The metabolic response to operative stress in infants

Perioperative nutritional prehabilitation in malnourished children with congenital heart disease: A randomized controlled trial

OBJECTIVE

The poor preoperative nutritional state of children with congenital heart disease (CHD) is often exacerbated postoperatively. The aim of this study was to evaluate the effect of perioperative 1- versus 2-wk nutritional prehabilitation programs on growth and surgical outcomes in malnourished children with CHD.

METHODS

Forty malnourished infants scheduled for elective CHD surgery were randomized to receive either 1 or 2 wk of a nutritional prehabilitation program. Pre- and postoperative anthropometric parameters and feeding characteristics, feeding tolerance, duration of mechanical ventilation, intensive care unit (ICU) length of stay (LOS) and total hospital LOS were documented.

RESULTS

The 2-wk prehabilitation group showed higher weight-for-age z-score and body mass index than the 1-wk group both preoperatively postnutritional, and postoperatively with significantly higher weight gain postoperatively. The 2-wk prehabilitation group had a shorter duration of postoperative mechanical ventilation, ICU LOS, and total hospital LOS.

CONCLUSION

The 2-wk prehabilitation program was associated with better anthropometric measurements, shorter ICU LOS postoperatively, and shorter duration of hospitalization and mechanical ventilation. The preoperative nutritional status of children with CHD had a negative effect on ICU LOS and duration of mechanical ventilation.

Current concepts in the surgical approach to necrotizing enterocolitis

Necrotizing enterocolitis (NEC) is the most common surgical emergency occurring in neonatal intensive care unit (NICU) patients. Among patients with NEC, those that require surgery experience the poorest outcomes and highest mortality. Surgical intervention, while attempting to address the intestinal injury and ongoing mulitfactorial physiologic insults in NEC is associated with its own stresses that may compound the ongoing physiologic derangement. Surgery is thus reserved for those patients with clear indication for intervention such as pneumoperitoneum, confirmed stool or pus in the peritoneal cavity, or worsening clinical status. The purpose of this review is to briefly describe the physiologic stress induced by surgical intervention in the preterm, low birth weight patient with NEC and to provide a contemporary overview of available surgical management options for NEC. The optimal surgical plan employed is strongly influenced by clinical judgment and theoretical benefits in terms of minimizing physiologic stressors while providing temporary and/or definitive treatment in a timely fashion. While the choice of operation has not been shown to have a significant effect on any clinically important outcomes, ongoing investigations continue to study both short and long-term outcomes in patients with NEC.

Thirty-day outcome in children randomized to open and laparoscopic Nissen fundoplication

BACKGROUND

Laparoscopic Nissen fundoplication (LNF) is considered by some to be superior to open Nissen fundoplication (ONF). To test this hypothesis, we compared early results after LNF and ONF in a randomized trial.

METHODS

All children accepted for antireflux surgery for gastroesophageal reflux disease were offered enrollment. Ethical approval and parental consent were obtained. Anesthesia, surgical methods, and postoperative treatment were standardized. Patient demographics, length of hospital stay (LOS), and complications occurring the first 30 postoperative days were registered.

RESULTS

Eighty-eight children were randomized to LNF (n = 44) or ONF (n = 44). The groups were comparable with regard to age, weight, and comorbidity. Duration of surgery was 150 ± 34 minutes for LNF and 89 ± 25 minutes for ONF (P < .001). Median LOS was 7.0 days (range, 3-57 days) and 7.5 days (range, 2-20 days) after LNF and ONF, respectively (P = .74). Postoperative complications occurred in 48 patients, 24 in both groups. Twenty-four patients (LNF: n = 12, ONF: n = 11) were readmitted to hospital because of complications occurring after discharge.

CONCLUSIONS

This study failed to show that LNF is superior to ONF when surgery duration, LOS, and complications occurring during the first postoperative month were compared. Apart from surgery duration, the results were surprisingly similar.

Resting energy expenditure after Fontan surgery in children with single-ventricle heart defects

BACKGROUND

Data on resting energy expenditure (REE) and oxygen consumption (VO(2)) after pediatric cardiopulmonary bypass (CPB) will facilitate optimal nutrient prescription.

METHODS

The authors measured continuous REE and VO(2), using an in-line indirect calorimetery (IC) in 30 consecutive children with single-ventricle physiology immediately after Fontan surgery. REE during steady state at 8 hours after surgery was compared with standard equation-estimated energy expenditure (EEE). Patients were classified into 3 groups: hypermetabolic (measured REE [MREE]/EEE ratio >1.2), hypometabolic (MREE/EEE ratio <0.8), and normometabolic (MREE/EEE ratio 0.8-1.2). Demographic, anthropometric, and perioperative clinical characteristics were examined for their correlation with metabolic status.

RESULTS

In 26 of 30 patients with completed IC, mean REE at 8 hours after surgery was 57 ± 20 kcal/kg/d, and mean VO(2) was 110 ± 35 mL/min. Mean values of VO(2) and REE did not change within the first 24 hours after surgery. There was poor correlation between MREE at 8 hours and the EEE using the World Health Organization equation (r = 0.32, P = .11). Most patients (n = 19, 73%) were either normometabolic or hypometabolic. Lack of hypermetabolism was significantly associated with higher intraoperative serum lactate level and positive fluid balance compared with the rest of the group.

CONCLUSIONS

The authors report a low prevalence of hypermetabolism in children with single-ventricle defects after Fontan surgery. Measured REE had poor correlation with equation-estimated energy expenditure in a majority of the cohort. The absence of increased energy expenditure after CPB will influence energy prescription in this group.

Energy imbalance and the risk of overfeeding in critically ill children

OBJECTIVE

To examine the role of targeted indirect calorimetry in detecting the adequacy of energy intake and the risk of cumulative energy imbalance in a subgroup of critically ill children suspected to have alterations in resting energy expenditure. We examined the accuracy of standard equations used for estimating resting energy expenditure in relation to measured resting energy expenditure in relation to measured resting energy expenditure and cumulative energy balance over 1 week in this cohort.

DESIGN

A prospective cohort study.

SETTING

Pediatric intensive care unit in a tertiary academic center.

INTERVENTIONS

A subgroup of critically ill children in the pediatric intensive care unit was selected using a set of criteria for targeted indirect calorimetry.

MEASUREMENTS

Measured resting energy expenditure from indirect calorimetry and estimated resting energy expenditure from standard equations were obtained. The metabolic state of each patient was assigned as hypermetabolic (measured resting energy expenditure/estimated resting energy expenditure >110%), hypometabolic (measured resting energy expenditure/estimated resting energy expenditure <90%), or normal (measured resting energy expenditure/estimated resting energy expenditure = 90-110%). Clinical variables associated with metabolic state and factors influencing the adequacy of energy intake were examined.

