Clinical Presentation and Multifactorial Pathogenesis of Necrotizing Enterocolitis in the Preterm Infant

Resuscitation strategies for surgical patients in the neonatal intensive care unit

Resuscitation of an infant with surgical complications includes both perioperative and post-operative management. In most cases this requires a multidisciplinary approach to achieve the best outcomes. Challenges include immediate expert management at infant delivery with the use of protocolized care, available anesthesia expertise, close monitoring of electrolytes with prompt attention to fluid status, and meticulous pain management. In this review, we will address contemporary research and ongoing challenges associated with resuscitation. We will make recommendations for effective resuscitation of this vulnerable and unique population from premature infant to term infant with complex surgical needs.

Development of a Prediction Model for Surgery or Early Mortality at the Time of Initial Assessment for Necrotizing Enterocolitis

OBJECTIVE

 No available scale, at the time of initial evaluation for necrotizing enterocolitis (NEC), accurately predicts, that is, with an area under the curve (AUC) ≥0.9, which preterm infants will undergo surgery for NEC stage III or die within a week.

STUDY DESIGN

 This is a retrospective cohort study (n = 261) of preterm infants with <33 weeks' gestation or <1,500 g birth weight with either suspected or with definite NEC born at Parkland Hospital between 2009 and 2021. A prediction model using the new HASOFA score (Hyperglycemia, Hyperkalemia, use of inotropes for Hypotension during the prior week, Acidemia, Neonatal Sequential Organ Failure Assessment [nSOFA] score) was compared with a similar model using the nSOFA score.

RESULTS

 Among 261 infants, 112 infants had NEC stage I, 68 with NEC stage II, and 81 with NEC stage III based on modified Bell's classification. The primary outcome, surgery for NEC stage III or death within a week, occurred in 81 infants (surgery in 66 infants and death in 38 infants). All infants with pneumoperitoneum or abdominal compartment syndrome either died or had surgery. The HASOFA and the nSOFA scores were evaluated in 254 and 253 infants, respectively, at the time of the initial workup for NEC. Both models were internally validated. The HASOFA model was a better predictor of surgery for NEC stage III or death within a week than the nSOFA model, with greater AUC 0.909 versus 0.825, respectively, p < 0.001. Combining HASOFA at initial assessment with concurrent or later presence of abdominal wall erythema or portal gas improved the prediction surgery for NEC stage III or death with AUC 0.942 or 0.956, respectively.

CONCLUSION

 Using this new internally validated prediction model, surgery for NEC stage III or death within a week can be accurately predicted at the time of initial assessment for NEC.

KEY POINTS

· No available scale, at initial evaluation, accurately predicts which preterm infants will undergo surgery for NEC stage III or die within a week.. · In this retrospective cohort study of 261 preterm infants with either suspected or definite NEC we developed a new prediction model (HASOFA score).. · The HASOFA-model had high discrimination (AUC: 0.909) and excellent calibration and was internally validated..

Impact of Size for Gestational Age on Multivariate Analysis of Factors Associated with Necrotizing Enterocolitis in Preterm Infants: Retrospective Cohort Study

OBJECTIVE

Necrotizing enterocolitis (NEC) primarily affects preterm, especially small for gestational age (SGA), infants. This study was designed to (1) describe frequency and timing of NEC in SGA versus non-SGA infants and (2) assess whether NEC is independently associated with the severity of intrauterine growth failure.

STUDY DESIGN

Retrospective cohort study of infants without severe congenital malformations born <33 weeks' gestational age (GA) carried out from 2009 to 2021. The frequency and time of NEC were compared between SGA and non-SGA infants. Multivariate logistic regression was used to assess whether NEC was independently associated with intrauterine growth restriction. Severe growth restriction was defined as birth weight Z-score <  -2.

RESULTS

Among 2,940 infants, the frequency of NEC was higher in SGA than in non-SGA infants (25/268 [9.3%] vs. 110/2,672 [4.1%], respectively, p < 0.001). NEC developed 2 weeks later in SGA than non-SGA infants. In multivariate analysis, the adjusted odds of NEC increased with extreme prematurity (<28 weeks' GA) and with severe but not moderate growth restriction. The adjusted odds of NEC increased with urinary tract infection or sepsis within a week prior to NEC, were lower in infants fed their mother's own milk until discharge, and did not change over five epochs. NEC was independently associated with antenatal steroid (ANS) exposure in infants with birth weight (BW) Z-score < 0.

CONCLUSION

NEC was more frequent in SGA than in non-SGA infants and developed 2 weeks later in SGA infants. NEC was independently associated with severe intrauterine growth failure and with ANS exposure in infants with BW Z-score < 0.

KEY POINTS

· We studied 2,940 infants <33 weeks' GA.. · We assessed NEC.. · NEC was more frequent in SGA infants.. · NEC occurred 2 weeks later in SGA infants.. · NEC was associated with severe growth restriction..

