Walter J. Chwals

Postoperative outcomes of extremely low birth-weight infants with necrotizing enterocolitis or isolated intestinal perforation: A prospective cohort study by the NICHD Neonatal Research Network

Objective:Purposes of this study were: 1) to compare mortality and postoperative morbidities (intra-abdominal abscess, wound dehiscence, and intestinal stricture) in extremely low birth weight (ELBW) infants who underwent initial laparotomy or drainage for necrotizing enterocolitis (NEC) or isolated intestinal perforation (IP); 2) to determine the ability to distinguish NEC from IP preoperatively and the importance of this distinction on outcome measures; and 3) to evaluate the association between extent of intestinal disease determined at operation and outcome measures. Background:ELBW infants who undergo operation for NEC or IP have a postoperative, in-hospital mortality rate of approximately 50%. Whether to perform laparotomy or drainage initially is controversial. Also unknown is the importance of distinguishing NEC from IP and the current ability to make this distinction based on objective data available prior to operation. Methods:A prospective, multicenter cohort study of 156 ELBW infants at 16 neonatal intensive care units (NICU) within the NICHD Neonatal Research Network. Results:Among the 156 enrolled infants, 80 underwent initial peritoneal drainage and 76 initial laparotomy. Mortality rate was 49% (76 of 156). Ninety-six patients had a preoperative diagnosis of NEC and 60 had presumed IP. There was a high level of agreement between the presumed preoperative diagnosis and intraoperative diagnosis in patients undergoing initial laparotomy (kappa = 0.85). The relative risk for death with a preoperative diagnosis of NEC (versus IP) was 1.4 (95% confidence interval, 0.99–2.1, P = 0.052). The overall incidence of postoperative intestinal stricture was 10.3%, wound dehiscence 4.4%, and intra-abdominal abscess 5.8%, and did not significantly differ between groups undergoing initial laparotomy versus initial drainage. Conclusions:Survival to hospital discharge after operation for NEC or IP in ELBW neonates remains poor (51%). Patients with a preoperative diagnosis of NEC have a relative risk for death of 1.4 compared with those with a preoperative diagnosis of IP. A distinction can be made preoperatively between NEC and IP based on abdominal radiographic findings and the patients age at operation. Future randomized trials that compare laparotomy versus drainage would likely benefit from stratification of treatment assignment based on preoperative diagnosis.

Early Experience with Single-Port Laparoscopic Surgery in Children

INTRODUCTION The current paradigm in laparoscopic surgery is for each instrument to enter the abdomen through its own separate incision. The advent of newer laparoscopic trocars and instruments now allows for all instruments to enter through a single incision. This may lead to less pain and improved cosmetic outcome. Single-incision laparoscopic surgery (SILS) has recently been described in adults. In this article, we report our preliminary experience of SILS in children. METHODS A retrospective review was performed of the operative database at Rainbow Babies and Childrens Hospital (Cleveland, OH) from March 2008 to March 2009, looking for all cases that were performed through a single laparoscopic incision. RESULTS A total of 72 SILS cases were performed. These included cholecystectomy, splenectomy, intussusception reduction, gastrostomy tube placement, thoracoscopic lung biopsy, thoracoscopic decortication, and appendectomy. Five appendectomies were converted to traditional three-port laparoscopy. There were two umbilical wound infections after an appendectomy. There were no other complications. CONCLUSION Preliminary experience with SILS in children appears to be safe and effective. Greater numbers and a prospective trial will be necessary to assess the true benefit of this approach.

Nutritional Support of the Pediatric Oncology Patient

The child with a malignancy frequently will have associated cachexia with significant weight loss and malnutrition. The reasons for this are multifactorial and may be related directly to the tumor, such as increased metabolic rate, circulating peptides leading to anorexia, and decreased intake due to poor appetite or gut involvement. There appears to be other reasons involved, including increased whole body protein breakdown, increased lipolysis, and increased gluconeogenesis. Release of certain cytokines, such as tumor necrosis factor, interleukin-1, interleukin-6, and others may increase the cancer cachexia. Malnutrition in these children leads to intolerance of chemotherapy and radiotherapy as well as increased local and systemic infections. For many years, oncologists were hesitant to provide nutrition support to cancer patients for fear that tumor growth would be enhanced. Pediatric oncologists learned early that starvation plays no positive role in cancer therapy. Adjunctive nutritional support, either enterally or parenterally, supports the patient during therapy with surgery, chemotherapy, or radiation. Many studies have now shown that the nutritionally replete patient tolerates therapy better and in some pediatric malignancies may enhance survival.