MAIN RESULTS

Children identified by criteria for targeted indirect calorimetry, had a median length of stay of 44 days, a high incidence (72%) of metabolic instability and alterations in resting energy expenditure with a predominance of hypometabolism in those admitted to the medical service. Physicians failed to accurately predict the true metabolic state in a majority (62%) of patients. Standard equations overestimated the energy expenditure and a high incidence of overfeeding (83%) with cumulative energy excess of up to 8000 kcal/week was observed, especially in children <1 yr of age. We did not find a correlation between energy balance and respiratory quotient (RQ) in our study.

CONCLUSIONS

We detected a high incidence of overfeeding in a subgroup of critically ill children using targeted indirect calorimetry The predominance of hypometabolism, failure of physicians to correctly predict metabolic state, use of stress factors, and inaccuracy of standard equations all contributed to overfeeding in this cohort. Critically ill children, especially those with a longer stay in the PICU, are at a risk of unintended overfeeding with cumulative energy excess.

Effect of laparoscopy and laparotomy on energy and protein metabolism in children: a randomized controlled trial

OBJECTIVE

To compare the effects of surgery on energy and protein metabolism in children randomized to undergo laparoscopic and open surgery.

STUDY DESIGN

We randomized 41 patients to open or laparoscopic Nissen fundoplication. Anesthesia and postoperative management were standardized. We recorded core temperature, respiratory gas exchange preoperatively, intraoperatively, and 4 and 24 hours postoperatively and calculated resting energy expenditure (REE). Protein breakdown was measured by using stable isotopic leucine infusion preoperatively and 4 hours postoperatively.

RESULTS

Intraoperative core temperature and oxygen consumption increased in the laparoscopic group compared with the open group. REE decreased in the early postoperative period in the open group, but did not decrease after laparoscopy. REE at 4 hours was higher after laparoscopy. Protein breakdown also decreased in the early postoperative period; the pattern of change between open and laparoscopic groups was of borderline significance.

CONCLUSIONS

Laparoscopy in children may alter the changes in energy metabolism observed after open surgery. These differences may be partially caused by alterations in intraoperative thermoregulation and protein breakdown during laparoscopy in children.

Metabolism and nutrition in the surgical neonate

Considerable improvements have been achieved in pediatric surgery during the last two decades: the mortality rate of neonates undergoing major operations has declined to less than 10%, and the morbidity of major operations has become negligible. This considerable improvement can be partly ascribed to a better understanding of the physiological changes that occur after an operation and to more appropriate management and nutrition of the critically ill and "stressed" neonates and children. The metabolic response to an operation is different in neonates from adults: there is a small increase in oxygen consumption and resting energy expenditure immediately after surgery with return to normal by 12-24 hours. The increase in resting energy expenditure is significantly greater in infants having a major operation than in those having a minor procedure. The limited increase in energy expenditure may be due to diversion of energy from growth to tissue repair. During parenteral nutrition, it is not advisable to administer more than 18 g/kg/day of carbohydrate because this intake will be associated with lipogenesis, increased CO(2) production, and increased free radical-mediated lipid peroxide formation. Glutamine intake is potentially beneficial during total parenteral nutrition, although a large, randomized, controlled trial in surgical neonates requiring parenteral nutrition is needed to provide evidence for its benefit.

[Evaluation of energy expenditure in children. Physiological and clinical implications and measurement methods]

The present article reviews the importance of the study of energy metabolism and its methods of assessment in children. Classically, energy requirements have been assessed by predictive equations based on anthropometric data. However, there are several physiologic and pathogenic states that may cause discrepancies between estimated and real values and consequently direct measurements of energy expenditure should be used. The gold standard to assess total energy expenditure during prolonged periods is the doubly labeled water method, which is mainly used for research studies. The best approach for resting energy expenditure determination in the clinical setting is indirect calorimetry. However, this method does not provide data on energy consumption under free-living conditions and its use in some critical care patients is restricted by technical limitations. Several other approaches to assess activity have been developed, based on heart rate, body temperature measurements, motion sensors and combined methods.

Total sulfur amino acid requirement and metabolism in parenterally fed postsurgical human neonates

BACKGROUND

Except for tyrosine, the amino acid requirements of human neonates receiving parenteral nutrition (PN) have not been experimentally derived.

OBJECTIVES

The objectives were to determine the total sulfur amino acid (TSAA) requirement (methionine in the absence of cysteine) of postsurgical, PN-fed human neonates by using the indicator amino acid oxidation (IAAO) technique with L-[1-(13)C]phenylalanine as the indicator.

DESIGN

Fifteen postsurgical neonates were randomly assigned to receive 1 of 18 methionine intakes ranging from 10 to 120 mg x kg(-1) x d(-1), delivered in a customized, cysteine-free amino acid solution. Breath and urine samples were collected for the measurement of (13)CO(2) and amino acid enrichment. Blood samples were collected at baseline and after the test methionine infusion for the measurement of plasma methionine, homocysteine, cystathionine, and cysteine concentrations.

RESULTS

Breakpoint analysis determined the mean TSAA requirements to be 47.4 (95% CI: 38.7, 56.1) and 49.0 (95% CI: 39.9, 58.0) mg x kg(-1) x d(-1) with the use of oxidation and F(13)CO(2), respectively.

CONCLUSIONS

This is the first study to report the TSAA requirement of postsurgical, PN-fed human neonates. The estimated methionine requirement expressed as a proportion of the methionine content of current commercial pediatric PN solutions was 90% (range: 48-90%) of that found in the lowest methionine-containing PN solution.

Impaired energy metabolism during neonatal sepsis: the effects of glutamine

Neonatal sepsis is an important cause of morbidity and mortality as a result of multiple organ system failure, particularly in neonates requiring total parenteral nutrition. Suitable therapies and support are needed both to prevent sepsis and to prevent multiple organ failure. After bacterial infection, pro-inflammatory cytokines trigger the antimicrobial activity of macrophages and neutrophils, resulting in production of reactive species such as H2O2, NO, superoxide and peroxynitrite. However, excess production can lead to host tissue damage. Incubation of either hepatocytes or heart mitochondria from neonatal rats with these reactive species, or with cytokines, leads to impairment of mitochondrial oxidative function, and in an animal model of neonatal sepsis similar results to thein vitrofindings have been demonstrated. Recentin vivostudies, using indirect calorimetry of suckling rat pups, show that during endotoxaemia there is a profound hypometabolism, associated with hypothermia. Having determined that cellular oxidative function may be impaired during sepsis, it is of great importance to try to identify therapeutic measures. Much interest has been shown in glutamine, which may become essential during sepsis. It has been shown that hepatic glutamine is rapidly depleted during endotoxaemia. When hepatocytes from endotoxaemic rats were incubated with glutamine, there was a restoration of mitochondrial structure and metabolism.In vivo, intraperitoneal injection of glutamine into endotoxic suckling rats partially reversed hypometabolism, markedly reduced the incidence of hypothermia and improved clinical status. These results suggest that glutamine has a beneficial effect during sepsis in neonates.

