Fetal pulse oximetry improves intrapartum fetal assessment

S184 SMFM Abstracts 451

December 2003 Am J Obstet Gynecol

IN CASES OF FETAL BRAIN INJURY, A SLOW HEART RATE AT BIRTH IS AN INDICATOR OF SEVERE ACIDOSIS JEFFREY PHELAN1, CORTNEY KIRKENDALL2, LISA KORST3, GILBERT MARTIN4, 1Citrus Valley Medical Center, Obstetrics and Gynecology, West Covina, CA 2Childbirth Injury Prevention Foundation, Pasadena, CA 3Chidren’s Hospital of Los Angeles, pediatrics, Los Angeles, CA 4Citrus Valley Medical Center, neonatology, West Covina, CA OBJECTIVE: To evaluate the association of a slow heart rate( < 100 bpm)at the moment of birth with an umbilical artery pH < 7.00 and a base deficit $12 among neonates with fetal brain injury. STUDY DESIGN: Umbilical artery cord blood gases from 300 singleton term neonates with permanent neurologic impairment were separated into 2 groups based on the presence of a slow ( < 100 bpm)or normal heart rate at birth. Cases without an umbilical artery cord blood gas or documentation of the heart rate at birth were excluded. Categorical and logistic regression analysis were performed to determine whether a pH < 7.00 and a base deficit $12 were related to a slow heart rate at birth. RESULTS: Of 300 cases,71 met entry criteria. Cases with a slow heart rate were 5.3X more likely to have an umbilical artery pH < 7.00 than those with a normal heart rate [26/34 (77%) vs. 14/37 (38%), OR 5.3, 95% CI (1.7, 17.3) P = 0.002]. Cases with a slow heart rate were 7.1X more likely to have a base deficit $12 compared with those with a normal heart rate [30/34 (88%) vs. 18/ 37 (51%), OR 7.1, 95% CI (1.9,29.6) P = 0.0009] The independence of this relationship from the more general intrapartum FHR classification of NR, HON, RPD was confirmed with multivariate logistic regression analysis. CONCLUSION: At the moment of birth, the umbilical artery cord pH and base deficit were strongly associated with the presence of a slow heart rate, and were independent of the FHR classification.

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SCREENING FOR INTRAUTERINE GROWTH RESTRICTION USING SECOND TRIMESTER DOPPLER ULTRASOUND MENACHEM GRAUPE1, CALVIN HOBEL2, 1Cedars-Sinai Medical Center, Maternal-Fetal Medicine & The Burns and Allen Research Institute, Milwaukee, WI 2Cedars-Sinai Medical Center, Maternal-Fetal Medicine & The Burns and Allen Research Institute, Los Angeles, CA OBJECTIVE: To identity risk factors for Intrauterine Growth Restriction (IUGR) using Doppler ultrasound. STUDY DESIGN: Umbilical and uterine artery perfusion and composite pregnancy perfusion scores were evaluated (at 18-20, 26-28 and 32-34 weeks gestation) in a cohort of pregnant women. IUGR was defined as birth weight below the tenth percentile for gestational age. RESULTS: IUGR was diagnosed in 54 of the 634 women completing the study. The initial pulsatility index (PI) in the left and right uterine arteries and umbilical artery was higher in infants later diagnosed IUGR (p < 0.0001, p = 0.03 and p = 0.03) for the first second and third scan. A composite pregnancy pulsatility index (PPI) was also increased in these infants (p < 0.0001). PPI above 6.0 was associated with birth weight below the tenth and fifth percentile (sensitivity 33% and 50%, negative predictive value 95% and 98%).

ROC for PPI at 18-20 weeks. (R = 0.683).

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FETAL PULSE OXIMETRY IMPROVES INTRAPARTUM FETAL ASSESSMENT JORGE CARRILLO1, ALVARO INSUNZA1, RODRIGO LATORRE1, MARCELO MERCADO2, FREDDY CARDENAS2, JOSE M. NOVOA2, ENRIQUE PAIVA1, 1Hospital Padre Hurtado, Universidad del Desarrollo, Santiago, Chile 2Hospital Padre Hurtado, Santiago, Chile OBJECTIVE: To correlate suspicious and pathologic electronic fetal heart rate (FHR) monitoring patterns with fetal pulse oximetry during labor and its association with neonatal outcomes. STUDY DESIGN: Prospective observational study. Inclusion criteria was a suspicious or pathologic FHR pattern according to definitions based in the NIH Monitoring Workshop. Fetal pulse oximetry (FPO) was began and recorded until delivery. Demographic, intrapartum and a composite neonatal outcome (including at least one of the following: fetal or infant death, need for intubationa at birth, Min-1 Apgar < 3, min-5 Apgar < 6, umbilical artery pH < 7.15, base excess <
12, admission to Neonatal Unit for asphyxia, diagnosis of hypoxic-ischemic encephalopathy at discharge) were collected. SPSS 10.0 statistical package was used for analysis, with p < 0.05 considered significant. RESULTS: 173 patients were analyzed. 75,8% of the FHR tracings were nonreassuring at delivery. There was 58,8% of operative deliveries, with 40% of them indicated for fetal distress. Composite adverse neonatal outcome was present in 24,2% of the neonates. 7 of them were diagnosed as hypoxic-ischemic encephalopathy (HIE). When a cut-off value of < 30% oxygen saturation for a period of 10 minutes was used, the test showed a modest sensitivity and PPV but high specificity and NPV for detecting HIE and neonatal acidosis. PPV improved when detecting the composite adverse neonatal outcome. CONCLUSION: When a non-reassuring FHR pattern presents in labor, the addition of fetal pulse oximetry improves specificity forthe assessment of the fetus, hence preventing from unnecessary interventions. Predictive values of FPO at saturation < 30% for various neonatal outcomes Sensitivity Specificity PPV NPV Composite adverse neonatal outcome (%) Hypoxic-ischemic encephalopathy (%) PH < 7.15 (%) BE <
12 (%)

9.7 20.0 5.9 10.0

98.6 96.2 96.4 97.5

75.0 20.0 25.0 50.0

70.8 96.2 83.5 81.3

Using Spearman analysis for smoothed birth weight percentile, prepregnancy Body Mass Index, height, weight, parity and number of cigarettes smoked were each associated with birth weight percentile. At the initial ultrasound femur length, abdominal circumference and estimated weight were also associated with birth weight percentile. Stepwise multiple linear regression was then used to allow prediction of birth weight percentile based on PI, maternal weight, parity and race, hypertension, and diabetes (R2 = 0.104). CONCLUSION: Combined assessment of maternal uterine PI and fetal umbilical artery PI allows early risk assessment for IUGR. PPI provides a possible new tool in the prediction of IUGR as early as the mid second trimester. A single test to find all IUGR is still ellusive this study shows that a good proportion of cases at risk can be found early. Early identification may lead to increased surveillance and intervention to minimize neonatal complications of IUGR.

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