Splanchnic Oxygenation at First Enteral Feeding in Preterm Infants: Correlation With Feeding Intolerance

Changes in adequacy of splanchnic oxygen delivery and splanchnic artery Doppler after bolus feedings in infants: A systematic review and meta-analysis

BACKGROUND

Current practice regarding timing of feed initiation and feed tolerance largely relies on anecdotal practice and protocols. This study aims to provide an objective measure to guide clinical practice by analyzing changes in splanchnic regional oxygen saturation and Doppler patterns with feeds.

METHODS

A systematic review was performed. Inclusion criteria were: 1) patients under 1 year of age; 2) splanchnic regional oxygen saturation with near infrared spectroscopy before and after feeds or mesenteric Doppler findings before and after feeds; and 3) clinical parameters must have been presented as either mean and standard deviation or median and range. Endpoints of interest included splanchnic regional oxygen saturation, splanchnic systolic velocity, and splanchnic diastolic velocity. Meta-analyses were conducted using an inverse-variance model. The pooled effects are reported as mean difference and 95% confidence interval. Meta-regression was conducted for each endpoint with the following independent variables entered into the model: study year, gestational age, birth weight, time to measurement, and age at time of study.

RESULTS

This study included 8 studies with a total of 240 patients. Splanchnic regional oxygen saturation did not significantly differ after feeds (mean difference +1.0, 95% CI -2.9 to 4.9, p-value 0.62). Sensitivity analyses demonstrated that gestational age under 28 weeks was associated with a significant decrease in splanchnic regional oxygen saturation and GA over 30 weeks was not. Splanchnic artery systolic velocity was significantly higher after feeds (mean difference +34.0 cm/s, 95% CI 11.1-57.0 cm/s, p-value <0.01). Sensitivity analyses for gestational age and birth weight did not find any significant difference in pooled effect.

CONCLUSION

Splanchnic regional oxygen saturation was significantly decreased after feeds in those patients under 28 weeks of gestation compared to those over 30 weeks. Systolic and diastolic Doppler velocities were significantly higher after feeds without differences in gestational age.

Biobehavioral Efficacy of the Elevated Side-Lying Position for Feeding Preterm Infants: Study Protocol

AIM

Present a study protocol investigating the biobehavioral efficacy of side-lying vs. supine positions on physiologic and behavioural responses of preterm infants during their transition from tube to full oral feeding, and identify associated infant characteristics.

DESIGN

Within-subject cross-over design.

METHODS

Sixty preterm infants born at ≤35 weeks gestational age (GA) from a level 3 NICU are observed during their transition to full oral feeding. Each undergoes two feedings within 24 h: One in the supine position and one in the side-lying position. Continuous physiologic and video data are collected 30 min before and after feeding. Physiologic measures include heart rate, respiratory rate, oxygen saturation, and autonomic nervous system regulation (heart rate variability and splanchnic-cerebral oxygen ratio). Behavioural responses are assessed via microanalysis of the sucking and breathing waveforms and videotaped feedings (Suck-breathe coordination and Early Feeding Skills assessment tool). Data are analysed using linear mixed-effects models. IRB was obtained in September 2021, with funding awarded by the National Institute of Nursing Research in July 2021.

CONCLUSION

This study will enhance our understanding of the effects of the side-lying position on preterm infant feeding, providing guidance for its clinical use as a feeding strategy.

IMPLICATIONS

Provides vital knowledge to guide evidence-based practices in enhancing oral feeding in preterm infants and inform future pivotal efficacy trials.

IMPACT

If effective, this intervention could significantly enhance the management of feeding challenges in preterm infants across neonatal care settings.

REPORTING METHOD

Standard Protocol Items: Recommendations for Interventional Trials (SPIRIT) 2013.

PATIENT OR PUBLIC CONTRIBUTION

While direct parent involvement was not documented in our protocol, informal feedback on data collection procedures from parents was incorporated. Additionally, extensive engagement with healthcare professionals during study design addressed patient safety, logistical challenges, and ethical standards in NICU settings.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT04942106; registered on 28 June 2021. Available at: https://clinicaltrials.gov/ct2/show/NCT04942106.

Nutritional Strategies for Preterm Neonates and Preterm Neonates Undergoing Surgery: New Insights for Practice and Wrong Beliefs to Uproot

The nutrition of preterm infants remains contaminated by wrong beliefs that reflect inexactitudes and perpetuate old practices. In this narrative review, we report current evidence in preterm neonates and in preterm neonates undergoing surgery. Convictions that necrotizing enterocolitis is reduced by the delay in introducing enteral feeding, a slow advancement in enteral feeds, and the systematic control of residual gastric volumes, should be abandoned. On the contrary, these practices prolong the time to reach full enteral feeding. The length of parenteral nutrition should be as short as possible to reduce the infectious risk. Intrauterine growth restriction, hemodynamic and respiratory instability, and patent ductus arteriosus should be considered in advancing enteral feeds, but they must not translate into prolonged fasting, which can be equally dangerous. Clinicians should also keep in mind the risk of refeeding syndrome in case of high amino acid intake and inadequate electrolyte supply, closely monitoring them. Conversely, when preterm infants undergo surgery, nutritional strategies are still based on retrospective studies and opinions rather than on randomized controlled trials. Finally, this review also highlights how the use of adequately fortified human milk is strongly recommended, as it offers unique benefits for immune and gastrointestinal health and neurodevelopmental outcomes.

