Undernutrition as a major contributing factor in the pathogenesis of bronchopulmonary dysplasia

The role of nutritional interventions in the prevention and treatment of chronic lung disease of prematurity

Chronic lung disease of prematurity or bronchopulmonary dysplasia (BPD) is a common complication of preterm birth. Nutrition may affect incidence and severity of BPD. In this context, the Section on Nutrition, Gastroenterology and Metabolism, the Pulmonary Section of the European Society for Paediatric Research (ESPR) and SPR have joined forces to review the current knowledge on nutritional issues related to BPD. The aim of this narrative review is to discuss the clinical implications for nutritional practice. Nutrient deficiencies may influence pathogenesis of BPD. Adequate nutrition and growth can play a crucial role in the prevention of and recovery from BPD. Optimal nutrition strategy is an important principle, especially in the early postnatal period. As optimal energy intake in infants at risk of BPD or with evolving BPD is not yet defined, further research with well-designed studies on nutritional strategies for preterm infants with BPD is urgently needed. IMPACT: Based on current evidence it seems reasonable to recommend that BPD diagnosed infants should receive an energy supply ranging from 120 to 150 Kcal/kg/d. Exclusive MOM feed with adequate fortification should be encouraged as this is associated with a significant reduction in the risk of BPD. Suboptimal nutritional delivery is often seen in preterm infants with BPD compared to controls.

Nutritional Needs of the Infant with Bronchopulmonary Dysplasia

Growth failure is a common problem in infants with established bronchopulmonary dysplasia (BPD). Suboptimal growth for infants with BPD is associated with unfavorable respiratory and neurodevelopmental outcomes; however, high-quality evidence to support best nutritional practices are limited for this vulnerable patient population. Consequently, there exists a wide variation in the provision of nutritional care and monitoring of growth for infants with BPD. Other neonatal populations at risk for growth failure, such as infants with congenital heart disease, have demonstrated improved growth outcomes with the creation and compliance of clinical protocols to guide nutritional management. Developing clinical protocols to guide nutritional management for infants with BPD may similarly improve long-term outcomes. Given the absence of high-quality trials to guide nutritional practice in infants with BPD, the best available evidence of systematic reviews and clinical recommendations can be applied to optimize growth and decrease variation in the care of these infants.

Postnatal growth restriction impairs rat lung structure and function

The negative impact of nutritional deficits in the development of bronchopulmonary dysplasia is well recognized, yet mechanisms by which nutrition alters lung outcomes and nutritional strategies that optimize development and protect the lung remain elusive. Here, we use a rat model to assess the isolated effects of postnatal nutrition on lung structural development without concomitant lung injury. We hypothesize that postnatal growth restriction (PGR) impairs lung structure and function, critical mediators of lung development, and fatty acid profiles at postnatal day 21 in the rat. Rat pups were cross-fostered at birth to rat dams with litter sizes of 8 (control) or 16 (PGR). Lung structure and function, as well as serum and lung tissue fatty acids, and lung molecular mediators of development, were measured. Male and female PGR rat pups had thicker airspace walls, decreased lung compliance, and increased tissue damping. Male rats also had increased lung elastance, increased lung elastin protein abundance, and lysol oxidase expression, and increased elastic fiber deposition. Female rat lungs had increased conducting airway resistance and reduced levels of docosahexaenoic acid in lung tissue. We conclude that PGR impairs lung structure and function in both male and female rats, with sex-divergent changes in lung molecular mediators of development.

A review and guide to nutritional care of the infant with established bronchopulmonary dysplasia

Bronchopulmonary dysplasia (BPD) remains the most common long-term morbidity of premature birth, and the incidence of BPD is not declining despite medical advancements. Infants with BPD are at high risk for postnatal growth failure and are often treated with therapies that suppress growth. Additionally, these infants may display excess weight gain relative to linear growth. Optimal growth and nutrition are needed to promote lung growth and repair, improve long-term pulmonary function, and improve neurodevelopmental outcomes. Linear growth in particular has been associated with favorable outcomes yet can be difficult to achieve in these patients. While there has been a significant clinical and research focus regarding BPD prevention and early preterm nutrition, there is a lack of literature regarding nutritional care of the infant with established BPD. There is even less information regarding how nutritional needs change as BPD evolves from an acute to chronic disease. This article reviews the current literature regarding nutritional challenges, enteral nutrition management, and monitoring for patients with established BPD. Additionally, this article provides a practical framework for interdisciplinary nutritional care based on our clinical experience at the Comprehensive Center for Bronchopulmonary Dysplasia.

Improved Macro- and Micronutrient Supply for Favorable Growth and Metabolomic Profile with Standardized Parenteral Nutrition Solutions for Very Preterm Infants

Very preterm infants are at high risk for suboptimal nutrition in the first weeks of life leading to insufficient weight gain and complications arising from metabolic imbalances such as insufficient bone mineral accretion. We investigated the use of a novel set of standardized parenteral nutrition (PN; MUC PREPARE) solutions regarding improving nutritional intake, accelerating termination of parenteral feeding, and positively affecting growth in comparison to individually prescribed and compounded PN solutions. We studied the effect of MUC PREPARE on macro- and micronutrient intake, metabolism, and growth in 58 very preterm infants and compared results to a historic reference group of 58 very preterm infants matched for clinical characteristics. Infants receiving MUC PREPARE demonstrated improved macro- and micronutrient intake resulting in balanced electrolyte levels and stable metabolomic profiles. Subsequently, improved energy supply was associated with up to 1.5 weeks earlier termination of parenteral feeding, while simultaneously reaching up to 1.9 times higher weight gain at day 28 in extremely immature infants (<27 GA weeks) as well as overall improved growth at 2 years of age for all infants. The use of the new standardized PN solution MUC PREPARE improved nutritional supply and short- and long-term growth and reduced PN duration in very preterm infants and is considered a superior therapeutic strategy.

Benefits of a Standardized Enteral Feeding Protocol on the Nutrition and Health Outcomes of Very Low Birth Weight Preterm Infants

Purpose: To compare nutrition and health outcomes before and after implementing a standardized enteral feeding protocol on nutrition and health outcomes in very low birth weight preterm infants.Methods: A retrospective chart review was performed evaluating preterm infants, born less than 34 weeks gestation and weighing less than 1500 g, before and after the implementation of a standardized enteral feeding protocol. Outcomes included weaning of parenteral nutrition, initiation and advancement of enteral feeds, initiation of human-milk fortifier (HMF), change in weight z-score and neonatal morbidities.Results: Fifty-six infants (30 in pre-group, 26 in post-group) met the inclusion criteria. Infants in the standardized enteral feeding protocol group started enteral feeds earlier (p = 0.039) and received full HMF fortification at lower weights (p = 0.033) than those in the pre-group. Fewer days on continuous positive airway pressure (p = 0.021) and lower rates of bronchopulmonary dysplasia (p = 0.018) were also observed in the post-group. Weaning of parenteral nutrition and weight z-score were not significantly different between groups. There were no differences in other morbidities.Conclusion: Study results suggest that adopting a standardized enteral feeding protocol may promote early initiation of enteral feeds and fortification.

Bronchopulmonary dysplasia-A historical perspective

Bronchopulmonary dysplasia (BPD) was first described by Northway et al in 1967. This article describes the evolution of our understanding of the pathophysiology of BPD and the approaches to treatments of this illness developed over the past fifty years. These interventions had their roots in the understanding of the principles of the surface tension present at air-liquid interfaces, which were developed over 150 years before BPD's initial description. Improving outcomes in neonatal care have led to greater survival of preterm and very preterm infants, and to an evolution of the pathogenesis and pathology of BPD, from an illness caused primarily by barotrauma and oxygen toxicity to one of interruption of lung development. While the incidence of BPD has remained about the same in recent decades, this is because survival of infants born at lower gestational ages is increasing. Understanding of molecular, genetic and physiologic mechanisms has led to newer treatments that have mitigated some of the harmful effects of prolonged mechanical ventilation. Recognition of BPD as a chronic multi-system disease has resulted in further improvements in care after discharge from neonatal intensive care. Since many of the origins of chronic obstructive lung disease in adults are based in childhood respiratory illnesses, improving outcomes of BPD in infancy and childhood will undoubtedly lead to improved respiratory outcomes in the adults that these children will become.

