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The use of a stable isotope-labeled [13C]bicarbonate infusion to measure energy expenditure is advantageous, as a complete collection of expired air is not required. This technique allows for facile measurements of energy expenditure in intubated neonates. The aim of the present study was to determine the accuracy of energy expenditure estimates in postsurgical neonates by using the [13C]bicarbonate method compared with the current standard, indirect calorimetry. Eight neonates who were receiving total parenteral nutrition [98 +/- 21 (SD) kcal x kg(-1) x d(-1); 3.1 +/- 0.7 (SD) protein g x kg(-1) x d(-1)] were studied on postoperative d 15.5 +/- 11.9. A primed continuous 3-h intravenous infusion of NaH13CO3 and indirect calorimetry were performed simultaneously. Energy expenditure was calculated separately from the Weir equation and from the dilution of 13CO2 in the breath in combination with the individual energy equivalents of CO2 from the diet. The rate of CO2 appearance and energy expenditure calculated from the bicarbonate method (0.725 +/- 0.021 mol x kg(-1) x d(-1); 89.5 +/- 2.5 kcal x kg(-1) x d(-1)) highly correlated (r = 0.94 and 0.98, respectively) with the CO2 excretion and energy expenditure determined by indirect calorimetry (0.489 +/- 0.016 mol x kg(-1) x d(-1); 60.2 +/- 2.0 kcal x kg(-1) x d(-1)) when analyzed nonproportionately to weight. Bland-Altman analysis demonstrated the 95% confidence interval to be +/- 8.2 kcal x kg(-1) x d(-1). Linear regression analysis revealed a highly statistically significant equation relating the two energy expenditures: Indircal (kcal/d) = -9.341 + [0.705 x Bicarb (dcal/d)]; p < 0.001, r2 = 96.4%. We conclude that energy expenditure in neonates can be accurately determined using the [13C]bicarbonate method and a regression equation. Therefore, the bicarbonate method may be useful for determining energy expenditure in neonates not readily accessible to indirect calorimetry, such as those being mechanically ventilated or on extracorporeal life support.

The central pathways of metabolism include glycolysis and gluconeogenesis, fatty acid synthesis and beta-oxidation, the citric acid cycle and ureagenesis. Because these pathways intersect, changes in one pathway, due to inborn error or disease, affect pathways that may seem remote from the initial metabolic defect. These metabolic interrelationships also present difficulties for isotopic studies, because once carbon derived from isotopic tracers is introduced into metabolism it is extensively recycled. The use of multiple labeled (especially uniformly 13C-labeled ([U-13C]), metabolic tracers, in conjunction with mass isotopomer distribution analysis of mass and nuclear magnetic spectra, has enabled the development of methods that resolve some of these difficulties. Suitable choices of tracers and analytes allow the simultaneous measurement of multiple pathways and, importantly, their kinetic interrelationships. We illustrate three uses of the technique: (1) the unequivocal determination of tracee fluxes; (2) the quantification of biosynthetic pathways; and (3) the dissection, in vivo, of the citric acid (Krebs) cycle. In each case, different combinations of [U-13C]tracer and metabolic end product have revealed metabolic phenomena that otherwise would remain unidentified. A particularly striking, and unexpected, observation that has emerged from recent studies using the technique, suggests that the key dehydrogenase reactions in the Krebs cycle may be reversible. Although this approach is of relatively recent development, it has already given a number of novel insights into the organization of the central metabolic pathways. It should provide a powerful method of investigating the metabolic impact of genetic disease and provide invaluable support of the assessment of new therapeutic interventions.