Changes in regional tissue oxygen saturation values during the first week of life in stable preterm infants

OBJECTIVES

Near infrared spectroscopy (NIRS) is a non-invasive method for monitoring regional tissue oxygen saturation (rSO2). The purpose of this study is to investigate the changes that occur in cerebral, splanchnic, and renal rSO2 and fractional tissue oxygen extraction (FTOE) in stable preterm infants in the first week of life.

METHODS

Prospective observational study of infants born 30-34 weeks gestation at NYU Langone Health between November 2017 and November 2018. Cerebral, renal, and splanchnic rSO2 were monitored from 12 to 72 h of life, and at seven days. Subjects were divided into gestational age (GA) cohorts. Average rSO2, splanchnic cerebral oxygen ratio (SCOR), FTOE, and regional intra-subject variability was calculated at each location at five different time intervals: 0-12 h, 12-24 h, 24-48 h, 48-72 h, and one week of life.

RESULTS

Twenty subjects were enrolled. The average cerebral rSO2 ranged from 76.8 to 92.8 %, renal rSO2 from 65.1 to 91.1 %, and splanchnic rSO2 from 36.1 to 76.3 %. The SCOR ranged from 0.45 to 0.94. The strongest correlation between the GA cohorts was in the cerebral region (R2=0.94) and weakest correlation was in the splanchnic region (R2=0.81). The FTOE increased in all three locations over time. Intra-subject variability was lowest in the cerebral region (1.3 % (±1.9)).

CONCLUSIONS

The cerebral region showed the strongest correlation between GA cohorts and lowest intra-subject variability, making it the most suitable for clinical use when monitoring for tissue hypoxia. Further studies are needed to further examine rSO2 in preterm infants.

[Application of near-infrared spectroscopy in the early identification of neonatal gastrointestinal diseases]

Necrotizing enterocolitis (NEC) is one of the most common gastrointestinal diseases in neonatal intensive care units, characterized by rapid progression and a high mortality rate. Local intestinal ischemia and hypoxia are significant contributors to NEC. Feeding intolerance (FI), which refers to a range of gastrointestinal manifestations arising from the inability to tolerate enteral nutrition, is one of the most common clinical issues in neonates, and preventing and treating FI is crucial for improving neonatal survival rates. Near-infrared spectroscopy is a clinical tool that can be used at the bedside to monitor regional oxygen saturation. It is non-invasive, reliable, and sustainable, and its feasibility and safety in assessing intestinal blood circulation have been validated. Early identification of intestinal ischemia and differentiation of FI from precursor symptoms of NEC, as well as predicting the occurrence of NEC, are extremely important for reducing intestinal injury and adverse long-term outcomes. In recent years, there has been new research progress related to the monitoring of intestinal tissue oxygen saturation and cerebral oxygen saturation for the early identification of FI and precursor symptoms of NEC, and this article provides a review of these developments.

Neonatal somatic oxygenation and perfusion assessment using near-infrared spectroscopy : Part of the series on near-infrared spectroscopy by the European Society of Paediatric Research Special Interest Group "Near-Infrared Spectroscopy"

In this narrative review, we summarize the current knowledge and applications of somatic near-infrared spectroscopy (NIRS), with a focus on intestinal, renal, limb, and multi-site applications in neonates. Assessing somatic oxygenation at various body locations in neonates may aid in the understanding of underlying pathophysiology of organ injury. Considering cerebral autoregulation may be active to protect the brain during systemic circulatory failure, peripheral somatic oxygenation may potentially provide an early indication of neonatal cardiovascular failure and ultimate hypoxemic injury to vital organs including the brain. Certain intestinal oxygenation patterns appear to be associated with the onset and course of necrotizing enterocolitis, whereas impaired renal oxygenation may indicate the onset of acute kidney injury after various types of hypoxic events. Peripheral muscle oxygenation measured at a limb may be particularly effective in the early prediction of shock in neonates. Using multi-site NIRS may complement current approaches and clinical investigations to alert for neonatal tissue hypoxemia, and potentially even guide management. However, somatic NIRS has its inherent limitations in regard to accuracy. Interpretation of organ-specific values can also be challenging. Last, currently there are limited prospective intervention studies, and clinical benefits need to be examined further, after the clarification of critical threshold-values. IMPACT: The assessment of somatic oxygenation using NIRS may contribute to the prediction of specific diseases in hemodynamically challenged neonates. Furthermore, it may give early warning signs for impending cardiovascular failure, and impaired cerebral circulation and oxygenation. We present a comprehensive overview of the literature on applications of NIRS to various somatic areas, with a focus on its potential clinical applicability, including future research directions. This paper will enable prospective standardized studies, and multicenter collaboration to obtain statistical power, likely to advance the field.