Energy requirements

The determination of the appropriate energy and nutritional requirements of a newborn infant requires a clear goal of the energy and other compounds to be administered, valid methods to measure energy balance and body composition, and knowledge of the neonatal metabolic capacities. Providing an appropriate amount of energy to newborn infants remains a challenge considering the great number of newborn infants who suffer in-hospital growth retardation. The energy requirements of a newborn infant are influenced by several factors - basal metabolism, growth, energy expenditure, and energy losses - which change continuously during development. Calculating the energy requirements of preterm infants is subject to error if general recommendations are applied without recognition of the large variation in factors that influence, for example, energy expenditure. Therefore, energy recommendations should be individualized and preferably based on measurements of energy expenditure. In particular, extremely low birth-weight and very low birth-weight infants are prone to develop negative energy and nutrient balances, due to low energy intake, low energy reserves and high energy demands. Early energy accretion is not only essential for growth but also influences neurodevelopmental outcome and physical health in the long term, thereby underlining the importance of adequate neonatal nutrition.

Effect of infection on energy requirements of infants and children

This is a brief review of the effects of infection and other forms of stress on the energy needs of infants and young children. The results of studies estimating energy expenditure in infants and young children during illness and convalescence were evaluated. Expectations that energy expenditure is influenced by the severity of illness, nutritional status, the nature of the illness, the presence and intensity of ‘catch-up growth,’ and the stage of convalescence are generally supported by the literature. The qualitative or quantitative nature of responses, however, are not uniform for diverse illnesses in children in diverse planes of nutritional adequacy.

Energy expenditure and balance following pediatric intensive care unit admission: a longitudinal study of critically ill children

OBJECTIVE

Longitudinal comparison of prescribed energy, actually administered energy, and energy expenditure (EE) predicted by Schofield's equations to actual EE, as determined by daily indirect calorimetry measurements in critically ill children during the first 7 days following admission.

DESIGN

Observational study.

SETTING

Pediatric intensive care unit, high and medium care wards, in a university hospital.

PATIENTS

Forty-six mechanically ventilated and spontaneously breathing infants and children (0-18 yrs) who were admitted with sepsis or following major abdominal or thoracic surgery or trauma.

INTERVENTIONS

Daily indirect calorimetry measurements and assessment of energy balance.

MEASUREMENTS AND MAIN RESULTS

Energy balance studies were performed for a total of 298 admission days in 13 sepsis, 27 surgery, and 6 trauma patients. Indirect calorimetry measurements were performed on 89% of the days. Mean measured EE was 44.6 +/- 15 kcal/kg.d and equaled predicted EE (44.2 +/- 12 kcal/kg.d; p = .56). Measured EE did not change over time, neither overall nor in diagnostic subgroups. Overall, median (range) administered energy was 31.1 (0-119) kcal/kg.d, which was significantly lower than measured EE (p < .001) and predicted EE (p < .001). Patients were underfed on 60% of days and overfed on 28% of days. Administered energy rose significantly in the course of admission, independently of diagnostic category, and did not differ from prescribed energy (p = .42). Energy intake was significantly higher in sepsis patients than in surgery and trauma patients during the whole course of the study (p < .01). The cumulative energy balance was positive only in sepsis patients. The administration of parenteral feeding was the single significant factor determining energy intake in mixed-effect modeling.

CONCLUSIONS

Measured EE was stable and not significantly different from predicted values over the course of hospitalization. Underfeeding was frequently present and mainly due to prescription and administration of energy amounts inferior to measured EE values in enterally fed patients.

Laparoscopic surgery in children is associated with an intraoperative hypermetabolic response

BACKGROUND

Laparoscopic surgery is thought to be associated with a reduced metabolic response compared to open surgery. Oxygen consumption (VO2) and energy metabolism during laparoscopic surgery have not been characterized in children.

METHODS

We measured respiratory gas exchange intraoperatively in children undergoing 19 open and 20 laparoscopic procedures. Premature infants and patients with metabolic, renal, and cardiac abnormalities were excluded. Anesthesia was standardized. Unheated carbon dioxide was used for insufflation. VO2 was measured by indirect calorimetry. Core temperature was measured using an esophageal temperature probe.

RESULTS

We found a steady increase in VO2 during laparoscopy. The increase in VO2 was more marked in younger children and was associated with a significant rise in core temperature. Open surgery was not associated with significant changes in core temperature or VO2.

CONCLUSIONS

Laparoscopy in children is associated with an intraoperative hypermetabolic response characterized by increased oxygen consumption and core temperature. These changes are more marked in younger children.

Intercellular adhesion molecule (ICAM-1) response after major neonatal surgery

Surgical stress induces systemic endocrine-metabolic responses that influence the function of endothelial cells (EC) to cause various systemic reactions. Intercellular adhesion molecule (ICAM)-1 is an adhesion molecule that plays an important role in inflammation, and increased expression of ICAM-1 on EC is a reflection of EC activation. In this study, we investigated the ICAM-1 response to surgical stress in neonates undergoing major surgery. Fifteen neonates (mean age at surgery: 3.5 +/- 1.2 days) were divided into two groups according to indications for surgery: Group I: Congenital diaphragmatic hernia without persistent pulmonary hypertension (n = 5); Group II: Gastrointestinal surgery [n = 10: duodenal atresia (n = 3), intestinal atresia (n = 6), and esophageal atresia (n = 1)]. Serum samples were obtained preoperatively, immediately after completion of surgery (time zero), and 24, 48, 72, 96, and 120 h after surgery to measure ICAM-1 levels using an enzyme-linked immunosorbent assay, C-reactive protein (CRP), and white blood cell count (WBC). Postoperative recovery was uneventful in all cases. ICAM-1 levels in both groups increased significantly within 24 h of surgery (Group I: P = 0.0038, Group II: P = 0.0320). In Group I, ICAM-1 peaked 72 h postoperatively while in Group II it continued to rise until 96 h postoperatively. The difference between peak levels reached was not significant. CRP was first detected 24 h postoperatively in both groups and continued to increase until 48 h postoperatively. Again, the difference between peak levels reached was not significant. No significant changes in WBC were observed in either group. We found that ICAM-1 increases in response to surgical stress in neonates, although there was no significant difference in levels. However, surgical stress as represented by serum ICAM-1 would appear to last longer with intestinal surgery than with non-intestinal surgery. Further research is required to establish the usefulness of ICAM-1 as an easily detectable substance associated with endothelial damage that reflects the host's response to major surgical stress.

