Perceived stress, social support, and affectionate behaviors of adolescent mothers with infants in neonatal intensive care.

INTRODUCTION: This article focuses on affectionate behaviors of adolescent mothers with their infants in a neonatal intensive care unit (NICU). Hypotheses derived from behavioral science theory posited the direct influence of social support and perceived stress on affectionate behaviors, the statistical interaction of social support and perceived stress on affectionate behaviors, and perceived stress as a mediator of the relationship between social support and affectionate behaviors. METHOD: Subjects were enrolled from July 1993 through September 1994. Information about perceived stress and social support was obtained twice by means of an interview. Affectionate behaviors were measured by NICU nurse observations. Analyses were conducted on subsamples ranging from 57 to 107 subjects. RESULTS: All hypotheses were rejected. Neither social supports nor perceived stress were related to affectionate behaviors, and no statistical interactions among the 3 variables were identified. DISCUSSION: The findings are considered in the context of the methodology used, stress and social support theory, and implications for practice and future research.

Effects of retinoic acid on airspace development and lung collagen in hyperoxia-exposed newborn rats.

Impaired septal formation and decreased alveolarization are often caused by hyperoxic injury to the developing lung and are characteristic features of bronchopulmonary dysplasia. Dexamethasone, frequently administered to infants during oxygen exposure, also inhibits septal formation in the newborn lung. Vitamin A administration reduces the incidence of bronchopulmonary dysplasia in vitamin A-deficient premature infants, and retinoic acid improves alveolarization in newborn rats treated with dexamethasone, indicating that retinoic acid may be useful in preventing hyperoxia-induced impaired septation in bronchopulmonary dysplasia. To investigate whether treatment with retinoic acid during exposure to hyperoxia would improve septal formation, newborn rats exposed to > or =90% O(2) from d 3 of life to d 14 were treated with retinoic acid (d 3-13 of life) and/or dexamethasone (d 4-13 of life). In contrast with the effects of retinoic acid on dexamethasone-induced inhibition of alveolarization, we found that retinoic acid did not improve septal formation or decrease airspace size in animals exposed to hyperoxia alone or to hyperoxia plus dexamethasone. Retinoic acid did, however, increase collagen in airspace walls as demonstrated by staining and immunohistochemistry. There was no increase in procollagen mRNA by Northern hybridization analysis, indicating that retinoic acid-associated increases in lung collagen are likely due to posttranscriptional regulation. There was a trend toward increased survival in hyperoxia in animals treated with retinoic acid to the extent that combined therapy with retinoic acid and dexamethasone resulted in the greatest improvement in animal survival. These results suggest that although retinoic acid may be of benefit in hyperoxia-induced lung injury and may have important effects on lung matrix, it does not prevent impairment of septation or induce alveolar formation during exposure to hyperoxia.

Measurement of affectionate behaviors adolescent mothers display toward their infants in neonatal intensive care.

This paper describes two studies that had three purposes: (a) to modify a parent-child interaction tool used previously in a neonatal intensive care unit (NICU); (b) to demonstrate interrater reliability, Chronbach's Alpha reliability, and construct validity of the tool with adolescent mothers, and (c) to determine the ability of nurses engaged in usual work duties to observe maternal behaviors. The first study tested interrater reliability. Two NICU nurses were trained, observed adolescent mothers (n = 20) for the same 15 min, and then separately completed the measure. The second study tested internal consistency reliability and construct validity with 107 adolescent mothers with infants in a NICU. Nurses in the neonatal intensive care unit completed the measure, and data on maternal visits were gathered for construct validity. The intraclass correlation coefficient for the first study was r = .83. Results of the second study demonstrated a Chronbach's Alpha of .85 and a significant correlation between ratings of maternal behavior and visits. The instrument obtained acceptably reliable and valid estimates of adolescent mothers' affectionate behaviors toward their infants. In addition, the studies demonstrated that nurses can observe maternal behaviors while performing their usual duties.

Delivery room resuscitation decisions for extremely premature infants.

