Abnormal heart rate characteristics before clinical diagnosis of necrotizing enterocolitis

Heart Rate Variability as a Prognostic Tool for Gastroschisis Infants in the Neonatal Intensive Critical Unit

OBJECTIVE

 Gastroschisis is the most common congenital abdominal wall defect, with an increasing incidence. It results in extrusion of abdominal contents with associated delayed intestinal motility. Abnormal heart rate characteristics (HRCs) such as decreased variability occur due to the inflammatory response to sepsis in preterm infants. This study aimed to test the hypothesis that infants with gastroschisis have decreased heart rate variability (HRV) after birth and that this physiomarker may predict outcomes.

STUDY DESIGN

 We analyzed heart rate data from and clinical variables for all infants admitted with gastroschisis from 2009 to 2020.

RESULTS

 Forty-seven infants were admitted during the study period and had available data. Complex gastroschisis infants had reduced HRV after birth. For those with sepsis and necrotizing enterocolitis, abnormal HRCs occurred early in the course of illness.

CONCLUSION

 Decreased HRV was associated with complex gastroschisis. Infants in this group experienced complications that prolonged time to full enteral feeding and time on total parenteral nutrition.

KEY POINTS

· Infants with gastroschisis can be classified into two subcategories, simple and complex disease.. · Those with complex disease often require prolonged stays in the neonatal intensive care unit and costly hospitalizations. We hypothesized that infants with complex gastroschisis are more likely to have abnormal HRC due to intestinal inflammation.. · In this study, we identified associations between abnormal HRV, heart rate characteristicHRC, and the development of gastroschisis complications. Additionally, we described differences in clinical characteristics between infants with complex versus simple gastroschisis..

Heart rate characteristics predict risk of mortality in preterm infants in low and high target oxygen saturation ranges

Background

The Neonatal Oxygenation Prospective Meta-analysis found that in infants <28 weeks gestational age, targeting an oxygen saturation (S pO2 ) range of 85-89% versus 91-95% resulted in lower rates of retinopathy of prematurity but increased mortality. We aimed to evaluate the accuracy of the heart rate characteristics index (HRCi) in assessing the dynamic risk of mortality among infants managed with low and high target S pO2 ranges.

Methods

We linked the SUPPORT and HRCi datasets from one centre in which the randomised controlled trials overlapped. We examined the maximum daily HRCi (MaxHRCi24) to predict mortality among patients randomised to the lower and higher target S pO2 groups by generating predictiveness curves and calculating model performance metrics, including area under the receiver operating characteristics curve (AUROC) at prediction windows from 1-60 days. Cox proportional hazards models tested whether MaxHRCi24 was an independent predictor of mortality. We also conducted a moderation analysis.

Results

There were 84 infants in the merged dataset. MaxHRCi24 predicted mortality in infants randomised to the lower target S pO2 (AUROC of 0.79-0.89 depending upon the prediction window) and higher target S pO2 (AUROC 0.82-0.91). MaxHRCi24 was an important additional predictor of mortality in multivariable modelling. In moderation analysis, in a model that also included demographic predictor variables, the individual terms and the interaction term between MaxHRCi24 and target S pO2 range all predicted mortality.

Conclusions

Associations between HRCi and mortality, at low and high S pO2 target ranges, suggest that future research may find HRCi metrics helpful to individually optimise target oxygen saturation ranges for hospitalised preterm infants.

Methods of identifying surgical Necrotizing Enterocolitis-a systematic review and meta-analysis

BACKGROUND

Current data suggests potential benefit of earlier surgery for necrotizing enterocolitis (NEC) however this requires accurate prognostication early in the disease course. This study aims to identify and determine the effectiveness of previously reported methods or tests for the identification of surgical NEC.

METHODS

Systematic review and meta-analysis with registration on PROSPERO including articles describing a method of identifying surgical NEC. Outcomes of interest were effectiveness and repeatability of index test.

RESULTS

Of the 190 full-text articles screened, 90 studies were included which contained 114 methods of identifying surgical NEC in 9546 infants. Of these methods, 44 were a scoring system, 37 a single biomarker, 24 an imaging method, and 9 an invasive method. Sensitivity and specificity ranged from 12.8-100% to 13-100%, respectively. Some methods (9.6%) provided insufficient methods for repeatability within clinical practice or research. Meta-analyses were possible for only 2 methods, the metabolic derangement 7 score and abdominal ultrasound.

CONCLUSIONS

A range of methods for identifying surgical NEC have been identified with varying overall performance and uncertainties about reproducibility and superiority of any method. External validation in large multicentre datasets should allow direct comparison of accuracy and prospective study should evaluate impact on clinical outcomes.

IMPACT

Earlier identification of need for surgery in necrotizing enterocolitis (NEC) has the potential to improve the unfavourable outcomes in this condition. As such, many methods have been developed and reported to allow earlier identification of surgical NEC. This study is the first synthesis of the literature which identifies previously reported methods and the effectiveness of these. Many methods, including scoring systems and biomarkers, appear effective for prognostication in NEC and external validation is now required in multicentre datasets prior to clinical utility.

