Current issues in Texas neonatology.

Since almost 10% of the births in the United States occur in Texas, issues that affect neonatal care in Texas are important for both the state and the nation. Although overall statistics are similar for the state and nation, closer examination reveals a need for improvement in specific areas, namely prenatal care, black and Hispanic mortality, and low birth-weight rates. Lay midwifery regulation has been an important concern in Texas. Surfactant use and education to prevent birth asphyxia have had a positive impact on perinatal health, contributing to public health efforts to improve perinatal outcome.

Follow-up of prematurely born infants.

Long-term developmental outcome of the prematurely born is generally related to birth weight as a reflection of gestational age: The more immature the infant, the greater the risk of abnormal developmental outcome. Due to improvements in fetal and neonatal care over the past 25 years, developmental outcome of the preterm group has steadily improved, now approaching the expected outcome for term neonates for those born weighing over 1,000 g. For the group of very immature infants (birth weight less than 1,000 g) abnormal developmental outcome remains a significant risk. For any individual preterm infant, long-term developmental outcome is generally related to the severity and duration of initial illness and the postdischarge environment. Specific causation of developmental abnormality in a particular infant is usually speculative. The overall improvement in the long-term outcome for preterm infants has been gained at great cost in medical resources and is accompanied by emotional costs to families that remain unmeasured. The key to further reducing the risk of abnormal developmental outcome remains the prevention of prematurity. Until that can be accomplished, continued meticulous attention to all the details of superb fetal and neonatal intensive care must be exercised to minimize the risk of handicap in this vulnerable group of patients.

Ventilatory management of infant baboons with hyaline membrane disease: the use of high frequency ventilation.

We tested the hypothesis that high frequency oscillatory ventilation (HFOV) would result in decreased pulmonary barotrauma in infants with hyaline membrane disease by comparing HFOV at 10 Hz to conventional positive pressure ventilation with continual distending airway pressure (PPV/PEEP) in premature baboons with hyaline membrane disease. Nineteen baboon fetuses were randomized to one of two treatment groups, delivered at 140 +/- 2 days, and, after stabilization and instrumentation of PPV/PEEP, placed in their respective ventilator group. Animals on conventional ventilation were managed by adjustment of tidal volume and frequency (to 1 Hz) to keep PaCO2 below 55 and by adjustment of the mean airway pressure. One of the "HFOV" group died of cardiovascular complications before going on HFOV and was eliminated from data analysis. The remaining HFOV baboons survived the 11-day experimental period without evidence of airleak. Six of the 11 prematures treated with PPV/PEEP developed pulmonary interstitial emphysema and/or pneumothorax and five of the animals died within 48 h. The intergroup differences in airleak were significant (p less than 0.05). Mean airway pressure (measured at the proximal airway) was higher initially with HFOV but then was lowered more rapidly than in the PPV/PEEP animals. The arterial to alveolar oxygen ratio rose and the FIO2 could be lowered more rapidly with HFOV than with conventional ventilation. These differences reached significance by 20 h. After 60 h there were no significant differences between HFOV and the PPV/PEEP survivors. HFOV resulted in more uniform saccular expansion, higher arterial to alveolar oxygen ratio, less oxygen exposure, and decreased acute barotrauma when compared to PPV/PEEP.(ABSTRACT TRUNCATED AT 250 WORDS)

Bronchopulmonary dysplasia in the tiny infant.

Bronchopulmonary dysplasia, defined as ventilator or oxygen dependence accompanied by characteristic x-ray changes, occurs frequently in the tiny baby. The authors report their own experience in a large metropolitan hospital. A review of etiologic factors and therapeutic interventions for bronchopulmonary dysplasia in tiny infants is detailed.

Management of neonatal subglottic stenosis.

When considering management of subglottic stenosis, all conservative efforts to establish a satisfactory airway must be considered prior to surgical reconstruction. However, the approach which allows for the earliest possible decannulation is the one which is sought because of high morbidity and mortality of tracheostomy in the pediatric population.

High-frequency ventilation compared to conventional positive-pressure ventilation in the treatment of hyaline membrane disease in primates.