Different Proinflammatory Cytokine Serum Pattern in Neonate Patients Undergoing Open Heart Surgery. Relevance of IL-8

The purpose of this work was to investigate the clinical significance of serum levels of proinflammatory cytokines in pediatric patients undergoing cardiopulmonary bypass. We divided the patients in two groups: 8 neonates, and 19 non-newborn children. IL-1beta, IL-6, IL-8, and TNF serum levels were quantified before sternotomy, at admission to the PICU (30 min postoperatively), 24 h after the onset of surgery and 3 days after the operation. Surgical cardiac stress elicits significant increments of IL-6, IL-8 and TNF serum concentrations in both neonates and non-neonates, regardless of their preoperative clinical condition. However, in newborns the magnitude of the proinflammatory cytokine increments was, in particular with IL-8, remarkably greater than in older children. Moreover, neonate and non-neonate patients showed clearly disparate patterns of serum concentrations over time of both IL-8 and TNF. There was a marked relationship between IL-8 levels and postoperative morbidity, evaluated by pulmonary dysfunction, days on inotropic support and days of PICU stay in both neonates and non-neonates patients. In contrast, we found no relationship between serum levels of IL-6 and TNF and postoperative clinical data. Newborn and non-newborn patients undergoing cardiopulmonary bypass exhibit dissimilar patterns of proinflammatory cytokines. IL-8 might be implicated in the multiorganic dysfunction related to cardiopulmonary bypass in pediatric patients.

Does neonatal surgery lead to increased pain sensitivity in later childhood?

Does pain or tissue damage in early life lead to hyperalgesia persisting into childhood? We performed a cross-sectional study in 164 infants to investigate whether major surgery within the first 3 months of life increases pain sensitivity to subsequent surgery and to elucidate whether subsequent surgery in the same dermatome or in a different dermatome leads to differences in pain sensitivity. All infants received standard intraoperative and postoperative pain management, with rescue analgesia guided by a treatment algorithm. Differences in pain sensitivity during surgery were assessed by the intraoperative fentanyl intake and by (nor)epinephrine plasma concentrations. Differences in postoperative pain sensitivity were assessed by the observational pain measures COMFORT and VAS, and by morphine intake and (nor)epinephrine plasma concentrations. Infants previously operated upon in the same dermatome needed more intraoperative fentanyl, had higher COMFORT and VAS scores, had greater (nor)epinephrine plasma concentrations, and needed also more morphine than did infants with no prior surgery. In contrast, infants who previously underwent surgery in another dermatome had only significant higher postoperative analgesic requirements and norepinephrine plasma concentrations in comparison with infants with no prior surgery. These preliminary differences may indicate the occurrence of spinal and supraspinal changes following neonatal surgery. We conclude that the long-term consequences of surgery in early infancy are greater in areas of prior tissue damage and that these effects may portend limited clinical but important neurobiological differences.

Glutamine supplementation of parenteral nutrition does not improve intestinal permeability, nitrogen balance, or outcome in newborns and infants undergoing digestive-tract surgery: results from a double-blind, randomized, controlled trial

OBJECTIVE

To assess the effect of isocaloric isonitrogenous parenteral glutamine supplementation on intestinal permeability and nitrogen loss in newborns and infants after major digestive-tract surgery.

SUMMARY BACKGROUND DATA

Glutamine supplementation in critically ill and surgical adults may normalize intestinal permeability, attenuate nitrogen loss, improve survival, and lower the incidence of nosocomial infections. Previous studies in critically ill children were limited to very-low-birthweight infants and had equivocal results.

METHODS

Eighty newborns and infants were included in a double-blind, randomized trial comparing standard parenteral nutrition (sPN; n = 39) to glutamine-supplemented parenteral nutrition (GlnPN; glutamine target intake, 0.4 g kg day; n = 41), starting on day 2 after major digestive-tract surgery. Primary endpoints were intestinal permeability, as assessed by the urinary excretion ratio of lactulose and rhamnose (weeks 1 through 4); nitrogen balance (days 4 through 6), and urinary 3-methylhistidine excretion (day 5). Secondary endpoints were mortality, length of stay in the ICU and the hospital, number of septic episodes, and usage of antibiotics and ICU resources.

RESULTS

Glutamine intake plateaued at 90% of the target on day 4. No differences were found between patients assigned sPN and patients assigned GlnPN regarding any of the endpoints. Glutamine supplementation was not associated with adverse effects.

CONCLUSIONS

In newborns and infants after major digestive-tract surgery, we did not identify beneficial effects of isonitrogenous, isocaloric glutamine supplementation of parenteral nutrition. Glutamine supplementation in these patients therefore is not warranted until further research proves otherwise.

Can energy expenditure be predicted in critically ill children?

OBJECTIVE

To determine whether critically ill children are hypermetabolic and to calculate whether predictive equations are appropriate for critically ill children.

DESIGN

Prospective, clinical study.

SETTING

Pediatric intensive care unit.

PATIENTS

A total of 57 children (39 boys) aged 9 months to 15.8 yrs.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

The median resting energy expenditure measurement measured by indirect calorimetry was 37.2 (range, 11.9-66.6) kcal x kg(-1) x day(-1). This was significantly lower than would be predicted using either the Schofield (42.7 [26.9-65.4] kcal x kg(-1) x day(-1)) or Fleisch equations (42.8 [20.9-66.2] kcalx kg(-1)-1 x day(-1), p < .001) but significantly higher than the White equation developed specifically for pediatric intensive care units (26.2 [8.5-70.1] kcal x kg(-1),day(-1), p < .0001). Methods comparison analysis showed the limits of agreement were -484 to 300, -461 to 319, and -3.2 to 854 kcal/day, respectively. Multivariate analysis indicated the following factors contribute to hypometabolism and hypermetabolism: age (p = .006), sex (p = .034), time spent in the pediatric intensive care unit (p = .001), diagnosis (p = .015), weight (p = .009), temperature (p = .04), continuous infusion for sedation (p = .04), and neuromuscular blockade (p = .03).

CONCLUSION

Children do not become hypermetabolic during critical illness. These data suggest that agreement between resting energy expenditure and the predictive equations are so broad that they are inappropriate for use in critically ill children.

Carbon dioxide elimination during laparoscopy in children is age dependent

The absorption of carbon dioxide (CO2) used for positive pressure pneumoperitoneum may lead to an increased CO2 load. CO2 elimination during laparoscopy has not been investigated previously in paediatrics. The aim of this study was to characterise the pattern of CO2 elimination during laparoscopic surgery in infants and children.

METHODS

Twenty children undergoing laparoscopy and 19 children undergoing laparotomy for elective abdominal operations were studied. Pneumoperitoneum was achieved using insufflation of unheated CO2. CO2 elimination (metabolically produced + absorbed; milliliters per kilogram per minute) was measured minute by minute during the operation by indirect calorimetry. End-tidal CO2 (kPa) was recorded every 10 minutes. The above variables were assessed before CO2 insufflation, during pneumoperitoneum, and after desufflation.

RESULTS

Before insufflation, CO2 elimination was 4.6 +/- 0.3 ml/kg/min and increased after 15 minutes of pneumoperitoneum to 5.2 +/- 0.3 (P <.001). Post desufflation, CO2 elimination decreased toward preinsufflation values, but did not return to baseline by the end of operation (5.8 +/- 0.3; P <.001). End-tidal CO2 was 4.7 +/- 0.2 preinsufflation, peaked at 1 hour (5.3 +/- 0.2; P <.001) and subsequently decreased in response to ventilatory adjustments. The total amount of CO2 insufflated was positively correlated with patient age (r2 = 0.27; P <.01). CO2 elimination was age related, as indicated by multilevel model analysis and by negative correlations between maximum increase in CO2 elimination and both age (r2 = 0.27; P <.01) and weight (r2 = 0.29; P <.01). These data suggest that the younger or smaller the child, the larger the increase in CO2 elimination. Seven patients (35%) responded to desufflation with a sharp transient increase in CO2 elimination, which did not appear to be related to patient age, length of pneumoperitoneum, abdominal pressure, or type of operation.

