Positive effect of NICU admission on breastfeeding of preterm US infants in 2000 to 2003.

OBJECTIVE: We hypothesized that neonatal intensive care unit (NICU) admission reduces breastfeeding in a recent population of US infants, adjusting for confounding factors. STUDY DESIGN: Using pregnancy risk assessment monitoring system data from 27 states for the years 2000 to 2003, we determined the relationship between breastfeeding and gestational age (GA) stratified by NICU status. We fitted a proportional odds model for breastfeeding duration as a function of NICU status adjusted for other covariates. SAS 9.1.3 and SUDAAN 9.0 were used for the weighted analyses. RESULT: In total 138 359 surveys, including 29 940 NICU-admitted infants, were analyzed. A total of 73% of mothers of nonadmitted infants initiated breastfeeding vs 70% of mothers of NICU-admitted infants. Mothers of GA <38 weeks NICU-admitted infants were 34% more likely to initiate breastfeeding and 21% more likely to breastfeed for 4 weeks than were mothers of nonadmitted preterm infants (P<0.001). However, mothers of term NICU-admitted infants were less likely to initiate and continue breastfeeding to 4 weeks than were mothers of term nonadmitted infants (P<0.001). Adjusting for GA, race, maternal age, maternal education, mode of delivery and Medicaid status, NICU admission was associated with increasing duration of breastfeeding (OR 1.10, CI 1.03, 1.17). Compared with mothers of term infants, mothers of <32-week infants were 40% more likely to continue breastfeeding for 4 weeks, mothers of 32 to 34 week infants were 13% less likely to continue and mothers of 35-37 week infants were 22% less likely to continue for at least 4 weeks (P<0.001). CONCLUSION: NICU admission is now a positive influence on breastfeeding continuation, improving the overall likelihood by 10%. Mothers of preterm NICU-admitted infants were more likely than mothers of nonadmitted infants to continue breastfeeding for 4 weeks, while mothers of term NICU-admitted infants were less likely to continue. Breastfeeding support should be enhanced for term and late preterm infants.

Feasibility of asynchronous independent lung high-frequency oscillatory ventilation in the management of acute hypoxemic respiratory failure: a case report.

OBJECTIVE: To report the first case of the use of asynchronous independent lung high-frequency oscillatory ventilation (AIL-HFOV) in the management of acute hypoxemic respiratory failure in a large pediatric patient with markedly asymmetric lung disease. DESIGN: Case study. SETTING: Tertiary pediatric intensive care unit in a pediatric teaching hospital. PATIENT: A 17-yr-old, 87-kg male patient with trisomy 21 and with respiratory failure and progressive hypoxemia because of pneumonia. INTERVENTIONS: Intubation with a 37-Fr double-lumen endobronchial tube and ventilation with two oscillatory ventilators for a total of 16 days. MEASUREMENTS AND MAIN RESULTS: Hemodynamic data were obtained using a pulmonary artery catheter. Adequate oxygenation and ventilation were readily achieved after institution of AIL-HFOV. The F(IO2)/PaO2 ratio increased from 52 to 224, and the shunt fraction decreased from 40 to 9 after 30 mins of AIL-HFOV. F(IO2) was rapidly reduced from 1.0 to 0.4 on the right lung and to 0.6 on the left lung. Mean arterial pressure was maintained, the cardiac index increased from 3.5 to 5.4 L/min/m2, the systemic vascular resistance index decreased from 1513 to 1225 dyne x sec/cm5 x m2, and the pulmonary vascular resistance index decreased from 723 to 428 dyne x sec/cm5 x m2 without the need for additional fluid boluses or increases in inotropic support. No airleaks developed during the entire hospital stay. CONCLUSIONS: AIL-HFOV improved oxygenation and hemodynamic performance in this large patient. This case demonstrates that it is feasible to use two high-frequency oscillatory ventilators to independently ventilate the lungs of a large patient with markedly asymmetric lung disease. We believe that AIL-HFOV deserves future study and development for the treatment of large patients with acute hypoxemic respiratory failure and asymmetric lung disease when other choices are limited.

Efficacy, safety, and cost of intravenous sedation versus general anesthesia in children undergoing endoscopic procedures.

