Antepartum high-frequency fetal heart rate sinusoidal rhythm: computerized detection and fetal anemia.

OBJECTIVE: Our aim was to identify antepartum fetal heart rate (FHR) records of high-frequency (HF) sinusoidal rhythms from an electronic database (1983-2003) and determine clinical outcomes. STUDY DESIGN: At the John Radcliffe Hospital (Oxford, UK), 72,297 traces from 19,506 women were analyzed using an algorithm that identifies HF sinusoidal rhythms. The case records were reviewed. RESULTS: There were 15 (0.21/1000) traces from 8 (0.41/1000) women with an HF sinusoidal rhythm. In 5 of 8 women (62.5%), this pattern was associated with fetal anemia (hemoglobin < 10.0 g/dL). Their FHR patterns were distinguished from those of the other nonanemic fetuses by significantly lower long-term variability. CONCLUSION: An antepartum HF sinusoidal rhythm is rare but associated with fetal anemia, particularly if it is combined with reduced long-term variability without episodes of high FHR variability within 60 minutes. The automated system can alert inexperienced staff, who supervise FHR monitoring, by an online warning.

The long-term outcome in surviving infants with Apgar zero at 10 minutes: a systematic review of the literature and hospital-based cohort.

OBJECTIVE: The purpose of this study was to investigate the outcomes of infants who had Apgar scores of zero at 10 minutes and were resuscitated successfully. STUDY DESIGN: The literature was reviewed systematically to identify the outcomes of cases; in addition, the perinatal database at the John Radcliffe Hospital, Oxford, was used to identify similar cases. Eligible infants were identified through hospital records, and outcomes of all infants with an Apgar score of zero at 10 minutes, who were born between January 1991 and December 2004, were reviewed. RESULTS: Eighty-five cases were identified from the literature. With the Oxford database, 9 of 83,065 infants (0.12/1000 births) met our study criteria. Six of the 9 infants died before leaving hospital. One infant with severe quadriparesis and microcephaly died at 11 months of age. One infant at follow-up examination at 5 years had severe spastic quadriparesis with severe global delay. One infant with grade 2 hypoxic-ischemic encephalopathy, who was born with severe anemia that was corrected promptly at birth, had mild disability at follow-up examination at 2 years. Thus, death or severe disability occurred in 8 of 9 infants. Combining the results of metaanalysis of published data with our results of 94 infants, 88 infants (94%) either died or were handicapped severely; 2 infants (2%) were handicapped moderately, and 1 infant (1%) was handicapped mildly. For 3 infants (3%), the long-term outcome could not be determined. CONCLUSION: The outcome of infants with an Apgar score of zero at 10 minutes is almost universally poor.

Umbilical cord gases in relation to the neonatal condition: the EveREst plot.

OBJECTIVE: To validate umbilical arterial and venous pH and base deficit (pH(UA), pH(UV), BD(UA), and BD(UV), respectively), as well as venous-arterial pH differences, as measures of perinatal condition at birth (in relation to emergency intervention, resuscitation, facial mask, low Apgar, seizures, other cerebral problems or death); to investigate whether BD(UA) or pH(UA) better measures perinatal risk. STUDY DESIGN: A novel method (Event Rate Estimate (EveREst) plots) was used to analyze cord blood gases and perinatal outcomes of 34,510 term singleton deliveries: cord blood gas values were grouped into exclusive quantiles (containing equal proportions of cases); the quantiles were plotted against per cent rates (event rates) for perinatal outcomes; the event rates for the different blood gases were compared using the χ² test for difference of proportions. RESULTS: Low pH(UA) predicts poor perinatal outcome better than or comparably to high BD(UA): pH(UA) is significantly better than BD(UA) for predicting low Apgar, resuscitation and facial mask (p<0.001, p<0.05, and p<0.001, respectively). For seizures and other cerebral problems, low pH(UA) is better than high BD(UA) but the difference is not statistically significant. For death, both measures perform equally well. Interventions for the specific reason of "fetal distress" increased as pH(UA) decreased but only where electronic fetal monitoring was used. In acidemic neonates (pH(UA) ≤ 7.05, n=1752), significantly more cord prolapses and placenta abruptions were associated with large and small venous-arterial pH difference (pH(VAD)) respectively (p<0.01). CONCLUSION: EveREst plots display clearly the diagnostic value of cord gases. They allow for the easy identification of background rates and increases above background, thresholds of interest, and comparison of the blood gas measures. Overall pH(UA) is the best umbilical blood measure of perinatal outcome. BD(UA) is comparable or inferior. Extremes of pH(VAD) (large or small) identify higher proportions of specific poor outcomes in acidemic neonates.

Computerized intrapartum electronic fetal monitoring: analysis of the decision to deliver for fetal distress.

We applied computerized methods to assess the Electronic Fetal Monitoring (EFM) in labor. We analyzed retrospectively the last hour of EFM for 1,370 babies, delivered by emergency Cesarean sections before the onset of pushing (data collected at the John Radcliffe Hospital, Oxford, UK). There were two cohorts according to the reason for intervention: (a) fetal distress, n(1) = 524 and (b) failure to progress and/or malpresentation, n(2) = 846. The cohorts were compared in terms of classical EFM features (baseline, decelerations, variability and accelerations), computed by a dedicated Oxford system for automated analysis--OxSys. In addition, OxSys was employed to simulate current clinical guidelines for the classification of fetal monitoring, i.e. providing in real time a three-tier grading system of the EFM (normal, indeterminate, or abnormal). The computerized features and the simulated guidelines corresponded well to the clinical management and to the actual labor outcome (measured by umbilical arterial pH).

Computerized fetal heart rate analysis in labor: detection of intervals with un-assignable baseline.

The fetal heart rate (FHR) is monitored during labor to assess fetal health. Both visual and computerized interpretations of the FHR depend on assigning a baseline to detect key features such as accelerations or decelerations. However, it is sometimes impossible to assign a baseline reliably, by eye or by numerical methods. To address this issue, we used the Oxford Intrapartum FHR Database to derive an algorithm based on the distribution of the FHR that detects heart rate intervals without a clear baseline. We aimed to recognize when a fetus cannot maintain its heart rate baseline and use this to assist computerized FHR analysis. Twenty-three FHR windows (15 min long) were used to develop the method. The algorithm was then validated by comparison with experts who classified 50 FHR windows into two groups: baseline assignable or un-assignable. The average agreement between experts (κ = 0.76) was comparable to the agreement between method and experts (κ = 0.67). The algorithm was used in 22 559 patients with intrapartum FHR records to retrospectively determine the incidence of intervals (defined as 15 min windows) that had un-assignable baselines. Sixty-six percent had one or more such episodes at some stage, most commonly after the onset of pushing (55%) and least commonly pre-labor (16%). These episodes are therefore relatively common. Their detection should improve the reliability of computerized analysis and allow further studies of what they signify clinically.

A computer system for the numerical analysis of nonstress tests.

The development and clinical validation of a computer system for the numerical analysis of nonstress tests is reviewed, and recent improvements are reported. The analysis was developed by using a database of 73,802 nonstress test readings to provide a numerical definition of reactivity that is tailored to the gestational age of the fetus and independent of the presence of accelerations. When used at the bedside, the analysis minimizes monitoring time by alerting the operator when monitoring can be safely stopped because the fetal heart rate is normal. It also detects potentially sinister sinusoidal patterns and improves the quality of nonstress test readings by quantifying signal loss and, if significant, alerting the operator.