Malnutrition, poor post-natal growth, intestinal dysbiosis and the developing lung

In extremely preterm infants, poor post-natal growth, intestinal dysbiosis and bronchopulmonary dysplasia are common, and each is associated with long-term complications. The central hypothesis that this review will address is that these three common conditions are interrelated. Challenges to studying this hypothesis include the understanding that malnutrition and poor post-natal growth are not synonymous and that there is not agreement on what constitutes a normal intestinal microbiota in this evolutionarily new population. If this hypothesis is supported, further study of whether "correcting" intestinal dysbiosis in extremely preterm infants reduces postnatal growth restriction and/or bronchopulmonary dysplasia is indicated.

Bronchopulmonary dysplasia and postnatal growth following extremely preterm birth

OBJECTIVES

To report the current incidence of bronchopulmonary dysplasia (BPD) and to compare changes in weight and head circumference between infants who developed BPD and infants who did not.

DESIGN

Retrospective, whole-population study.

SETTING

All neonatal units in England between 2014 and 2018.

PATIENTS

All liveborn infants born <28 completed weeks of gestation.

INTERVENTIONS

The change in weight z-score (ΔWz) was calculated by subtracting the birthweight z-score from the weight z-score at 36 weeks postmenstrual age (PMA) and at discharge. The change in head circumference z-score (ΔHz) was calculated by subtracting the birth head circumference z-score from the head circumference z-score at discharge.

MAIN OUTCOME MEASURE

BPD was defined as the need for any respiratory support at 36 weeks PMA.

RESULTS

11 806 infants were included in the analysis. The incidence of BPD was 57.5%, and 18.9% of the infants died before 36 weeks PMA. The median (IQR) ΔWz from birth to 36 weeks PMA was significantly smaller in infants who developed BPD (-0.69 (-1.28 to -0.14), n=6105) than in those who did not develop BPD (-0.89 (-1.40 to -0.33), n=2390; adjusted p<0.001). The median (IQR) ΔHz from birth to discharge was significantly smaller in infants who developed BPD (-0.33 (-1.69 to 0.71)) than in those who did not develop BPD (-0.61 (-1.85 to 0.35); adjusted p<0.001).

CONCLUSIONS

Postnatal growth was better in infants diagnosed with BPD compared with infants without BPD possibly due to more aggressive nutrition strategies.

Antibiotic exposure and growth patterns in preterm, very low birth weight infants

BACKGROUND

Antibiotic exposure in term infants has been associated with later obesity. Premature, very-low-birth-weight (birth weight ≤ 1500 g) infants in the neonatal intensive care unit frequently are exposed to antibiotics. Our hypothesis was that in preterm infants, there is a positive linear and dose-dependent relationship between antibiotic exposure and growth from birth through 12 months' corrected age.

METHODS

Retrospective analysis of prospectively collected data of all antibiotic use among inborn, preterm (≤32 weeks' gestation), very-low-birth-weight infants admitted to the neonatal intensive care unit at Parkland Memorial Hospital and followed in the Low Birth Weight Clinic at Children's Medical Center, Dallas, TX. Antibiotic use was quantified by days of therapy which was compared with weight and length parameters at birth, 36 weeks' postmenstrual age, and 2, 4, 6, and 12 months' corrected age. The change in weight and length z-scores from birth to all subsequent age points was calculated. Stepwise multivariate regression analysis was performed to determine predictors of weight, length, and weight-for-length delta z-scores from birth to each subsequent age point.

RESULTS

During the 18-month study, 161 infants received a median of 11 (IQR, 5.5-19.5) antibiotic days of therapy which was not associated with weight or length delta z-scores from birth through 12 months' corrected age.

CONCLUSION

Association of prolonged antibiotic use and neonatal morbidities and mortality may override the potential association with increased weight gain in the NICU and beyond.

Early energy restriction in premature infants and bronchopulmonary dysplasia: a cohort study

Bronchopulmonary dysplasia (BPD) is a multifactor pathology. Animal studies and cohort studies suggest that poor nutrient intake after birth increases the risk of BPD. The objective of the present study was to determine the existence of association between BPD in very low birth weight (VLBW) and energy intake during the first week of life. We recorded in a retrospective cohort study the intake of enteral and parenteral macronutrients during this period by examining the nutritional and clinical history of 450 VLBW newborns admitted to the neonatal intensive care unit. After applying the relevant exclusion criteria, data for 389 VLBW infants were analysed, of whom 159 developed some degree of BPD. Among the newborns with BPD, energy and lipid intake was significantly lower and fluid intake was significantly higher. The energy intake for the 25th percentile in the group without BPD was 1778·2 kJ/kg during the first week of life. An energy intake <1778·2 kJ/kg in this period was associated with a 2-fold increase in the adjusted risk of BPD (OR 2·63, 95 % CI 1·30, 5·34). The early nutrition and the increase of energy intake in the first week of life are associated in our sample with a lower risk of BPD developing.

Prolonged ventilation and postnatal growth of preterm infants

Background Extremely premature infants often need invasive respiratory support from birth, but have low nutritional reserves and high metabolic demands. Our aim was to determine if there was a relationship between prolonged ventilation and reduced postnatal growth in such infants. Methods A retrospective, observational study was undertaken. Data from infants born at less than 28 weeks of gestational age and ventilated for 7 days or more were collected and analysed including gestational age, gender, birth and discharge weight, birth and discharge head circumference, days of invasive mechanical ventilation and use of postnatal corticosteroids. The duration of invasive mechanical ventilation and the differences in weight (ΔWz) and head circumference (ΔHz) z-score from birth to discharge were calculated. Results Fifty-five infants were studied with a median [interquartile range (IQR)] gestational age at birth of 25.3 (24.3-26.7) weeks and birth weight of 0.73 (0.65-0.87) kg. The median duration of mechanical ventilation was 45 (33-68) days. Both ΔWz and ΔHz were significantly negatively correlated to the number of invasive mechanical ventilation days (P = 0.01 and P = 0.03, respectively), but not to the use of postnatal corticosteroids. Conclusion Poor postnatal growth is significantly negatively associated with a longer duration of mechanical ventilation in extremely prematurely born infants.

Mitochondrial bioenergetics and pulmonary dysfunction: Current progress and future directions

This review summarizes current understanding of mitochondrial bioenergetic dysfunction applicable to mechanisms of lung diseases and outlines challenges and future directions in this rapidly emerging field. Although the role of mitochondria extends beyond the term of cellular "powerhouse", energy generation remains the most fundamental function of these organelles. It is not counterintuitive to propose that intact energy supply is important for favorable cellular fate following pulmonary insult. In this review, the discussion of mitochondrial dysfunction focuses on those molecular mechanisms that alter cellular bioenergetics in the lungs: (a) inhibition of mitochondrial respiratory chain, (b) mitochondrial leak and uncoupling, (c) alteration of mitochondrial Ca²⁺ handling, (d) mitochondrial production of reactive oxygen species and self-oxidation. The discussed lung diseases were selected according to their pathological nature and relevance to pediatrics: Acute lung injury (ALI), defined as acute parenchymal lung disease associated with cellular demise and inflammation (Acute Respiratory Distress Syndrome, ARDS, Pneumonia), alveolar developmental failure (Bronchopulmonary Dysplasia, BPD or chronic lung disease in premature infants), obstructive airway diseases (Bronchial asthma) and vascular remodeling affecting pulmonary circulation (Pulmonary Hypertension, PH). The analysis highlights primary mechanisms of mitochondrial bioenergetic dysfunction contributing to the disease-specific pulmonary insufficiency and proposes potential therapeutic targets.