BACKGROUND: Neonatologists are criticized for overtreating extremely premature infants who die despite invasive and costly care. Withholding resuscitation at delivery has been recommended as a way to minimize overtreatment. It is not known how decisions to forgo initiating aggressive care are made, or whether this strategy effectively decreases overtreatment. OBJECTIVE: To identify whether physicians' or parents' preferences primarily determine the amount of treatment provided at delivery, to examine factors associated with the provision of resuscitation, and to assess whether resuscitation at delivery significantly postpones death in nonsurvivors. METHODS: We evaluated delivery room resuscitation decisions and mortality for all infants born at 23 to 26 weeks gestation at the University of North Carolina Hospitals from November 1994 to October 1995. On the day of delivery, the attending neonatologist completed a questionnaire regarding discussion with the parents before delivery, the prognosis for survival estimated before delivery, the degree of certainty about the prognosis, parents' preference for the amount of treatment at delivery, and the degree of influence exerted by parents and physicians on the amount of delivery room treatment provided. Medical records were reviewed for demographics and hospital course. RESULTS: Thirty-one of 41 infants were resuscitated (intubation and/or cardiopulmonary resuscitation) at delivery. Resuscitation correlated with increasing gestational age, higher birth weight, estimated prognosis for survival greater than or equal to 10%, and uncertainty about prognostic accuracy. Physicians saw themselves as primarily responsible for delivery room resuscitation decisions when the parents' wishes about initiating care were unknown, and as equal partners with parents when they agreed on the level of care. When disagreement existed, doctors always thought parents preferred more aggressive resuscitation, and identified parents as responsible for the increased amount of treatment at delivery. Twenty-four infants died before hospital discharge. The median age at death was 2 days when physicians primarily determined the amount of treatment at delivery, 1 day when parents primarily determined the amount of treatment, and < 1 day when responsibility was shared equally. The median age at death was < 1 day when physicians and parents agreed about the preferred amount of treatment at delivery and 1.5 days when they disagreed. The median age at death was < 1 day when parents' preferences were known before delivery and 4 days when parents' preferences were unknown. CONCLUSIONS: Physicians resuscitated extremely premature infants at delivery when they were very uncertain about an infant's prognosis or when the parents' desires about treatment were unknown. When parents' preferences were known, parents usually determined the amount of treatment provided at delivery. Resuscitation at delivery usually postponed death by only a few days, decreasing prognostic uncertainty and honoring what physicians perceived were parents' wishes for care, without substantially contributing to overtreatment.

Effects of retinol deficiency and hyperoxia on collagen gene expression in rat lung.

Exposure to hyperoxia results in lung injury and a decrease in lung collagen. Retinol is known to influence collagen gene expression, and retinol deficiency has been shown to potentiate hyperoxic lung injury. To investigate the combined effects of retinol deficiency and hyperoxia on lung collagen expression, retinol-deficient rats were exposed to acute hyperoxia, and expression of the alpha-1 chains of type I procollagen [pro alpha 1 (I)] and type III procollagen [pro alpha 1 (III)] were determined using Northern hybridization analyses and immunohistochemical staining. Hyperoxia alone reduced pro alpha 1 (I) mRNA by 60 +/- 4% (p < .05) and pro alpha 1 (III) mRNA by 30 +/- 5% (p < .05), and retinol deficiency alone reduced pro alpha 1 (I) mRNA abundance by 49 +/- 8.8% (p < .05) and pro alpha 1 (III) mRNA abundance by 14 +/- 7.5% (p = not significant), respectively. Retinol deficiency plus hyperoxia did not cause any further reduction in procollagen mRNA than that seen with oxygen exposure alone. Immunohistochemical staining demonstrated decreased staining for type I collagen in retinol-deficient animals. Hyperoxic exposure resulted in decreased connective tissue staining and increased alveolar wall staining for type I collagen. Retinol deficiency and hyperoxia together resulted in a marked increase in alveolar exudates staining for type I collagen. No changes in type III collagen staining were seen. These findings demonstrate that while retinol deficiency does not potentiate hyperoxia-induced reductions in procollagen mRNA, it is associated with alterations in collagen staining in distal lung and immunohistologic evidence of collagen fragments in alveolar exudates.

Re-emergence of a fetal pattern of insulin-like growth factor expression during hyperoxic rat lung injury.