Neonatal sepsis and cardiovascular dysfunction I: mechanisms and pathophysiology

The highest incidence of sepsis across all age groups occurs in neonates leading to substantial mortality and morbidity. Cardiovascular dysfunction frequently complicates neonatal sepsis including biventricular systolic and/or diastolic dysfunction, vasoregulatory failure, and pulmonary arterial hypertension. The haemodynamic response in neonatal sepsis can be hyperdynamic or hypodynamic and the underlying pathophysiological mechanisms are heterogeneous. The diagnosis and definition of both neonatal sepsis and cardiovascular dysfunction complicating neonatal sepsis are challenging and not consensus-based. Future developments in neonatal sepsis management will be facilitated by common definitions and datasets especially in neonatal cardiovascular optimisation. IMPACT: Cardiovascular dysfunction is common in neonatal sepsis but there is no consensus-based definition, making calculating the incidence and designing clinical trials challenging. Neonatal cardiovascular dysfunction is related to the inflammatory response, which can directly target myocyte function and systemic haemodynamics.

Prediction of outcome of hypoxic-ischemic encephalopathy in newborns undergoing therapeutic hypothermia using heart rate variability

OBJECTIVE

To assess the use of continuous heart rate variability (HRV) as a predictor of brain injury severity in newborns with moderate to severe HIE that undergo therapeutic hypothermia.

STUDY DESIGN

Two cohorts of newborns (n1 = 55, n2 = 41) with moderate to severe hypoxic-ischemic encephalopathy previously treated with therapeutic hypothermia. HRV was characterized by root mean square in the short time scales (RMSS) during therapeutic hypothermia and through completion of rewarming. A logistic regression and Naïve Bayes models were developed to predict the MRI outcome of the infants using RMSS. The encephalopathy grade and gender were used as control variables.

RESULTS

For both cohorts, the predicted outcomes were compared with the observed outcomes. Our algorithms were able to predict the outcomes with an area under the receiver operating characteristic curve of about 0.8.

CONCLUSIONS

HRV assessed by RMSS can predict severity of brain injury in newborns with HIE.

Impact of low-level prenatal alcohol exposure and maternal stress on autonomic regulation

BACKGROUND

Prenatal alcohol exposure (PAE) impacts the neurodevelopment of the fetus, including the infant's ability to self-regulate. Heart rate variability (HRV), that is, the beat-to-beat variability in heart rate, is a non-invasive measurement that can indicate autonomic nervous system (ANS) function/dysfunction.

METHODS

The study consisted of a subset of our ENRICH-2 cohort: 80 participants (32 PAE and 48 Controls) who had completed three visits during pregnancy. The participants completed a comprehensive assessment of PAE and other substances throughout pregnancy and assessments for stress, anxiety, and depression in the third trimester. At 24 h of age, infant HRV was assessed in the hospital during the clinically indicated heel lance; 3- to 5-min HRV epochs were obtained during baseline, heel lancing, and recovery episodes.

RESULTS

Parameters of HRV differed in infants with PAE compared to Controls during the recovery phase of the heel lance (respiratory sinus arrhythmia (RSA) and high-frequency (HF), p < 0.05). Increased maternal stress was also strongly associated with abnormalities in RSA, HF, and low-frequency / high-frequency (LF/HF, p's < 0.05).

CONCLUSIONS

Alterations in ANS regulation associated with PAE and maternal stress may reflect abnormal development of the hypothalamic-pituitary-adrenal axis and have long term implications for infant responsiveness and self-regulation.

IMPACT

Previous studies have focused on effects of moderate to heavy prenatal alcohol exposure (PAE) on autonomic dysregulation, but little is known about the effects of lower levels of PAE on infant self-regulation and heart rate variability (HRV). Prenatal stress is another risk factor for autonomic dysregulation. Mild PAE impacts infant self-regulation, which can be assessed using HRV. However, the effect of prenatal stress is stronger than that of mild PAE or other mental health variables on autonomic dysregulation.

Transforming neonatal care with artificial intelligence: challenges, ethical consideration, and opportunities

Artificial intelligence (AI) offers tremendous potential to transform neonatology through improved diagnostics, personalized treatments, and earlier prevention of complications. However, there are many challenges to address before AI is ready for clinical practice. This review defines key AI concepts and discusses ethical considerations and implicit biases associated with AI. Next we will review literature examples of AI already being explored in neonatology research and we will suggest future potentials for AI work. Examples discussed in this article include predicting outcomes such as sepsis, optimizing oxygen therapy, and image analysis to detect brain injury and retinopathy of prematurity. Realizing AI's potential necessitates collaboration between diverse stakeholders across the entire process of incorporating AI tools in the NICU to address testability, usability, bias, and transparency. With multi-center and multi-disciplinary collaboration, AI holds tremendous potential to transform the future of neonatology.