CONCLUSIONS

During pneumoperitoneum, younger children absorb proportionately more CO2 than older individuals. The short-lived increase in CO2 elimination postdesufflation may be related to an increase in venous return from the lower limbs after release of the abdominal pressure. These findings suggest that small children warrant close monitoring during laparoscopy and during the immediate postoperative period.

Nutrition for the pediatric surgical patient: approach in the peri-operative period

Nutrition is essential for maintenance of physiologic homeostasis and growth. Hypermetabolic states lead to a depletion of body stores, with decreased immunocompetence and increased morbidity and mortality. The purpose of this paper is to provide an update regarding the provision of appropriate nutrition for the pediatric surgical patient, emphasizing the preoperative and postoperative periods. Modern nutritional support for the surgical patient comprises numerous stages, including assessment of nutritional status, nutritional requirements, and nutritional therapy. Nutritional assessment is performed utilizing the clinical history, clinical examination, anthropometry, and biochemical evaluation. Anthropometric parameters include body weight, height, arm and head circumference, and skinfold thickness measurements. The biochemical evaluation is conducted using determinations of plasma levels of proteins, including album, pre-albumin, transferrin, and retinol-binding protein. These parameters are subject to error and are influenced by the rapid changes in body composition in the peri-operative period. Nutritional therapy includes enteral and/or parenteral nutrition. Enteral feeding is the first choice for nutritional therapy. If enteral feeding is not indicated, parenteral nutrition must be utilized. In all cases, an individualized, adequate diet (enteral formula or parenteral solution) is obligatory to decrease the occurrence of overfeeding and its undesirable consequences.

Nutritional support of the critically ill child

The pediatric metabolic response to injury and operation is proportional to the degree of stress and causes an increase in the turnover of proteins, fats, and carbohydrates. Thereby, substrates are made readily available for the immune response and wound healing. Because this process requires energy, the resting energy expenditure of ill patients increases. Whole-body protein degradation rates are elevated out of proportion to synthetic rates, and negative protein balance also ensues. Neonates and children are particularly susceptible to the loss of lean body mass and its attendant increased morbidity and mortality caused by an intrinsic lack of endogenous stores and greater baseline requirements. An appropriately designed mixed fuel system of nutritional support replete in protein does not quell this metabolic response but can result in anabolism and continued growth in ill children. In addition, the use of adequate analgesia and anesthesia is a readily available and proven means of reducing the magnitude of the catabolism associated with operation and injury. Finally, as hormonal- and cytokine-mediated metabolic alterations are better understood, therapeutic interventions may become available to directly modulate the metabolic response to illness, thus potentially further improving clinical outcome in pediatric surgical patients.

Metabolism and nutritional support in the surgical neonate

Various factors can influence the metabolism of surgical neonates. These include prematurity, operative stress, critical illness, and sepsis. The nutritional management of surgical infants with congenital or acquired intestinal abnormalities has improved after the introduction of parenteral nutrition. This article is focused on the energy and protein metabolism of surgical neonates with particular reference to the metabolic response to operative trauma and sepsis. The metabolic utilization of intravenous nutrients also is discussed. The metabolic response to operative trauma is different between neonates and adults. Infants have high rates of protein turnover and are avid retainers of nitrogen. Energy expenditure increases only transiently (4 to 6 hours) after major surgery in neonates. Protein turnover and catabolism seems not to be affected by major operative procedures in neonates. In neonates on parenteral nutrition, carbohydrate and fat have an equivalent effect on protein metabolism. The main determinants of fat utilization are carbohydrate intake and resting energy expenditure. Parenteral nutrition in surgical neonates is associated with increased production of oxygen-free radicals. This seems to be related to intravenous fat administration. Promoting fat utilization by reducing the carbohydrate to fat ratio in the intravenous diet reduces free radical activity to a similar extent as fat exclusion. Glutamine appears to be safe for use in neonates and infants and is "conditionally essential" in very-low birth weight infants and in septic neonates. Enteral glutamine supplementation in very-low birth weight infants reduces the risk of sepsis. The metabolism of surgical neonates is affected by operative trauma, critical illness, and sepsis. Nutritional support in surgical neonates has a profound impact on outcome. Exogenous glutamine can modulate immune, metabolic, and inflammatory responses. Further investigations are needed to clarify the clinical benefit of parenteral or enteral glutamine administration in surgical neonates.

Monocyte and neutrophil activity after minor surgical stress

BACKGROUND/PURPOSE

Surgical stress produces changes in the immune status of patients. In adults, major surgery causes immunosuppression, whereas minor operations stimulate immune responses. In children, the immunologic response to surgery has not been elucidated completely. The authors investigated the effects of minor surgery on immune response by analyzing neutrophil and monocyte phagocytosis and oxidative burst activity.

METHODS

Sixteen children undergoing elective minor surgery were enrolled. Blood samples were collected before the operation (at time of induction of anesthesia), at the end of operation, and 72 hours after surgery. Neutrophil and monocyte phagocytosis and oxidative burst activity were studied using a flow cytometric method.

RESULTS

Phagocytosis and oxidative burst increased significantly at the end of the operation, both in neutrophils (7.4% and 14.3%, respectively) and monocytes (11.6% and 27%, respectively). The increase was only significant for monocytes (17.5%) 72 hours after surgery. White cell count did not show any significant changes. There was no significant correlation between phagocytosis, oxidative burst activity, and white cell count or neutrophil and monocyte count.

CONCLUSIONS

This study shows that minor surgery in children induces immune activation by increasing neutrophil and monocyte phagocytosis and oxidative burst activity. Further studies are required to understand the molecular basis of these findings.

Effective and efficient nutritional support for the injured child

This article discusses the critical points in nutritional support of the injured child. Each applies currently understood basic science information to practical bedside care.

Newborn patients exhibit an unusual pattern of interleukin 10 and interferon gamma serum levels in response to cardiac surgery

OBJECTIVE

The aim of this study was to determine the clinical significance of serum levels of interleukin 10 and interferon gamma in pediatric patients undergoing cardiopulmonary bypass.

METHODS

We divided the patients into 2 groups: 8 neonates and 19 non-newborn children. Interleukin 10 and interferon gamma serum levels were quantified before sternotomy, at admission to the pediatric intensive care unit (30 minutes postoperatively), 24 hours after the onset of the operation, and 3 days after the operation.