Small for gestational age and extremely low birth weight infant outcomes

Background Small for gestational age (SGA) infants are less likely to develop respiratory distress syndrome (RDS), but more likely to develop bronchopulmonary dysplasia (BPD) and have a higher mortality. Our aim was to focus on outcomes of those with a birth weight less than or equal to 750 g. Methods The mortality, BPD severity, necrotising enterocolitis (NEC), home oxygen requirement and length of hospital stay were determined according to SGA status of all eligible infants in a 5-year period admitted within the first 24 h after birth. Results The outcomes of 84 infants were assessed, and 35 (42%) were SGA. The SGA infants were more mature (P<0.001), had a lower birth weight centile (P<0.001) and a greater proportion exposed to antenatal corticosteroids (P=0.022). Adjusted for gestational age (GA), there was no significant difference in mortality between the two groups (P=0.242), but a greater proportion of the SGA infants developed severe BPD (P=0.025). The SGA infants had a lower weight z-score at discharge (-3.64 vs. -1.66) (P=0.001), but a decrease in z-score from birth to discharge was observed in both groups (median -1.53 vs. -1.07, P=0.256). Conclusion Despite being more mature, the SGA infants had a similar mortality rate and a greater proportion developed severe BPD.

Early energy and protein intakes and associations with growth, BPD, and ROP in extremely preterm infants

BACKGROUND & AIM

Extremely preterm infants face substantial neonatal morbidity. Nutrition is important to promote optimal growth and organ development in order to reduce late neonatal complications. The aim of this study was to examine the associations of early nutritional intakes on growth and risks of bronchopulmonary dysplasia (BPD) and retinopathy of prematurity (ROP) in a high-risk population.

METHODS

This population-based cohort study includes infants born before 27 0/7 weeks of gestational age without severe malformations and surviving ≥10 days. Intake of energy and protein on postnatal days 4-6 and association with weight standard deviation score (WSDS) from birth to day 7, as well as intakes of energy and protein on postnatal days 4-6 and 7 to 27, respectively, and association with composite outcome of death and BPD and separate outcomes of BPD and ROP were examined, and adjusted for potential confounders.

RESULTS

The cohort comprised 296 infants with a median gestational age of 25 3/7 weeks. Expressed as daily intakes, every additional 10 kcal/kg/d of energy during days 4-6 was associated with 0.08 higher WSDS on day 7 (95% CI 0.06-0.11; p < 0.001). Between days 7 and 27, every 10 kcal/kg/d increase in energy intake was associated with a reduced risk of BPD of 9% (95% CI 1-16; p = 0.029) and any grade of ROP with a reduced risk of 6% (95% CI 2-9; p = 0.005) in multivariable models. This association was statistically significant in infants with ≤10 days of mechanical ventilation. In infants with >10 days of mechanical ventilation, a combined higher intake of energy and protein was associated with a reduced risk of BPD.

CONCLUSION

Early provision of energy and protein may reduce postnatal weight loss and risk of morbidity in extremely preterm infants.

Alveolar formation is dysregulated by restricted nutrition but not excess sedation in preterm lambs managed by noninvasive support

BACKGROUND

Preterm birth and respiratory support with invasive mechanical ventilation frequently leads to bronchopulmonary dysplasia (BPD). A hallmark feature of BPD is alveolar simplification. For our preterm lamb model of BPD, invasive mechanical ventilation is associated with postnatal feeding intolerance (reduced nutrition) and sedation. In contrast, preterm lambs managed by noninvasive support (NIS) have normal alveolar formation, appropriate postnatal nutrition, and require little sedation. We used the latter, positive-outcome group to discriminate the contribution of reduced nutrition vs. sedation on alveolar simplification. We hypothesized that, restricted nutrition, but not sedation with pentobarbital, contributes to impaired indices of alveolar formation in preterm lambs managed by NIS.

METHODS

Preterm lambs managed by NIS for 21d were randomized into three groups: NIS control, NIS plus restricted nutrition, and NIS plus excess sedation with pentobarbital. We quantified morphological and biochemical indices of alveolar formation, as well as mesenchymal cell apoptosis and proliferation.

RESULTS

Restricted nutrition impaired morphological and biochemical indices of alveolar formation, and reduced mesenchymal cell apoptosis and proliferation. Excess sedation with pentobarbital did not alter these indices, although mesenchymal cell apoptosis was less.

CONCLUSION

Our results demonstrate that restricted nutrition, but not excess sedation, contributes to impaired alveolar formation during the evolution of BPD in chronically ventilated preterm lambs.

Antecedent Predictors of Feeding Outcomes in Premature Infants With Protracted Mechanical Ventilation

OBJECTIVES

The aim of the present study was to define risk factors associated with gastrostomy in premature infants receiving protracted mechanical ventilation (≥30 days).

METHODS

Retrospective data collected on 170 preterm neonates (birth weight <1500 g) who received uninterrupted mechanical ventilation for ≥30 days were analyzed with logistic regression methods to predict the association of gastrostomy with cardiorespiratory, infectious, and neurological morbidities.

RESULTS

A total of 32 of 170 infants had gastrostomy tubes. Including all of the covariates in 1 model, duration of cumulative ventilation (P < 0.001) and uninterrupted ventilation (P < 0.001), and ventriculoperitoneal shunt (P = 0.02) were significant predictors, whereas sepsis, intraventrical hemorrhage grade III or IV, and patent ductus arteriosus ligation were not. Respiratory severity score (mean airway pressure × fraction of inspired oxygen) calculated at 30 days of life was also a significant predictor (P = 0.01).

CONCLUSIONS

In infants with protracted mechanical ventilation, the degree of respiratory support at 1 month of age, prolonged respiratory morbidity, and neuropathology are the significant predictors for gastrostomy.

The impact of small-for-gestational-age on neonatal outcome among very-low-birth-weight infants

BACKGROUND

This study aimed to evaluate the impact of small-for-gestational-age (SGA) on mortality and morbidity in very-low-birth-weight (VLBW) infants.

METHODS

We conducted a retrospective cohort study on VLBW infants registered at the Premature Baby Foundation of Taiwan between 2007 and 2011. All 21 neonatal departments in Taiwan participated in the data collection, and a total of 4636 VLBW infants were registered during the study period. The SGA group (n = 560) was selected from the database on the basis of birth weight below the 10(th) percentile for gestational age, whereas the appropriate-weight-for-gestational-age (AGA) group (n = 1120) included infants randomly selected via incidence density sampling with a 2:1 match for each SGA case. The association of SGA with individual outcome variables including mortality, respiratory distress syndrome, necrotizing enterocolitis, retinopathy of prematurity (ROP), intraventricular hemorrhage, periventricular leukomalacia, and bronchopulmonary dysplasia (BPD) was evaluated after adjustment for potential confounders.

RESULTS

The SGA group was associated with increased risks of mortality [odds ratio (OR) 1.89; 95% confidence interval (CI) 1.39‒2.58], severe ROP (OR 1.56; 95% CI 1.13-2.14), and BPD (OR 2.08; 95% CI 1.58-2.75) compared to the AGA group. Further subgroup analysis showed that SGA had significant effects on mortality in the VLBW infants with a gestational age of 24-29 weeks, as well as on BPD in those with a gestational age of 27-32 weeks. By contrast, the association of SGA with severe ROP was only significant in the VLBW infants with a gestational age of 27-29 weeks.

CONCLUSION

Our data provide evidence that SGA may be associated with increased risks of neonatal mortality, ROP, and BPD in VLBW infants.

Respiratory outcomes of children with BPD and gastrostomy tubes during the first 2 years of life

OBJECTIVES

Infants with bronchopulmonary dysplasia (BPD) often undergo gastrostomy tube (GT) placement and/or Nissen fundoplication (Nissen) to improve weight gain and to attenuate chronic respiratory symptoms related to feeding difficulties. After initial hospitalization little is known how these children do with regard to respiratory symptoms when compared to children with BPD who did not receive GTs. This study was done to determine if differences in respiratory outcomes were associated with the presence of a GT or Nissen/GT in children with BPD during the first 2 years of life.

METHODS

Children (n = 398) were recruited from the Johns Hopkins BPD Outpatient Clinic. Medical charts were reviewed and acute care usage and respiratory symptoms were assessed by caregiver questionnaires.