Assessment of inflammatory biomarkers to identify surgical/death necrotizing enterocolitis in preterm infants without pneumoperitoneum

BACKGROUND

Necrotizing enterocolitis (NEC) is a life-threatening disease that affects premature infants. However, the role of inflammatory biomarkers in identifying surgical/death NEC without pneumoperitoneum remains elusive.

PURPOSE

We aimed to verify the value of platelet-to-lymphocyte ratio (PLR) and the combination of white blood cell (WBC), absolute neutrophil count (ANC), absolute lymphocyte count (ALC), neutrophil lymphocyte ratio (NLR), PLR, C reactive protein (CRP) and procalcitonin (PCT) in predicting the severity of NEC, and to construct a model to differ surgically NEC from non-surgically NEC.

METHODS

A retrospective analysis was performed on 191 premature infants with NEC. Based on the inclusion and exclusion criteria, 90 infants with Stage II and IIIA NEC were enrolled in this study, including surgical/death NEC (n = 38) and medical NEC (n = 52). The values of inflammatory biomarkers were collected within 24 h of onset.

RESULTS

The univariate analysis revealed that the values of WBC (p = 0.040), ANC (p = 0.048), PLR (p = 0.009), CRP (p = 0.016) and PCT (p < 0.01) in surgical/death NEC cohort were significantly higher than medical NEC cohort. Binary multivariate logistic regression analysis indicates that ANC, PLR, CRP, and PCT are capable of distinguishing infants with surgical/death NEC, and the AUC of the regression equation was 0.79 (95% CI 0.64-0.89; sensitivity 0.63; specificity 0.88), suggesting the equation has a good discrimination.

IMPLICATIONS FOR PRACTICE AND RESEARCH

Elevated PLR is associated with severe inflammation in surgical/death NEC patients. The prediction modelling of combination of ANC, PLR, CRP and PCT can differentiate surgical/death NEC from infants with medical NEC, which may improve risk awareness and facilitate effective communication between nurses and clinicians. However, multicentre research is needed to verify these findings for better clinical management of NEC.

Feeding intolerance scoring system in very preterm and very low birth weight infants using clinical and ultrasound findings

Very preterm infants are at a high risk of developing feeding intolerance; however, there are no widely accepted definitions of feeding intolerance. This study aimed to develop a scoring system for feeding intolerance in very preterm infants by combining clinical symptoms and ultrasonography (US) findings. This prospective cohort study included very preterm and/or very low birth weight infants. We defined feeding intolerance as the inability to achieve full feeding (150 ml/kg/day) by 14 days of life. The clinical findings included vomiting, abdominal distention, and gastric fluid color. US findings included intestinal peristaltic frequency, gastric residual volume, peak systolic velocity, and the resistive index of the superior mesenteric artery. We conducted multivariate analyses to evaluate the potential predictors and developed a scoring system to predict feeding intolerance. A total of 156 infants fulfilled the eligibility criteria; however, 16 dropped out due to death. The proportion of patients with feeding intolerance was 60 (42.8%). Based on the predictive ability, predictors of feeding intolerance were determined using data from the US at 5-7 days of age. According to multivariate analysis, the final model consisted of 5 predictors: abdominal distention (score 1), hemorrhagic gastric fluid (score 2), intestinal peristaltic movement ≤18x/2 min (score 2), gastric fluid residue >25% (score 2), and resistive index >0.785 (score 2). A score equal to or above 5 indicated an increased risk of feeding intolerance with a positive predictive value of 84.4% (95% confidence interval:73.9-95.0) and a negative predictive value of 76.8% (95% confidence interval:68.4-85.3). The scoring system had good discrimination (area under the receiver operating characteristic curve:0.90) and calibration (p = 0.530) abilities. This study developed an objective, accurate, easy, and safe scoring system for predicting feeding intolerance based on clinical findings, 2D US, and color Doppler US.

Impact of fetal inflammatory response on the severity of necrotizing enterocolitis in preterm infants

OBJECTIVE

Neonates born with fetal inflammatory response (FIR) are at increased risk for adverse neonatal outcomes. Our objective was to determine whether FIR and its severity is associated with severity of necrotizing enterocolitis (NEC) in preterm infants.

METHODS

A case-control retrospective study of infants <33 weeks gestational age or <1500 g birthweight, including 260 with stage I-III NEC and 520 controls matched for gestational age. Placental pathology was evaluated, and FIR progression and its severity were defined according to Amsterdam classification.

RESULTS

In this study, mild FIR (i.e., stage 1 FIR) was present in 52 controls (10.0%) and 22 infants with stage I-III NEC (8.5%), while moderate to severe FIR (i.e., ≥stage 2 FIR) was present in 16 controls (3.1%) and 47 infants with stage I-III NEC (18.1%). Both stage and grade of FIR were associated with stage of NEC (P < 0.001). On multinomial logistic regression, stage III NEC was associated with stage of FIR (P < 0.001).