RESULTS

Newborn patients displayed significantly greater amounts of serum interleukin 10 than older children, not only in regard to the peak level achieved but also at every postoperative time point analyzed. In contrast, no significant changes in interferon gamma serum levels were observed in neonates at any time point, whereas non-newborn pediatric patients showed a significant increase in interferon gamma serum concentrations immediately after the operation. This unusual pattern of cytokine response in newborn patients was not associated with modifications in cortisol serum levels. Furthermore, although neonates had significantly different surgical and clinical variables than did the non-newborn pediatric patients, the variation in interleukin 10 production in neonates could not be accounted for by differences in the magnitude of surgical injury. In the group of neonates, there were significant positive correlations between peak interleukin 10 serum levels and both partial pressure of arterial oxygen/fraction of inspired oxygen ratio and postoperative body weight gain.

CONCLUSIONS

Newborn patients undergoing cardiopulmonary bypass exhibit a distinctive biologic response pattern characterized by high levels of serum interleukin 10 without changes in serum interferon gamma. This cytokine imbalance could have potential clinical implications.

Energy expenditure and intake in children with sickle cell disease during acute illness

BACKGROUND

Children with sickle cell disease have frequent bouts of pain and infection which may increase energy expenditure, decrease energy intake and lead to a subsequent energy deficit.

METHODS

Two groups of African-American children with sickle cell disease-SS genotype were enrolled in this study upon hospital admission for a sickle cell disease related illness: a younger (<6 years, n=14, 7 M) and older group (> or =6 years, n=17, 8 M). Body composition and dietary intake were assessed, and sleeping (younger) or resting energy expenditure (older) were measured by indirect calorimetry at admission and one month later at steady state.

RESULTS

Energy expenditure was not different between the two timepoints for younger children, but was slightly elevated at steady state (+50 kcal/d, P=0.049) in the older group. After controlling for gender, changes in fat-free mass and dietary intake, the significance disappeared. Energy intake in both groups was significantly depressed at admission compared to follow-up (P<0.01).

CONCLUSIONS

These children and adolescents did not expend excess energy during their acute illness, however, an energy deficit was observed secondary to poor energy intake. Since 20% of patients with sickle cell disease have multiple hospitalizations per year, these results provide justification for the development and evaluation of nutrition care protocols to maintain adequate caloric intake during hospitalization and recovery.

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.

Estimating energy expenditure in critically ill adults and children

Designing effective nutrition support regimens for critically ill patients requires an understanding of the energy needs of each patient. Many disease processes result in elevated caloric requirements, whereas some clinical procedures and medications may diminish the metabolic response. Experienced clinicians are unable to predict the extent to which trauma or injury will affect energy requirements for an individual. Both under- and overfeeding a critically ill patient may prolong hospitalization and increase morbidity and mortality. Applying equations that were originally developed for healthy nonhospitalized individuals to predict the energy requirements of critically ill patients will often result in significant errors and may lead to provision of inappropriate nutritional support. The measurement of resting energy expenditure by indirect calorimetry is a valuable tool and can be used to predict energy requirements for most spontaneously breathing critically ill patients, but may lead to spurious results in mechanically ventilated pediatric patients. In the complex and rapidly changing context of critical illness, individualized assessment of energy requirements is crucial. Whichever technique is used initially to assess energy requirements, sequential monitoring and constant reassessment of each patient is essential to provide the appropriate nutritional care regimen. The purpose of this article is to review the equations for estimating and the techniques, practical aspects, and interpretation of measuring energy expenditure in critically ill patients.

Growth, nutrition and energy expenditure in pediatric heart failure

Disturbances in growth are often a consequence of congenital heart disease during infancy and childhood. The magnitude of the growth disturbance is generally related to the anatomical lesion and is most severe in infants and children with congestive heart failure. Presently, surgical repair in this population is often delayed in order to permit increased weight gain. Surgery is preformed when a patient reaches an ideal weight and age, or failure to thrive precludes further waiting. The available data indicate that caloric intake in these infants and children may be nearly adequate for age, but is inadequate to permit normal growth rates. Energy expenditure appears to be significantly elevated in this population relative to that of age-matched infants and children. Therefore, while caloric intake may be appropriate for age, increased energy expenditure leaves the infant or child with congenital heart disease with little energy available for growth. More information is needed on energy intakes and expenditures of specific patient populations, and especially of patients with congestive heart failure, before accurate predictions of their metabolic needs are possible. This knowledge may allow us to better meet the nutritional needs of these populations and decrease the risk of malnutrition and failure to thrive, in turn decreasing surgical risk for these patients.

The metabolic needs of critically ill children and neonates

The pediatric metabolic response to injury and operation is proportional to the degree of stress and causes an increase in the turnover of proteins, fats, and carbohydrates. Thereby, substrates are made readily available for the immune response and wound healing. Because this process requires energy, the resting energy expenditure of ill patients increases. Whole-body protein degradation rates are elevated out of proportion to synthetic rates, and negative protein balance also ensues. Neonates and children are particularly susceptible to the loss of lean body mass and its attendant increased morbidity and mortality caused by an intrinsic lack of endogenous stores and greater baseline requirements. An appropriately designed mixed fuel system of nutritional support replete in protein does not quell this metabolic response but can result in anabolism and continued growth in ill children. In addition, the use of adequate analgesia and anesthesia is a readily available and proven means of reducing the magnitude of the catabolism associated with operation and injury. Finally, as hormonal- and cytokine-mediated metabolic alterations are better understood, therapeutic interventions may become available to directly modulate the metabolic response to illness, thus potentially further improving clinical outcome in pediatric surgical patients.

Prediction of hyperglycemia in preterm newborn infants

Many conditions are associated with hyperglycemia in preterm neonates because they are very susceptible to changes in carbohydrate homeostasis. The purpose of this study was to evaluate the occurrence of hyperglycemia in preterm infants undergoing glucose infusion during the first week of life, and to enumerate the main variables predictive of hyperglycemia. This prospective study (during 1994) included 40 preterm neonates (gestational age < 37 weeks); 511 determinations of glycemic status were made in these infants (average 12.8/infant), classified by gestational age, birth weight, glucose infusion rate and clinical status at the time of determination (based on clinical and laboratory parameters). The clinical status was classified as stable or unstable, as an indication of the stability or instability of the mechanisms governing glucose homeostasis at the time of determination of blood glucose; 59 episodes of hyperglycemia (11.5%) were identified. A case-control study was used (case = hyperglycemia; control = normoglycemia) to derive a model for predicting glycemia. The risk factors considered were gestational age (< or = 31 vs. > 31 weeks), birth weight (< or = 1500 vs. > 1500 g), glucose infusion rate (< or = 6 vs. > 6 mg/kg/min) and clinical status (stable vs. unstable). Multivariate analysis by logistic regression gave the following mathematical model for predicting the probability of hyperglycemia: 1/exp{-3.1437 + 0.5819(GA) + 0.9234(GIR) + 1.0978 (Clinical status)}The main predictive variables in our study, in increasing order of importance, were gestational age, glucose infusion rate and, the clinical status (stable or unstable) of the preterm newborn infant. The probability of hyperglycemia ranged from 4.1% to 36.9%.

