Necrotizing enterocolitis: a practical guide to its prevention and management

Umbilical arterial catheter duration as risk factor for Bell's Stage III necrotizing enterocolitis in preterm neonates

Objectives

To explore risk factors for Stage-III necrotizing enterocolitis (NEC-III) in preterm neonates.

Methods

This was a retrospective case-control study of neonates born <33 weeks gestational age (GA) who were admitted to a tertiary neonatal intensive care unit, between 2015 and 2018. NEC-III cases were compared with Stage-II NEC (NEC-II) and non-NEC controls. Two to four non-NEC controls were matched by GA ± 1 week and date of birth ± 3 months, to one NEC-III case. Univariate and multivariate analyses were used to examine risk factors for NEC-III.

Results

Of 1360 neonates born <33 weeks, 71 (5.2%) had NEC-II and above, with 46% being NEC-III. Mean age of onset of NEC-III was 13.7 days versus 23.9 days for NEC-II (p = 0.01). Neonates with NEC-III were of lower GA (NEC-III 25.4 weeks, NEC-II 27.3 weeks, and non-NEC 26 weeks; p = 0.0008) and had higher Score for Neonatal Acute Physiology Perinatal Extension-II scores (NEC-III 47.5, NEC-II 28.4 and non-NEC 37, p = 0.003). Multivariate analysis showed duration of umbilical arterial catheter (UAC) >5 days was significantly associated with the development of NEC-III with adjusted odds ratio (AOR) 3.8; 95% confidence interval (CI) (1.05-13.66) for NEC-III versus non-NEC and AOR 5.57; 95% CI (1.65-18.73), p = 0.006 for NEC-III versus NEC-II. Rupture of membranes (ROM) >1 week was associated with NEC-III (AOR 6.93; 95% CI [1.56-30.69] vs. non-NEC and AOR 11.74; 95% CI [1.14-120.34] vs. NEC-II).

Conclusion

The increased association of NEC-III with duration of UAC and ROM could be further examined in prospective studies, and an upper limit for UAC duration could be considered in NEC prevention bundles.

The children of the missed pill

We assess the impact of exogenous variation in oral contraceptives prices-a year-long decline followed by a sharp increase due to a documented collusion case-on fertility decisions and newborns' outcomes. Our empirical strategy follows an interrupted time-series design, which is implemented using multiple sources of administrative information. As prices skyrocketed (45% within a few weeks), the Pill's consumption plunged, and weekly conceptions increased (3.2% after a few months). We show large effects on the number of children born to unmarried mothers, to mothers in their early twenties, and to primiparae women. The incidence of low birth weight and fetal/infant deaths increased (declined) as the cost of birth control pills rose (fell). In addition, we document a disproportional increase in the weekly miscarriage and stillbirth rates. As children reached school age, we find lower school enrollment rates and higher participation in special education programs. Our evidence suggests these "extra" conceptions were more likely to face adverse conditions during critical periods of development.

Extracardiac Complications in Intensive Care Units after Surgical Repair for Congenital Heart Disease: Imaging Review with a Focus on Ultrasound and Radiography

Pediatric patients show various extracardiac complications after cardiovascular surgery, and radiography and ultrasound are routinely performed in the intensive care unit to detect and evaluate these complications. This review presents images of these complications, sonographic approach, and timing of occurrence that are categorized based on their extracardiac locations and include complications pertaining to the central nervous system, mediastinum, thorax and lung parenchyma, diaphragm, liver and biliary system, and kidney along with pleural effusion and iatrogenic complications. This pictorial review will make it easier for medical doctors in intensive care units to identify and manage various extracardiac complications in pediatric patients after cardiovascular surgery.

Association between extrauterine growth restriction and changes of intestinal flora in Chinese preterm infants

The aim of the study was to investigate any association between extrauterine growth restriction (EUGR) and intestinal flora of <30-week-old preterm infants. A total of 59 preterm infants were assigned to EUGR (n=23) and non-EUGR (n=36) groups. Intestinal bacteria were compared by using high-throughput sequencing of bacterial rRNA. The total abundance of bacteria in 344 genera (7568 v. 13,760; P<0.0001) and 456 species (10,032 v. 18,240; P<0.0001) was significantly decreased in the EUGR group compared with the non-EUGR group. After application of a multivariate logistic model and adjusting for potential confounding factors, as well as false-discovery rate corrections, we found four bacterial genera with higher and one bacterial genus with lower abundance in the EUGR group compared with the control group. In addition, the EUGR group showed significantly increased abundances of six species (Streptococcus parasanguinis, Bacterium RB5FF6, two Klebsiella species and Microbacterium), but decreased frequencies of three species (one Acinetobacter species, Endosymbiont_of_Sphenophorus_lev and one Enterobacter_species) compared with the non-EUGR group. Taken together, there were significant changes in the intestinal microflora of preterm infants with EUGR compared to preterm infants without EUGR.