Comparison of simultaneous auscultation and ultrasound for clinical assessment of bowel peristalsis in neonates

Introduction

Assessment of bowel health in ill preterm infants is essential to prevent and diagnose early potentially life-threatening intestinal conditions such as necrotizing enterocolitis. Auscultation of bowel sounds helps assess peristalsis and is an essential component of this assessment.

Aim

We aim to compare conventional bowel sound auscultation using acoustic recordings from an electronic stethoscope to real-time bowel motility visualized on point-of-care bowel ultrasound (US) in neonates with no known bowel disease.

Methods

This is a prospective observational cohort study in neonates on full enteral feeds with no known bowel disease. A 3M™ Littmann® Model 3200 electronic stethoscope was used to obtain a continuous 60-s recording of bowel sounds at a set region over the abdomen, with a concurrent recording of US using a 12l high-frequency Linear probe. The bowel sounds heard by the first investigator using the stethoscope were contemporaneously transferred for a computerized assessment of their electronic waveforms. The second investigator, blinded to the auscultation findings, obtained bowel US images using a 12l Linear US probe. All recordings were analyzed for bowel peristalsis (duration in seconds) by each of the two methods.

Results

We recruited 30 neonates (gestational age range 27-43 weeks) on full enteral feeds with no known bowel disease. The detection of bowel peristalsis (duration in seconds) by both methods (acoustic and US) was reported as a percentage of the total recording time for each participant. Comparing the time segments of bowel sound detection by digital stethoscope recording to that of the visual detection of bowel movements in US revealed a median time of peristalsis with US of 58%, compared to 88.3% with acoustic assessment (p < 0.002). The median regression difference was 26.7% [95% confidence interval (CI) 5%-48%], demonstrating no correlation between the two methods.

Conclusion

Our study demonstrates disconcordance between the detection of bowel sounds by auscultation and the detection of bowel motility in real time using US in neonates on full enteral feeds and with no known bowel disease. Better innovative methods using artificial intelligence to characterize bowel sounds, integrating acoustic mapping with sonographic detection of bowel peristalsis, will allow us to develop continuous neonatal bowel sound monitoring devices.

Recent advances in our understanding of NEC diagnosis, prognosis and surgical approach

Necrotising enterocolitis (NEC) remains a devasting condition that has seen limited improvement in outcomes in recent years. The incidence of the disease is increasing as more extremely premature infants survive. NEC is responsible for 1 in 10 neonatal deaths and up to 61% of survivors have significant neurodevelopmental delay. The aim of this review is to highlight recent advances in diagnosis, prognosis and surgical approach in this condition. Many recent studies have reported novel methods of diagnosis of NEC with the aim of earlier and more accurate identification. These include imaging and machine learning techniques. Prognostication of NEC is particularly important to allow earlier escalation of therapy. Around 25% of infants with NEC will require surgery and recent data has shown that time from disease onset to surgery is greater in infants whose indication for surgery is failed medical management, rather than pneumoperitoneum. This indication was also associated with worse outcomes compared to pneumoperitoneum. Ongoing research has highlighted several new methods of disease prognostication which includes differentiating surgical from medical NEC. Finally, recent randomised controlled trials in surgical technique are discussed along with the implications of these for practice. Further, high quality research utilising multi-centre collaborations and high fidelity data from electronic patient records is needed to address the issues discussed and ultimately improve outcomes in NEC.

Heart Rate Characteristics Monitoring for Late-Onset Sepsis in Preterm Infants: A Systematic Review

BACKGROUND

Early diagnosis of late-onset sepsis (LOS) and necrotizing enterocolitis (NEC) by monitoring heart rate characteristics (HRC) of preterm infants might reduce the risk of death and morbidities. We aimed to systematically assess the effects of HRC monitoring on death, LOS, and NEC.

METHODS

A systematic search was performed in MEDLINE, Embase, Cochrane Library, and Web of Science.

RESULTS

Fifteen papers were included in this review. Three of these papers reported results from the only identified randomized controlled trial (RCT). This RCT showed that HRC monitoring resulted in a small but significant reduction in mortality (absolute risk reduction 2.1% [95% confidence interval 0.01-4.14]) without any differences in neurodevelopmental impairment. The risk of bias was rated high due to performance and detection bias and failure to correct for multiple testing. Most diagnostic cohort studies showed high discriminating accuracy in predicting LOS but lacked sufficient quality and generalizability. No studies for the detection of NEC were identified.

CONCLUSION

Supported by multiple observational cohort studies, the RCT identified in this systematic review showed that HRC monitoring as an early warning system for LOS might reduce the risk of death in preterm infants. However, methodological weaknesses and limited generalizability do not justify implementation of HRC in clinical care. A large international RCT is warranted.