RESULTS

Ninety-two children with BPD had GTs, with the majority placed by 6 months of age. Of children with GTs, 64.7% also had Nissen fundoplication. Children with Nissen/GTs were more likely to have birth weights <10th percentile and to be discharged on supplemental oxygen. After initial hospitalization, children with GTs and Nissen/GTs weaned off supplemental oxygen at significantly older ages than children without GTs. Children with Nissen/GTs also had more hospitalizations than children without GTs. Caregivers of children with GTs and Nissen/GTs reported similar respiratory symptoms as caregivers of children without GTs.

CONCLUSION

Weaning off supplemental oxygen occurred later in children with GTs and Nissen/GTs compared to children without GTs. Although children with Nissen/GTs had more re-hospitalizations, there were no differences in reported respiratory symptoms between any of the groups by caregiver questionnaire.

Nutrition and bronchopulmonary dysplasia

We aimed to assess the current knowledge on the nutritional management of preterm infants at risk of developing bronchopulmonary dysplasia (BPD) or with BPD. We considered the evidence supporting the actual fluid and energy intake, proteins, lipids, and electrolytes requirement, and need for other nutrients in preterm infant at risk of developing BPD or with BPD. We concluded that, although many areas remain to be investigated, early nutrition support and careful adjustment of parenteral nutrition and appropriate enteral feeding selection may enhance the growth and contribute a better neurodevelopment in these patients.

Standard two-compartment formulation for total parenteral nutrition in the neonatal intensive care unit: A fluid tolerance based system

The nutrient requirements of most (pre) term newborns receiving intensive care appear to be relatively fixed. The range of optimal fluid load however, is perceived as being quite narrow and highly variable in time. We designed four amino acid-dextrose mixtures for a standardized neonatal parenteral nutrition, delivering a fixed amount of nutrients in four dilutions with water and corresponding to a fluid load of 90, 110, 130 or 170 ml/kg per day. The addition of a lipid emulsion completes the TPN. In a pilot study, we followed the weight of 30 very low birthweight infants on this parenteral nutrition. After a stabilisation period, the weight gain was found to be similar to the normal fetal weight accretion in utero. We have now infused these solutions in to more than 1000 infants, without significant complications. These formulations proved to have substantial advantages compared to the individualized prescription in terms of availability, safety and time- and cost-effectiveness.

Nutritional strategies and growth in extremely low birth weight infants with bronchopulmonary dysplasia over the past 10 years

OBJECTIVE

Changes in nutritional strategies over the past decade have been shown to improve postnatal growth in extremely low birth weight (ELBW) infants. We showed 10 years ago that the majority of these ELBW infants with bronchopulmonary dysplasia (BPD) suffer postnatal growth failure. We theorized that recent changes in nutritional support strategies would positively affect growth outcomes in ELBW infants with BPD.

STUDY DESIGN

A retrospective study of 88 ELBW infants with BPD. Nutritional data, postnatal growth and BPD severity were compared across three cohorts: (1) weight gain ≤14 g kg(-1) per day, (2) 14.1 to 16 g kg(-1) per day and (3) ≥16 g kg(-1) per day from return to birth weight through discharge. We also compared these to a historical cohort.

RESULT

In all, 73% of current subjects grew at or above fetal rates. There was less extrauterine growth restriction (EUGR) by weight and head circumference for those ELBW infants with BPD receiving higher amounts of protein. Aggressive early TPN and receipt of caloric-dense milk seemed to be the 'new' nutritional strategies improving growth for current ELBW infants with BPD compared with those 10 years ago.

CONCLUSION

Despite a diagnosis of BPD, improved nutritional strategies have enhanced postnatal growth in infants at high risk for EUGR.

Bronchopulmonary dysplasia: then and now

When bronchopulmonary dysplasia (BPD) was first described in 1967, the use of assisted ventilation in neonates was in its infancy. High concentrations of oxygen were implicated, and BPD was equated with 'pulmonary oxygen toxicity'. The etiologic role of not only oxygen but also peak inspiratory pressures and the duration of exposure to both was emphasized in the 1970s, but BPD remained a dreaded complication of managing respiratory distress syndrome in the 1980s. It was only after exogenous surfactant became commercially available for endotracheal administration that 'classical' BPD began to disappear and was replaced by the 'new' BPD. 'Classical' BPD was seen in more mature preterm infants (>28 weeks' gestational age) and in its severe form was characterized radiographically by micro- and macrocysts of the lung, lung hyperinflation and flattening of the diaphragms. In contrast, 'new' BPD is seen in less mature infants (<28 weeks' gestational age), has comparatively mild radiographic abnormalities and has been defined as continued oxygen requirement at 36 weeks' postmenstrual age. Pathologically, 'classical' BPD frequently revealed obstructive bronchiolitis and fibrosis of lung parenchyma, whereas 'new' BPD demonstrates minimal fibrosis but uniform arrest of development. Herein, factors which may contribute to the etiology of BPD are described, as well as possible preventative and therapeutic strategies.

Does more protein in the first week of life change outcomes for very low birthweight babies?

BACKGROUND

Following publication of revised recommended nutrient intakes (RNI) for infants <1500 g, our intravenous nutrition (IVN) solutions were reformulated to deliver RNI in a restricted volume to ensure additional non-nutritional fluids did not detract from nutritional intake. An audit was performed to determine whether these changes achieved RNI and influenced growth, clinical or neurodevelopmental outcomes.

METHODS

Two cohorts of 40 infants <1500 g were identified from a prospectively maintained database: babies born before and after reformulation of the IVN solutions. Data on nutritional intakes for the first 30 days of life, growth and clinical outcomes were collected. Neurodevelopmental outcomes at 18 months corrected age (CA) were obtained from a Bayley III assessment. Results are presented as mean ± SD.

RESULTS

The 'after' group received significantly less fluid (105 ± 12 vs. 132 ± 15 mL/kg/day, P < 0.001) but more protein (3.2 ± 0.6 vs. 2.4 ± 0.5 g/kg/day, P < 0.001) in the first week of life. There were no differences in clinical outcome, growth z-scores at 4 weeks of age or neurodevelopmental outcome at 18 months CA between the 'before' and 'after' infants. Enteral protein intake in the first 2 weeks of life was positively associated with neurodevelopmental outcome (cognitive score r(2) = 0.13 P= 0.03, motor score r(2) = 0.27 P= 0.001).

CONCLUSION

Although the new IVN regimen achieved intakes closer to RNI, there were no major effects on growth, clinical outcome or neurodevelopmental outcome at 18 months CA. Enteral protein intake in the first two weeks was positively associated with neurodevelopmental outcome, suggesting early enteral protein intake is important for optimal brain function.

A comprehensive approach to the prevention of bronchopulmonary dysplasia

The current bronchopulmonary dysplasia (BPD) is seen in infants born extremely premature, with less severe respiratory distress syndrome (RDS) and who received prenatal steroids-"new BPD". The pathophysiology of BPD is based on an impairment of lung maturation with prenatal and postnatal multi-hit insults and genetic susceptibility. This multifactorial pathophysiology of BPD suggests that no single "magic bullet" will prevent it. Thus, to avoid BPD we need to implement a complex and comprehensive strategy. This strategy is based on ventilatory and non-ventilatory measures. The ventilatory route allows an individualized endotracheal intubation approach. Early lung recruitment with nasal respiratory support (nasal continuous positive airway pressure [NCPAP] or nasal intermittent positive pressure ventilation [NIPPV] / synchronized NIPPV [SNIPPV]) and the INSURE (intubation, surfactant and early extubation) approach are discussed. Initial treatment with NCPAP did not reduce the rate of BPD compared to endotracheal ventilation and surfactant administration. While NIPPV/SNIPPV may have short-term advantages over NCPAP, the effect on BPD needs to be further studied. During hospitalization the respiratory goals should aim for adequate oxygenation, permissive hypercapnia, and gentle ventilation. However, these goals were found to have short-term benefits but did not reduce significantly the rate of BPD. Selective use of a short course of low dose corticosteroids can be considered after the first or second week of life in infants who are unable to be weaned from the ventilator and are at high risk for BPD. Non-ventilatory measures include early nutritional support with fluid restriction, caffeine and consideration of vitamin A. Hemodynamic significant patent ductus arteriosus (PDA) may be associated with BPD, but medical or surgical treatment of PDA were not shown to decrease BPD. Each component and the strategy as a whole needs to be further studied in large randomized prospective studies or by meta-analyses, especially in the target population of extremely premature infants who are the most prone to BPD.