Near-infrared spectroscopy in the medical management of infants

Near-infrared spectroscopy (NIRS) is a technology that is easy to use and can provide helpful information about organ oxygenation and perfusion by measuring regional tissue oxygen saturation (rSO2) with near-infrared light. The sensors can be placed in different anatomical locations to monitor rSO2 levels in several organs. While NIRS is not without limitations, this equipment is now becoming increasingly integrated into modern healthcare practice with the goal of achieving better outcomes for patients. It can be particularly applicable in the monitoring of pediatric patients because of their size, and especially so in infant patients. Infants are ideal for NIRS monitoring as nearly all of their vital organs lie near the skin surface which near-infrared light penetrates through. In addition, infants are a difficult population to evaluate with traditional invasive monitoring techniques that normally rely on the use of larger catheters and maintaining vascular access. Pediatric clinicians can observe rSO2 values in order to gain insight about tissue perfusion, oxygenation, and the metabolic status of their patients. In this way, NIRS can be used in a non-invasive manner to either continuously or periodically check rSO2. Because of these attributes and capabilities, NIRS can be used in various pediatric inpatient settings and on a variety of patients who require monitoring. The primary objective of this review is to provide pediatric clinicians with a general understanding of how NIRS works, to discuss how it currently is being studied and employed, and how NIRS could be increasingly used in the near future, all with a focus on infant management.

Is acidemia at birth a risk factor for functional gastrointestinal disorders?

Functional gastrointestinal disorders (FGIDs) are common in early childhood. It has been demonstrated that neonatal acidemia at delivery can lead to significant neonatal morbidity. The primary aim of this study was to evaluate the relationship between acidemia at birth and the development of FGIDs, as regurgitation, colic, and constipation, in term infants. Term newborns born at the Foggia University Hospital, Italy during the year 2020 were included in the study. As per routine clinical practice, a cord blood gas analysis on a blood sample drawn from the umbilical artery (UA) of each infant immediately after birth was performed, and Apgar score was recorded. One year after birth, each infant's parents were interviewed through a phone call to investigate development of FGIDs, feeding practices, and morbidities. During the study period, 1574 term newborns met the inclusion criteria. The prevalence of infantile colic, regurgitation, and constipation was higher in infants with low UA pH (colic 51.5% vs. 25.4%, p < 0.001; regurgitation 30.6% vs. 15.2%, p < 0.001; constipation 24.6% vs. 16.0%, p = 0.015), with infants having moderate-severe acidemia facing the highest risk for all the examined FGIDs. In binary logistic regression analyses, UA pH and perinatal antibiotic exposure proved to be independently associated with the later diagnosis of each FGID.

CONCLUSION

Newborns with acidemia at birth appear to face a higher risk of FGIDs in infancy. Avoiding low cord blood pH should continue to be the goal for obstetricians, while enhanced long-term surveillance for infants who experienced birth acidemia should be required.

WHAT IS KNOWN

• Cord blood gas analysis is recommended in all high-risk deliveries, and in some centers, it is performed after all deliveries. • Neonatal acidemia at birth has been linked to adverse outcomes, mainly neurological. Recently, perinatal asphyxia has been reported to increase the risk of developing necrotizing enterocolitis in term infants.

WHAT IS NEW

• An association between acidemia at birth and risk of developing FGIDs such as regurgitation and colic during the first year of life had never been described so far. • An increased surveillance of infants with low UA pH at birth may be beneficial and could allow for early detection of any of the reported FGIDs.

Regional Splanchnic Oxygenation during Continuous versus Bolus Feeding among Stable Preterm Infants

Introduction: There is no agreement regarding the best method for tube-feeding preterm infants. Few studies, to date, have evaluated the influence of different methods of enteral feeding on intestinal oxygenation. The use of near-infrared spectroscopy (NIRS) has permitted the noninvasive measurement of splanchnic regional oxygenation (rSO₂S) in different clinical conditions. The aim of this prospective, single-center study was to compare rSO₂S during continuous versus bolus feeding among stable preterm infants. Methods: Twenty-one preterm infants, less than 32 weeks gestation and appropriate for gestational age, were enrolled. All infants were clinically stable and on full tube feedings. Each infant received a bolus feeding initially (20 min duration), and after 3 h, a continuous feeding (5 h duration). Infants were evaluated 30 min before and 30 min after the bolus and continuous feedings. The regional splanchnic saturation (rSO₂S) was measured using near-infrared spectroscopy (NIRS) technology and systemic saturation was measured with pulse oximetry. From these measurements, we calculated the splanchnic fractional oxygen extraction ratio (FOES) for each of the four intervals. Results: rSO₂S decreased after continuous vs. bolus feeding (p = 0.025), while there was a trend toward decreased SaO₂ after bolus feeding (p = 0.055). The FOES, which reflects intestinal oxygen extraction, was not affected by the feeding mode (p = 0.129). Discussion/Conclusion: Continuous vs. bolus feeding decreases rSO₂S but does not affect oxygen extraction by intestinal tissue; after bolus feeding there was a trend towards decreased systemic saturation.