The overall survival of neonates with congenital diaphragmatic hernia (CDH) remains poor despite the advent of extracorporeal membrane oxygenation (ECMO). Attempts at accurately predicting survival have been largely unsuccessful. The purpose of this study was twofold: (1) to identify independent predictors of survival from a cohort of CDH neonates treated at the authors' institution when ECMO was not available and combine them to form a predictive equation, and (2) to apply the equation prospectively in a cohort of CDH neonates, treated at the same institution when ECMO was available, to determine whether ECMO improves outcome. From the clinical data of 62 CDH neonates treated at the authors' center by the same team of university neonatologists and pediatric surgeons between 1983 and 1993 (before ECMO availability), 15 preoperative and seven operative variables were selected as potential independent predictors. When subjected to multivariate, stepwise logistic regression analysis, four variables were identified as statistically significant (P < .05), independent predictors of survival: (1) ventilatory index (VI), (2) best preoperative PaCO2, (3) birth weight (BW), and (4) Apgar score at 5 minutes. When combined via logistic regression analysis, the following predictive equation was formulated: P (probability of survival to discharge) = [1 + e(x)]-1 where x = 4.9 - 0.68 (Apgar) - 0.0032 (BW) + 0.0063 (VI) + 0.063 (PaCO2). Applying a standard cut-off rate of survival at less than 20%, the equation yielded a sensitivity of 94% and a specificity of 82% in identifying the correct outcome of patients treated with conventional ventilatory management. The overall survival rate was 66%. Since the availability of ECMO at the center, 32 CDH neonates were treated using the same conventional ventilatory treatment and surgical repair by the same university staff. The overall survival rate was 69%. The predictive equation was applied prospectively to all neonates to determine predicted outcome, but was not used to decide the treatment method. Eighteen neonates received conventional therapy alone; 16 of 18 survived (89%). Fifteen of the 16 patients who survived had their outcomes predicted correctly (94%). Fourteen neonates did not respond to conventional therapy and required ECMO; 6 of 14 survived (43%). Six of the eight patients predicted to survive, lived (75%). All six patients predicted to die, died despite the addition of ECMO therapy (100%). The mean hospital cost, per ECMO patient who died, was $277,264.75 +/- $59,500.71 (SE). An odds ratio analysis, using the four independent predictors to standardize for degree of illness, was performed to assess the risk associated with adding ECMO therapy. The result was 1.25 (P = 0.75). Although the cohort was not large enough to eliminate significant beta error, the data strongly suggested no advantage of ECMO. At this center, absolute survival rates for neonates with CDH have not been significantly altered since ECMO has become available (66% v 69%). The authors conclude that the predictive equation remains an accurate measurement of survival at their center even when ECMO is used as a salvage therapy. The method of creating a predictive equation may be applied at any institution to determine the potential outcome of CDH neonates and assess the effect of ECMO, or other salvage therapies, on survival rates.

Purpose The management of giant omphalocele presents a major challenge to pediatric surgeons. Current treatment modalities often result in wound infection, fascial separation, and abdominal domain loss. Human acellular dermis (AlloDerm), as a primary abdominal fascial substitute, may prevent these complications. We present our experience with its application in neonates with giant omphalocele. Methods Charts of patients with giant omphalocele from January 2003 to September 2004 were reviewed and data collected regarding wound healing, rate of infection, ventilatory support, and outcome. Results Three neonates underwent abdominal wall closure with AlloDerm (gestational ages: 38, 37, and 28 weeks; birthweights 2880, 2640, and 1160 g, respectively). All had cardiac anomalies; 1 required cardiac surgery and 1 was ventilator-dependent, secondary to pulmonary hypoplasia. Omphalocele repair was performed on day-of-life 9, 2, and 87. No fascial dehiscence or infection was encountered. Neovascularization was noted by day 7. Two died of cardiopulmonary disease (6 months and 1 year). The third exhibited normal growth and development without complication. Conclusions AlloDerm provides visceral coverage without compromising cardiopulmonary function, diminishing abdominal domain, or requiring multiple operations, allowing prompt treatment of associated anomalies. AlloDerm represents an exciting alternative in the treatment of giant omphalocele. Further study is required to determine long-term benefits.

All-terrain vehicle (ATV) sales have climbed 89% in the last 5 years. We sought to determine if pediatric ATV accidents have increased in frequency and morbidity.Medical records of children treated in our emergency unit for ATV accidents from 1993 to 2003 were reviewed. The 11 years were divided into 2 periods, January 1993 to June 1998 and July 1998 to December 2003, to allow comparisons and analysis of trends over time.We treated 184 children, with 90% requiring admission. Comparing the first and second halves of the study, patients treated increased from 8.7 +/- 4.8 (mean +/- SD) to 24.5 +/- 11.1 per year (P.01), patients requiring immediate operation increased from 4 (9%) of 44 to 24 (17%) of 140, and patients with serious injuries (resulting in direct intensive care unit admission, immediate operation, or death) rose from 12 (27%) of 44 to 51 (36%) of 140. Patient age was 11.5 +/- 3.9 years. Sixty-eight percent of the children sustained multiple injuries and 50% required surgery. Only 35% of the children wore helmets.Over the 2 periods, there was a significant increase in number of patients treated, and considerable increases in serious injuries, and need for immediate operation. Despite inherent risks with riding ATVs, helmet use and patient age were remarkably low.

