Predicting the need for exchange transfusion in newborn infants. A comparison of five methods.

The need for exchange transfusion was analyzed retrospectively using several different methods (total bilirubin binding capacity, birth weight, plasma protein level, and two published charts). These predictive methods were applied to 175 jaundiced infants for whom all the data were available and to 19 infants who were actually exchanged. Most of the patients were sick, premature infants. This study demonstrates the lack of agreement among the predictive methods.

Lung water and vascular permeability-surface area in newborn lambs delivered by Caesarean section compared with the 3-5 days-old lamb and adult sheep.

Extravascular lung water and vascular permeability-surface area products were measured with a multiple indicator dilution method in five unanaesthetized newborn lambs 2 to 7 h following delivery by Caesarean section at a gestational age of 135-142 days. The indicators used were 51Cr-labelled erythrocytes, [125I] albumin, [3H] water and [14C] urea. Post-mortem determination of extravascular lung water and dry bloodless lung weight were also performed. The results were compared with previously obtained data in unanaesthetized 3-5 days-old lambs and adult sheep. Normalized to dry lung weight, extravascular lung water by both techniques was significantly higher in lambs after Caesarean section than in either the 3-5 days-old lambs or the adult sheep (P less than 0.05). (Indicator values = 3.9 +/- 0.2 (SEM) ml/g for Caesarean section lambs, 3.1 +/- 0.3 for 3-5 days-old lambs and 3.3 +/- 0.5 for adult sheep; post-mortem values were 6.12 +/- 0.28 g/g for after Caesarean section lambs, 4.07 +/- 0.26 for 3-5 days old lambs and 4.03 +/- 0.17 for sheep). Vascular permeability-surface area product for [14C] urea, computed by a mathematical model, was significantly higher (P less than 0.05) in lambs after Caesarean section than in adult sheep (0.18 +/- 0.02 compared with 0.10 +/- 0.03). In 3-5 days-old lambs the value was 0.16 +/- 0.04. It is concluded that, when normalized to dry lung weight, lung following Caesarean section delivery near the end of gestation. Adult values for lung water have been reached by the age of 3-5 days.

Impedance cardiographic assessment of symptomatic patent ductus arteriosus.

A modified impedence cardiographic technique was developed using a tetrapolar apnea monitor and minicomputer system. Evaluation of this technique in premature infants with and without symptomatic patent ductus arteriosus indicates that the magnitude of the cardiac-related deflection in the impedance signal is useful in the assessment of ductus shunting. Since the infant under study is involved only by the attachment of two double electrodes to the thorax, continuous assessment of ductur shunting is possible without disturbing routine care.

The effects of ACTH on lung maturation in fetal lambs.

The ability of adrenocorticotrophic hormone (ACTH) to induce lung maturation was evaluated in fetal lambs. One member of 14 twin pairs between 114 and 138 days of gestation was infused intravenously with 0.5 mg ACTH over 5 days. The lungs of treated versus control lambs were judged more mature by morphologic criteria by the use of light and electron microscopy and by biochemical criteria by the use of lamellar-body-rich cell fractions. None of 5 premature lambs treated with ACTH and allowed to breathe showed evidence of hyaline membrane disease, while 3 untreated control lambs showed typical hyaline membranes.

Laryngeal chemoreflex in newborn lambs: respiratory and swallowing response to salts, acids, and sugars.

The laryngeal chemoreflex was tested in a standardized manner in eighteen 1- to 6-day-old lambs. The respiratory and swallowing components of the reflex response to chemical solutions introduced to the larynx were quantified to characterize the function of the receptors and to elucidate what kind of receptors most likely are involved. A relationship between the strength of the stimulus and the respiratory response was found. The response was suppressed with the addition of small amounts of CaCl2, NaCl, and LiCl. NaCl, 0.3--0.6 M, 0.15 M NaCl titrated to a pH of 3--5 with hydrochloric or acetic acid, and 0.25--1.0 M glucose in 0.15 M NaCl elicited the reflex response. A quantitative separation was seen in the respiratory response to equimolar concentrations of the salt solutions as well as to the acid solutions in normal saline with equal pH. The response to glucose was significantly reduced after application of potassium gymnemate (P less than 0.001). A direct relationship between the amount of swallowing and the respiratory response was found (r = 0.83). The laryngeal chemoreflex responses to the stimuli used have certain functional characteristics that are similar to taste receptor responses. This would suggest that the taste bud-like structures present in the laryngeal area are likely receptors for mediation of the reflex.

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.

Randomized trial of early closure of symptomatic patent ductus arteriosus in small preterm infants.

As a result of randomized assignment, 15 preterm infants weighing 1,500 gm or less at birth and who had a symptomatic PDA were treated according to a medical management protocol, and ten according to an early surgical closure protocol. All infants required mechanical ventilation at the time of study entry, which was one week after birth. Birth weight, gestational age, age at onset of congestive failure, age at study entry, and the initial morbidity of members of the two groups were similar. The nine surviving infants managed according to the surgical closure protocol were weaned from mechanical ventilation sooner, had a decreased need for digoxin and furosemide, achieved gastrointestinal function sooner, and had a smaller hospital bill than the 12 survivors of the medical management group. These results indicate that infants with a symptomatic PDA still requiring mechanical ventilation at one week after birth will benefit from surgical closure of the ductus at that time.

Medical management of small preterm infants with symptomatic patent ductus arteriosus.

During 1975, 38 of 44 infants with a birth weight of less than or equal to 1,500 gm who developed pulmonary edema and congestive heart failure due to a patent ductus arteriosus were managed medically until the ductus closed spontaneously days or weeks later. Overall survival was 71%, and there were no deaths among 11 infants weighing more than 1,250 gm. Pulmonary complications were prevalent and were attributed to the extensive use of mechanical ventilation required to control pulmonary edema. The results of this study document the results to be expected when small preterm infants with a symptomatic patent ductus arteriosus are managed without surgical or pharmacologic intervention and provide a basis for the rational design of clinical trials evaluating other management approaches.