CONCLUSION

This is the first report demonstrating the association between progression and increasing severity of FIR and stage of NEC.

IMPACT

Fetal Inflammatory Response (FIR) and its progression and severity are associated with the stages of necrotizing enterocolitis (NEC). This is the first study demonstrating the impact of progression and severity of FIR on stage III NEC. These observations provide additional insight into understanding the impact of intrauterine exposure to inflammation on the severity of NEC in preterm infants.

Plant-Derived Substances for Prevention of Necrotising Enterocolitis: A Systematic Review of Animal Studies

Inflammation, oxidative injury, and gut dysbiosis play an important role in the pathogenesis of necrotising enterocolitis (NEC). Plant-derived substances have historically been used as therapeutic agents due to their anti-inflammatory, antioxidant, and antimicrobial properties. We aimed to review pre-clinical evidence for plant-derived substances in the prevention and treatment of NEC. A systematic review was conducted using the following databases: PubMed, EMBASE, EMCARE, MEDLINE and Cochrane Library (PROSPERO CRD42022365477). Randomized controlled trials (RCTs) and quasi-RCTs that evaluated a plant-derived substance as an intervention for NEC in an animal model of the illness and compared pre-stated outcomes (e.g., clinical severity, severity of intestinal injury, mortality, laboratory markers of inflammation and oxidative injury) were included. Sixteen studies (n = 610) were included in the systematic review. Ten of the sixteen included RCTs (Preterm rat pups: 15, Mice: 1) reported mortality and all reported NEC-related histology. Meta-analysis showed decreased mortality [12/134 vs. 27/135; RR: 0.48 (95% CI: 0.26 to 0.87); p = 0.02, 10 RCTs] and decreased NEC in the experimental group [24/126 vs. 55/79; RR: 0.34 (95% CI: 0.22 to 0.52); p < 0.001, 6 RCTs]. Markers of inflammation (n = 11) and oxidative stress (n = 13) improved in all the studies that have reported this outcome. There was no significant publication bias for the outcome of mortality. Plant-derived substances have the potential to reduce the incidence and severity of histologically diagnosed NEC and mortality in rodent models. These findings are helpful in guiding further pre-clinical studies towards developing a food supplement for the prevention of NEC in preterm infants.

Role of the microbiome in pathophysiology of necrotising enterocolitis in preterm neonates

Although necrotising enterocolitis (NEC) is a serious, life-threatening disease, improved neonatal care is increasing the number of survivors with NEC among extremely preterm neonates. Therapy is nevertheless mostly symptomatic and the mortality rate remains high, especially among neonates requiring surgery. Therefore, it is important to focus on preventing the disease and modifiable risk factors. NEC's pathophysiology is multifaceted, with key factors being immaturity of the immune and barrier protective mechanisms of the premature gut and exaggerated proinflammatory reaction to insults like gut hypoxia, enteral nutrition or microbial dysbiosis. The role of the intestinal microbiome in the pathophysiology of NEC has been a subject of research for many years, but to date no specific pathogen or type of dysbiosis has been connected with NEC development. This review assesses current knowledge as to the role of the intestinal microbiota in the pathophysiology of NEC and the possibilities for positively influencing it.

Can Enterococcus faecium prevent NEC in preterm infants?: A systematic review and meta-analysis

OBJECTIVE

Previous some systematic reviews reported that probiotics may benefit the prevention of NEC in preterm infants. But dissimilar bacterial strains and taxa used in included studies possibly result in bias. There is not a rounded systematic review which has estimated the benefit and safety of Enterococcus faecium to prevent NEC in preterm infants to date before we conducted.

METHODS

This systematic review of randomized controlled trials and retrospective studies analyzing the benefit of Enterococcus faecium to prevent NEC in preterm infants was performed using PubMed, Web of Science, Cochrane Library, EMBASE, Wanfang data and China National Knowledge Infrastructure databases from inception to April 14, 2023. The search terms were "preterm" AND "necrotizing enterocolitis" AND "Enterococcus faecium OR probiotics." Studies reporting NEC involving preterm infants who were given Enterococcus faecium were included in this systematic review. A sensitivity analysis was conducted to assess the stability of results. A funnel plot was generated to identify publication bias. Two authors appraised studies quality and extracted data independently. This work has been reported according with preferred reporting items for systematic reviews and meta-analyses and assessing the methodological quality of systematic reviews. Statistical analysis was conducted using Review Manager 5.3 software. Risk ratio (RR) with 95% confidence intervals (CI) was calculated and analyzed.