Protective effects of amniotic fluid in the setting of necrotizing enterocolitis

Necrotizing enterocolitis (NEC) is the most common life threatening condition affecting preterm infants. NEC occurs in 1-5% of all neonatal intensive care admissions and 5-10% of very low birth weight infants. The protective role of human breast milk (BM) has been well established. It has also been shown that amniotic fluid (AF) and BM have many similarities in terms of presence of growth and other immune-modulatory factors. This finding led to the initial hypothesis that AF may exert similar protective effects against the development of NEC, as does BM. Multiple studies have elucidated the presence of growth factors in AF and the protective effect of AF against NEC. Studies have also described possible mechanisms how AF protects against NEC. At present, research in this particular area is extremely active and robust. This review summarizes the various studies looking at the protective effects of AF against the development of NEC. It also provides an insight into future directions, the vast potential of AF as a readily available biologic medium, and the ethical barriers that must be overcome before using AF.

Neonatal Perforated Appendicitis Attributed to Localized Necrotizing Enterocolitis of the Appendix: A Review

Neonatal appendicitis is a rare clinical entity associated with remarkable morbidity and mortality. Appendicular perforation is common and the diagnosis is usually made intra-operatively. The causative etiology of neonatal perforated appendicitis (NPA) is a subject of debate and has not been elucidated. Although many etiologic theories exist, increasing evidence suggests a subset of NPA cases may represent a form of necrotizing enterocolitis (NEC) localized to the appendix. We herein present a review of the current literature to include cases of NPA attributed to localized NEC. A high index of clinical suspicion and early laparotomy are recommended.

Maternal and neonatal outcomes of respiratory failure during pregnancy

BACKGROUND

Obstetric patients comprise a limited portion of intensive care unit patients, but they often present with unfamiliar conditions and exhibit the potential for catastrophic deterioration. This study evaluated the maternal and neonatal outcomes of respiratory failure during pregnancy.

METHODS

Information on 71 patients at >25 weeks gestation in the ICU with respiratory failure was recorded between 2009 and 2013. The characteristics and outcomes of mothers and fetuses were determined through a retrospective chart review and evaluated using Student's t test, chi-square test, and Fisher's exact test.

RESULTS

The leading causes of respiratory failure were postpartum hemorrhage and severe preeclampsia in the obstetric causes group and pneumonia in the nonobstetric causes group during pregnancy and the peripartum period. The non-obstetric causes group exhibited a higher incidence of acute respiratory distress syndrome and renal replacement therapy as well as requiring more ventilator days. The patients in the obstetric causes group showed significant improvement after delivery in the partial pressure of arterial oxygen to the fraction of inspired oxygen and peak inspiratory pressure decrease. Both groups exhibited high incidences of neonatal respiratory distress syndrome. Neonatal complications resulting from meconium aspiration syndrome (MAS) and sepsis were more common in the non-obstetric causes group; however, neurological development impairment was more common in the obstetric causes group.

CONCLUSION

Obstetric cause was associated with longer ventilator free days and fewer episodes of ARDS after delivery. Neonatal complications resulting from different etiologies of respiratory failure were found to differ.

Clinical significance of FABP2 expression in newborns with necrotizing enterocolitis

BACKGROUND

This meta-analysis aimed to determine the role of human fatty acid binding protein 2 (FABP2) expression in the diagnosis of necrotizing enterocolitis (NEC) of newborns.

DATA SOURCES

Eligible studies for further statistical analysis were identified from various databases including PubMed, Expert Medica Database, Web of Science, Cochrane Library, Google Scholar, China BioMedicine and China National Knowledge Infrastructure. Random effects model was used, and summary standardized mean difference (SMD) with its 95% confidence interval (CI) was calculated to assess the association of FABP2 expression and NEC.

