The metabolic needs of critically ill children and neonates

BCG-Induced Immune Training: Interplay between Trained Immunity and Emergency Granulopoiesis

Bacille Calmette-Guérin (BCG) is the most commonly administered vaccine in human history. The medical application of BCG extends far beyond the fight against tuberculosis. Despite its stellar medical record over 100 years, insight into how BCG provides this vast range of benefits is largely limited, both for its pathogen-specific (tuberculosis) as well as pathogen-agnostic (other infections, autoimmunity, allergies, and cancer) effects. Trained immunity and emergency granulopoiesis have been identified as mediating BCG's pathogen-agnostic effects, for which some of the molecular mechanisms have been delineated. Upon review of the existing evidence, we postulate that emergency granulopoiesis and trained immunity are a continuum of the same effect cascade. In this context, we highlight that BCG's pathogen-agnostic benefits could be optimized by taking advantage of the age of the recipient and route of BCG administration.

Programmed and environmental determinants driving neonatal mucosal immune development

The mucosal immune system of neonates goes through successive, non-redundant phases that support the developmental needs of the infant and ultimately establish immune homeostasis. These phases are informed by environmental cues, including dietary and microbial stimuli, but also evolutionary developmental programming that functions independently of external stimuli. The immune response to exogenous stimuli is tightly regulated during early life; thresholds are set within this neonatal "window of opportunity" that govern how the immune system will respond to diet, the microbiota, and pathogenic microorganisms in the future. Thus, changes in early-life exposure, such as breastfeeding or environmental and microbial stimuli, influence immunological and metabolic homeostasis and the risk of developing diseases such as asthma/allergy and obesity.

A role for metabolism in determining neonatal immune function

Immune responses of neonates differ markedly to those of adults, with skewed cytokine phenotypes, reduced inflammatory properties and drastically diminished memory function. Recent research efforts have started to unravel the role of cellular metabolism in determining immune cell fate and function. For studies in humans, much of the work on metabolic mechanisms underpinning innate and adaptive immune responses by different haematopoietic cell types is in adults. Studies investigating the contribution of metabolic adaptation in the unique setting of early life are just emerging, and much more work is needed to elucidate the contribution of metabolism to neonatal immune responses. Here, we discuss our current understanding of neonatal immune responses, examine some of the latest developments in neonatal immunometabolism and consider the possible role of altered metabolism to the distinctive immune phenotype of the neonate. Understanding the role of metabolism in regulating immune function at this critical stage in life has direct benefit for the child by affording opportunities to maximize immediate and long-term health. Additionally, gaining insight into the diversity of human immune function and naturally evolved immunometabolic strategies that modulate immune function could be harnessed for a wide range of opportunities including new therapeutic approaches.

Influence of innate immune activation on endocrine and metabolic pathways in infancy

Prematurity is the leading cause of neonatal morbidity and mortality worldwide. Premature infants often require extended hospital stays, with increased risk of developing infection compared with term infants. A picture is emerging of wide-ranging deleterious consequences resulting from innate immune system activation in the newborn infant. Those who survive infection have been exposed to a stimulus that can impose long-lasting alterations into later life. In this review, we discuss sepsis-driven alterations in integrated neuroendocrine and metabolic pathways and highlight current knowledge gaps in respect of neonatal sepsis. We review established biomarkers for sepsis and extend the discussion to examine emerging findings from human and animal models of neonatal sepsis that propose novel biomarkers for early identification of sepsis. Future research in this area is required to establish a greater understanding of the distinct neonatal signature of early and late-stage infection, to improve diagnosis, curtail inappropriate antibiotic use, and promote precision medicine through a biomarker-guided empirical and adjunctive treatment approach for neonatal sepsis. There is an unmet clinical need to decrease sepsis-induced morbidity in neonates, to limit and prevent adverse consequences in later life and decrease mortality.

Energy Demands of Early Life Drive a Disease Tolerant Phenotype and Dictate Outcome in Neonatal Bacterial Sepsis

Bacterial sepsis is one of the leading causes of death in newborns. In the face of growing antibiotic resistance, it is crucial to understand the pathology behind the disease in order to develop effective interventions. Neonatal susceptibility to sepsis can no longer be attributed to simple immune immaturity in the face of mounting evidence that the neonatal immune system is tightly regulated and well controlled. The neonatal immune response is consistent with a "disease tolerance" defense strategy (minimizing harm from immunopathology) whereas adults tend toward a "disease resistance" strategy (minimizing harm from pathogens). One major advantage of disease tolerance is that is less energetically demanding than disease resistance, consistent with the energetic limitations of early life. Immune effector cells enacting disease resistance responses switch to aerobic glycolysis upon TLR stimulation and require steady glycolytic flux to maintain the inflammatory phenotype. Rapid and intense upregulation of glucose uptake by immune cells necessitates an increased reliance on fatty acid metabolism to (a) fuel vital tissue function and (b) produce immunoregulatory intermediates which help control the magnitude of inflammation. Increasing disease resistance requires more energy: while adults have fat and protein stores to catabolize, neonates must reallocate resources away from critical growth and development. This understanding of sepsis pathology helps to explain many of the differences between neonatal and adult immune responses. Taking into account the central role of metabolism in the host response to infection and the severe metabolic demands of early life, it emerges that the striking clinical susceptibility to bacterial infection of the newborn is at its core a problem of metabolism. The evidence supporting this novel hypothesis, which has profound implications for interventions, is presented in this review.

