American journal of perinatology
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Comparative Study
Corticosteroid binding globulin, total serum cortisol, and stress in extremely low-birth-weight infants.
Our objective was to determine if low levels of corticosteroid binding globulin (CBG) might explain the low serum total cortisol levels found in some extremely low-birth-weight (ELBW) infants. In a prospective study, serum total cortisol and CBG were measured in single blood samples from 31 ELBW infants, with a gestational age less than 28 weeks, in the first 8 days of life. Severity of illness was assessed using the Score for Neonatal Acute Physiology Perinatal Extension (SNAP-PE). ⋯ Estimated mean serum free cortisol concentrations in these five infants (0.76 mcg/dL) were comparable to estimated free cortisol levels diagnostic of adrenal insufficiency in sick adult patients. Our findings indicate that CBG levels are lower in ELBW infants than in term infants, but low CBG levels do not explain the low serum total cortisol levels found in some very sick infants. Low cortisol levels in small premature infants may be adequate to support growth if the infant is well, but may result in a syndrome of adrenal insufficiency in those with severe illnesses.
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We tested the hypothesis that in preterm infants, prolonged apneas (apneas > or = 20 sec) are not random events but are preceded by frequent and progressively longer respiratory pauses associated with changes in ventilatory variables. We studied 36 preterm infants with apnea [birth weight 1190 +/- 60 g (mean +/- SEM), study weight 1300 +/- 60 g, gestational age 28 +/- 1 weeks, and postnatal age 23 +/- 2 days]. A nosepiece with a flow-through system was used to measure ventilation and alveolar gases. ⋯ When the 1 min before prolonged apnea was compared with the 1 min of similar sleep state not having prolonged apnea, minute ventilation decreased, primarily due to a decrease in respiratory frequency. Oxygen saturation decreased and alveolar PCO2 did not change. These findings suggest that prolonged apnea is not a random event but is preceded by a disturbance of the respiratory control system characterized by (1) frequent apneas of progressive duration, (2) decrease in respiratory minute volume and frequency, and (3) decreased O2 saturation.
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Transient altered fetal behavior manifested by decreased fetal biophysical score at 37 weeks' gestation following maternal injuries sustained in a motor vehicle accident, represented an immediate fetal response to fetomaternal hemorrhage occurring during the accident. Although cesarean delivery had initially been considered due to fetal distress (fetal biophysical score of 4 of 10), the fetal biophysical score improved within 2 hr, permitting spontaneous vaginal delivery of a nonasphyxiated fetus, 24 hr after the traumatic event. To our knowledge this is the first report of a transient abnormal fetal biophysical profile in association with a large fetomaternal hemorrhage.
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Fetal bradycardia is a well-known response to maternal hypothermia, as induced at open-heart surgery, but heretofore has not been reported in conjunction with hypothermia from urosepsis. A 24-year-old Vietnamese woman admitted at 33 weeks estimated gestational age with pyelonephritis secondary to Escherichia coli developed several episodes of maternal hypothermia to 35-36 degrees C. ⋯ Interpretation of fetal bradycardia during episodes of maternal urosepsis is complex. If seen in conjunction with maternal hypothermia, and in the presence of normal maternal cardiac and respiratory function, bradycardia is unlikely to represent fetal distress.