RESULTS

Ten articles which included 572 infants (262 infants with NEC and 310 healthy controls) were included in the current meta-analysis. FABP2 showed a positive relationship with NEC of newborns (SMD=2.88, 95% CI=2.09-3.67, P<0.001). And FABP2 expression was higher in patients with advanced stage of NEC (stage III or stage II+III) than in those with early stage of NEC (stage I) (SMD=-0.48, 95% CI=-0.87 to -0.09, P=0.015). Ethnicity-stratified analysis yielded significantly different estimates with a high FABP2 expression in NEC in both Caucasians (SMD=3.16, 95% CI=1.90-4.43, P<0.001) and Asians (SMD=2.57, 95% CI=1.50-3.64, P<0.001). Sample-based subgroup analysis showed that FABP2 expression was positively correlated with neonatal NEC in both urinary- and blood-sample subgroups (all P<0.05).

CONCLUSION

The results prove that the high FABP2 expression is related to the damage to intestinal cells, which may be a possible early detection marker identifying neonatal NEC.

The Infant Microbiome: Implications for Infant Health and Neurocognitive Development

BACKGROUND

Beginning at birth, the microbes in the gut perform essential duties related to the digestion and metabolism of food, the development and activation of the immune system, and the production of neurotransmitters that affect behavior and cognitive function.

OBJECTIVES

The objectives of this review are to (a) provide a brief overview of the microbiome and the "microbiome-gut-brain axis"; (b) discuss factors known to affect the composition of the infant microbiome: mode of delivery, antibiotic exposure, and infant-feeding patterns; and (c) present research priorities for nursing science and clinical implications for infant health and neurocognitive development.

DISCUSSION

The gut microbiome influences immunological, endocrine, and neural pathways and plays an important role in infant development. Several factors influence colonization of the infant gut microbiome. Different microbial colonization patterns are associated with vaginal versus surgical birth, exposure to antibiotics, and infant-feeding patterns. Because of extensive physiological influence, infant microbial colonization patterns have the potential to impact physical and neurocognitive development and life course disease risk. Understanding these influences will inform newborn care and parental education.

Probiotics and prebiotics in neonatal necrotizing enterocolitis: New opportunities for translational research

Neonatal necrotizing enterocolitis (NEC) in premature infants has been recognized as a defined disease entity for at least four decades. Although survival has increased due to the advent of more sophisticated intensive care, incidence and long term health impacts due to NEC remain unchanged and no preventive therapy is currently available. Different probiotic strains of bacteria have been examined in their ability to prevent NEC with varied but encouraging results. Undigestable prebiotic sugars known to promote the growth of probiotic bacteria in the colon have been used in neonates with no clear benefit. The literature on NEC and probiotics is now cluttered with more reviews and meta-analyses than number of clinical trials. On the other hand, significant new information is available on microbiota and their impact on gut immunity. This review attempts to reiterate the risk factors of NEC and the pathogenesis of NEC with special reference to gut permeability. The reader is then introduced to gut microbiota, uniqueness and differences among probiotic strains, and how multiple resident flora talk to each other in the community setting in the human gut. After presenting a concise review of available clinical research results, the reader is challenged to question as to why no precise answer is available at present. Some modalities to examine the complex microflora and changes in the neonatal gut are then proposed including non-invasive methods and mathematical modeling. The review concludes by attracting the reader's attention to known immunomodulators of inflammation and injury. Justice to this review will be done only if the readers, clinical, and basic science investigators from multiple fields gather courage for a paradigm shift and embark on understanding the pathophysiology of the disease and attempt to discern the difference from equally preterm, equally vulnerable neonates that do not develop NEC. Learning about the developing microbiota in neonatal gut and its immunological impacts on the host in the face of many variables will provide a leap in our pursuit to select better, if not the best candidate probiotics, and put them to work against this stubborn disease that continues to take a toll on our precious neonates and the society.

Concurrent bloodstream infections in infants with necrotizing enterocolitis

OBJECTIVE

To determine the incidence, microbiology, risk factors, and outcomes related to bloodstream infections (BSIs) concurrent with the onset of necrotizing enterocolitis (NEC).

STUDY DESIGN

We performed a retrospective review of all cases of NEC in a single center over 20 years. BSI was categorized as "NEC-associated" if it occurred within 72 hours of the diagnosis of NEC and "post-NEC" if it occurred >72 hours afterwards. Demographics, hospital course data, microbiologic data, and outcomes were compared via univariate and multivariate analyses.

