Arthur I. Eidelman

Esophageal Perforation—A Complication of Neonatal Resuscitation

Oropharyngeal suctioning and tracheal intubation form critical therapeutic elements in the resuscitation of compromised neonates. These standard procedures reduce both the morbidity and mortality associated with such conditions as perinatal asphyxia and intrapartum fetal meconium passage. Recently, however, the need for aggressive airway management to prevent meconium aspiration has been questioned (l), especially in light of documented morbidity such as laryngeal stridor and residual hoarseness associated with suctioning and intubation. Traumatic perforation of the hypopharynx has also been described following oropharyngeal suctioning at birth to clear secretions or during the passage of an orogastric or nasogastric tube for lavage or decompression (2-5). We present three cases of iatrogenic perforation of the esophagus secondary to upper airway suctioning and/or intubation. Delivery room personnel entrusted with the critical task of neonatal resuscitation must weigh the risks and advantages of these procedures in developing appropriate protocols for the care of compromised newborn infants.

Alpha-Methyldopa Disposition in Mothers with Hypertension and in Their Breast-fed Infants

To assess the problem of alpha-methyldopa dosing in lactating mothers with hypertension, we studied three breast-feeding women to determine simultaneous plasma and breast milk concentrations of alpha-methyldopa after a 500 mg oral dose while receiving continuous therapy. Peak excretion of free alpha-methyldopa in breast milk ranged from 0.02 to 1.14 microgram/ml. The breast milk/whole plasma ratios of alpha-methyldopa ranged from 0.19 to 0.34. In two of the three breast-fed infants, plasma levels of alpha-methyldopa were undetectable (less than 0.05 microgram/ml) 6 hours after maternal ingestion of the drug, but in one of these the plasma alpha-methyldopa concentration was 0.09 microgram/ml 10 hours after maternal dosing. It is estimated that when the mother receives 1 gm alpha-methyldopa a day, the maximal cumulative dose of alpha-methyldopa would be 855 micrograms and the average cumulative alpha-methyldopa load to the breast-fed infant would be 195 micrograms, or 0.02% of the maternal dose.

Increased Arterial Pressure Variability After Arterial Baroreceptor Denervation in Fetal Lambs

Baroreceptor reflexes can be demonstrated during fetal life, but whether baroreceptors normally regulate fetal arterial pressure is unknown. This problem was addressed directly by measuring arterial pressure and analyzing its variation in eight unanesthetized fetal lambs throughout the last third of gestation, and comparing these data with similar measurements made in seven fetal lambs with denervated arterial baroreceptors. Measurements were made at 5-minute intervals over 24 hours in a total of thirty-three experiments. The coefficient of variation of mean arterial pressure (standard deviation of mean arterial pressure/mean value of mean arterial pressure) expressed as a percentage was used as an index of blood pressure variability. Coefficients averaged 7.0% in intact lambs and 12.1% in barodenervated lambs (P less than 0.001), signifying considerably increased variability of mean arterial pressure after barodenervation. Mean arterial pressure averaged over 24 hours was not different between the two groups prior to 120 days (0.8) of gestation. Between 120 days and term, mean pressure was significantly greater in the denervated fetuses (65 cm H2O) than in the sham-operated controls (60 cm H2O, P less than 0.025). These data demonstrate that a baroreceptor-blood pressure reflex functions during late gestational development in lambs and signify an important role of arterial baroreceptors in regulating fetal arterial pressure. Failure to regulate arterial pressure in the barodenervated fetus could result in significant alterations in placental perfusion and exchange, and in the regional delivery of oxygen and substrates to developing organs in these animals.

Fetal Scalp Temperature during Labor and Its Relation to Acid-Base Balance and Condition of the Newborn

Fetal scalp temperature and fetal-maternal temperature gradient were studied during well-established labor in a group of 97 patients using a technique that ensured at the same time the adhesion and the thermal insulation of the probe. In 78 infants with a one-minute Apgar score of 7 or above, a positive gradient of 0.2C was maintained throughout labor between the warmer fetal scalp temperature (37.3C) and the maternal rectal temperature. Periodic drops of temperature related to the uterine contractions occurred in only 43% of the cases. In a group of ten infants with a one-minute Apgar score of 6 or below, the fetal-maternal gradient was significantly different from this schema. There was an inversion of the gradient, the fetal scalp temperature becoming cooler (36.9C) than the maternal rectal temperature. The gradient was -0.2C at the beginning of the study and -0.5C 20 minutes before delivery. Periodic drops of temperature with uterine contractions were constant. In dead fetuses, fetal scalp temperature was much below that of the mother and this difference increased steadily until delivery. A good relationship was found between fetal-maternal gradient and the pH of the umbilical artery blood sampled at birth. When the mean gradient was 0.2C ± 1 SD, pH averaged 7.27; in the group below 1 SD, mean pH was 7.19 (P<.01).

Physical and Social Environment of Newborn Infants in Special Care Units

Infants in newborn intensive and convalescent care units are exposed to large amounts of sensory stimulation of various sorts. Although infants in these units do not lack visual, auditory, and tactile stimulation, they receive relatively infrequent coordinated sensory experiences. Furthermore, there is no diurnal rhythmicity in physical and social stimulation across days.

Effect of Maternal Lorazepam on the Neonate

Fifty-three neonates born to 51 mothers treated with lorazepam were followed up for five days after delivery. Lorazepam had been given by mouth to 35 mothers and intravenously to 16. In general, maternal plasma concentrations of lorazepam were higher than the corresponding cord plasma concentrations. Cord plasma concentrations exceeding 45 micrograms/l were associated with three-quarters of the infants requiring ventilation at birth. Neonates conjugate lorazepam slowly to the pharmacologically inactive glucuronide, which is then excreted in the urine, where it is detectable for over seven days. Though lorazepam was detectable in breast milk, the maximum amounts that an infant could absorb would be pharmacologically insignificant. Full-term neonates whose mothers had received oral lorazepam had no complications apart from slight delay in establishing feeding, which in seven out of 29 cases was associated with relatively large doses of lorazepam. Intravenous lorazepam for severe hypertension was associated with significantly low Apgar scores, need for ventilation, hypothermia, and poor suckling. Preterm babies whose mothers had been given lorazepam by either route had a high incidence of low Apgar scores, need for ventilation, hypothermia, and poor suckling. These babies had lower Apgar scores than those whose mothers had received diazepam, but the diazepam group were heavier and more mature. Lorazepam was an effective sedative and anxiolytic by either route, and there were no eclamptic fits among the lorazepam-treated patients. The effects of lorazepam on neonates indicate that its intravenous use at any stage in pregnancy and oral use before 37 weeks should be restricted to hospitals with facilities for neonatal intensive care.