Protein catabolism appears to be markedly elevated among neonates on extracorporeal membrane oxygenation (ECMO). The aim of this study was to determine the effect of dietary caloric intake on protein catabolism in neonates on ECMO to help construct therapies that may promote anabolism.Twelve total parenteral nutrition (TPN)-fed (88.1 +/- 5.0 [SE] kcal/kg/d; range, 60 to 113 kcal/kg/d; 2.3 +/- 0.2 g/kg/d protein) neonates were studied on ECMO at day of life 7.2 +/- 0.8 d. Protein kinetics were determined using infusions of NaH13CO3 and 1-[13C]leucine.As expected, C-reactive protein levels were significantly elevated compared with normal controls (44.0 +/- 7.6 mg/L v 1.9 +/- 1.1 mg/L; P.001). Negative protein balance (-2.3 +/- 0.6 g/kg/d; range, 1 to -6.4 g/kg/d) highly correlated (r = -0.88, P.001) with total protein turnover. Increased dietary caloric intake correlated with increased amino acid oxidation (r = 0.85, P.001), increased total protein turnover (r = 0.73, P.01), continued negative protein balance (r = 0.72, P.01), increased whole-body protein breakdown (r = 0.66, P.05), and increased CO2 production rate (r = 0.73, P.01).A surplus of dietary caloric intake does not improve protein catabolism and merely increases CO2 production in these highly stressed neonates. Thus, judicious caloric supplementation is warranted.

The conversion of D-[U- 13 C]glucose to proline (Pro), aspartate (Asp), and cysteine (Cys) is limited in premature neonates, implying that these amino acids (AA) are conditionally essential. This study was performed to determine whether these findings resulted from an insufficient precursor dose or intracellular compartmentation of newly synthesized amino acids, rather than inadequate synthesis. In the first phase of this study, seven total parenteral nutrition-fed, premature neonates received IV D-[U 13 C]glucose at 5 mg/kg/min for 4 hr. In the second phase, a separate cohort of eight patients received an identical infusion. Blood was obtained before and at the end of the infusion. Isotopic enrichments of the free plasma AA and glucose were measured using gas chromatography/mass spectrometry in both studies. In phase 2, the isotopic enrichments of the AA bound to the hepatically synthesized proteins, fibrinogen and VLDL-apolipoprotein B-100 (apo B-100), were measured. In phase 1, despite a glucose precursor enrichment greater than 66%, Pro, Asp, and Cys remained the least enriched of all amino acids studied (P < 0.05). Asp, but not Pro, demonstrated very high enrichments in apo B-100 (P < 0.001), reflecting distinct intracellular compartmentation. We conclude that the limited conversion of D-[U- 13 C]glucose to Pro, Asp, and Cys did not result from low precursor glucose enrichment and that there is evidence of Asp compartmentation (intracellular) in premature neonates. However, the low Pro enrichment in the free plasma AA pool and the absence of intracellular Pro compartmentation suggest that Pro may be a conditionally essential AA for premature neonates.

Dermatofibrosarcoma protuberans (DFSP) is an uncommon malignant mesenchymal tumor characterized by local invasion and recurrence. Fewer than 50 cases have been reported in the pediatric population. We reviewed our experience in the treatment of children with DFSP to define clinical and pathological characteristics. Seven pediatric patients were included in the study (mean age, 11.7 yr). Clinically, the tumors were described as firm nodules fixed to the skin but mobile over the deep fascia, with slow, progressive growth. Diagnosis was made by excisional biopsy in 6 patients and punch biopsy in 1 patient. Six of 7 patients had positive margins after the diagnostic procedure. Pathologically, diagnosis was based on histology, with confirmation by CD34 staining. Definitive surgical therapy consisted of wide local excision (1-3 cm margins) in 5 patients and Moh's micrographic resection in 2 patients. There have been no local recurrences or distant metastases, with a mean follow-up of 15.1 months. Pathological and clinical diagnostic criteria for the pediatric population are reviewed, and treatment options are discussed.