RESULTS

NEC occurred in 410 infants with mean gestational age and birth weight of 29 weeks and 1290 g, respectively; 158 infants were diagnosed with at least one BSI; 69 (43.7%) with NEC-associated BSI, and 89 (56.3%) with post-NEC BSI. Two-thirds of NEC-associated BSI were due to gram-negative bacilli compared with 31.9% of post-NEC BSI (OR: 4.27; 95% CI: 2.02, 9.03) and 28.5% of all BSI in infants without NEC (OR: 5.02; 95% CI: 2.82, 8.96). Infants with NEC-associated BSI had higher odds of requiring surgical intervention (aOR: 3.51; 95% CI: 1.98, 6.24) and death (aOR: 2.88; 95% CI: 1.39, 5.97) compared with those without BSI.

CONCLUSIONS

BSI is a common, underappreciated complication of NEC occurring concurrent with the onset of disease and afterwards. The microbiologic etiology of NEC-associated BSI is different from post-NEC and late-onset BSI in infants without NEC with a predominance of gram-negative bacilli. Infants with NEC-associated BSI are significantly more likely to die than those with post-NEC BSI and NEC without BSI.

Relationship of neonatal treatments with the development of necrotizing enterocolitis in preterm infants

BACKGROUND

Although many therapeutic interventions are necessary for the survival of the preterm infant, understanding the potential effects of these treatments is important to decrease the rate of necrotizing enterocolitis (NEC) in preterm infants.

OBJECTIVE

The aim of this study was to examine the relationship between preterm infant treatments administered prior to the development of NEC, specifically the number of packed red blood cell (PRBC) transfusions, weeks of antibiotic therapy for nosocomial infection, and number of mechanical ventilation days, and the development of NEC in preterm infants.

METHODS

A retrospective cohort controlled study design examining 4 years of raw data of preterm infants between the gestational ages of 23 and 30 6/7 weeks was used. Of the 549 infants, there were 65 cases of NEC. Using logistic regression, the relationship between NEC and PRBC transfusions administered prior to NEC, number of mechanical ventilation days prior to NEC, and number of weeks of antibiotic therapy for nosocomial infections experienced prior to NEC (proxy for nosocomial infection) were examined.

RESULTS

Preterm infants from 23 to 30 6/7 weeks who developed NEC experienced significantly more PRBC transfusions and more weeks of antibiotic therapy for nosocomial infection prior to the development of NEC than did infants who did not develop NEC. There was no relationship between mechanical ventilation days and the development of NEC.

DISCUSSION

Future research should focus on causal relationships between NEC and PRBC administration and the reduction of nosocomial infections in preterm infants to minimize risk for NEC in this population.

Meta-analysis of randomized trials comparing antibiotic therapy with appendectomy for acute uncomplicated (no abscess or phlegmon) appendicitis

BACKGROUND

The objective was to conduct a meta-analysis of randomized controlled trials evaluating the efficacy and morbidity of the management of acute uncomplicated (no abscess or phlegmon) appendicitis by antibiotics versus appendectomy.

METHODS

Appropriate trials were identified. The seven outcome variables were overall complication rate, treatment failure rate for index hospital admission, overall treatment failure rate, length of stay (LOS), utilization of pain medication, duration of pain, and sick leave. Both fixed and random effects meta-analyses were performed using odds ratios (ORs) and weighted or standardized mean differences (WMDs or SMDs, respectively).

RESULTS

Five trials totaling 980 patients (antibiotics=510, appendectomy=470) were analyzed. In three of the seven outcome analyses, the summary point estimates favored antibiotics over appendectomy, with a 46% reduction in the relative odds of complications (OR 0.54; 95% confidence interval [CI] 0.37, 0.78; p=0.001); a reduction in sick leave/disability (SMD -0.19; CI -0.33, -0.06; p=0.005), and decreased pain medication utilization (SMD -1.55; CI -1.96, -1.14; p<0.0001). For overall treatment failure, the summary point estimate favored appendectomy, with a 40.2% failure rate for antibiotics versus 8.5% for appendectomy (OR 6.72; CI 0.08, 12.99; p<0.001). Initial treatment failure, LOS, and pain duration were similar in the two groups.