Improving the quality of nutrition in pediatric trauma

Purpose

Nutrition plays a key role in the recovery of pediatric trauma patients. A catabolic state in trauma patients may hinder recovery and inadequate nutrition may increase morbidity, mortality and length of hospital stay. The purpose of this paper is to review the current nutrition support practices for pediatric trauma patients at McMaster Children’s Hospital (MCH), describe patient demographics and identify areas to improve the quality of patient care.

Design/methodology/approach

A retrospective chart review was conducted on pediatric trauma patients (age<18 years) identified through the trauma registry of MCH. Pediatric trauma patients admitted from January 2010 to March 2014 with an Injury Severity Score (ISS)=12 and a hospitalization of =24 hours were included.

Findings

In total, 130 patients were included in this study, 61.1 percent male, median age ten years (range: 0-17 years) and median ISS of 17 (range: 12-50). Blunt trauma accounted for 97.7 percent of patients admitted and 73.3 percent had trauma team activation. In total, 93 patients (71.5 percent) had ICU stays. The median time to feed was 29 hours (interquartile range: 12.5-43 hours) from the time of admission. An increased hospital length of stay was associated with longer time to initiation of nutrition support, a higher ISS and greater number of surgeries (p<0.05).

Originality/value

Local nutritional support practices for pediatric trauma patients correspond with recommended principles of early feeding and preferential enteral nutrition. Harmonization of paper-based and electronic data collection is recommended to ensure that prescribed nutritional support is being delivered and nutritional needs of pediatric trauma patients are being met.

Nutrition in the pediatric population in the intensive care unit

Nutrition is an essential component of patient management in the pediatric intensive care unit (PICU). Poor nutrition status accompanies many childhood chronic illnesses. A thorough assessment of the critically ill child is required to inform the plan for nutrition support. Accurate and clinically relevant nutritional assessment, including growth measurements, provides important guidance. Indirect calorimetry provides the most accurate measurement of resting energy expenditure, but is too often unavailable in the PICU. To prevent inappropriate caloric intake, reassessment of the child's nutrition status is imperative. Enteral nutrition is the recommended route of intake. Human milk is preferred for infants.

Adequate enteral protein intake is inversely associated with 60-d mortality in critically ill children: a multicenter, prospective, cohort study

BACKGROUND

The impact of protein intake on outcomes in pediatric critical illness is unclear.

OBJECTIVE

We examined the association between protein intake and 60-d mortality in mechanically ventilated children.

DESIGN

In a prospective, multicenter, cohort study that included 59 pediatric intensive care units (PICUs) from 15 countries, we enrolled consecutive children (age: 1 mo to 18 y) who were mechanically ventilated for ≥48 h. We recorded the daily and cumulative mean adequacies of energy and protein delivery as a percentage of the prescribed daily goal during the PICU stay ≤10 d. We examined the association of the adequacy of protein delivery with 60-d mortality and determined variables that predicted protein intake adequacy.

RESULTS

We enrolled 1245 subjects (44% female) with a median age of 1.7 y (IQR: 0.4, 7.0 y). A total of 985 subjects received enteral nutrition, 354 (36%) of whom received enteral nutrition via the postpyloric route. Mean ± SD prescribed energy and protein goals were 69 ± 28 kcal/kg per day and 1.9 ± 0.7 g/kg per day, respectively. The mean delivery of enteral energy and protein was 36 ± 35% and 37 ± 38%, respectively, of the prescribed goal. The adequacy of enteral protein intake was significantly associated with 60-d mortality (P < 0.001) after adjustment for disease severity, site, PICU days, and energy intake. In relation to mean enteral protein intake <20%, intake ≥60% of the prescribed goal was associated with an OR of 0.14 (95% CI: 0.04, 0.52; P = 0.003) for 60-d mortality. Early initiation, postpyloric route, shorter interruptions, larger PICU size, and a dedicated dietitian in the PICU were associated with higher enteral protein delivery.

CONCLUSIONS

Delivery of >60% of the prescribed protein intake is associated with lower odds of mortality in mechanically ventilated children. Optimal prescription and modifiable practices at the bedside might enhance enteral protein delivery in the PICU with a potential for improved outcomes. This trial was registered at clinicaltrials.gov as NCT02354521.