Chronic injury to the developing lung results in cell proliferation and characteristic architectural changes. It is likely that growth factors produced and acting locally are important to these processes. Insulin-like growth factors I and II (IGF-I and IGF-II) are peptide growth factors expressed by lung cells. Roles for IGF-I and IGF-II in lung injury are suggested by their expression during lung development and by studies showing changes in IGF-I expression by activated alveolar macrophages, and increases in IGF-II peptide in oxidant arrested alveolar epithelial cells. To investigate whether the expression of IGF-I and IGF-II are changed with hyperoxic exposure, newborn rats were exposed to 80-90% oxygen for up to 6 wk and Northern hybridization analyses, in situ hybridization histochemistry, immunohistochemical staining, and reverse transcription-polymerase chain reaction (RT-PCR) studies were performed. Northern hybridization analyses of RNA extracted from whole lung showed increases in IGF-I and IGF-II mRNAs with prolonged hyperoxia. In situ hybridization histochemistry and immunohistochemical staining demonstrated spatial patterns of IGF-I and IGF-II expression similar to those seen during fetal lung development. In addition, alveolar macrophages express IGF-I and type II epithelial cells express IGF-II in control and oxygen-injured lung. These results suggest that in lung injury resident lung cells may re-express IGFs in a manner reminiscent of fetal development, and activated inflammatory cells may contribute to the proliferative response through autocrine and paracrine mechanisms.

Changes in decorin expression with hyperoxic injury to developing rat lung.

Proteoglycans are extracellular matrix components that appear to play important roles in lung development and in the response to injury. Decorin, a small extracellular matrix-associated proteoglycan, is known to be involved in collagen fibrillogenesis and is a likely participant in the pathogenesis of lung injury. We hypothesized that chronic exposure of the developing lung to hyperoxia would result in temporal and spatial changes in decorin expression. To determine the expression of decorin in normal and oxygen-injured lung, newborn rats were exposed to hyperoxia for 6 wk. Decorin mRNA abundance was determined using Northern hybridization analyses, and decorin expression was localized by in situ hybridization and immunohistochemistry. Decorin mRNA expression in type II pneumocytes was studied using reverse transcription-polymerase chain reaction. Oxygen exposure is associated with a 77% reduction in decorin mRNA in whole lung and a decrease in decorin immunoreactivity in connective tissues surrounding large airways and blood vessels, but an increase in decorin mRNA and protein expression at the tips of alveolar septa. Studies using isolated cells indicate that macrophages and polymorphonuclear neutrophils contain decorin core protein but not decorin mRNA. Type II pneumocytes do not contain either decorin mRNA or core protein. These findings demonstrate that hyperoxic lung injury is associated with localized changes in decorin expression, changes that are not reflected in whole lung RNA studies. It is likely that regional changes in lung decorin expression are influenced by factors produced and acting locally, and that such changes may contribute to the morphologic alterations characteristic of oxygen-induced lung injury.

Temporal and spatial expression of biglycan in chronic oxygen-induced lung injury.

To assess the temporal and spatial expression of the matrix-associated proteoglycan, biglycan, in a model of chronic hyperoxia-induced lung injury, changes in mRNA and protein were examined using Northern blot analyses and immunohistochemistry. Newborn rats were exposed to 85% or 100% oxygen for 6 and 4 wk, respectively. Exposure to 85% oxygen for up to 6 wk resulted in a reduction in lung surface area and the development of focal areas of fibrosis. In contrast, exposure to 100% oxygen resulted in gross alterations in lung histology with greatly enlarged airspaces and septal thickening. Biglycan mRNA increased at 3 to 5 wk in control animals, then returned to baseline, while oxygen-exposed animals showed a further increase after 2 to 4 wk of exposure. Immunoreactive biglycan decreased with postnatal age but increased in alveolar cells of animals exposed to 100% oxygen for 4 wk and in alveolar cells and along alveolar septae of animals exposed to 85% oxygen for 6 wk. We speculate that biglycan binds growth factors such as transforming growth factor-beta near these cells, acting in an autoregulatory fashion to support epithelial cell proliferation and inhibit mesenchymal cell proliferation.

Prenatal ultrasound findings of linear nevus sebaceous and its association with cystic adenomatoid malformation of the lung.

BACKGROUND: Nevus sebaceous is a congenital hamartomatous skin lesion that is commonly associated with other abnormalities and is most frequently located on the face and head. To our knowledge, there are no previous reports of the ultrasonographic appearance of nevus sebaceous or of an association with cystic adenomatoid malformation of the lung. CASE: A patient was referred at 25 weeks' gestation with multiple fetal anomalies, including echogenic soft-tissue structures external to the cranium and face, a large right-side intrathoracic mass, and abdominal ascites. After a preterm delivery, nevus sebaceous and a congenital cystic adenomatoid malformation of the lung were diagnosed. Neonatal death occurred secondary to pulmonary hypoplasia. CONCLUSION: Nevus sebaceous should be considered in the differential diagnosis when echogenic soft-tissue structures are seen on prenatal ultrasound. A detailed ultrasound examination is warranted to rule out other associated abnormalities.