CONCLUSIONS

Non-operative management of uncomplicated appendicitis with antibiotics was associated with significantly fewer complications, better pain control, and shorter sick leave, but overall had inferior efficacy because of the high rate of recurrence in comparison with appendectomy.

Risk factors for necrotizing enterocolitis totalis: a case-control study

OBJECTIVE

The objective of this study was to compare demographic and clinical events in three groups of preterm neonates: those with necrotizing enterocolitis totalis (NEC-T), those with NEC non-totalis (NEC non-T) and in preterm patients without NEC.

STUDY DESIGN

This retrospective case-control study was conducted at Yale New Haven Children's Hospital using patient data from January 1991 to December 2007. Study patients were less than 36 weeks of gestational age (GA) at birth, without gastrointestinal (GI) malformations. Cases (NEC-T) were diagnosed at operation or at autopsy with observation of >80% necrosis of the GI tract. Two control groups were assigned: Group 1 or NEC non-T and Group II or Non-NEC. Two to four controls per case were matched to cases by GA at birth±2 weeks. Demographic and clinical data for the day of diagnosis and retrospectively up to 7 days preceding diagnosis were recorded for those with NEC-T and NEC. Group II controls were matched for date of birth and day of life, in addition to GA at birth.

RESULT

A total of 14 075 patients were admitted to the Newborn Special Care Unit during the study interval. Overall 328 patients (2.3%) developed NEC≥Bell's Stage II; 39 patients met inclusion criteria for NEC-T case status; 148 NEC non-T and 110 non-NEC controls were assigned. In the comparison of NEC T and NEC non-T neonates, use of breast milk was associated with decreased risk of NEC-T, adjusted odds ratio (OR)=0.26, 95% confidence interval (CI) of OR=0.08-0.085, P=0.03. When NEC T and non-NEC patients were compared, having reached full-enteral feeds before the date of diagnosis of the matched case (adjusted OR=28.5, 95% CI of OR=2.7-299, P=0.005) and use of breast milk (adjusted OR=0.09, 95% CI of OR=0.02-0.56, P=0.01) were significantly different between the two groups.

CONCLUSION

Breast milk usage was significantly associated with decreased occurrence of NEC-T in our comparison of NEC-T, NEC non-T and non-NEC patients. Although there were some differences, the majority of demographic and clinical variables assessed were not shown to be significantly different between cases and controls. This highlights the need for more biological data in assessing risk of developing NEC-T.

Abdominal pathology requiring laparotomy in very preterm infants is associated with need for surgical closure of patent ductus arteriosus

BACKGROUND

Extensive intestinal surgery in very preterm infants and its influence on somatic growth is of major concern. There is little consensus as to which is the most appropriate surgical approach in extremely low-birth-weight infants with abdominal pathology. Laparotomy is currently advocated, but peritoneal drainage is also discussed.

OBJECTIVE

To study laparotomy as surgical intervention in newborn infants with less than 28 gestational weeks and to investigate associated mortality and morbidity and its impact on short-term growth.

STUDY DESIGN/METHODS

The study was a retrospective case-control study of newborn infants requiring laparotomy. All infants with gestational age less than 28 weeks who were subject to acute laparotomy in the neonatal period at Sahlgrenska University Hospital during a 5-year period (2003-2007) were included in the study (n = 20). The control group consisted of infants admitted to the unit with the same gestational age but not requiring laparotomy. Infants with severe malformations were excluded.

SUMMARY AND CONCLUSION

Extensive abdominal surgery was feasible in very preterm infants. Necrotizing enterocolitis dominated the abdominal pathology requiring surgery. Patent ductus arteriosus requiring surgical closure occurred more often in the lapatotomy group and in those diagnosed as necrotizing enterocolitis. There was no impact on first year somatic growth.

Antibiotic exposure in the newborn intensive care unit and the risk of necrotizing enterocolitis

OBJECTIVE

To determine whether duration of antibiotic exposure is an independent risk factor for necrotizing enterocolitis (NEC).

STUDY DESIGN

A retrospective, 2:1 control-case analysis was conducted comparing neonates with NEC to those without from 2000 through 2008. Control subjects were matched on gestational age, birth weight, and birth year. In each matched triad, demographic and risk factor data were collected from birth until the diagnosis of NEC in the case subject. Bivariate and multivariate analyses were used to assess associations between risk factors and NEC.