The Impact of Neonatal Illness on Nutritional Requirements-One Size Does Not Fit All

Sick neonates are at high risk for growth failure and poorer neurodevelopment than their healthy counterparts. The etiology of postnatal growth failure in sick infants is likely multi-factorial and includes undernutrition due to the difficulty of feeding them during their illness and instability. Illness also itself induces fundamental changes in cellular metabolism that appear to significantly alter nutritional demand and nutrient handling. Inflammation and physiologic stress play a large role in inducing the catabolic state characteristic of the critically ill newborn infant. Inflammatory and stress responses are critical short-term adaptations to promote survival, but are not conducive to promoting long-term growth and development. Conditions such as sepsis, surgery, necrotizing enterocolitis, chronic lung disease and intrauterine growth restriction and their treatments are characterized by altered energy, protein and micronutrient metabolism that result in nutritional requirements that are different from those of the healthy, growing term or preterm infant.

Nutritional support of the pediatric trauma patient

Of all the interventions available to aid recovery of the injured child, few have the power of proper nutritional support. Healing after trauma depends not only on restoration of oxygen delivery, but on "substrate delivery," or provision of calories to support metabolic power and specific nutrients to allow rebuilding of injured tissue. Failure to deliver adequate substrate to the cells is revealed as another form of shock. Nutritional interventions after trauma are most effective when informed by the specific ways that children diverge physiologically (metabolic rate, biomechanics, physiological response to trauma) from adults. This review describes these responses and outlines a general strategy for safely delivering energy and specific substrates to protect and heal injured children, regardless of body size and type of injury.

Anesthesia and analgesia during and after surgery in neonates

BACKGROUND

Historically, the use of anesthetics and analgesics in neonates and infants has been based on extrapolations from studies performed in adults and older children. Over the past 20 years, there has been a growing body of research on the clinical pharmacology and clinical outcomes of these agents in neonates and infants.

OBJECTIVE

This article summarizes clinical pharmacology and clinical outcomes studies of opioids, opioid antagonists, sedative-hypnotics, nonsteroidal anti-inflammatory drugs and acetaminophen, and local anesthetics in neonates and infants to highlight gaps in the available knowledge, review some concerns about study design, and identify drugs that should receive high priority for future study.

METHODS

Relevant studies were identified through a search of MEDLINE and a review of textbooks, conference proceedings, and abstracts. The available literature was subjected to expert committee-based review.

CONCLUSIONS

There is a growing body of information on analgesic and anesthetic pharmacokinetics, pharmacodynamics, and clinical outcomes in neonates and infants, permitting safe and effective use in some clinical settings. Major gaps in knowledge persist, however. Future research may involve a combination of clinical trials and preclinical studies in suitable infant animal surrogate models.

Multiple trauma in children: critical care overview

Multiple trauma is more than the sum of the injuries. Management not only of the physiologic injury but also of the pathophysiologic responses, along with integration of the child's emotional and developmental needs and the child's family, forms the basis of trauma care. Multiple trauma in children also elicits profound psychological responses from the healthcare providers involved with these children. This overview will address the pathophysiology of multiple trauma in children and the general principles of trauma management by an integrated trauma team. Trauma is a systemic disease. Multiple trauma stimulates the release of multiple inflammatory mediators. A lethal triad of hypothermia, acidosis, and coagulopathy is the direct result of trauma and secondary injury from the systemic response to trauma. Controlling and responding to the secondary pathophysiologic sequelae of trauma is the cornerstone of trauma management in the multiply injured, critically ill child. Damage control surgery is a new, rational approach to the child with multiple trauma. The selection of children for damage control surgery depends on the severity of injury. Major abdominal vascular injuries and multiple visceral injuries are best considered for this approach. The effective management of childhood multiple trauma requires a combined team approach, consideration of the child and family, an organized trauma system, and an effective quality assurance and improvement mechanism.

Effect of thermal injury on relative anaplerosis and gluconeogenesis in the rat during infusion of [U-13C] propionate

A new approach for the analysis of hepatic metabolism after burn injury is introduced. Relative anaplerotic, pyruvate recycling and gluconeogenic fluxes were measured by 13C NMR isotopomer analysis of blood glucose from rats with 40% body surface area injury, and from rats exposed to sham injury. A short chain fatty acid, [U-13C] propionate which is avidly extracted by the liver, was infused intravenously to deliver 13C into the citric acid cycle. There was no difference in the multiplets detected in the glucose carbon-2 (C-2) anomer from blood or liver after 45 or 60 min of infusion of propionate, indicating that steady-state isotopic conditions were achieved. Gluconeogenesis relative to citric acid cycle flux was not altered by burn injury; in both sham and burn groups the rate of glucose production was about equal to flux through citrate synthase. In the sham group of animals the rate of entry of carbon skeletons into the citric acid cycle was about four times citric acid cycle flux in animals after thermal injury. Similarly, flux through pyruvate kinase (again relative to citrate synthase) was significantly increased in burn injury.