A systematic review of the definitions and prevalence of feeding intolerance in preterm infants

BACKGROUND & AIMS

Feeding intolerance (FI) is a common phenomenon experienced in preterm infants in neonatal intensive care units, as well as being a focus of many research studies into feeding methods, particularly in relation to comorbidities. There is no widely accepted definition of FI. This systematic review aimed to explore the range of definitions used for FI and provide an estimate of the prevalence amongst preterm infants.

METHODS

Searches were completed on MEDLINE (includes the Cochrane library), Embase, PsycInfo, CINAHL, NHS Evidence and Web of Science. Inclusion criteria; preterm infants in neonatal units, a clear definition of FI, >10 patients and be available in English language. Case reports were excluded.

RESULTS

One hundred studies were included. Definitions of FI were inconsistent. Studies were grouped according to definition used into: Group A - measuring gastric residual volume (GRV) only; group B - GRV and abdominal distension (AD); group C - GRV, AD and gastrointestinal symptoms (GI) which included any of vomiting, bilious vomiting and blood in stool; group D- GRV and GI; group E - AD and GI; group F - GI only and group G - any other elements used. Meta-analysis demonstrated that prevalence of FI between groups varied from 15 to 30% with an overall prevalence of 27% (95% confidence interval 23-31%). Group A had the highest prevalence. Review of time to full enteral feed was performed (37 studies) which demonstrated a range of 11.3-18.3 days depending on which FI definition used.

DISCUSSION

Definitions of FI in research are inconsistent, a similar finding to that seen in studies in both paediatric and adult critical care populations. The difficulty of defining FI in the preterm population is the concern regarding necrotising enterocolitis, with some studies using an overlap in their definitions, despite differing pathophysiology and management. Due to the heterogeneity of data obtained in this review regarding definitions used, further robust research is required in order to conclude which elements which should be used to define FI in this population.

PROSPERO NUMBER

CRD42019155596. Registered November 2019.

NIRS as a biomarker of bowel ischaemia & surgical pathology: A meta-analysis of studies in newborns

OBJECTIVE

We performed a meta-analysis on Near-infrared Spectroscopy (NIRS) as a biomarker of bowel ischaemia.

SUMMARY BACKGROUND DATA

NIRS allows non-invasive assessment of gastrointestinal regional oxygen saturation (GrSO₂). Studies to date have focused on the feasibility of NIRS in clinical practice and its reproducibility. GrSO₂ can be used alone, or in conjunction with cerebral NIRS to give a Cerebral Splanchnic Oxygenation Ratio (CSOR). We assess published data on abdominal NIRS as a marker of bowel ischaemia.

METHODS

A literature review was conducted using the PRISMA method. Data on GrSO₂ and CSOR in controls and patients with confirmed ischaemia was included in a meta-analysis, and used to identify a diagnostic threshold.

RESULTS

14 studies were identified. Meta-analysis demonstrated that GrSO₂ (p < 0.01) and CSOR (p < 0.01) were significantly lower in neonates with bowel pathology associated with ischaemia than controls. Area under the curve for GrSO₂ was 0.80, with Youden's index highest (0.52) at a GrSO₂ of 42% (specificity 91% and sensitivity 62%). For CSOR, area under the curve is 0.89, with Youden's index highest (0.69) at 0.76 (specificity of 80%, sensitivity 90%).

CONCLUSIONS

Splanchnic NIRS correlates with bowel ischaemia. Low GrSO₂ is consistently associated with ischaemia, although a specific cut off level in each patient is hard to define. However, values below 42% correlate strongly with ischaemia while values above 52% are more suggestive of patients without bowel pathology. CSOR of below 0.76 is strongly suggestive of ischaemia. Trends within individuals are likely to be able to provide even more clinically correlatable and diagnostic data.

Regional splanchnic oxygen saturation for preterm infants in the first week after birth: reference values

BACKGROUND

Near-infrared spectroscopy is used in the assessment of regional splanchnic oxygen saturation (r_sSO₂), but solid reference values are scarce. We aimed to establish reference values of r_sSO₂ for preterm infants during the first week after birth, both crude and modeled based on predictors.

METHODS

We included infants with gestational age (GA) <32 weeks and/or birth weight <1200 g. We excluded infants who developed necrotizing enterocolitis or sepsis or who died. In the first week after birth, we determined a daily 2-h mean of r_sSO₂ to assess its associations with sex, GA, postnatal age (PNA), small-for-gestational age (SGA) status, patent ductus arteriosus, hemoglobin, nutrition, and head circumference at birth and translated those into a prediction model.