RESULTS

One hundred twenty-four cases of NEC were matched with 248 control subjects. Cases were less likely to have respiratory distress syndrome (P = .018) and more likely to reach full enteral feeding (P = .028) than control subjects. Cases were more likely to have culture-proven sepsis (P < .0001). Given the association between sepsis and antibiotic use, we tested for and found a significant interaction between the two variables (P = .001). When neonates with sepsis were removed from the cohort, the risk of NEC increased significantly with duration of antibiotic exposure. Exposure for >10 days resulted in a nearly threefold increase in the risk of developing NEC.

CONCLUSIONS

Duration of antibiotic exposure is associated with an increased risk of NEC among neonates without prior sepsis.

Novel use of tryptose sulfite cycloserine egg yolk agar for isolation of Clostridium perfringens during an outbreak of necrotizing enterocolitis in a neonatal unit

Clostridium perfringens has been associated with necrotizing enterocolitis (NEC), which is a serious disease of neonates. Our study describes the novel use of selective tryptose sulfite cycloserine with egg yolk agar (TSC-EYA) during a nursery outbreak. This medium provides a rapid, sensitive, and accurate presumptive identification of C. perfringens.

Incidence of necrotizing enterocolitis in very-low-birth-weight infants related to the use of Lactobacillus GG

BACKGROUND

One of the five level III neonatal intensive care units (NICU) in Finland has used prophylactic Lactobacillus GG (LGG) for very-low-birth-weight (VLBW) infants since 1997.

AIM

To examine retrospectively the incidence of necrotizing enterocolitis (NEC) in all five university hospital NICUs in Finland in relation to the use of LGG during the years each unit has belonged to the Vermont Oxford Network (VON).

METHODS

The incidence of NEC was analysed from the national database and from the VON databases separately in all five level III NICUs and additionally in three groups according to the probiotic practice in the hospitals: prophylactic LGG group, probiotics 'on demand' group and no probiotics group.

RESULTS

The incidence of NEC was 4.6% vs. 3.3% vs. 1.8% in the prophylactic LGG group, the no probiotics group and the probiotics 'on demand' group [corrected] respectively; p = 0.0090, chi-square. LGG had no influence on the clinical course of NEC.

CONCLUSIONS

The results of this retrospective report failed to show that LGG prophylaxis protects VLBW infants from the occurrence of NEC, in contrast to previously published results. Our results call for more research regarding effective ways to administer probiotics, including data on appropriate bacteria, strain, dose and timing of administration to achieve clinically robust effects.

Surgery for appendicitis: is it necessary?

BACKGROUND

Appendectomy for acute appendicitis is an effective, universally accepted procedure performed more than 300,000 times annually in the United States. It is generally believed that appendicitis progresses invariably from early inflammation to later gangrene and perforation, and that appendectomy is required for surgical source control. Although non-operative management with antibiotics of uncomplicated diverticulitis, salpingitis, and neonatal enterocolitis is now established, the non-operative management of appendicitis remains largely unexplored.

METHODS

Systematic review of published literature and derived expert opinion.

RESULTS

Clinical, epidemiologic, radiologic, and pathologic evidence is presented for spontaneous resolution of uncomplicated acute appendicitis. The pathogenesis of appendicitis is reviewed with specific consideration of the role of bacterial infection in the pathogenesis. Evidence is also provided documenting the clinical success of non-operative management.

CONCLUSIONS

Appendectomy may not be necessary for the majority of patients with acute uncomplicated appendicitis, as many patients resolve spontaneously and others may be treatable with antibiotics alone. However, the supporting documentation is scant and of poor quality. A randomized, prospective trial of non-operative management versus early appendectomy of acute uncomplicated appendicitis corroborated by radiologic imaging is called for.