Metabolic effects of infection and postnatal steroids

Optimal development of the newborn depends on rapid accretion of substrate in the neonatal period, particularly in the premature infant. Steroids and infection not only induce catabolism, but associated endogenous responses reprioritize crucial substrate to restore homeostasis. The result is a protein/energy deficit and concomitant delay in growth and development. Innovative feeding strategies and novel therapies are needed to reduce the impact of catabolism in this population.

Nutritional morbidity in survivors of congenital diaphragmatic hernia

PURPOSE

The purpose of this report is to detail the nutritional sequelae seen in survivors of congenital diaphragmatic hernia (CDH) followed in a multidisciplinary clinic.

METHODS

Data on 121 surviving CDH patients seen between 1990 and 2000 were collected. Regression analysis was used to determine the impact of factors such as Apgar score, birth weight, extracorporeal membrane oxygenation (ECMO), and patch repair on outcomes associated with nutritional morbidity.

RESULTS

There were 100 left and 21 right CDH defects. Mean birth weight and 5-minute Apgar score were 3.1 kg (+/-0.8) and 6.8(+/-2), respectively. Extracorporeal membrane oxygenation was required in 43 (36%) patients and patch repair in 39 (32%). A gastrostomy was required in 39 (32%) patients and a fundoplication in 23 (19%) patients. The side of the defect did not affect the frequency of these procedures. Fifty-six percent of patients were below the 25th percentile for weight during most of their first year. Regression analysis found that duration of ventilation (P <.001) and the presence of a patch repair (P =.03) were independent variables predictive of failure to thrive thereby requiring a gastrostomy tube. Patch repair also was predictive of need for subsequent fundoplication caused by gastroesophageal reflux (P <.001). Twenty-nine patients (24%) had severe oral aversion. Risk factors were prolonged ventilation (P =.001) and oxygen requirement at discharge (P =.015). Two thirds of these patients subsequently improved.

CONCLUSIONS

Nutritional problems continue to be a source of morbidity for survivors of CDH, particularly in the first year of life. Not surprisingly, patients who had prolonged intubation and prosthetic material at the gastroesophageal junction fared worse. Despite aggressive nutritional management, 56% of the population remained below the twenty-fifth percentile for weight. These data show the need for careful nutritional assessment in all CDH patients, especially those at high risk for malnutrition.

Do critically ill surgical neonates have increased energy expenditure?

BACKGROUND/PURPOSE

Adult metabolic studies suggest that critically ill patients have increased energy expenditures and thus require higher caloric allotments. To assess whether this is true in surgical neonates the authors utilized a validated, gas leak-independent, nonradioactive, isotopic technique to measure the energy expenditures of a stable postoperative group and a severely stressed cohort.

METHODS

Eight (3.46+/-1.0 kg), hemodynamically stable, total parenteral nutrition (TPN)-fed, nonventilated, surgical neonates (5 with gastroschisis, 2 with intestinal atresia, and 1 with intestinal volvulus) were studied on postoperative day 15.5+/-11.9. These were compared with 10 (BW = 3.20+/-0.2 kg), TPN-fed, extracorporeal life support (ECLS)-dependent neonates, studied on day of life 7.0+/- 2.8. Energy expenditure was obtained using a primed, 3-hour infusion of NaH(13)CO(3'), breath (13)CO(2) enrichment determination by isotope ratio mass spectroscopy, and the application of a standard regression equation. Interleukin (IL)-6 levels and C-reactive protein (CRP) concentrations were measured to assess metabolic stress. Comparisons between groups were made using 2 sample Student's t tests.

RESULTS

The mean energy expenditure was 53+/-5.1 kcal/kg/d (range, 45.6 to 59.8 kcal/kg/d) for the stable cohort and 55+/-20 kcal/kg/d (range, 32 to 79 kcal/kg/d) for the ECLS group (not significant, P =.83). The IL-6 and CRP levels were significantly higher in the ECLS group (29 +/-11.5 v 0.7+/-0.6 pg/mL [P<.001], and 31+/-22 v 0.6+/-1.3 mg/L [P<.001], respectively). Mortality rate was 0% for the stable postoperative patients and 30% for the ECLS group.

CONCLUSIONS

Severely stressed surgical neonates, compared with controls, generally do not show increased energy expenditures as assessed by isotopic dilution methods. These data suggest that the routine administration of excess calories may not be warranted in critically ill surgical neonates and support the hypothesis that neonates obligately redirect energy, normally used for growth, to fuel the stress response. This is a US government work. There are no restrictions on its use.