Enteral Feeding and Antibiotic Treatment Do Not Influence Increased Coefficient of Variation of Total Fecal Bile Acids in Necrotizing Enterocolitis

Introduction

Necrotizing enterocolitis (NEC) is the most common gastrointestinal emergency in preterm infants. In animal models, the accumulation of ileal bile acids (BAs) is a crucial component of NEC pathophysiology. Recently, we showed that the coefficient of variation of total fecal BAs (CV-TBA) was elevated in infants who develop NEC compared to matched controls. However, neither the type of enteral nutrition nor antibiotic treatments-parameters that could potentially influence BA levels-were used to match pairs. Thus, we assessed the relationships between exposure to enteral feeding types and antibiotic treatments with NEC status and CV-TBA.

Materials and methods

Serial fecal samples were collected from 79 infants born with birth weight (BW) ≤1800 gm and estimated gestational age (EGA) ≤32 weeks; eighteen of these infants developed NEC. Total fecal BA levels (TBA) were determined using a commercially available enzyme cycling kit. Relationships between CV-TBA and dichotomous variables (NEC status, demographics, early exposure variables) were assessed by independent samples t-tests. Fisher's exact tests were used to assess relationships between NEC status and categorical variables.

Results

High values for CV-TBA levels perfectly predicted NEC status among infants in this study. However, feeding type and antibiotic usage did not drive this relationship.

Conclusions

As in previous studies, high values for the CV-TBA levels in the first weeks of life perfectly predicted NEC status among infants. Importantly, feeding type and antibiotic usage-previously identified risk factors for NEC-did not drive this relationship.

Sepsis and Mortality Prediction in Very Low Birth Weight Infants: Analysis of HeRO and nSOFA

OBJECTIVE

Scores to predict sepsis or define sepsis severity could improve care for very low birth weight (VLBW) infants. The heart rate characteristics (HRC) index (HeRO score) was developed as an early warning system for late-onset sepsis (LOS), and also rises before necrotizing enterocolitis (NEC). The neonatal sequential organ failure assessment (nSOFA) was developed to predict sepsis-associated mortality using respiratory, hemodynamic, and hematologic data. The aim of this study was to analyze the HRC index and nSOFA near blood cultures in VLBW infants relative to diagnosis and sepsis-associated mortality.

STUDY DESIGN

Retrospective, single-center study of VLBW infants from 2011 to 2019. We analyzed HRC index and nSOFA around blood cultures diagnosed as LOS/NEC. In a subgroup of the cohort, we analyzed HRC and nSOFA near the first sepsis-like illness (SLI) or sepsis ruled-out (SRO) compared with LOS/NEC. We compared scores by diagnosis and mortality during treatment.

RESULTS

We analyzed 179 LOS/NEC, 93 SLI, and 96 SRO blood culture events. In LOS/NEC, the HRC index increased before the blood culture, while nSOFA increased at the time of culture. Both scores were higher in nonsurvivors compared with survivors and in LOS/NEC compared with SRO. The nSOFA 12 hours after the time of blood culture predicted mortality during treatment better than any other time point analyzed (area under the curve 0.91).

CONCLUSION

The HRC index provides earlier warning of imminent sepsis, whereas nSOFA after blood culture provides better prediction of mortality.

KEY POINTS

· The HRC index and nSOFA provide complementary information on sepsis risk and sepsis-related mortality risk.. · This study adds to existing literature evaluating these risk scores independently by analyzing them together and in cases of not only proven but also suspected infections.. · The impact of combining risk models could be improved outcomes for premature infants..

Predicting clinical outcomes using artificial intelligence and machine learning in neonatal intensive care units: a systematic review

BACKGROUND

Advances in technology, data availability, and analytics have helped improve quality of care in the neonatal intensive care unit.

OBJECTIVE

To provide an in-depth review of artificial intelligence (AI) and machine learning techniques being utilized to predict neonatal outcomes.

METHODS

The PRISMA protocol was followed that considered articles from established digital repositories. Included articles were categorized based on predictions of: (a) major neonatal morbidities such as sepsis, bronchopulmonary dysplasia, intraventricular hemorrhage, necrotizing enterocolitis, and retinopathy of prematurity; (b) mortality; and (c) length of stay.

RESULTS

A total of 366 studies were considered; 68 studies were eligible for inclusion in the review. The current set of predictor models are primarily built on supervised learning and mostly used regression models built on retrospective data.

CONCLUSION

With the availability of EMR data and data-sharing of NICU outcomes across neonatal research networks, machine learning algorithms have shown breakthrough performance in predicting neonatal disease.

Monitoring of heart rate characteristics to detect neonatal sepsis

BACKGROUND

Monitoring of heart rate characteristics (HRC) index may improve outcomes of late-onset neonatal sepsis (LOS) through early detection. We aimed at describing the association between LOS and elevated HRC index.