Measured energy expenditure in critically III infants and young children

Technological limitations have impeded accurate energy expenditure assessment in critically ill infants and young children. Instead, a predicted energy expenditure (PEE) is derived based on weight, heat loss, activity, growth requirements, and degree of stress. This study compared actual measured energy expenditure (MEE) with conventional predicted values in 20 critically ill infants and children using a validated metabolic cart designed for use in this age group. All patients were studied either within 4 days of major surgery or during an acute disease process necessitating intensive care. All were severely stressed clinically and were studied while mechanically ventilated in a temperature-controlled environment. The study interval ranged from 1 to 12 hr and averaged 4 hr after a stabilization period of 30 min. The mean MEE was significantly lower than the mean PEE (52.2 +/- 16 kcal/kg/day vs 101.8 +/- 17 kcal/kg/day, P less than 0.001) with a mean MEE/PEE of 52.6 +/- 17% (range 26 to 92%). In a subgroup of 7 paralyzed patients, the mean MEE was significantly lower than in the 13 nonparalyzed patients when compared with PEE and predicted basal metabolic rate (PBMR). The coefficient of variance, conventionally recognized to be approximately 15% for PEE, averaged 6.35% for MEE in this study. These data indicate that if PEE is used as the sole guide for caloric repletion in the stressed infant or child, these patients will be substantially overfed.

Pediatric wound infections: a prospective multicenter study.

OBJECTIVE Surgical wound infections remain a significant source of postoperative morbidity. This study was undertaken to determine prospectively the incidence of postoperative wound infections in children in a multi-institutional fashion and to identify the risk factors associated with the development of a wound infection in this population. SUMMARY BACKGROUND DATA Despite a large body of literature in adults, there have been only two reports from North America concerning postoperative wound infections in children. METHODS All infants and children undergoing operation on the pediatric surgical services of three institutions during a 17-month period were prospectively followed for 30 days after surgery for the development of a wound infection. RESULTS A total of 846 of 1021 patients were followed for 30 days. The overall incidence of wound infection was 4.4%. Factors found to be significantly associated with a postoperative wound infection were the amount of contamination at operation (p = 0.006) and the duration of the operation (p = 0.03). Comparing children who developed a wound infection with those who did not, there were no significant differences in age, sex, American Society of Anesthesiologists (ASA) preoperative assessment score, length of preoperative hospitalization, location of operation (intensive care unit vs. operating room), presence of a coexisting disease or remote infection, or the use of perioperative antibiotics. CONCLUSIONS Our results suggest that wound infections in children are related more to the factors at operation than to the overall physiologic status. Procedures can be performed in the intensive care unit without any increase in the incidence of wound infection.

Early postoperative alterations in infant energy use increase the risk of overfeeding.

AIM OF STUDY Energy needs in infants are decreased after surgery because of growth inhibition (resulting from catabolic stress metabolism), decreased insensible losses, and inactivity. Using standardized formulas that account for growth, activity, and insensible losses during this stress period can lead to overfeeding in excess of 200% of the actual measured requirement. Overfeeding during this acute injury period can result in increased CO2 production from lipogenesis. This study determined the effects of a reduced rate of mixed caloric repletion on infant energy use during the early postoperative period. METHODS C-reactive protein (CRP), oxygen consumption (VO2), carbon dioxide production (VCO2), measured energy expenditure (MEE), and total urinary nitrogen (TUN) were measured serially in seven infants (average age, 78 days) during the first 72 hours after abdominal or thoracic surgery. Nonprotein respiratory quotient (RQnp), and values for oxidation of carbohydrate (Ce) and fat (Fe) were calculated. Injury severity was stratified based on serum CRP concentrations of > or = 6.0 mg/dL (high stress) or < 6.0 mg/dL (low stress). Recovery from acute stress was analyzed by comparing studies in which CRP had decreased to < or = 2.0 mg/dL (resolving stress group) with those in which CRP values were greater than 2.0 mg/dL (acute stress group). RESULTS Average total caloric intake (64.56 +/- 18.51 kcal/kg/d; approximately 50% of predicted energy requirement) exceeded average MEE (42.90 +/- 9.98 kcal/kg/d) by approximately 50%. Average TUN was 0.18 +/- 0.07 g/kg/d (high stress 0.2 +/- 0.05 versus low stress 0.16 +/- 0.09 g/kg/d). Average RQnp was 1.05 +/- 0.13 and average Ce was 37.28 +/- 16.86 kcal/kg/d. The average calculated Fe was 0.0 +/- 12.27 kcal/kg/d, reflecting approximately equal amounts of fat oxidized compared with fat generated from excess glucose (lipogenesis). When individual studies were analyzed at a CRP cutpoint of 2.0 mg/dL, overfeeding (RQ > 1.0) was significantly less likely in the resolving (2/6 studies, 33.4%) versus acute stress (9/13 studies, 69.2%, Z test P < .001) group. Five of seven (5/7) patients (9/19 individual studies) had negative Fe values (average -9.89 +/- 10.02) reflecting net lipogenesis. The RQnp for these nine studies was 1.14 +/- 0.11 versus 0.97 +/- 0.09 for the remaining 10, and this difference was significant (P < .01). A significant correlation existed between carbohydrate intake and VCO2 (Pearson r = .6951, P < .01). In addition, there was a good correlation between carbohydrate intake and VCO2 (Pearson r = .6591, P < .01). The coefficient of variation for MEE was 8.0% (low stress) versus 30.2% (high stress). CONCLUSION Lipogenesis with increased CO2 production is substantial, even at reduced caloric delivery rates that exceeded MEE by only 50%, during the early postoperative acute metabolic stress period in infants. These data suggest that caloric requirements during stress are likely equal to or only minimally in excess of actual MEE. Intersubject variability, especially in more severely stressed infants, underscores the importance of serial measurements of energy expenditure to enable precise caloric delivery and avoid overfeeding. In the absence of calorimetric measurement, the data suggest that PBMR (predicted basal metabolic rate) should be used to estimate caloric delivery until CRP values are < or = 2.0 mg/dL.