We prospectively evaluated 226 patients under 18 years of age who underwent 296 procedures, and intravenous sedation and general anesthesia were compared in regard to efficacy, safety, and cost. Children 6 to 9 years of age required the highest doses of midazolam (0.14 +/- 0.04 mg/kg) and meperidine (2.5 +/- 0.8 mg/kg). A Relative Adequacy Scale, constructed to assess each patient's arousal and cooperation during intravenous sedation, revealed a 95% completion rate. Heart rate monitored before, during, and after the procedure was similar in both groups during the procedure, but a lower preprocedure heart rate was noted in older patients having intravenous sedation, suggesting less patient anxiety. Average charges, excluding endoscopist's and pathology fees, were $768.52 in the intravenous sedation group versus $1,965.42 in the general anesthesia group. Endoscopic procedures can be performed safely, effectively, and at a lower cost to the patient under intravenous sedation in a properly equipped and staffed pediatric endoscopy suite.

Drowning and near-drowning.

The incidence, epidemiology, and pathophysiology of drowning and near-drowning are presented. Particular attention is paid to the neurologic and pulmonary pathophysiology indicators for monitoring and laboratory tests. Special attention to transportation of patients is given, and treatment in the field, emergency department, and pediatric intensive care unit is delineated.

Evidence for a role of volatile amines in the development of neonatal hypergastrinemia.

We investigated the presence of volatile aliphatic amines by fluorescamine and gas chromatographic-head space analysis in human breast milk and amniotic fluid to assess their role in neonatal hypergastrinemia. These volatile nitrogenous amino acid metabolites have been previously demonstrated to stimulate gastrin release in in vivo and in vitro laboratory preparations. In the present study we demonstrated that these gastrin-stimulatory volatile amines were present in significant concentrations in breast milk during the first several weeks after parturition and in amniotic fluid. The individual amines that were identified in both human milk and amniotic fluid samples were methylamine, dimethylamine, ethylamine, trimethylamine, propylamine, isobutylamine, and butylamine. This study provides indirect evidence to support the possibility that the hypergastrinemia measured in the fetus/neonate during the period immediately before and after birth may be attributable, in part, to the ingestion of fluid containing high concentrations of gastrin-stimulating amines.

Ontogenic development of gastrointestinal motility: IV. Duodenal contractions in preterm infants.

Duodenal motility was studied by intraluminal manometry in 27 healthy infants of 26 to 42 weeks, gestational age. The frequency of contractions, the number of contractions per burst, and the intraluminal peak pressure during contractions all increased during a narrow postconceptual period, 29 to 32 weeks, regardless of length of gestation before birth. Antenatal beta-methasone administration to the mothers of 11 additional infants of 26 to 32 weeks gestational age was associated with increased duodenal contraction rate, number of contractions per burst, and intraluminal peak pressure compared with infants of similar gestational age whose mothers did not receive beta-methasone. The maturational effect of beta-methasone on duodenal motility was most pronounced in infants whose gestational age at birth was 26 to 29 weeks. Seven infants of 31 weeks' or longer gestational duration who had a CNS abnormality or insult had fasting duodenal contraction rates that were less than one half of the rate for normal infants of similar gestational age. These observations suggest that neonatal duodenal motility undergoes marked maturational changes between 29 and 32 weeks after conception and that these changes may be inducible before 29 weeks by corticosteroid administration. An intact CNS appears to be required for full expression of the maturational changes.

Relationship of human milk pH during course of lactation to concentrations of citrate and fatty acids.

Human milk pH was measured in 309 samples obtained from 52 women who had delivered at term and lactated for as long as 10 months thereafter. The mean pH decreased from 7.45 for colostrum to a nadir of 7.04 during the second week of lactation. Thereafter, the pH of milk remained between 7.0 and 7.1 until 3 months postpartum and then increased gradually to 7.4 by 10 months. The change in hydrogen ion concentration in milk was associated with corresponding changes throughout lactation in the concentration of citrate but not with the concentration of lactose. Lactose concentration increased gradually for 3 weeks; the concentration of saturated medium-chain fatty acids increased more rapidly. One interpretation of these findings is that the hydrogen ions and citrate generated by mammary secretory cell metabolism are used after the second week of lactation for de novo synthesis of fatty acids more rapidly than they are synthesized. Milk samples from ruminants were found to have concentrations of hydrogen ions and citrate that are greater than and pH that is less than the respective measurements in human milk. The significance for the recipient infant of the predictable changes in human milk pH during lactation and of the higher pH of human milk throughout lactation relative to bovine milk is unknown. However, drug excretion into milk, milk enzyme activity, milk leukocyte function, and neonatal gastrointestinal function are affected by ambient pH and may be influenced by the pH of milk.