METHODS

This single-center retrospective case-control study included neonates who presented with blood culture-proven hospital-acquired LOS. Controls were matched to cases (ratio 1:2) based on gestational age, postnatal age, and birthweight. We compared the highest HRC indexes in the 48 h preceding blood culture sampling in LOS cases to the highest HRC indexes at the same postnatal days in controls.

RESULTS

In 59 LOS cases and 123 controls, an HRC index > 2 was associated with LOS (OR 7.1, 95% CI 2.6-19.0). Sensitivity and specificity of an HRC index > 2 to predict LOS were 53% (32/59) and 79% (98/123). Sensitivity increased from 25% in infants born > 32 weeks to 76% in infants born < 28 weeks. Specificity decreased from 97% in infants > 32 weeks to 63% in those born < 28 weeks.

CONCLUSIONS

An increase of HRC index > 2 has a significant association with the diagnosis of LOS, supporting the use of HRC monitoring to assist early detection of LOS. Clinicians using HRC monitoring should be aware of its diagnostic accuracy and limitations in different gestational age groups.

IMPACT

There is a paucity of data regarding the predictive value of heart rate characteristics (HRC) monitoring for early diagnosis of late-onset neonatal sepsis (LOS) in daily clinical practice. Monitoring of heart rate characteristics provides valuable information to assist the early diagnosis of LOS across all gestational age groups. However, the strong influence of gestational age on positive and negative predictive values adds complexity to the interpretation of HRC indexes.

In infants with congenital heart disease autonomic dysfunction is associated with pre-operative brain injury

BACKGROUND

Brain injury is a serious and common complication of critical congenital heart disease (CHD). Impaired autonomic development (assessed by heart rate variability (HRV)) is associated with brain injury in other high-risk neonatal populations.

OBJECTIVE

To determine whether impaired early neonatal HRV is associated with pre-operative brain injury in CHD.

METHODS

In infants with critical CHD, we evaluated HRV during the first 24 h of cardiac ICU (CICU) admission using time-domain (RMS 1, RMS 2, and alpha 1) and frequency-domain metrics (LF, nLF, HF, nHF). Pre-operative brain magnetic resonance imaging (MRI) was scored for injury using an established system. Spearman's correlation coefficient was used to determine the association between HRV and pre-operative brain injury.

RESULTS

We enrolled 34 infants with median birth gestational age of 38.8 weeks (IQR 38.1-39.1). Median postnatal age at pre-operative brain MRI was 2 days (IQR 1-3 days). Thirteen infants had MRI evidence of brain injury. RMS 1 and RMS 2 were inversely correlated with pre-operative brain injury.

CONCLUSIONS

Time-domain metrics of autonomic function measured within the first 24 h of admission to the CICU are associated with pre-operative brain injury, and may perform better than frequency-domain metrics under non-stationary conditions such as critical illness.

IMPACT

Autonomic dysfunction, measured by heart rate variability (HRV), in early transition is associated with pre-operative brain injury in neonates with critical congenital heart disease. These data extend our earlier findings by providing further evidence for (i) autonomic dysfunction in infants with CHD, and (ii) an association between autonomic dysfunction and brain injury in critically ill neonates. These data support the notion that further investigation of HRV as a biomarker for brain injury risk is warranted in infants with critical CHD.

Using Temporal Data Mining on Patient Data for Clinical Decision Making in the Care of the Sick Newborn

BACKGROUND

In a neonatal intensive care unit, streaming healthcare data comes from many sources, but humans are unable to understand relationships between data variables. Data mining and analysis are just beginning to get utilized in critical care. We present a case study using electronic medical record data in the neonatal intensive care unit and explore possible avenues of advancement using temporal data analytics.

CASE PRESENTATION

Electronic medical record data were collected for physiological monitor data. Heart rate, respiratory rate, oxygen saturation and temperature data were retrospectively analyzed by temporal data mining. Three premature babies were selected and data de-identified. The first case of a urinary tract infection showed nursing ability to synthesize data streams coming from a patient. For the second case of necrotizing enterocolitis, Temporal-Data-Mining analysis of combinations of clinical events based on deviations from the mean showed specific heuristic biomarkers related to events before discovery of necrotizing enterocolitis. Specific sequences 6-event and 5-event in length were identified with nursing unease at clinical deterioration, which were 100- and 87-times unlikely to occur randomly with 99.5% confidence. No such sequences were found in the rest of the 37 days for the second case and entire 133 days of stay in the third case of an uneventful premature baby.

CONCLUSION

Temporal data mining is a possible clinical tool in providing useful information in the neonatal intensive care unit for diagnosis of adverse clinical occurrences such as necrotizing enterocolitis. There is the possibility of changing the clinical paradigm of episodic watchfulness to constant vigilance using real-time data gathering.

Longitudinal Analysis of Continuous Pulse Oximetry as Prognostic Factor in Neonatal Respiratory Distress

OBJECTIVE

Analysis of longitudinal data can provide neonatologists with tools that can help predict clinical deterioration and improve outcomes. The aim of this study is to analyze continuous monitoring data in newborns, using vital signs to develop predictive models for intensive care admission and time to discharge.