Nutrition of preterm infants in relation to bronchopulmonary dysplasia

BACKGROUND

The pathogenesis of bronchopulmonary dysplasia (BPD) is multifactorial. In addition to prenatal inflammation, postnatal malnutrition also affects lung development.

METHODS

A retrospective study was performed to analyse during the first two weeks of life the total, enteral and parenteral nutrition of premature infants (<31 weeks, birth weight ≤1500 g) born between 08/04 and 12/06.

RESULTS

Ninety-five premature infants were analysed: 26 with BPD (27 ± 1 weeks) and 69 without BPD (28 ± 1 weeks). There was no statistical significant difference in the total intake of fluids, calories, glucose or protein and weight gain per day in both groups. The risk of developing BPD was slightly increased in infants with cumulative caloric intake below the minimal requirement of 1230 kcal/kg and a cumulative protein intake below 43.5 g/kg. Furthermore, the risk of developing BPD was significantly higher when infants had a cumulative fluid intake above the recommended 1840 ml/kg. In infants who developed BPD, the enteral nutrition was significantly lower than in non-BPD infants [456 ml/kg (IQR 744, 235) vs. 685 (IQR 987, 511)]. Infants who did not develop BPD reached 50% of total enteral feeding significantly faster [9.6 days vs. 11.5].

CONCLUSIONS

Preterm infants developing BPD received less enteral feeding, even though it was well compensated by the parenteral nutrient supply. Data suggest that a critical minimal amount of enteral feeding is required to prevent development of BPD; however, a large prospective clinical study is needed to prove this assumption.

Prevention of bronchopulmonary dysplasia

Considerable effort has been devoted to the development of strategies to reduce the incidence of bronchopulmonary dysplasia (BPD), including use of medications, nutritional therapies, and respiratory care practices. Unfortunately, most of these strategies have not been successful. To date, the only two treatments developed specifically to prevent BPD whose efficacy is supported by evidence from randomized, controlled trials are the parenteral administration of vitamin A and corticosteroids. Two other therapies, the use of caffeine for the treatment of apnea of prematurity and aggressive phototherapy for the treatment of hyperbilirubinemia, were evaluated for the improvement of other outcomes and found to reduce BPD. Cohort studies suggest that the use of continuous positive airway pressure as a strategy for avoiding mechanical ventilation might also be beneficial. Other therapies reduce lung injury in animal models but do not appear to reduce BPD in humans. The benefits of the efficacious therapies have been modest, with an absolute risk reduction in the 7-11% range. Further preventive strategies are needed to reduce the burden of this disease. However, each will need to be tested in randomized, controlled trials, and the expectations of new therapies should be modest reductions of the incidence of the disease.

Chronic lung disease of prematurity: a short history

Chronic lung disease of prematurity (CLD) is commonly considered to be a consequence of assisted ventilation. However, prior to the description in 1967 of bronchopulmonary dysplasia (BPD), following ventilator therapy for respiratory distress syndrome, Wilson-Mikity syndrome (WMS) had been described in very preterm infants on minimal oxygen supplementation. In the 1970s and 1980s, many infants treated with assisted ventilation required prolonged mechanical ventilation after developing radiographic features of coarse infiltrates, severe hyperinflation, and microcystic changes, associated with hypercarbemia and the need for increased inspired oxygen concentrations. Some infants died and showed evidence of pulmonary fibrosis, obstructive bronchiolitis, and dysplastic change. The role of supplemental oxygen, positive pressure ventilation, and the immaturity of the lung have long been considered important in the etiology of CLD/BPD. More recently, the role of inflammation (particularly antenatal exposure to cytokines) and individual susceptibility (genetic predisposition) have assumed greater etiologic importance. The historical setting into which corticosteroid treatment for BPD was introduced is also discussed. After the licensing of exogenous surfactant to treat RDS in the early 1990s and more widespread use of prenatal corticosteroids in the mid-1990s, severe BPD became an unusual event. Gradually, the diagnosis of CLD, still often referred to as BPD, was based on an oxygen requirement at 36 weeks postmenstrual age. However, it is not clear that this 'new BPD' is substantially different from WMS. It is difficult to make prognostications about long-term lung function of these infants based on oxygen 'requirement' at 36 weeks, since supplemental oxygen is frequently used unnecessarily.

Differences in short-term neonatal outcomes between discordant twins

PURPOSE

To evaluate short-term outcomes associated with discordant twin pairs admitted to the NICU.

DESIGN

A retrospective descriptive study comparing discordant twin pairs.

SUBJECTS

Three hundred eighty-four discordant twin pairs were included. Mean gestational age of the twin pairs was 32.6 weeks (range, 24-39).

METHODS

The ParadigmHealth database was queried for all twin admissions from January 2001 to June 2004 admitted to 453 NICUs across the United States. Discordance was calculated for each twin set as defined as greater than 20% difference in birth weight. Exclusion criteria were death of a twin, congenital anomalies, or extracorporeal life support.

MAIN OUTCOME MEASURES

Demographics, respiratory needs, feeding characteristics, complications, and discharge needs.

RESULTS

A total of 384 discordant twin pairs met inclusion criteria. The larger twins required more ventilation/continuous positive airway pressure (55% vs 44%, P < .01) and/or oxygen therapy (50% vs 41%, P = .02) compared with smaller twins. Smaller twins reached full oral (PO) feeds an average of 0.6 weeks later than larger twins (P < .0001) but had more weight gain per day. Smaller twins transitioned to an open crib at lower weights but at slightly greater age. No differences were noted with necrotizing enterocolitis or apnea. Smaller twins had increased nosocomial infections. Mean length of stay was shorter (P = .0036) in the larger twin group. Only 33% of the twin pairs were discharged on the same day.

CONCLUSIONS

Larger twins had more acute respiratory issues but achieved certain milestones more rapidly with fewer complications, thus leading to earlier discharge compared with their smaller twin counterparts.

Improved growth and decreased morbidities in <1000 g neonates after early management changes

OBJECTIVE

To test the hypothesis that three changes in the early management of extremely low birth weight (ELBW) neonates would decrease the incidence of extra-uterine growth restriction (EUGR) by 25%. The three early management practice changes (EMPC) included surfactant at delivery followed by immediate extubation to nasal continuous positive airway pressure (CPAP), decreased oxygen exposure and early parenteral amino acids.

STUDY DESIGN

Historical cohort study of preterm infants<or=1000 g birth weight (BW) born at the University of Texas Medical Branch between January 2001 and June 2002 (pre-EMPC, before changes, n=87) and July 2004 to December 2005 (post-EMPC, after changes, n=76). Outcomes measured included feeding and growth parameters, morbidities and interventions. Statistical analysis included chi2-analysis, Student's t-test, and analysis of variance.

RESULT

Infants in the post-EMPC cohort regained BW more quickly, maintained appropriate size for weight at 36 weeks and had less morbidity associated with poor long-term outcome. Predictors of EUGR included BW<750 g and surgical necrotizing enterocolitis.

CONCLUSION

The introduction of surfactant at delivery followed by immediate extubation to CPAP, decreased oxygen exposure and early parenteral amino acids in ELBW infants is possible, safe and associated with improvements in growth and morbidity.

Decreased incidence of bronchopulmonary dysplasia after early management changes, including surfactant and nasal continuous positive airway pressure treatment at delivery, lowered oxygen saturation goals, and early amino acid administration: a historical cohort study

OBJECTIVE

The goal was to investigate the clinical impact of 3 early management practice changes for infants of < or = 1000 g.

METHODS

We performed an historical cohort study of appropriately sized, preterm infants without congenital anomalies who were born between January 2001 and June 2002 (pre-early management practice change group; n = 87) and between July 2004 and December 2005 (post-early management practice change group; n = 76).