RESULTS

Seven studies (N = 1487 participants) were included in this systematic review, and 6 randomized, controlled trials (N = 1237 participants) were included in the meta-analysis. Comparing with the control groups, the Enterococcus faecium groups had a significant decline in the incidence of NEC Bell stage II or higher (RR: 0.3138, 95% CI: 0.1983-0.4965; P < .00001; 6 studies, n = 1237) and infection (RR: 0.4818, 95% CI: 0.2950-0.7869; P = .004; 3 studies, n = 710).

CONCLUSIONS

Enterococcus faecium is effective and safe in preventing NEC (Bell stage II or higher) in preterm infants. But all studies included came from China. The dosages and durations of taking Enterococcus faecium were various.

Does protocol miconazole administration improve mortality and morbidity on surgical necrotizing enterocolitis?

PURPOSE

Our previous clinical pilot study reported that miconazole (MCZ) prevented morbidity from surgical necrotizing enterocolitis (NEC). The present study re-investigated this effect in a long-term cohort over 20 years.

METHODS

We conducted a retrospective cohort study from April 1998 to March 2020. A total of 1169 extremely low-birth-weight infants (ELBWIs) admitted to our neonatal intensive care unit, including 45 with NEC (3.8%), underwent surgery. Since 2002, protocol MCZ administration for 3 weeks has been applied for neonates born before 26 weeks' gestation or weighing under 1000 g. We compared the background characteristics and clinical outcomes between patients with and without MCZ administration.

RESULTS

The morbidity rate decreased after applying the MCZ protocol, but no improvement in mortality was seen. A propensity score-matched analysis indicated that treated patients by MCZ showed a delay in developing surgical NEC by 12 days. The MCZ protocol also helped increase body weight at surgery. Prophylactic MCZ administration did not improve the neurological development of the language-social and postural-motor domains in the surgical NEC patients. But cognitive-adaptive domain caught up by a chronological age of 3 years old.

CONCLUSIONS

Revising the protocol to extend the dosing period may improve the outcomes of surgical NEC after the onset.

Vitamin d deficiency with high parathyroid hormone levels is related to late onset SEPSIS among preterm infants

Preterm infants (PTs) are at greater risk for vitamin D deficiency, which relates to the possibility of a higher incidence of comorbidities. Our goal was twofold, 1) to monitor vitamin D, calcium, phosphorus, parathyroid hormone (PTH), matrix metalloproteinase-8 (MMP-8) serum levels at three-time points during hospitalization, and 2) to assess the association between 25-hydroxyvitamin D (25OHD) levels and outcomes in PTs.

METHODS

We carried out a follow-up on 50 Caucasian PTs ≤ 32 weeks of gestational age (GA) and/or ≤ 1500 g birth weight at 28 days and at 4 months. PTs were divided into two subgroups for tests of association with clinical outcomes based on vitamin D deficient infants 25(OH) D cord blood levels: ≤ 20 ng/ml). At an initial stage, 25(OH) D levels were determined in maternal/preterm blood samples and were compared to full term delivery infants.

RESULTS

There were no differences in 25(OH) D serum levels at birth when comparing PTs to term infants, or regarding maternal levels. A strong positive correlation was detected between maternal and neonatal 25(OH) D serum levels among PTs and term infants (r: 0.466; p < 0.001). Neonates with vitamin D deficiency did not present a higher incidence of comorbidities. PTs were classified in two subgroups based on vitamin D and PTH (group 1: vitamin D < 20 ng/mL and PTH > 60 pg/mL; group 2: vitamin D > 20 and PTH < 60 pg/mL). The PTs in group 1 showed a higher incidence of LOS (RR: 2; 95% CI: 1.31-3.55). No relationship was observed between MMP-8 serum levels and the incidence of sepsis.

CONCLUSIONS

This study did not find any evidence of an increase in preterm birth risk related to vitamin D level at birth. Vitamin D deficiency by itself is not associated with a higher incidence of comorbidities. However, the binomial vitamin D-PTH must be taken into consideration.

Necrotizing enterocolitis, gut microbes, and sepsis

Necrotizing enterocolitis (NEC) is a devastating disease in premature infants and the leading cause of death and disability from gastrointestinal disease in this vulnerable population. Although the pathophysiology of NEC remains incompletely understood, current thinking indicates that the disease develops in response to dietary and bacterial factors in the setting of a vulnerable host. As NEC progresses, intestinal perforation can result in serious infection with the development of overwhelming sepsis. In seeking to understand the mechanisms by which bacterial signaling on the intestinal epithelium can lead to NEC, we have shown that the gram-negative bacterial receptor toll-like receptor 4 is a critical regulator of NEC development, a finding that has been confirmed by many other groups. This review article provides recent findings on the interaction of microbial signaling, the immature immune system, intestinal ischemia, and systemic inflammation in the pathogenesis of NEC and the development of sepsis. We will also review promising therapeutic approaches that show efficacy in pre-clinical studies.