STUDY DESIGN

We conducted a retrospective cohort study, including term and preterm newborns with respiratory distress patients admitted to the neonatal ward. Clinical and epidemiological data, as well as mean heart rate and saturation, at every minute for the first 12 hours of admission were collected. Multivariate mixed, survival and joint models were developed.

RESULTS

A total of 56,377 heart rate and 56,412 oxygen saturation data were analyzed from 80 admitted patients. Of them, 73 were discharged home and 7 required transfer to the intensive care unit (ICU). Longitudinal evolution of heart rate (p < 0.01) and oxygen saturation (p = 0.01) were associated with time to discharge, as well as birth weight (p < 0.01) and type of delivery (p < 0.01). Longitudinal heart rate evolution (p < 0.01) and fraction of inspired oxygen at admission at the ward (p < 0.01) predicted neonatal ICU (NICU) admission.

CONCLUSION

Longitudinal evolution of heart rate can help predict time to transfer to intensive care, and both heart rate and oxygen saturation can help predict time to discharge. Analysis of continuous monitoring data in patients admitted to neonatal wards provides useful tools to stratify risks and helps in taking medical decisions.

KEY POINTS

· Continuous monitoring of vital signs can help predict and prevent clinical deterioration in neonatal patients.. · In our study, longitudinal analysis of heart rate and oxygen saturation predicted time to discharge and intensive care admission.. · More studies are needed to prospectively prove that these models can helpmake clinical decisions and stratify patients' risks..

The principles of whole-hospital predictive analytics monitoring for clinical medicine originated in the neonatal ICU

In 2011, a multicenter group spearheaded at the University of Virginia demonstrated reduced mortality from real-time continuous cardiorespiratory monitoring in the neonatal ICU using what we now call Artificial Intelligence, Big Data, and Machine Learning. The large, randomized heart rate characteristics trial made real, for the first time that we know of, the promise that early detection of illness would allow earlier and more effective intervention and improved patient outcomes. Currently, though, we hear as much of failures as we do of successes in the rapidly growing field of predictive analytics monitoring that has followed. This Perspective aims to describe the principles of how we developed heart rate characteristics monitoring for neonatal sepsis and then applied them throughout adult ICU and hospital medicine. It primarily reflects the work since the 1990s of the University of Virginia group: the theme is that sudden and catastrophic deteriorations can be preceded by subclinical but measurable physiological changes apparent in the continuous cardiorespiratory monitoring and electronic health record.

Fetal heart rate variability is a biomarker of rapid but not progressive exacerbation of inflammation in preterm fetal sheep

Perinatal infection/inflammation can trigger preterm birth and contribute to neurodevelopmental disability. There are currently no sensitive, specific methods to identify perinatal infection. We investigated the utility of time, frequency and non-linear measures of fetal heart rate (FHR) variability (FHRV) to identify either progressive or more rapid inflammation. Chronically instrumented preterm fetal sheep were randomly assigned to one of three different 5d continuous i.v. infusions: 1) control (saline infusions; n = 10), 2) progressive lipopolysaccharide (LPS; 200 ng/kg over 24 h, doubled every 24 h for 5d, n = 8), or 3) acute-on-chronic LPS (100 ng/kg over 24 h then 250 ng/kg/24 h for 4d plus 1 μg boluses at 48, 72, and 96 h, n = 9). Both LPS protocols triggered transient increases in multiple measures of FHRV at the onset of infusions. No FHRV or physiological changes occurred from 12 h after starting progressive LPS infusions. LPS boluses during the acute-on-chronic protocol triggered transient hypotension, tachycardia and an initial increase in multiple time and frequency domain measures of FHRV, with an asymmetric FHR pattern of predominant decelerations. Following resolution of hypotension after the second and third LPS boluses, all frequencies of FHRV became suppressed. These data suggest that FHRV may be a useful biomarker of rapid but not progressive preterm infection/inflammation.

Vital signs as physiomarkers of neonatal sepsis

Neonatal sepsis accounts for significant morbidity and mortality, particularly among premature infants in the Neonatal Intensive Care Unit. Abnormal vital sign patterns serve as physiomarkers of sepsis and provide early warning of illness before overt clinical decompensation. The systemic inflammatory response to pathogens signals the autonomic nervous system, leading to changes in temperature, respiratory rate, heart rate, and blood pressure. In infants with comorbidities of prematurity, vital sign abnormalities often occur in the absence of infection, which confounds sepsis diagnosis. This review will cover the mechanisms of vital sign changes in neonatal sepsis, including the cholinergic anti-inflammatory pathway mediated by the vagus nerve, which is critical to the host response to infectious and inflammatory insults. We will also review the clinical implications of vital sign changes in neonatal sepsis, including their use in early warning scores and systems to direct clinicians to the bedside of infants with physiologic changes that might be due to sepsis. IMPACT: This manuscript summarizes and reviews the relevant literature on the physiological manifestations of neonatal sepsis and how we monitor and analyze these through vital signs and advanced analytics.