RESULTS

Only 1 (1%) of 87 infants in the pre-early management practice change group received continuous positive airway pressure treatment in the first 24 hours of life, compared with 61 (80%) of 76 infants in the post-early management practice change group. The proportions of infants who required any synchronized intermittent mandatory ventilation during their hospital stays were 98.8% and 59.5%, respectively. The mean durations of synchronized intermittent mandatory ventilation were 35 days and 15 days, respectively. The combined incidence rates of moderate and severe bronchopulmonary dysplasia at corrected gestational age of 36 weeks were 43% and 24%, respectively. The use of vasopressor support for hypotension in the first 24 hours of life decreased from 39.1% (before early management practice changes) to 19.7% (after practice changes), the cumulative days of oxygen therapy decreased from 77 +/- 52 days to 56 +/- 47 days, and the proportions of infants discharged with home oxygen therapy decreased from 25.7% to 10.1%; the incidence of patent ductus arteriosus requiring surgical ligation increased from 1% to 10%. There were no differences in rates of death, intraventricular hemorrhage, periventricular leukomalacia, pneumothorax, necrotizing enterocolitis, or retinopathy of prematurity.

CONCLUSIONS

Successful early management of extremely preterm infants with surfactant treatment followed by continuous positive airway pressure treatment at delivery, lowered oxygen saturation goals, and early amino acid supplementation is possible and is associated with reductions in the incidence and severity of bronchopulmonary dysplasia.

The role of nutrition in the prevention and management of bronchopulmonary dysplasia

Nutrition plays a critical role in the prevention and management of bronchopulmonary dysplasia (BPD). Growth failure in infants with BPD is predominantly due to malnutrition. Malnutrition can worsen BPD by compromising lung growth. Feeding difficulties in these infants can further affect nutrition. Dexamethasone, used to facilitate extubation and treat severe BPD, is known to have adverse effects on growth. Nutritional management of very low birth weight (VLBW) infants should be addressed from the first day of life to enhance growth and minimize respiratory morbidity. Fluid restriction, parenteral nutrition with protein and lipids, and early enteral feeding may help decrease the incidence of BPD. High calorie concentrated formula can be used in infants to achieve adequate growth if total daily fluid intake is restricted. Vitamin A supplementation may help to prevent further damage to lungs. The role of such therapies as inositol, vitamin E, and selenium in management of these infants remains speculative. Close post discharge follow up of infants with BPD is necessary to monitor growth and to ensure intake of sufficient protein and calories.

Site-specific characteristics of infants developing bronchopulmonary dysplasia

HYPOTHESIS

Site-specific variables that contribute to the pathogenesis of bronchopulmonary dysplasia (BPD) can be identified.

OBJECTIVES

To evaluate the demographic, nutrition and growth characteristics of infants at risk for developing BPD at two neonatal intensive care units (NICUs: sites A and O).

STUDY DESIGN

Records of 306 infants of < or = [corrected] 30 weeks gestational age (GA) who survived to at least 36 weeks postmenstrual age were retrospectively reviewed. Data were obtained for maternal and neonatal demographics, weights, total fluids, calories, carbohydrate, protein and fat intake at birth, 7, 14, 21 and 28 days of life.

RESULTS

BPD rates were not different at the two sites. No statistical differences were noted in the incidence of maternal chorioamnionitis, pregnancy-induced hypertension or use of antenatal steroids among infants who developed BPD (n = 169) and those who did not (n = 137). White race, birth weight, respiratory distress syndrome requiring surfactant, sepsis and patent ductus arteriosus were significantly associated (all P < or =0.03) with BPD. After controlling for significant confounding variables, infants who developed BPD had significantly (P < 0.001) less weight gain, received less calories and fat in the first postnatal month. In the 26 to 28 weeks GA group, the odds of getting BPD were 5.4 (95%CI: 1.4 to 21.3) times greater for site A than site O (P = 0.017).

CONCLUSION

Our analysis suggests that while some decrease in BPD can be achieved by focusing on ventilation/oxygen use, this approach is unlikely to impact on the youngest infants.

Audit of feeding practices in babies<1200 g or 30 weeks gestation during the first month of life

AIM

In 2002, the composition of the breast milk fortifier used in our hospital changed, giving increased protein and energy. We therefore decided to prospectively audit nutritional management in our unit and to compare nutritional intake and growth in our babies with published data.

METHODS

Data were prospectively collected over a 3-month period on infants<1200 g or 30 weeks gestation. Prescribed and delivered volumes of all parenteral and enteral fluids were recorded. Babies were weighed as per unit protocol.

RESULTS

Thirty-four infants met the audit criteria. Data are median (range). After the first week of life, energy and protein intakes were 147 (78-174) kcal/kg/day and 3.9 (2.1-4.8) g/kg/day respectively. Daily weight gain was 17 (-3.2-35.4) g/kg and was significantly associated with both energy and protein intakes (P<0.001). However, standard deviation scores for weight fell from 0.15 (-1.9-2.0) at birth to -1.0 (-2.9-0.8) by 36 weeks corrected age. Time to commencing enteral feeds was 1 (1-3) day and to full enteral feeds was 8 (5-28) days. One infant was diagnosed with necrotising enterocolitis and eight with chronic lung disease. Mean protein intake was significantly lower in babies with chronic lung disease (P=0.005).

CONCLUSION

Overall, nutritional intakes and weight gain in this cohort of babies lie within the recommended ranges, although protein intakes in the smallest babies are at the lower end of the range. Enteral feeds are introduced early and advanced rapidly, but we have a low incidence of necrotising enterocolitis. However, babies still fell across weight centiles, suggesting that actual intakes for these tiny babies may be inadequate.

Growth in the neonatal intensive care unit influences neurodevelopmental and growth outcomes of extremely low birth weight infants

OBJECTIVES

The objectives of this study were to assess whether (1) in-hospital growth velocity is predictive of neurodevelopmental and growth outcomes at 18 to 22 months' corrected age among extremely low birth weight (ELBW) infants and (2) in-hospital growth velocity contributes to these outcomes after controlling for confounding demographic and clinical variables.

METHODS

Infants 501 to 1000 g birth weight from a multicenter cohort study were divided into quartiles of in-hospital growth velocity rates. Variables considered for the logistic-regression models included gender, race, gestational age, small for gestational age, mother's education, severe intraventricular hemorrhage, periventricular leukomalacia, age at regaining birth weight, necrotizing enterocolitis, late-onset infection, bronchopulmonary dysplasia, postnatal steroid therapy for pulmonary disease, and center.

RESULTS

Of the 600 discharged infants, 495 (83%) were evaluated at 18 to 22 months' corrected age. As the rate of weight gain increased between quartile 1 and quartile 4, from 12.0 to 21.2 g/kg per day, the incidence of cerebral palsy, Bayley II Mental Developmental Index (MDI) <70 and Psychomotor Developmental Index (PDI) <70, abnormal neurologic examination, neurodevelopmental impairment, and need for rehospitalization fell significantly. Similar findings were observed as the rate of head circumference growth increased. The in-hospital rate of growth was associated with the likelihood of anthropometric measurements at 18 months' corrected age below the 10th percentile values of the Centers for Disease Control and Prevention 2000 growth curve. Logistic-regression analyses, controlling for potential demographic or clinical cofounders, and adjusted for center, identified a significant relationship between growth velocity and the likelihood of cerebral palsy, MDI and PDI scores of <70, and neurodevelopmental impairment.

CONCLUSIONS

These analyses suggest that growth velocity during an ELBW infant's NICU hospitalization exerts a significant, and possibly independent, effect on neurodevelopmental and growth outcomes at 18 to 22 months' corrected age.

Fetal growth and postnatal growth failure in very-low-birthweight infants

AIM

To determine in a cohort of very-low-birthweight (VLBW) infants the incidence of postnatal growth failure and the influence of intrauterine growth and neonatal morbidities on the risk for severe postnatal growth failure (PNGF).