Cell-specific alterations in expression of hyperoxia-induced mRNAs of lung.

Hyperoxic lung injury is an unfortunate consequence of ventilatory oxygen therapy that is necessary to sustain life in certain clinical situations. The biochemical events that accompany hyperoxia of the lung, and the molecular mechanisms underlying these events, are incompletely understood. To better understand hyperoxic lung injury, our laboratory has cloned a set of genes corresponding to mRNAs that increase in abundance in the lungs of hyperoxic rabbits. In this report, we focus on three hyperoxia-induced cDNA clones, which encode surfactant apoprotein A (SP-A), the tissue inhibitor of metalloproteinases (TIMP), and metallothionein. In situ hybridizations and RNA dot blots of isolated lung cell populations indicate that the abundance of mRNA encoding all three proteins is increased by hyperoxia in specific cell types. SP-A mRNA increases in type II alveolar epithelial cells and in bronchiolar epithelial cells. TIMP mRNA increases in interstitial fibroblasts, in chondrocytes of the cartilage surrounding airways, and in endothelial cells of a specific subset of vessels, probably venules. Metallothionein transcripts also increase in chondrocytes and pulmonary fibroblasts. A comparison of the increase in these mRNAs during hyperoxic exposure in adults and newborns indicates that adults respond faster and to a greater extent than newborns and suggests that the rate and extent of these increases is correlated with the time course and severity of the injury.

Pulmonary function testing prior to extubation in infants with respiratory distress syndrome.

Pulmonary function testing was performed just prior to extubation on 50 infants mechanically ventilated for treatment of respiratory distress syndrome. All infants were ready for extubation as defined by clinical criteria. Pulmonary mechanics and energetics were measured by a computerized technique that consists of a pneumotachometer to measure flow rates and an esophageal balloon and differential transducer to estimate transpulmonary pressure. Tidal volume, minute ventilation, dynamic lung compliance, pulmonary resistance, and resistive work of breathing were then calculated by high speed microcomputer processing. Successful extubation was defined as greater than 72 hours without respiratory decompensation requiring reinstitution of ventilatory support. Thirty-six (72%) infants were successfully extubated and 14 (28%) infants failed extubation. Infants in the success and failure groups were matched for birth weight, gestational age, age at study, weight at study, weight at study relative to birth weight, use of nasal continuous positive airway pressure (CPAP), and methylxanthines. No statistically significant differences in pulmonary mechanics were seen between the two groups. Data suggests that successful withdrawal of mechanical ventilation may be related to multiple factors such as central inspiratory drive, diaphragmatic endurance, and chest wall stability, in addition to improved lung mechanics. Pulmonary function testing criteria alone may not be useful in determining optimal timing of extubation in premature infants.

Changes in pulmonary mechanics after the administration of surfactant to infants with respiratory distress syndrome.

We assessed pulmonary mechanics in 35 premature infants with respiratory distress syndrome just before and one hour after the administration of 90 mg of surfactant to each infant. Transpulmonary pressure was measured between the airway opening and an esophageal balloon with use of a differential transducer, and flow rates were measured by a pneumotachometer. Values for pulmonary mechanics were then calculated by microcomputer processing. The administration of surfactant produced a large decrease (56 percent) in the mean (+/- SEM) ratio of alveolar to arterial oxygen, from 7.1 +/- 0.5 to 3.1 +/- 0.2 (P less than 0.0001)--a change that indicates improvement in gas exchange. Associated changes in pulmonary mechanics were not demonstrable when 10 of the infants were studied during continuous mechanical ventilation. However, in the 25 infants examined during spontaneous breathing with continuous positive airway pressures (identical airway pressures before and after treatment), large and consistent improvements in pulmonary mechanics were found after the administration of surfactant. Tidal volume increased by 32 percent (P less than 0.03), minute ventilation by 38 percent (P less than 0.02), dynamic compliance by 29 percent (P less than 0.004), and inspiratory flow rates by 54 percent (P less than 0.01). We conclude that significant improvement in pulmonary mechanics results from surfactant-replacement therapy for respiratory distress syndrome, but that these mechanical changes are apparent only during spontaneous respiration and can be masked if measurements are made during mechanical ventilation.