Newborns' clinical conditions are correlated with the neonatal assessment manual scorE (NAME)

OBJECTIVE

To investigate the relationship between the Neonatal Assessment Manual scorE (NAME) and newborns' clinical condition on a large number of infants. The NAME model was developed as an instrument to assess the infant's general conditions, especially in NICUs, by evaluating how the infant's body responds to an external stressor such as static touch. Previous studies, employing experienced assessors, showed good validity indices as well as high inter-rater reliability.

STUDY DESIGN

Newborns were recruited at the "Vittore Buzzi" Pediatric Hospital NICU ward in Milan and their clinical conditions were collected through a standardized form-the complexity index. Two manual practitioners assessed all eligible newborns using the NAME scores. Data was analyzed using Kendall's τ correlation and odds ratio (OR) to assess the relationship between the NAME scores and the complexity index.

RESULTS

Two hundred two newborns (46% female; 34.1 w ± 4.3; birth weight of 2,093.4 gr ± 879.8) entered the study. The Kendall's correlation between the clinical conditions (complexity index) and the NAME score was -0.206 [95% CI: (-0.292, -0.116), p-value < 0.001], corresponding to an OR of 0.838 [95% CI: (0.757, 0.924), p-value < 0.001]. Further exploratory analyses showed significant correlation between gestational age, birth weight and NAME scores.

CONCLUSION

The present paper adds evidence to the NAME model validity by demonstrating its applicability in the clinical neonatological context.

Ideal algorithms in healthcare: Explainable, dynamic, precise, autonomous, fair, and reproducible

Established guidelines describe minimum requirements for reporting algorithms in healthcare; it is equally important to objectify the characteristics of ideal algorithms that confer maximum potential benefits to patients, clinicians, and investigators. We propose a framework for ideal algorithms, including 6 desiderata: explainable (convey the relative importance of features in determining outputs), dynamic (capture temporal changes in physiologic signals and clinical events), precise (use high-resolution, multimodal data and aptly complex architecture), autonomous (learn with minimal supervision and execute without human input), fair (evaluate and mitigate implicit bias and social inequity), and reproducible (validated externally and prospectively and shared with academic communities). We present an ideal algorithms checklist and apply it to highly cited algorithms. Strategies and tools such as the predictive, descriptive, relevant (PDR) framework, the Standard Protocol Items: Recommendations for Interventional Trials-Artificial Intelligence (SPIRIT-AI) extension, sparse regression methods, and minimizing concept drift can help healthcare algorithms achieve these objectives, toward ideal algorithms in healthcare.

Neonatal heart rate variability: a contemporary scoping review of analysis methods and clinical applications

BACKGROUND

Neonatal heart rate variability (HRV) is widely used as a research tool. However, HRV calculation methods are highly variable making it difficult for comparisons between studies.

OBJECTIVES

To describe the different types of investigations where neonatal HRV was used, study characteristics, and types of analyses performed.

ELIGIBILITY CRITERIA

Human neonates ≤1 month of corrected age.

SOURCES OF EVIDENCE

A protocol and search strategy of the literature was developed in collaboration with the McGill University Health Center's librarians and articles were obtained from searches in the Biosis, Cochrane, Embase, Medline and Web of Science databases published between 1 January 2000 and 1 July 2020.

CHARTING METHODS

A single reviewer screened for eligibility and data were extracted from the included articles. Information collected included the study characteristics and population, type of HRV analysis used (time domain, frequency domain, non-linear, heart rate characteristics (HRC) parameters) and clinical applications (physiological and pathological conditions, responses to various stimuli and outcome prediction).

RESULTS

Of the 286 articles included, 171 (60%) were small single centre studies (sample size <50) performed on term infants (n=136). There were 138 different types of investigations reported: physiological investigations (n=162), responses to various stimuli (n=136), pathological conditions (n=109) and outcome predictor (n=30). Frequency domain analyses were used in 210 articles (73%), followed by time domain (n=139), non-linear methods (n=74) or HRC analyses (n=25). Additionally, over 60 different measures of HRV were reported; in the frequency domain analyses alone there were 29 different ranges used for the low frequency band and 46 for the high frequency band.

CONCLUSIONS

Neonatal HRV has been used in diverse types of investigations with significant lack of consistency in analysis methods applied. Specific guidelines for HRV analyses in neonates are needed to allow for comparisons between studies.

Surgical necrotizing enterocolitis: Association between surgical indication, timing, and outcomes

BACKGROUND/PURPOSE

Despite improvements in neonatal care the outcomes of Necrotizing Enterocolitis (NEC) remain unchanged over previous decades. The study aims to explore whether different indications for surgical intervention in NEC are associated with timing of surgery and outcomes.