Ontogeny of ovine fetal liver and kidney plasma membrane insulin receptors and fetal growth.

This investigation was performed to define certain characteristics of insulin-receptor interaction during the last 2 months of gestation in fetal sheep liver and kidney. Twenty-one sheep carrying a total of 46 fetuses were sacrificed at various gestational ages from 94 days to term; fetal and maternal livers and kidneys were analyzed by a radioreceptor assay for insulin binding characteristics. Specific binding of insulin to partially purified ovine fetal liver and kidney plasma membranes increased as gestation approached term, at which time specific binding was two- to fourfold greater to fetal than to maternal tissues. Associated with increased specific binding were late gestational increases in affinity of insulin for receptors in both fetal liver and kidney and an earlier increase in insulin receptor concentration in fetal kidney. These observations in fetal sheep liver and kidney are similar to reported observations in other species. However, the increase in specific binding of insulin to male fetal liver membranes was exponential; in contrast, there was no apparent increase in specific binding to female fetal liver membranes during the gestational interval surveyed. Both the weights and the vertebral column lengths of these fetuses were shown by multivariate analysis to be significantly affected by the interaction between specific binding of insulin and fetal sex. However, in 30 additional sheep fetuses we observed no difference between male and female fetuses in the increase with time in liver glycogen content. The lack of sex difference in this postreceptor event is consonant with the demonstrated dissociation between liver insulin receptors and glycogen synthesis in the late fetal rat. Our observations suggest that late gestational differences between male and female sheep fetuses in insulin specific binding to liver and, possibly, to other tissues such as cartilage, muscle, and/or fat, that are coupled to postreceptor events may account for differences in fetal growth between the sexes.

Fetal cartilage xylosyltransferase activity and skeletal growth in sheep.

The activity of UDP-D-xylose:proteoglycan core protein beta-D-xylosyltransferase (EC 2.4.2.26), the enzyme that catalyzes the initiation of the polysaccharide chain linkage to the core protein of proteoglycans, was measured in costal cartilage from 20 fetal sheep of 65-138 days gestation. Activity of the enzyme was estimated from the transfer of [14C]xylose from UDP-[14C]xylose to silk as the acceptor protein. The specific activity decreased approximately 10-fold and was found to be highly correlated with the decremental rate of growth in length of the fetal vertebral column. These observations, together with the known gestational decrease in the in vitro rate of uptake of radiolabeled sulfate by ovine fetal cartilage, a subsequent step in proteoglycan synthesis, support the hypothesis that normal fetal skeletal growth is dependent during the last one-half of gestation on the activity of xylosyltransferase in cartilage.

Effects of ovine maternal hyperglycemia on fetal regional blood flows and metabolism.

Fetal combined ventricular output (CVO) and regional distribution of blood flow were measured in 12 ewes in late gestation by the radiolabeled microsphere method. Three sets of determinations were made in sequence beginning with a control study and repeating the measurements after the ewe had received intravenous glucose at 0.35 g X min-1 for 90 min and again after the ewe had received glucose at 0.85 g X min-1 for a second 90-min period. Maternal whole blood glucose concentrations were 2.98 +/- 0.18 (means +/- SE), 10.43 +/- 0.45, and 21.59 +/- 0.90 mM during the respective study periods. Fetal CVO did not change during maternal hyperglycemia; however, it was redistributed, with a decrease in umbilical blood flow to the placenta from 43.5% of CVO to 31.9 and 30.8%, respectively. The fetal carcass, heart, intestines, kidneys, liver, and adrenals each received increased percent CVO; these increases equaled the decrease in placental blood flow. Fetuses became hypoxemic and developed a mixed acidemia during induced maternal hyperglycemia, but oxygen delivery to the heart, brain, and kidneys was unchanged. These observations indicate that maternal hyperglycemia results in previously unsuspected fetal cardiovascular responses.

Decreases in ovine fetal cartilage sulfate uptake and serum sulfate during gestation.