RESULTS

We included 220 infants. On day 1, the mean ± SD r_sSO₂ value was 48.2% ± 16.6. The nadir of r_sSO₂ was on day 4 (38.7% ± 16.6 smoothed line) to 5 (37.4%±17.3, actual data), after which r_sSO₂ increased to 44.2% ± 16.6 on day 7. The final model of the reference values of r_sSO₂ included the following coefficients: r_sSO₂ = 3.2 - 7.0 × PNA + 0.8 × PNA² - 4.0 × SGA + 1.8 × GA.

CONCLUSIONS

We established reference values of r_sSO₂ for preterm infants during the first week after birth. GA, PNA, and SGA affect these values and need to be taken into account.

IMPACT

Regional splanchnic oxygen saturation is lower in infants with a lower gestational age and in small-for-gestational age infants. Regional splanchnic oxygen saturation decreases with a higher postnatal age until day 4 after birth and then increases until day 7 after birth. Gestational age, postnatal age, and small-for-gestational age status affect regional splanchnic oxygen saturation and need to be taken into account when interpreting regional splanchnic oxygen saturations using NIRS. Reference values for infant regional splanchnic oxygen saturation can be computed with a formula based on these variables, as provided by this study.

The Physiologic Significance of Early Urinary Intestinal Fatty Acid Binding Protein Levels in Preterm Infants: A Prospective Cohort Study

Intestinal fatty acid binding protein (I-FABP) is released from mature enterocytes when cell membrane integrity is disrupted. This study aimed to prospectively investigate the physiologic significance of early urinary I-FABP and whether it might reflect intestinal compromise in preterm infants. We conducted a prospective cohort study of 100 preterm infants weighing <1250 g and collected serial urine samples at 12, 24, and 48 h after birth. The correlations between initial urinary I-FABP/urinary creatinine (creatinine_u) levels and associated factors were analyzed. Among 100 patients, 15 were diagnosed with meconium obstruction of prematurity, and five were diagnosed with necrotizing enterocolitis during the hospital stay. Early urinary I-FABP/creatinine_u levels were inversely correlated with both gestational age (Spearman’s rank correlation coefficient (Rs) −0.381, p < 0.01) and birth weight ((Rs) −0.424, p < 0.01). Early urinary I-FABP/creatinine_u levels were associated with cord pH ((Rs) −0.436, p < 0.01) and base excess ((Rs) −0.258, p = 0.021). There were significantly positive correlations between early urinary I-FABP/creatinine_u levels and the time to full enteral feeding in preterm infants without specific intestinal morbidities. Therefore, a more premature gut with acute perinatal ischemia is expected to exhibit increased I-FABP levels shortly after birth. Because of small sample size, further large-scale studies are needed.

Effects of Caffeine on Splanchnic Oxygenation in Preterm Infants

OBJECTIVE

The aim of this study is to assess the effects of administering 20 mg/kg loading dose of caffeine citrate intravenously on splanchnic oxygenation in preterm infants.

STUDY DESIGN

The infants with a gestational age (GA) of <34 weeks who were administered with a 20 mg/kg intravenous loading dose of caffeine citrate within 48 hours after birth were investigated prospectively. Regional splanchnic oxygen saturation (rsSO₂) and splanchnic fractional tissue oxygen extraction rate (sFTOE) were measured using near-infrared spectroscopy before caffeine infusion, immediately after caffeine infusion and 1, 2, 3, 4, and 6 hours (h) after dose completion; postdose values were compared with predose values.

RESULTS

A total of 41 infants with a mean GA of 29.2 ± 1.6 weeks and birth weight of 1,315 ± 257 g as well as postnatal age of 32.2 ± 10.8 hours were included in the study. rsSO₂ significantly reduced from 63.1 to 57.5% immediately after caffeine infusion, 55.1% after 1 hour, and 55.2% after 2 hours with partial recovery at 3-hour postdose. sFTOE increased correspondingly.

CONCLUSION

Caffeine reduces splanchnic oxygenation and increases splanchnic oxygen extraction for at least 2 hours with partial recovery to predose levels at 3-hour postdose.

Low Splanchnic Oxygenation and Risk for Necrotizing Enterocolitis in Extremely Preterm Newborns

OBJECTIVE

The aim of the study was to investigate whether splanchnic oxygenation (SrSO2), measured with near-infrared spectroscopy (NIRS), during the first week of life is associated with the risk of developing necrotizing enterocolitis (NEC) in extremely preterm infants.