METHODS

The study was based on analysis of data from the Israel Neonatal Network database on VLBW infants born between 1995 and 2001. Z-score was determined for weight at birth and discharge, and severe PNGF was defined as a decline in z-score of greater than 2. Univariate analysis and multi-linear regression determined the effect of fetal growth and neonatal morbidities on the risk for severe PNGF.

RESULTS

Severe PNGF occurred in 10.6% of the cohort. The mean+/-SD birthweight (BW) z-score was -0.59+/-0.74, decreasing to -1.67+/-0.77 at discharge. The incidence of severe PNGF increased significantly with decreasing BW and gestational age. Each 1-unit increase in z-score BW was associated with a 2.37-fold increased risk for severe PNGF. Severe respiratory distress syndrome, patent ductus arteriosus, sepsis, necrotizing enterocolitis, and bronchopulmonary dysplasia were associated with severe PNGF.

CONCLUSION

Severe PNGF among VLBW infants was markedly influenced by intrauterine growth as well as major morbidities. In the assessment of postnatal growth among VLBW infants, growth status at birth should be considered.

The contribution of body protein to the supply of energy in starved newborn piglets is not preferentially suppressed by intravenous provision of glucose and fat

Newborn piglets were used to study body protein preservation because it is critical to the survival of premature infants. Quantitative estimates of endogenous fuel use were obtained from 12 to 72 h of age in male piglets. Of the 40 piglets used (1300 +/- 205 g, mean +/- SD), 16 served as a 12-h-old body composition reference (R), 16 were starved (S) and received water only, and 8 received supplemental energy (E), obtaining 70% [210 kJ/(kg x d)] of their resting energy requirement as an i.v. mixture of glucose and Intralipid (65:35 energy ratio). Urine was collected continuously from the bladder via an umbilical urachal catheter. Total body water, glycogen, lipid, ash, and Kjeldahl-N were determined on whole-pig homogenates. Comparative slaughter was used to estimate the disappearance of body constituents of S and E pigs from 12 to 72 h of age. Midpoint body weight was used in these calculations. Supplemental energy decreased use of all body energy sources as indicated by the decrease in body dry matter disappearance, 41.6 +/- 8.8 vs. 25.5 +/- 5.9 g/kg (P = 0.0021) and protein (urinary N excretion), 995 +/- 508 vs. 329 +/- 135 mg/kg (P = 0.0119) over 60 h. Supplemental energy did not preferentially spare the percentage of the resting energy expenditure supplied by endogenous body protein (protein 37.6% +/- 9.6 vs. 41.7% +/- 10.4; lipid 25.7% +/- 5.2 vs. 20% +/- 4.1; glycogen 36.8% +/- 7.5 vs. 38.3% +/- 9.9; S vs. E) because it made up approximately 40% of the total in food-deprived and supplemented piglets.

Bronchopulmonary dysplasia in preterm infants: pathophysiology and management strategies

Bronchopulmonary dysplasia (BPD) has classically been described as including inflammation, architectural disruption, fibrosis, and disordered/delayed development of the infant lung. As infants born at progressively earlier gestations have begun to survive the neonatal period, a 'new' BPD, consisting primarily of disordered/delayed development, has emerged. BPD causes not only significant complications in the newborn period, but is associated with continuing mortality, cardiopulmonary dysfunction, re-hospitalization, growth failure, and poor neurodevelopmental outcome after hospital discharge. Four major risk factors for BPD include premature birth, respiratory failure, oxygen supplementation, and mechanical ventilation, although it is unclear whether any of these factors is absolutely necessary for development of the condition. Genetic susceptibility, infection, and patent ductus arteriosus have also been implicated in the pathogenesis of the disease. The strategies with the strongest evidence for effectiveness in preventing or lessening the severity of BPD include prevention of prematurity and closure of a clinically significant patent ductus arteriosus. Some evidence of effectiveness also exists for single-course therapy with antenatal glucocorticoids in women at risk for delivering premature infants, surfactant replacement therapy in intubated infants with respiratory distress syndrome, retinol (vitamin A) therapy, and modes of respiratory support designed to minimize 'volutrauma' and oxygen toxicity. The most effective treatments for ameliorating symptoms or preventing exacerbation in established BPD include oxygen therapy, inhaled glucocorticoid therapy, and vaccination against respiratory pathogens.Many other strategies for the prevention or treatment of BPD have been proposed, but have weaker or conflicting evidence of effectiveness. In addition, many therapies have significant side effects, including the possibility of worsening the disease despite symptom improvement. For instance, supraphysiologic systemic doses of glucocorticoids lessen the incidence of BPD in infants at risk for the disease, and promote weaning of oxygen and mechanical ventilation in infants with established BPD. However, the side effects of systemic glucocorticoid therapy, most notably the recently recognized adverse effects on neurodevelopment, preclude their routine use for the prevention or treatment of BPD. Future research in BPD will most probably focus on continued incremental improvements in outcome, which are likely to be achieved through the combined effects of many therapeutic modalities.

Nutrition services in Canadian neonatal follow-up programs

The benefits of nutrition assessment and support of the high-risk infant are well established. The premature infant remains vulnerable for poor growth and developmental disabilities, thus requiring consistent monitoring, intervention, and follow-up care. The purpose of this study was to determine the registered dietitian's role in neonatal/perinatal follow-up programs. A survey was sent to the 26 follow-up programs in Canada. The questionnaire response rate was 81%. Registered dietitians were involved in 67% of these programs. Of these dietitians, 43% were assigned to neonatal/perinatal follow-up programs while 57% were involved only by consult. The average time that assigned registered dietitians devoted to programs was 0.35 full-time equivalents. Over 80% of the dietitians did ongoing development, evaluation, and modification of nutrition care plans; 71% screened new patients for nutritional risk, and 100% instructed patient families and developed teaching materials. The study findings will assist program planners who wish to establish a dietitian position in a neonatal/ perinatal follow-up program. For registered dietitians already working in such programs, the results may provide some guidance on role definition and expansion.

Comparisons of mortality and pre-discharge respiratory outcomes in small-for-gestational-age and appropriate-for-gestational-age premature infants

Background

There are differences in the literature regarding outcomes of premature small-for-gestational-age (SGA) and appropriate-for gestational-age (AGA) infants, possibly due to failure to take into account gestational age at birth.

Objective

To compare mortality and respiratory morbidity of SGA and AGA premature newborn infants.

Design/Methods

A retrospective study was done of the 2,487 infants born without congenital anomalies at ≤36 weeks of gestation and admitted to the neonatal intensive care unit (NICU) at John Dempsey Hospital, between Jan. 1992 and Dec. 1999. Recent (1994–96) U.S. birth weight percentiles for gestational age (GA), race and gender were used to classify neonates as SGA (<10th percentile for GA) or AGA (10^th–90th percentile for GA). Using multivariate logistic regression and survival analyses to control for GA, SGA and AGA infants were compared for mortality and respiratory morbidity.

Results

Controlling for GA, premature SGA infants were at a higher risk for mortality (Odds ratio 3.1, P = 0.001) and at lower risk of respiratory distress syndrome (OR = 0.71, p = 0.02) than AGA infants. However multivariate logistic regression modeling found that the odds of having respiratory distress syndrome (RDS) varied between SGA and AGA infants by GA. There was no change in RDS risk in SGA infants at GA ≤ 32 wk (OR = 1.27, 95% CI 0.32 – 1.98) but significantly decreased risk for RDS at GA > 32 wk (OR = 0.41, 95% CI 0.27 – 0.63; p < 0.01). After controlling for GA, SGA infants were observed to be at a significantly higher risk for developing chronic lung disease as compared to AGA infants (OR = 2.2, 95% CI = 1.2 – 3.9, P = 0.01). There was no significant difference between SGA and AGA infants in total days on ventilator. Among infants who survived, mean length of hospital stay was significantly higher in SGA infants born between 26–36 wks GA than AGA infants.

Conclusions

Premature SGA infants have significantly higher mortality, significantly higher risk of developing chronic lung disease and longer hospital stay as compared to premature AGA infants. Even the reduced risk of RDS in infants born at ≥32 wk GA, (conferred possibly by intra-uterine stress leading to accelerated lung maturation) appears to be of transient effect and is counterbalanced by adverse effects of poor intrauterine growth on long term pulmonary outcomes such as chronic lung disease.

