increased in cortex/subcortex after resuscitation with 100% O2 compared with 21% O2 (all p < 0.05) and to controls (all p < 0.05). Increased cellular expression of IL-1β was localized to sub-meningeal cortical layers and to sub-cortical white matter. Hyperoxic resuscitation at birth following fetal asphyxia induces a cerebral pro-inflammatory response with an up-regulation of TLR-2 and -4. These may be early events leading to increased tissue damage after exposure to hyperoxemia at birth.

ST analysis of the fetal electrocardiogram during labor: Nordic observational multicenter study

Objective: To assess the diagnostic power of cardiotocography (CTG) plus the ST interval of the electrocardiogram (ECG) clinical guidelines with combined fetal heart rate and ST waveform analysis of the fetal ECG recorded during labor, to identify an adverse labor outcome (neonatal neurological symptoms and/or metabolic acidosis). Study design: An observational, multicenter study was undertaken in 12 Nordic labor wards. A total of 573 women in labor were monitored using a prototype of the STAN® S 21 recorder with fetal ECG data and computerized ST analysis. Results: Fifteen cases of intrapartum fetal hypoxia identified from neurological neonatal symptoms and/or cord artery pH < 7.05 with base deficit in extracellular fluid > 12.0 mmol/l were recorded. All these cases were identified by CTG + ST clinical guidelines. Five developed neonatal symptoms and had ECG abnormalities during the first stage of labor and, of the remaining ten, eight showed ST changes during active pushing in the second stage. Another eight cases had acidemia only and normal neonatal outcome. Seven of these displayed CTG + ST abnormalities. The high sensitivity of CTG + ST to predict fetal acidosis was associated with a marked increase in positive predictive values compared with conventional CTG. Conclusion: The STAN clinical guidelines identify fetuses at risk of intrapartum asphyxia.

Swedish randomized controlled trial of cardiotocography only versus cardiotocography plus ST analysis of fetal electrocardiogram revisited: analysis of data according to standard versus modified intention-to-treat principle

Objective. To undertake a renewed analysis of data from the previously published Swedish randomized controlled trial on intrapartum fetal monitoring with cardiotocography (CTG‐only) vs. CTG plus ST analysis of fetal electrocardiogram (CTG+ST), using current standards of intention‐to‐treat (ITT) analysis and to compare the results with those of the modified ITT (mITT) and per protocol analyses. Methods. Renewed extraction of data from the original database including all cases randomized according to primary case allocation (n=5 049). Main outcome measure. Metabolic acidosis in umbilical artery at birth (pH <7.05, base deficit in extracellular fluid >12.0mmol/l) including samples of umbilical vein blood or neonatal blood if umbilical artery blood was missing. Results. The metabolic acidosis rates were 0.66% (17 of 2 565) and 1.33% (33 of 2 484) in the CTG+ST and CTG‐only groups, respectively [relative risk (RR) 0.50; 95% confidence interval (CI) 0.28–0.88; p=0.019]. The original mITT gave RR 0.47, 95%CI 0.25–0.86 (p=0.015), mITT with correction for 10 previously misclassified cases RR 0.48, 95%CI 0.24–0.96 (p=0.038) and per protocol analysis RR 0.40, 95%CI 0.20–0.80 (p=0.009). The level of significance of the difference in metabolic acidosis rates between the two groups remained unchanged in all analyses. Conclusion. Re‐analysis of data according to the ITT principle showed that regardless of the method of analysis, the Swedish randomized controlled trial maintained its ability to demonstrate a significant reduction in metabolic acidosis rate when using CTG+ST analysis for fetal surveillance in labor.

Fetal heart rate patterns and ECG ST segment changes preceding metabolic acidaemia at birth.

Objectives  To compare the rates of abnormal ST segment patterns of the ECG and cardiotocographic (CTG) abnormalities in fetuses with metabolic acidaemia at birth and controls. To evaluate the inter‐observer agreement in interpretation of ST analysis and CTG.

Evaluation and impact of cardiotocography training programmes: a systematic review.

Please cite this paper as: Pehrson C, Sorensen J, Amer‐Wåhlin I. Evaluation and impact of cardiotocography training programmes: a systematic review. BJOG 2011;118:926–935.

Implementation of new medical techniques: experience from the Swedish randomized controlled trial on fetal ECG during labor.

Background. In a large Swedish multicenter randomized controlled trial (RCT) on intra partum fetal monitoring with automatic analysis of fetal ECG waveform (STAN) in combination with cardiotocography (CTG) (4966 parturients, 300 obstetricians and midwives managing the patients), interim analysis revealed protocol violations. By a post hoc analysis of the results over time, factors affecting the acceptance of the new technique were analyzed. Methods. The rates of primary and secondary outcome measures (fetal outcome, operative deliveries) were compared in the two study groups (CTG + ST and CTG only). Changes over time were statistically evaluated using a test for homogeneity between the two periods. Results. After retraining, the CTG + ST group showed the lowest rates of operative delivery for fetal distress, fetal blood sampling and admissions to neonatal intensive care unit. Operative deliveries (p = 0.02) and the number of fetal blood sampling decreased significantly over time (p = 0.001). Conclusions. Training and education probably predisposed the clinicians to a change and reinforced it when it occurred as a result of increased personal experience. The audit and feedback together with the influence of opinion leaders and inter-collegial interactions seem to have been of importance for the successively increasing acceptance of the new method during the RCT.