METHODS

This was a prospective observational cohort study including extremely preterm infants (<28 weeks of gestation) born at Karolinska University Hospital from September 2014 to December 2016. Using 1-hour NIRS monitoring during enteral feeding, mainly continuous enteral feeding, in the first week of life we measured both cerebral and splanchnic oxygenation. Primary outcome was risk of developing NEC (Bell stage ≥ II). Secondary outcome was the association between low mean SrSO2 during the first week of life and postnatal age at full enteral nutrition.

RESULTS

We enrolled 52 extremely preterm newborns, but only 45 infants had complete NIRS data. One infant developed NEC within 1 day of NIRS monitoring and was excluded from the study. Median gestational age was 25.6 weeks (range 23.0-27.9) and median birth weight 698 g (range 485-1353). Eight infants developed NEC at the median postnatal age of 15 days (range 6-35). Median postnatal age at full enteral nutrition was 10 days (range 6-23). Infants with mean SrSO2 <30% had a higher risk for developing NEC compared with those with SrSO2 >30% (crude risk ratio 5.25; 95% CI [1.19-23.01]). Small for gestational age, gestational age, birth weight, postnatal age did not affect the results. We found no association between SrSO2 and age at full enteral nutrition.

CONCLUSIONS

Low mean SrSO2 (<30%) during the first week of life is associated with an increased risk for developing NEC in extremely preterm infants on mainly continuous enteral nutrition.

Transfusion-related Gut Injury and Necrotizing Enterocolitis

Necrotizing enterocolitis (NEC) accounts for 10% of deaths in neonatal intensive care units. Several causal mechanisms are likely to lead to a final common disease phenotype. This article summarizes recent data on NEC following red blood cell (RBC) transfusion, with a focus on the most recent literature and ongoing trials. It highlights potential mechanisms from preclinical and human physiologic studies. It also discusses the role of feeding during RBC transfusion and the risk of NEC. Ongoing randomized trials will provide important data on how liberal or conservative approaches to RBC transfusion influence the risk of NEC.

Red blood cell transfusions alter splanchnic oxygenation response to enteral feeding in preterm infants: an observational pilot study

BACKGROUND

Preterm infants often require red blood cell (RBC) transfusions, which may impair splanchnic hemodynamics, thus predisposing to necrotizing enterocolitis (NEC). The aim of this study was to evaluate whether RBC transfusions alter splanchnic oxygenation patterns in response to enteral feeding in this population.

MATERIALS AND METHODS

Preterm neonates (gestational age < 32 weeks and/or birth weight < 1500 g) requiring RBC transfusions for anemia underwent a 12-hour Near Infrared Spectroscopy monitoring of splanchnic (SrSO₂ ) and cerebral (CrSO₂ ) oxygenation, including the transfusion period, one feed before and one after. Splanchnic-cerebral oxygenation ratio (SCOR) was also calculated. Patterns of CrSO₂ , SrSO₂ , and SCOR changes from baseline (Δ) in response to feed before and after transfusion were analyzed.

RESULTS

Twenty neonates were enrolled; none of them developed any gastrointestinal complication within 48 hours after transfusion. Pre-transfusion ΔSrSO₂ and ΔSCOR increased significantly in response to feeding; on the contrary, a significant post-prandial decrease of ΔSrSO₂ and ΔSCOR occurred after transfusion (p < 0.05). No difference in pre- and post-transfusion ΔCrSO₂ patterns was observed.

CONCLUSIONS

In preterm infants, RBC transfusions may alter splanchnic oxygenation response to enteral feeds. Whether these changes are involved in the pathogenesis of transfusion-associated NEC has to be evaluated in further larger trials.

Predicting intestinal recovery after necrotizing enterocolitis in preterm infants

BACKGROUND

Intestinal recovery after NEC is difficult to predict in individuals. We evaluated whether several biomarkers predict intestinal recovery after NEC in preterm infants.

METHODS

We measured intestinal tissue oxygen saturation (r_intSO₂) and collected urinary intestinal-fatty acid binding protein (I-FABP_u) levels 0-24 h and 24-48 h after NEC onset, and before and after the first re-feed. We assessed intestinal recovery in two ways: time to full enteral feeding (FEFt; below or equal/above group's median) and development of post-NEC complications (recurrent NEC/post-NEC stricture). We determined whether the r_intSO₂, its range, and I-FABP_u differed between groups.

RESULTS

We included 27 preterm infants who survived NEC (Bell's stage ≥ 2). Median FEFt was 14 [IQR: 12-23] days. Biomarkers only predicted intestinal recovery after the first re-feed. Mean r_intSO₂ ≥ 53% combined with mean r_intSO_2range ≥ 50% predicted FEFt < 14 days with OR 16.7 (CI: 2.3-122.2). The r_intSO_2range was smaller (33% vs. 51%, p < 0.01) and I-FABP_u was higher (92.4 vs. 25.5 ng/mL, p = 0.03) in case of post-NEC stricture, but not different in case of recurrent NEC, compared with infants without complications.

CONCLUSION

The r_intSO₂, its range, and I-FABP_u after the first re-feed after NEC predicted intestinal recovery. These biomarkers have potential value in individualizing feeding regimens after NEC.