In vitro assays for [35S]sulfate uptake by ovine fetal costal cartilage were used to assess gestational changes in cartilage metabolism. Addition of 20% normal human serum to the incubation medium increased fetal cartilage [35S]sulfate incorporation into glycosaminoglycans. Both basal and human serum-stimulated uptakes of [35S]sulfate by fetal sheep cartilage decreased from midgestation to full term. The incremental response in [35S]sulfate uptake that was stimulated by human serum decreased as gestation proceeded to full-term. Fetal serum sulfate concentration decreased logarithmically during gestation, raising the possibility that cartilage sulfate uptake might become substrate limited as full term is approached. Perfusion of seven late gestation sheep fetuses for 7 days with Na2SO4 to achieve serum sulfate concentrations similar to those observed earlier in gestation resulted in a 33% increase in mean cartilage [35S]sulfate uptake compared with that of control twin fetuses, but uptake was not increased to values that occurred spontaneously earlier in gestation. These results suggest that the decreasing rate of [35S]sulfate uptake by fetal cartilage during the last half of gestation is associated only minimally with decreasing serum sulfate levels and is most consistent with intrinsic change in resting chondrocyte metabolism during gestation.

Contraplacental hypogastrinemic effect of gastrin infusion in sheep.

Infusion of gastrin, G-17I, at 0.4 microgram/min into either the maternal or fetal venous circulation of six late gestation sheep was associated with increases in serum gastrin concentration in the infused circulation and reciprocal decreases in the serum gastrin concentration in the other circulation (contraplacental) that perfused the placenta. Pentagastrin infusion at 0.4 microgram/min was associated with an increase in C-terminal specific gastrin immunoreactivity in both the infused and the contraplacental circulations. These observations suggest that biologically active fragments of gastrin, but not the intact molecule, may cross the ovine placenta. An alternative explanation for our results is that gastrin infusion into either the maternal or fetal circulation which perfuses the placenta may result in the release of an inhibitor (i.e., somatostatin) into the other circulation. Of broad importance, these observations indicate that although intact polypeptide hormones may not traverse the placenta, their concentrations in maternal and fetal sera may not be as independent as previously believed. Serum gastrin half-life values in late gestation sheep fetuses, lambs, and ewes were determined to be 13.7 +/- 1.9, 16.7 +/- 2.6, and 15.2 +/- 2.8 min, respectively. These similar values indicate that the relatively high serum gastrin concentrations observed in near-term sheep fetuses are not the result of prolonged half-life in the fetus.

Infants of diabetic mothers. Fetal and neonatal pathophysiology.

Most of the clinical problems experienced by the IDM in the immediate neonatal period are manifestations of abnormal fetal developmental physiology that occur in response to an increased flux of glucose from mother to fetus. The principal fetal responses are hyperglycemia, hyperinsulinemia, increased metabolic rate, and hypoxemia. Those fetal responses very likely lead to a redistribution of cardiac output, increased release of norepinephrine, and blunted release of glucagon. More fat is stored in adipocytes; more glycogen is stored in the liver; the heart may develop asymmetric septal hypertrophy; and lung metabolism is altered to delay the appearance of mature surfactant. At birth, the macrosomic IDM develops hypoglycemia that has a multifactorial basis (hyperinsulinemia, hypoglucagonemia, and probably diminished gluconeogenic and cortisol production rates). The IDM may experience respiratory symptoms from one of three causes: IRDS, persistent pulmonary hypertension, or congestive heart failure. Hyperbilirubinemia may occur because of increased rate of hemolysis; hypocalcemia and hypomagnesemia are likely within the first 3 days in association with a sluggish PTH response; and abnormal levels of inhibitors of fibrinolysis and platelet prostaglandin E-like substances may stimulate abnormal thrombosis.

Umbilical glucose and lactate extractions during maternal hyperglycemia in sheep.

Umbilical glucose and lactate extractions were determined in previously instrumented pregnant ewes into some of which D-glucose was infused to produce graded levels of maternal hyperglycemia as great as 20 mM. While fetal arterial glucose concentration continued to increase linearly as a function of maternal arterial glucose concentration during maternal hyperglycemia, the umbilical venoarterial difference in blood glucose concentration did not, and umbilical glucose extraction approached a plateau at approximately 0.063 mmol X min-1 X kg fetus-1 at maternal glucose concentrations greater than approximately 8 mM. The observed plateau in glucose extraction is consistent with saturation at high maternal glucose concentrations of the carrier mechanism for transport of glucose from the maternal to the fetal aspects of the trophoblast. The observed value of the plateau in umbilical extraction of glucose is slightly less than the maximum extraction predicted from previously published equations for this species, but the maternal blood glucose concentration at which the observed maximum occurred agrees closely with the value predicted by those equations. Umbilical lactate extraction, 0.031 +/- 0.021 mmol X min-1 X kg fetus-1, was independent of maternal arterial blood glucose and lactate concentrations and was independent of umbilical glucose extraction.