Nutrition et dysplasie bronchopulmonaire

Bronchopulmonary dysplasia remains a frequent complication of extreme prematurity. In preterm neonates catch-up and pulmonary alveolar growth occur during the first two years of life. However 10 to 25% of preterm infants with bronchopulmonary dysplasia are under-nourished after two years of age, and 30 to 60% of them also suffer from persistent airway obstruction, hyperinflation and bronchial hyperreactivity. Recommendations on nutritional requirements in this population are not yet clearly defined, but an adequate nutritional status in prenatal and early postnatal period can have long-term consequences on brain and lung development. There are a few randomised trial of nutrition for preterm infants with bronchopulmonary dysplasia after discharge. Caloric and protein requirements in this population are probably higher than in full-term infants. Moreover there are potential benefits in using specific nutrients: supplementation with long chain polyunsaturated fatty acids could decrease lung inflammation injuries, glutamine is the main source of energy of pneumocyte, vitamin A is essential for lung development, inositol is necessary for surfactant synthesis, vitamin E and selenium have anti-oxidant effects. Controlled nutritional trial are needed with a long term follow-up in late childhood in order to test their effects on growth and pulmonary status.

Current perspectives on the prevention and management of chronic lung disease in preterm infants

Chronic lung disease (CLD) or bronchopulmonary dysplasia is a recognized sequel of preterm birth. With improving survival of infants at lower gestational ages, the incidence is on the rise. Pathological features of CLD include alveolar maldevelopment, with or without areas of pulmonary fibrosis. Assisted ventilation, infection/inflammation, oxygen administration, and fluid overload are the major risk factors in the evolution of CLD.Interventions, including the treatment of maternal infection, administration of prenatal glucocorticoids, and postnatal surfactant replacement therapy, improve the survival of preterm infants; however, their effect on CLD is difficult to determine. Strategies that have been effective in reducing CLD are the administration of retinol (vitamin A), high frequency oscillatory ventilation, and administration of glucocorticoids. Previous concerns regarding neurological problems associated with high frequency ventilation have not been substantiated in recent studies. Current recommendations do not advise the routine use of glucocorticoids due to concerns regarding long-term neurodevelopment. Therapies that were found to be ineffective in reducing the incidence of CLD include prenatal thyrotropin, cromolyn sodium (sodium cromoglycate), alpha-1 antitrypsin, superoxide dismutase, tocopherol (vitamin E), ascorbic acid (vitamin C), allopurinol, ambroxol, inositol, inhaled bronchodilators, and fluid restriction. Strategies that may be effective in reducing lung injury and subsequent CLD include avoiding assisted ventilation, lung protective ventilatory maneuvers, permissive hypercapnia, prevention of infection, early aggressive nutrition, and the treatment of a patent ductus arteriosus. The use of inhaled glucocorticoids improves pulmonary dynamics but long-term effects are unknown. The management of infants with established CLD has not been studied adequately, and the role of various ventilatory strategies for infants with established CLD is not clear. Adequate oxygenation should be maintained to prevent hypoxic episodes. Diuretics are helpful during acute decompensation; however, their long-term impact has not been well studied. Provision of adequate nutrition, immunization (routine and against respiratory syncytial virus), follow-up, and monitoring are the key elements in the long-term management of infants with CLD. Future research priorities should be to identify strategies to prevent/treat inflammation and promote the healing processes in the injured lung. The long-term effects of lung-protective ventilation strategies need to be studied.

Prediction of extrauterine growth retardation (EUGR) in VVLBW infants

BACKGROUND

Long-term growth failure in very very low birth weight (VVLBW) infants is a common complication of extreme prematurity. Critical illnesses create challenges to adequate nutriture.

PURPOSE

To identify predictors of extrauterine growth retardation (EUGR) in VVLBW infants and to evaluate their nutritional intake and subsequent growth.

STUDY DESIGN

A 4-year retrospective chart review of 221 infants <or=1000 g birth weight and <or=29 weeks gestational age who were admitted within 24 hours of birth, were free of major congenital anomalies and survived at least 7 days. Daily intakes and anthropomorphic data were collected and analyzed. Significant events during hospitalization were documented.

RESULTS

Mean energy and protein intakes during hospitalization did not reach recommendations of 120 kcal/kg/d and 3.0 g/kg/day. In utero growth rates could not be consistently reached or sustained. As expected, BW (as measured by BW percentile score) was highly predictive of EUGR (p<0.001). When the independent effect of other predictors of EUGR was considered, only days of total parenteral nutrition (p<0.001) and HC percentile at return to birth weight (p<0.001) made a significant contribution to the prediction of EUGR, once the effect of BW was taken into account.

Effect of amino acids on glucose tolerance and hyperkalemia in very low birth weight infants

OBJECTIVE

The purpose of the study was to investigate alimentation of very low birth weight (VLBW) infants and its effect on blood concentration of glucose, urea nitrogen, creatinine and potassium.

METHODS

The subjects were 100 VLBW infants born between 1993-1999. The gestational age ranged from 23 to 32 weeks and the birth weight from 443 to 1470 g. Intravenous glucose infusions were begun shortly after birth, amino acids on day 3 and lipids on day 4. Blood samples were drawn for determinations of urea nitrogen, creatinine and potassium.

RESULTS

Mean caloric intake of glucose rose from 24.7 kcal/kg/day on day 1 to 58.1 kcal/kg/day on day 8 (p < 0.0001) and of amino acids from 1.1 g/kg/day on day 3 to 1.9 g/kg/day on day 8 (p < 0.0001). Potassium administration increased from 1 mq/kg/day on day 2 to 1.9 mq/kg/day on day 8. Urea nitrogen was at a mean level of 21.4 mg/dl on day 4 and declined afterwards (p < 0.0001). Serum potassium levels declined from 5.9 mmol/L on day 2 to 4.1 mmol/L on day 8 (p < 0.0001), while creatinine levels remained stable.

CONCLUSION

Our findings suggest that a catabolic state in VLBW infants begins to be reversed when the caloric intake of 40-50 kcal/kg/day is achieved.

Effects of fasting on tissue contents of coenzyme A and related intermediates in rats

Exposure of rats and mice to hyperoxia decreases lung coenzyme A (CoASH) contents, with a decrease of 50% observed in adult male Fischer-344 rats exposed to >95% O(2) for 48 h. Decreases in lung CoASH levels are not accompanied by increases in contents of the mixed glutathione disulfide of CoA, as might be expected of a primary oxidative stress on CoASH status. Animals exposed to hyperoxia exhibit decreased food intake, and the present studies were to test the hypothesis that fasting would decrease lung CoASH contents, thereby suggesting a mechanism for the effects of hyperoxia. Adult male Fischer-344 rats were examined after 0, 24, or 48 h of fasting (n = 5, 6, and 6, respectively). Fasting for 24 or 48 h did not affect lung CoASH levels or lung weights, despite 6 and 12% losses in body weight. Lung glutathione concentrations (nanomoles per gram of tissue) and contents (nanomoles per whole organ) and glutathione disulfide contents were 10 to 20% lower in rats fasted for 48 h than in fed rats. Liver weights and glutathione and glutathione disulfide contents and concentrations were 30 to 70% lower in rats fasted for 24 or 48 h than in fed rats. Hepatic CoASH concentrations increased during fasting, but hepatic contents of CoASH remained remarkably constant. Liver protein contents (milligrams of protein per whole organ) decreased after 24 and 48 h of fasting, but protein concentrations (milligrams of protein per gram of tissue) were higher in rats fasted 48 h than in fed rats. Overall, glutathione, glutathione disulfide, and protein contents in liver and skeletal muscle decreased with fasting, but significant changes in CoASH contents were not observed. Diminished food intake in animals does not explain the effects of hyperoxia on lung CoASH contents. CoASH and derived thioesters participate in many cellular functions, and if depletion of lung CoASH during hyperoxia proves to be relevant to mechanisms of lung injury, support of mechanisms needed to sustain CoA levels could be helpful in prematurely born infants and in adults.