Measurement of gut oxygenation in the neonatal population using near-infrared spectroscopy: a clinical tool?

CONTEXT

Near-infrared spectroscopy (NIRS) is a non-invasive bedside monitor of tissue oxygenation that may be a useful clinical tool in monitoring of gut oxygenation in newborn infants.

OBJECTIVE

To systematically review literature to determine whether NIRS is a reliable tool to monitor gut oxygenation on neonatal units.

DATA SOURCES

PubMed and Embase databases were searched using the terms 'neonate', 'preterm infants', 'NIRS' and 'gut oxygenation' (2001-2018).

STUDY SELECTION

Studies were included if they met inclusion criteria (clinical trial, observational studies, neonatal population, articles in English and reviewing regional gut oxygen saturations) and exclusion criteria (not evaluating abdominal NIRS or regional oxygen saturations).

DATA EXTRACTION

Two authors independently searched PubMed and Embase using the predefined terms, appraised study quality and extracted from 30 studies the study design and outcome data.

LIMITATIONS

Potential for publication bias, majority of studies were prospective cohort studies and small sample sizes.

RESULTS

Thirty studies were reviewed assessing the validity of abdominal NIRS and potential application in neonates. Studies reviewed assessed abdominal NIRS in different settings including normal neonates, bolus and continuous feeding, during feed intolerance, necrotising enterocolitis and transfusion with packed red cells. Several observational studies demonstrated how NIRS could be used in clinical practice.

CONCLUSIONS

NIRS may prove to be a useful bedside tool on the neonatal unit, working alongside current clinical tools in the monitoring of newborn infants (preterm and term) and inform clinical management. We recommend further studies including randomised controlled trials looking at specific measurements and cut-offs for abdominal NIRS for use in further clinical practice.

The effect of enteral bolus feeding on regional intestinal oxygen saturation in preterm infants is age-dependent: a longitudinal observational study

Background

The factors that determine the effect of enteral feeding on intestinal perfusion after preterm birth remain largely unknown. We aimed to determine the effect of enteral feeding on intestinal oxygen saturation (r_intSO₂) in preterm infants and evaluated whether this effect depended on postnatal age (PNA), postmenstrual age (PMA), and/or feeding volumes. We also evaluated whether changes in postprandial r_intSO₂ affected cerebral oxygen saturation (r_cSO₂).

Methods

In a longitudinal observational pilot study using near-infrared spectroscopy we measured r_intSO₂ and r_cSO₂ continuously for two hours on postnatal Days 2 to 5, 8, 15, 22, 29, and 36. We compared preprandial with postprandial values over time using multi-level analyses. To assess the effect of PNA, PMA, and feeding volumes, we performed Wilcoxon signed-rank tests or logistic regression analyses. To evaluate the effect on r_cSO₂, we also used logistic regression analyses.

Results

We included 29 infants: median (range) gestational age 28.1 weeks (25.1–30.7) and birth weight 1025 g (580–1495). On Day 5, r_intSO₂ values decreased postprandially: mean (SE) 44% (10) versus 35% (7), P = .01. On Day 29, r_intSO₂ values increased: 44% (11) versus 54% (7), P = .01. Infants with a PMA ≥ 32 weeks showed a r_intSO₂ increase after feeding (37% versus 51%, P = .04) whereas infants with a PMA < 32 weeks did not. Feeding volumes were associated with an increased postprandial r_intSO₂ (per 10 mL/kg: OR 1.63, 95% CI, 1.02–2.59). We did not find an effect on r_cSO₂ when r_intSO₂ increased postprandially.

Conclusions

Our study suggests that postprandial r_intSO₂ increases in preterm infants only from the fifth week after birth, particularly at PMA ≥ 32 weeks when greater volumes of enteral feeding are tolerated. We speculate that at young gestational and postmenstrual ages preterm infants are still unable to increase intestinal oxygen saturation after feeding, which might be essential to meet metabolic demands.

Trial registration

For this prospective longitudinal pilot study we derived patients from a larger observational cohort study: CALIFORNIA-Trial, Dutch Trial Registry NTR4153.

Effect of Patent Ductus Arteriosus on Splanchnic Oxygenation at Enteral Feeding Introduction in Very Preterm Infants

Because of its possible effect on mesenteric blood flow, the presence of a hemodynamically significant patent ductus arteriosus (PDA) is often of concern for the introduction of enteral feeds in preterm neonates. Near-infrared spectroscopy allows a continuous monitoring of splanchnic oxygenation (SrSO2) and may provide useful hemodynamic information. This observational study evaluated SrSO2 patterns in response to first feed administration in 50 preterm infants <32 weeks' gestation with different ductal status. According to their echocardiographic characteristics, the enrolled infants were divided into the following groups: pulsatile PDA with hemodynamically significant features, restrictive PDA, and no evidence of PDA. The presence of PDA, either with restrictive or hemodynamically significant characteristics, does not significantly affect SrSO2 response to enteral feeding introduction and is not associated with increased rates of gut complications. This finding may provide encouraging evidence in support of early enteral nutrition in very preterm infants with PDA.