Characteristics of protein and energy metabolism in neonates with necrotizing enterocolitis--a pilot study

BACKGROUND/PURPOSE

It is assumed that neonates with necrotizing enterocolitis (NEC) are hypermetabolic. However, the dynamics of protein and energy metabolism in neonates with NEC have not been characterized. The purpose of this study was to test the hypothesis that protein turnover and energy expenditure are increased during the acute stage of NEC and later return to normal values.

METHODS

A pilot study was performed on six neonates with proven NEC (Bell's stage II or III). Patients were studied in two phases: (1) in the acute stage of their disease and (2) when their clinical condition had stabilized. Whole-body protein turnover was calculated using an intravenous infusion of [1-13C] leucine and by measuring the isotopic enrichment of plasma [13C]alpha-ketoisocaproic acid and 13CO2. Respiratory gas exchange was measured simultaneously by computerized indirect calorimetry.

RESULTS

Median gestational age was 36 weeks (range, 28 to 40) with a median postnatal age of 21 days (range, 6 to 47). All patients recovered from the acute episode, although three patients died after recovering from the acute disease from other conditions. The patients studied showed marked variability in protein metabolism kinetics. However, there was no difference in whole-body protein flux between the acute phase (7.6 g/kg/d; range, 5.6 to 18.2) and the recovery phase (7.0 g/kg/d; range, 6.9 to 12.2; P = .89). Furthermore, there was no difference in any of the component parts of wholebody protein turnover. Resting energy expenditure did not change between the acute phase (42.8 kcal/kg/d; range, 34.4 to 52.5) and the recovery phase (51.0 kcal/kg/d; range, 34.9 to 55.3; P = .18).

CONCLUSIONS

This pilot study shows that the rates of protein and energy metabolism in neonates with NEC are comparable with reported values in stable neonates. There was no difference in protein or energy dynamics between study phases. The authors speculate that neonates with NEC may divert the products of protein synthesis from growth to tissue repair.

Protein and energy requirements in healthy and ill paediatric patients

A reappraisal of available data, together with new studies, suggests that normal infants' energy and protein requirements might be substantially lower than previously estimated. For example, the safe level of protein intake would amount to only 10 g per day during the first 2 years of life and to about 12 g per day during the third. This has direct consequences for the management of malnourished children, particularly for defining an optimal protein:energy ratio. A reduced food intake has long been accepted as the main cause of malnutrition. However, evidence has accumulated suggesting that metabolic dysregulation may also play a part. This is particularly true for proteins. Net protein deposition in the growing child results from protein synthesis rates being higher than protein breakdown. However, this setting can be disrupted by a significant increase in protein breakdown in response to cytokines. This mechanism, which is found in acute as well as in chronic inflammatory processes, may lead to severe protein malnutrition and is not always amenable to nutritional support.

Immune response: effects of operative stress in a pediatric model

PURPOSE

The purpose of this study is to delineate the effect of different operative procedures on the cell-mediated immune response in a pediatric animal model using the delayed type hypersensitivity (DTH) skin test.

METHODS

Sprague Dawley rats (1 week old) were sensitized against keyhole limpet hemocyanin (KLH). Animals were challenged 2 weeks later by an intradermal injection of KLH (0.3 mg) in sterile saline. Rats with positive DTH skin reactions at 24 and 48 hours after challenge (baseline) were divided randomly into five groups (n = 10 each): group I, unmanipulated control; group II, anesthesia; group III, anesthesia and midline extraperitoneal incision; Group IV, anesthesia and laparoscopy (pneumoperitoneum with carbon dioxide); Group V, anesthesia and midline laparotomy. Before each procedure (day 0) and on postoperative days 3 and 6, animals were again challenged intradermally with KLH (0.3 mg). DTH skin reaction was evaluated 24 and 48 hours later.

RESULTS

A statistically significant difference (P < .05) in DTH skin reaction at 24 and 48 hours was observed between postoperative days 1 to 5 in the extraperitoneal and laparotomy groups with respect to baseline and the control group. Statistically significant differences were found in postoperative days 1, 4, and 5 between laparoscopy and laparotomy. The laparoscopy group showed a statistically significant decrease in DTH skin induration on postoperative day 2 when compared with the control group. At postoperative day 7 and 8 there was no statistical difference in DTH skin response comparing baseline values or between groups.

CONCLUSIONS

These results suggest that in a pediatric animal model, abdominal surgical procedures accompanied by extensive tissue dissection produce a cellular immunosuppression, lasting up to 7 days, which is not observed in less invasive procedures. Observations concerning lesser immunosuppressive effects of laparoscopy when compared with laparotomy in adult models, as previously described by our laboratory, were also found in this pediatric model.

Effect of major abdominal operations on energy and protein metabolism in infants and children

PURPOSE

The authors attempted to test the hypothesis that infants and children increase whole-body protein flux and energy metabolism during the early postoperative period.

METHODS

Ten infants and children (age range, 2 days to 3 years; weight range, 1.5 to 14.2 kg) who had undergone a major operation were studied. Anaesthesia was standardised, and operative stress score (OSS) recorded. Patients were studied for 4 hours preoperatively and for the first 6 hours after surgery. Respiratory gas exchange was measured by computerised indirect calorimetry. The components of whole-body protein turnover were estimated by giving an intravenous infusion of [1-13C]leucine, and by measuring the isotopic enrichment of plasma [13C]alpha-ketoisocaproic acid by gas chromatograph mass spectrometry and 13CO2 enrichment by isotope ratio mass spectrometry.

RESULTS

Median duration of the operation was 73.5 minutes (range, 28 to 285 minutes) with a OSS of 8 (range, 7-17). There were no significant differences in oxygen consumption and resting energy expenditure between the two study phases. The respiratory quotient (RQ) fell from a preoperative value of 0.92 (range, 0.81 to 1.08) to 0.89 (range, 0.79 to 0.95) postoperatively (P = .04). The authors found no significant differences in the rates of whole body protein flux, protein synthesis, amino acid oxidation, and protein degradation between the study phases.

CONCLUSIONS

Infants and children do not increase their whole-body protein turnover and metabolic rate after major operations. The observed decrease in RQ reflects mobilisation of endogenous fat. We speculate that the lack of catabolism observed in children is caused by a diversion of protein synthesis from growth to tissue repair.

Energy requirements of surgical newborn infants receiving parenteral nutrition

The energy requirement for mature newborn infants receiving total parenteral nutrition is approximately 100 kcal.kg-1.d-1. There is no necessity to increase the caloric intake after an uncomplicated operation. Energy requirements are affected by the maturity of the infant, the degree of operative stress, opioid medication, and the presence or absence of sepsis. In general, glucose intake should not exceed the resting energy expenditure. Glucose administration exceeding 18 g.kg-1.d-1 is associated with lipogenesis and reduced oxygenation of exogenous lipid. Resting energy expenditure varies widely between infants, and energy intake, based on clinical and biochemical monitoring, should be adjusted for individual patients.