High-frequency ventilation (HFV) has been suggested as an alternative to conventional positive-pressure ventilation (PPV) in the treatment of infants with hyaline membrane disease (HMD). Using a previously validated primate model of HMD, 15 baboon fetuses were delivered at 75% of gestation and randomly assigned to 1 of 3 ventilator treatment groups: PPV, HFV delivered by an oscillator (HFO), or HFV delivered by a flow interrupter (HFFI). All animals had clinical and radiographic evidence of HMD. At 96 h of life, all animals were sacrificed and clinical and pathologic findings were analyzed. During the first 10 h of the experiment, the HFO animals required higher mean proximal airway pressures than either the HFFI or PPV groups. However, both the HFFI and HFO animals had higher PaO2/PAO2 ratios than the PPV controls, suggesting earlier saccular recruitment. Thus, HFV is as effective as PPV in the treatment of HMD in baboons. Whether it will decrease the risk of bronchopulmonary dysplasia is not known.

Pulmonary interstitial emphysema in the premature baboon with hyaline membrane disease.

During experiments designed to develop an appropriate ventilatory strategy for high-frequency ventilation (HFV) in the premature baboon with hyaline membrane disease (HMD), we observed the development of pulmonary interstitial emphysema (PIE). Four study groups of 5 animals each received positive-pressure ventilation and positive end-expiratory pressure (PPV/PEEP) or HFV and 1 of 3 sighing techniques. Pathologically, all animals ventilated with PPV/PEEP or HFV with a carefully controlled intermittent sigh developed dilatation of the distal conducting airway and alveolar duct, with poorly expanded pulmonary saccules. The imposition of a sigh with inappropriate timing or excessive volume ruptured the dilated airway walls and caused interstitial air to accumulate. This was evident from the location of striking dilation of the distal airways and pseudocysts in areas of atelectasis. Thus, early in the course of HMD when saccular aeration is minimal, the pathogenesis of PIE is related to airway rather than alveolar rupture.

Perinatal mortality in a large perinatal center: five-year review of 31,000 births.

The perinatal mortality rate for 30,928 babies born at Medical Center Hospital, San Antonio, Texas, between 1978 and 1982, was 20.3/1,000 births. Neonatal and fetal mortality rates were, respectively, 10.1/1,000 live births and 10.4/1,000 births. Exclusion of babies who weighed less than 500 gm yielded adjusted fetal, neonatal, and perinatal mortality rates of, respectively, 9.2, 9.8, and 17.9. Birth weight-specific mortality rates were calculated by groups of 250 gm birth weight for all neonates and by increments of 100 gm for babies who weighed 500 to 1,499 gm. Male infants, intrauterine growth-retarded babies, and babies whose mothers were less than 15 years old contributed more deaths than would be expected from the characteristics of the obstetric population. Presumptive cause of fetal death was unknown in 32%, fetal anoxia in 21%, maternal pathologic conditions in 20%, inappropriate fetal growth in 13%, congenital malformations in 8%, and systemic fetal infections in 6%. Leading presumptive causes of neonatal death were immaturity (29%), congenital malformations (18%), hemorrhages (16%), and systemic infections (10%). Hyaline membrane disease and necrotizing enterocolitis contributed, respectively, 7% and 6% of deaths. Past and future trends of perinatal mortality are discussed.

Effects of epidermal growth factor on lung maturation in fetal lambs.

The ability of epidermal growth factor (EGF) to induce lung maturation was evaluated in fetal and neonatal lambs. EGF was infused (3-5 days) into one member of 10 fetal twin pairs, one member of 2 term twin pairs, and 2 singleton term lambs. All EGF-treated lambs had evidence of epithelial hyperplasia of the conducting airways typical of the EGF effect. With the exception of the most immature pair, the lungs of treated versus control lambs were judged more mature by morphologic criteria by use of light and electron microscopy. None of the 6 premature lambs treated with EGF and allowed to breath showed evidence of hyaline membrane disease, while 3 untreated control lambs developed typical hyaline membranes when delivered by cesarean section after maternal hypotension. All untreated control animals showed more severe clinical symptoms of respiratory distress than did the EGF-treated animals.

Effect of epidermal growth factor on lung maturation in fetal rabbits.

Injection of epidermal growth factor (EGF) into 24-day rabbit fetuses (5 microgram, im or ip) induced accelerated maturation of the lung. On sacrifice at day 27, there was greater distensibility and stability on deflation associated with the appearance of a complement of type II cells approaching that of the rabbit at term. EGF treatment had no demonstrable effect on body weight or lung weight in this group of animals. Saline-injected control fetuses were not affected significantly.

Hyperbilirubinaemia and bacterial infection in the newborn. A prospective study.

The incidence of bacterial infection associated with unexplained hyperbilirubinaemia was determined prospectively in 69 infants under 2 weeks of age. Blood and urine cultures were obtained from all patients, and 22 patients had their CSF cultured. Bacterial infection was documented in only 2 infants, who had asymptomatic Gram-negative urinary tract infection.