Regional tissue oxygenation monitoring in the neonatal intensive care unit: evidence for clinical strategies and future directions

Near-infrared spectroscopy (NIRS)-based monitoring of regional tissue oxygenation (rSO₂) is becoming more commonplace in the neonatal intensive care unit (NICU). While increasing evidence supports rSO₂ monitoring, actual standards for applying this noninvasive bedside technique continue to evolve. This review highlights the current strengths and pitfalls surrounding practical NIRS-based monitoring in the neonatal population. The physiologic background of rSO₂ monitoring is discussed, with attention to understanding oxygen delivery/consumption mismatch and its effects on tissue oxygen extraction. The bedside utility of both cerebral and peripheral rSO₂ monitoring in the NICU is then explored from two perspectives: (1) disease/event-specific "responsive" monitoring and (2) "routine," continuous monitoring. Recent evidence incorporating both monitoring approaches is summarized with emphasis on practical applicability in the NICU. Finally, a future paradigm for a broad-based NIRS monitoring strategy is presented, with attention towards improving personalization of neonatal care and ultimately enhancing long-term outcomes.

Electrogastrography, Near-infrared Spectroscopy, and Acoustics to Measure Gastrointestinal Development in Preterm Babies

OBJECTIVES

The aim of the study was to obtain objective measures indicative of gastrointestinal maturity using 3 noninvasive technologies.

METHODS

Electrogastrography (EGG), abdominal near-infrared spectroscopy (NIRS), and bowel sound/acoustics (AC) monitoring were used simultaneously to obtain physiologic measures of the gastrointestinal system of 18 preterm and 5 term neonates who were tolerating enteral feedings. Measures of EGG slow wave voltage (EGG dominant power) and AC signal amplitude (AC dominant power) were obtained after spectral density analysis. Mean abdominal regional saturations (A-rSO2) were obtained directly from NIRS. The relationship of these 3 measures with postmenstrual age (PMA) was assessed.

RESULTS

The results of the 3 methods differed depending on whether the measurements were pre- or postprandial. Postprandial EGG dominant power increases with PMA (r = 0.67, P = 0.003), both pre- and postprandial abdominal NIRS mean regional saturation increase with PMA (r = 0.73, P < 0.001 and r = 0.55, P = 0.009), and postprandial AC dominant power (at 300-500 Hz) increases with PMA (r = -0.48, P = 0.025).

CONCLUSIONS

EGG, abdominal NIRS, and AC, whenever used simultaneously, can provide objective and synergistic measures that correlate with PMA. These findings may be helpful in the assessment of feeding readiness because they reveal quantitative measures suggestive of the developmental process of the gut.

Splanchnic NIRS monitoring in neonatal care: rationale, current applications and future perspectives

Near infrared spectroscopy (NIRS) provides a non-invasive, continuous monitoring of regional tissue oxygenation. NIRS assessment of neonatal splanchnic oxygenation (SrSO₂) has gained increasing interest over the last decade, as local hypoxia and ischemia underlie the most feared gut complications in neonates. Current literature provides encouraging evidence in support of SrSO₂ reliability in detecting mesenteric hemodynamic changes related to various physiological and pathological conditions in-term and preterm infants. Even so, while splanchnic NIRS monitoring looks promising for investigating gut physiopathology in research settings, further studies are needed to evaluate its feasibility as a routine monitoring tool in neonatal care and to investigate its potential role in clinical decision making. After a brief introduction to NIRS technical principles, this review aims to provide a complete overview of current neonatal applications for splanchnic NIRS monitoring, to discuss its possible limitations and to suggest future directions for research and clinical applications.

Feed-related Splanchnic Oxygenation in Preterm Infants With Abnormal Antenatal Doppler Developing Gut Complications

Preterm infants with antenatal absent or reversed end diastolic flow (AREDF) in umbilical arteries are at major risk for gastrointestinal (GI) complications, such as necrotizing enterocolitis, intestinal perforation and feeding intolerance. Near-infrared spectroscopy provides continuous monitoring of splanchnic oxygenation (SrSO2) and may represent a useful tool to predict GI outcomes in this high-risk population. This observational, pilot study assessed feed-related SrSO2 patterns at enteral feeding introduction and full enteral feeding (FEF) achievement in twenty AREDF infants with gestational age ≤34 weeks. Enrolled infants were divided into 2 groups according to the development versus lack of GI complications. Infants developing GI complications showed significantly lower SrSO2 and increased splanchnic oxygen extraction in response to enteral feeds at both enteral feeding introduction and FEF. The potential role of these findings in predicting GI complications in AREDF preterm infants seems promising and deserves further evaluation.