Stratification of injury severity using energy expenditure response in surgical infants

AIM OF STUDY

Injury severity stratification has important clinical outcome significance and can influence nutritional management. Although surgery alone has been shown not to increase measured energy expenditure (MEE) substantially, large increases in MEE can result from severe underlying acute illness, which frequently necessitates surgery (like sepsis or intense inflammation). The authors hypothesized that the magnitude and duration of the MEE response to surgery associated with a severe preoperative acute injury would exceed that of surgery in which no substantial preoperative stress was present, thus representing an index of overall injury severity in surgical infants.

METHODS

MEE (kcal/kg/d) was determined on postoperative days (POD) 2, 5, and 8 in 12 infants (average age, 47 days) after two separate injury insults (at least 8 days apart). In each patient, one operation resulted in a peak serum C-reactive protein (CRP) concentration of less than 6.5 mg/dL (low stress), and the second operation, preoperatively associated with sepsis or a major inflammatory insult, resulted in a peak CRP of more than 6.5 mg/dL (high stress). Data were paired so that each child served as his or her own control. The initial basal protein-calorie delivery was similar in both groups.

MAIN RESULTS

The mean peak CRP values were 14.1 +/- 10.7 mg/dL (high stress) and 4.1 +/- 2.3 mg/dL (low stress) and returned to normal levels earlier (before POD 8) after injury insult in the low-stress group. Analysis of energy expenditure on POD 2 demonstrated significantly elevated mean MEE values in the high-stress group (58.0 +/- 12.2 kcal/kg/d v 39.4 +/- 9.5 kcal/kg/d in the low-stress group; P = .0001). In contrast, analysis of POD 8 energy expenditure showed significantly lower mean MEE values in the high-stress group (50.7 +/- 12.0 kcal/kg/d) v (66.4 +/- 15.1 kcal/kg/d in the low-stress group; P = .0118) group.

CONCLUSION

The early (POD 2) hypermetabolic response to injury as determined by MEE effectively differentiated the two stress groups. This finding suggests that acute underlying illness is an important determinant of postoperative MEE. Furthermore, in the low-stress group, serial CRP levels returned to normal earlier, associated with significantly greater late (POD 8) MEE values. Because MEE is directly proportional to growth rate in healthy infants, and growth is retarded during acute metabolic stress, these findings suggest that increased energy is utilized for growth recovery following the earlier resolution of the acute injury response in the low-stress group. These data indicate that serial postoperative MEE can be used to stratify injury severity and may be an effective parameter to monitor the return of normal growth metabolism in surgical infants.

Hypoalbuminaemia in surgical neonates receiving parenteral nutrition

The aim of this study was to define the prevalence of hypoalbuminaemia (HA), its predisposing factors, and its effect on outcome in infants. Fifty-six consecutive infants receiving parenteral nutrition (PN) for gastrointestinal disease were divided into two groups according to their lowest measured serum albumin level. The reference range (27.9 to 50.9 g/L) for serum albumin was derived from measurements taken in 37 (22 term and 15 preterm) normal enterally fed newborn infants. HA group (serum albumin < 27.9 g/L) included 15 infants (27%); NA group (serum albumin > or = 27.9 g/L) included 41 infants (73%). HA infants received more albumin than NA infants (median 66 versus 14 mL/kg; P = .005). There was no significant difference between HA and NA groups in gestational age, postmenstrual age at time of start of PN, composition of PN, nor mean weight gain. HA was unrelated to biochemical signs of liver dysfunction, C-reactive protein elevation, septicaemic episodes, or time from operation. HA occurred within the first week of starting PN in 10 infants and returned to normal values within 5 days. HA was a recurrent phenomenon in three patients. Mortality was higher in the HA group (33.3%) than in the NA group (4.9%; P = .02) but was apparently causally unrelated to the low serum albumin level. Hypoalbuminaemia is a common finding in neonates on PN despite the administration of exogenous albumin. Monitoring serum albumin levels in surgical infants on PN seems to be of little clinical value.

Protein metabolism kinetics in neonates: effect of intravenous carbohydrate and fat

The aim of this study was to determine the effect of different glucose/fat ratios on protein metabolism kinetics in newborn infants receiving total parenteral nutrition (TPN). Eighteen studies were done on 14 infants receiving TPN (weight 3.15 +/- 0.22 kg [mean +/- SEM]; gestational age 37.8 +/- 0.9 weeks; postnatal age 14.0 +/- 3.7 days). There were two study groups. Group A infants (n = 9) received 10.0 g/kg/d of dextrose and 4.0 g/kg/d of fat; group B infants (n = 9) received 19.0 g/kg/d of dextrose and 0.5 g/kg/d of fat. Caloric intake (86 kcal/kg/d) and amino-acid intake (2.5 g/kg/d) were the same in the two groups. There was no difference between the groups with regard to weight, gestational age, and postnatal age. Intravenous diet was constant during the 3-day study period. Timed urinary nitrogen excretion was determined. On day 3 of the study, each infant received a priming dose of 15 mumol/kg of [13C]leucine followed by a 6-hour infusion at 6 mumol/kg/h. Plasma and breath samples were taken at hourly intervals, and CO2 production was measured by indirect calorimetry. Plateau levels of plasma [13C]-alpha Ketoisocaproic acid (KIC) enrichment and expired 13CO2 enrichment were determined by gas chromatograph mass spectrometry. Protein metabolism kinetics were calculated. Results were: nitrogen balance 0.27 +/- 0.01 g/kg/d, total protein flux 10.38 +/- 0.34 g/kg/d, total protein synthesis 9.64 +/- 0.31 g/kg/d, total protein breakdown 7.86 +/- 0.38 g/kg/d, and total protein oxidation/excretion 0.92 +/- 0.04 g/kg/d.(ABSTRACT TRUNCATED AT 250 WORDS)

Postoperative changes in resting energy expenditure and interleukin 6 level in infants

The relationship was determined between resting energy expenditure (REE) and interleukin (IL)6 level following surgery in infants. Sixteen infants of mean(s.e.m.) weight 3.2(0.2) kg undergoing uncomplicated surgery were studied. The operative stress score was recorded and plasma IL-6 levels were measured before and 4, 8, 12 and 24 h after surgery. Respiratory gas exchange was measured by indirect calorimetry before and at 2, 4, 6, 8, 10, 12, 24 and 48 h. Urinary nitrogen excretion was measured and calculated. IL-6 levels increased significantly after surgery (P = 0.006) and were maximal at 12 h. There was a linear correlation between the increase in IL-6 level and operative severity score (r = 0.61, P = 0.012). REE increased significantly after operation (P < 0.001), peaking at 2-4 h, and returned to baseline levels by 12 h. The changes in REE preceded those in IL-6. IL-6 is a marker of the stress response in infants and may play a role in the subsequent modulation of this response.