Necrotizing enterocolitis in newborns: pathogenesis, prevention and management

Necrotizing enterocolitis (NEC) is primarily a disease process of the gastrointestinal (GI) tract of premature neonates that results in inflammation and bacterial invasion of the bowel wall. Despite advances in the care of premature infants, NEC remains one of the leading causes of morbidity and mortality in this population. It occurs in 1-5% of all neonatal intensive care admissions and 5-10% of all very low birthweight (<1500 g) infants. Although research has presented an interesting array of potential contributing factors, the precise aetiology of this multifactorial disease process remains elusive. Historically, it was believed that NEC arose predominantly from ischaemic injury to the immature GI tract, yet alternate plausible hypotheses indicate that many factors are likely to be involved. These may include issues related to the introduction and advancement of enteric feeding, alterations in the normal bacterial colonization of the GI tract, bacterial translocation and activation of the cytokine cascade, decreased epidermal growth factor, increased platelet activating factor, and mucosal damage from free radical production. Clinical manifestations of NEC may be vague, including increased episodes of apnoea, desaturations, bradycardia, lethargy and temperature instability. There may also be GI-specific symptoms such as feeding intolerance, emesis, bloody stools, abdominal distention and tenderness, and abdominal wall discolouration. Laboratory values may be indicative of infection, coagulation abnormalities and fluid retention. Radiographic signs may include ileus, dilated or fixed intestinal loops, air in the intestinal wall or free air in the abdomen. Medical treatment typically consists of bowel rest and decompression, antibacterial therapy, and management of other haematological or electrolyte imbalances. Increased respiratory and cardiovascular support is sometimes needed. In neonates who do not respond adequately to medical management, or if pneumoperitoneum is present, surgical intervention may occur with either use of a peritoneal drain or laparotomy. Advances in antenatal and neonatal care have resulted in increased survival of extremely preterm neonates. As this at-risk population continues to increase, an effective preventative strategy for NEC is needed. One preventative strategy is the use of antenatal corticosteroids to enhance maturation of the fetus if preterm delivery is likely. Recommendation of use of breast milk, early initiation of trophic feeds and judicoius advancement of enteric feeds are current postnatal strategies. Other preventative strategies that have been investigated include the use of oral antibacterials, antioxidants, supplementation of arginine and epidermal growth factor, none of which have changed clinical practice. Recent promising data indicate that prophylactic use of probiotics may play a role in preventing the onset of NEC. However, more large-scale, definitive studies are needed.

Root cause analysis and Bayesian networks of Down syndrome and necrotizing enterocolitis

OBSERVATION

This study demonstrates the use of root cause analysis and Bayesian networks in assessing risk of Down syndrome and infant mortality due to necrotizing enterocolitis (NEC).

SUBJECTS AND METHODS

The contribution of maternal age, ethnicity, smoking, and infant's comorbidities on mortality associated with NEC (83 cases) was investigated using data obtained from the North Carolina linked birth/infant death files from 1999 to 2003. The data related to Down syndrome, which included 747 infants born with Down syndrome between the years of 1999 and 2003, were provided by the North Carolina Birth defects Monitoring Program. Flowcharts were built to identify potential risk factors and their associations, while the Bayesian network methodology was utilized to encode probabilistic relationships among these variables.

RESULTS AND CONCLUSIONS

On the basis of the NEC model, the 3 most common causes of NEC infant mortality were respiratory tract conditions, cardiac, and infection-related problems. For the second application, prior live births (at least 1 prior birth) and infant's gender (male) were found to be the most prevalent causes of Down syndrome. Bayesian belief networks constitute an excellent tool for explorative and causal data analysis, and can assist health care providers in gaining insight into a complex problem.

The role of the intestinal barrier in the pathogenesis of necrotizing enterocolitis

Necrotizing enterocolitis (NEC) is the leading cause of death from gastrointestinal disease in neonates and is increasing in frequency because of recent advances in neonatal care. NEC develops in a stressed preterm infant in the setting of intestinal barrier disruption, systemic inflammation, and leads to, multisystem organ failure. The intestinal barrier lies at the interface between microbes within the intestinal lumen and the immune system of the host, and has both immunological and mechanical components. These components serve to protect the host from invading pathogens and, at the same time, provide a surface area for nutrient absorption. Factors that lead to impairments in the function of the intestinal barrier may predispose the host to the invasion of gut-derived microbes and to the development of systemic inflammatory disease. This process, termed "bacterial translocation," may be compounded during instances in which the mechanisms that regulate the repair of the intestinal barrier are disrupted. Bacterial translocation is of particular concern to the newborn patient, in which immaturity of the mechanical barrier and incomplete development of the host immune system combine to render the host at particular risk for the development of intestinal inflammation. This review will serve to provide an overview of recent evidence regarding the components of the intestinal barrier, and the mechanisms by which disruptions in barrier function may contribute to the pathogenesis of NEC.