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.

Bedside assessment of the work of breathing.

The oxygen consumption (VO2) of healthy volunteers and patients recovering from respiratory failure in the ICU was measured by indirect calorimetry during complete mechanical (VO2vent) and spontaneous (VO2wean) ventilation. The work of breathing was calculated as the difference in VO2 between spontaneous and mechanical ventilation and expressed as a percentage of VO2vent (% delta VO2). The average % delta VO2 for eight normal healthy volunteers was 3.7 +/- 1.8%, while it was 7.7 +/- 8.8% with the Bechman and Utah metabolic carts for patients recovering from ventilatory failure who were weaned successfully from respiratory support based on clinical criteria within 24 h of their metabolic study. In patients who were not weaned successfully, the average % delta VO2 measured was 24.7 +/- 12.3%. Indirect calorimetry is a relatively simple, reliable bedside technique for determining the oxygen cost of breathing. In our sample, the oxygen cost of breathing was a reliable predictor of weaning and extubation in patients recovering from respiratory failure. This measurement may be clinically useful in identifying the patient who cannot sustain spontaneous ventilation because of excessive respiratory work.

Computed tomography before transfer to a level I pediatric trauma center risks duplication with associated increased radiation exposure

INTRODUCTION Community hospitals commonly obtain computed tomographic (CT) imaging of pediatric trauma patients before triaging to a level I pediatric trauma center (PTC). This practice potentially increases radiation exposure when imaging must be duplicated after transfer. METHODS A retrospective review of our level 1 PTC registry from January 1, 2004, to December 31, 2006, was conducted. Level I and II trauma patients were grouped based on whether they had undergone outside CT examination (head and/or abdomen) at a referring hospital (group 1) or received initial CT examination at our institution (group 2). Subgroups were analyzed based on whether duplicate CT examination was required at our PTC (Fischers Exact test). RESULTS A duplicate CT scan (within 4 hours of transfer) was required in 91% (30/33) of group 1 transfer patients, whereas no group 2 patient required a duplicate scan (0/55; P < .0001). There was no significant difference within the groups for weight, age, or intensive care unit length of stay. CONCLUSION A significant number of pediatric trauma patients who receive CT scans at referring hospitals before transfer to our level I PTC require duplicate scans of the same anatomical field(s) after transfer, exposing them to increase potential clinical risk and cost.

Hamartomas of the chest wall in infants

Chest wall hamartomas in infancy are rare lesions with distinct clinical, radiologic, and pathologic characteristics. Four cases treated at Childrens Hospital of Los Angeles are presented and previously reported cases are reviewed. Chest wall hamartomas arise antenatally and present as hard, immobile masses, which may cause respiratory insufficiency. An extrapleural mass arising from the ribs can be seen radiographically. Histologically, these lesions are hypercellular and consist of a disorganized array of mesenchymal tissues endogenous to the chest wall. Rapid growth may occur, but usually is self-limited. Chest wall hamartomas are usually benign. This series includes the malignant transformation of one of these lesions. En bloc resection is curative, but the large residual chest wall defect frequently results in scoliosis.