METHODS

Population-based, prospective, observational study of all 27 paediatric surgical centres in the United Kingdom and Ireland identified using the British Association of Paediatric Surgeons Congenital Anomalies Surveillance System from 1st February 2013 to 28th February 2014. Infants were included if they had NEC and underwent first surgical intervention within 7 days of diagnosis. Primary outcomes were death, parenteral nutrition requirement or a composite outcome of death or PN requirement at 28 days post surgery.

RESULTS

There were 133 infants meeting inclusion criteria. Indications for surgery were bowel perforation (n = 67), suspected necrotic bowel without bowel perforation and not deemed to have failed medical management (n = 20), those who had failed medical management (n = 42) and a palpable mass without any other indication (n = 4). Failed medical treatment as an indication for surgery was associated with an increased time to surgery of 30.28 (95% CI 13.46-47.10) hours from those whose indication was perforation and was also the strongest predictor of PN requirement or death at 28 days post-surgery (OR 4.54 [1.59-13.0]).

CONCLUSIONS

Failed medical treatment as an indication for surgery for NEC is associated with poor outcome. Earlier intervention in these infants represents a potential opportunity to improve outcomes in this population.

A Review on the Vagus Nerve and Autonomic Nervous System During Fetal Development: Searching for Critical Windows

The autonomic nervous system (ANS) is one of the main biological systems that regulates the body's physiology. Autonomic nervous system regulatory capacity begins before birth as the sympathetic and parasympathetic activity contributes significantly to the fetus' development. In particular, several studies have shown how vagus nerve is involved in many vital processes during fetal, perinatal, and postnatal life: from the regulation of inflammation through the anti-inflammatory cholinergic pathway, which may affect the functioning of each organ, to the production of hormones involved in bioenergetic metabolism. In addition, the vagus nerve has been recognized as the primary afferent pathway capable of transmitting information to the brain from every organ of the body. Therefore, this hypothesis paper aims to review the development of ANS during fetal and perinatal life, focusing particularly on the vagus nerve, to identify possible "critical windows" that could impact its maturation. These "critical windows" could help clinicians know when to monitor fetuses to effectively assess the developmental status of both ANS and specifically the vagus nerve. In addition, this paper will focus on which factors-i.e., fetal characteristics and behaviors, maternal lifestyle and pathologies, placental health and dysfunction, labor, incubator conditions, and drug exposure-may have an impact on the development of the vagus during the above-mentioned "critical window" and how. This analysis could help clinicians and stakeholders define precise guidelines for improving the management of fetuses and newborns, particularly to reduce the potential adverse environmental impacts on ANS development that may lead to persistent long-term consequences. Since the development of ANS and the vagus influence have been shown to be reflected in cardiac variability, this paper will rely in particular on studies using fetal heart rate variability (fHRV) to monitor the continued growth and health of both animal and human fetuses. In fact, fHRV is a non-invasive marker whose changes have been associated with ANS development, vagal modulation, systemic and neurological inflammatory reactions, and even fetal distress during labor.

Signal Processing of Heart Rate for Predicting Sepsis in Premature Neonates

The heart rate characteristic (HeRO score) is a figure derived from the analysis of premature neonate's electrocardiogram signals, and can be used to detect infection before the onset of clinical symptoms. The United States and Europe accept this diagnostic technique, but we require more tests to prove its efficacy. This method is not accepted in other developed countries so far. The present study aimed to investigate changes in the heart characteristics of two neonates in Akbar Abadi Hospital in Tehran. Experts chose one newborn as a sepsis case, and the other neonate was healthy. The results were analyzed and compared with previous studies. In this research, a group of five neonates was selected randomly from the neonatal intensive care unit, and cardiac leads were attached to them for recording heart rates. We selected two neonates from the five cases, as a case (proven sepsis) and control, to analyze heart rate variability (HRV). Then, we compared the differences in the heart rate of both neonates. Analysis of HRV of these two neonates showed that the pattern of HRV is compatible with reports from US studies. Considering the results of this study, heart rates and their analysis can provide useful indicators for mathematical modeling before the onset of clinical symptoms in newborns.

Maturation of the cardiac autonomic regulation system, as function of gestational age in a cohort of low risk preterm infants born between 28 and 32 weeks of gestation

OBJECTIVES

The maturation of the sympathetic nervous system (SNS) occurs steadily throughout gestation while the myelinated vagus has accelerated maturation periods, between 25 and 32 weeks of gestation and a further increase around 37-38 weeks of gestation. The aim was to quantify the cardiac autonomic regulation maturation, as a function of gestational age (GA) in a cohort of low risk preterm infants born between 28 and 32 weeks of gestation by assessing heart rate variability (HRV) at week 32, and at week 35 postmenstrual age (PMA).

METHODS

Forty preterm infants were recruited, 24 h recordings of breathing rate and RR intervals were obtained at week 32 and week 35 PMA.

RESULTS

A significant difference was noted between preterm infants born before 32 weeks GA and preterm infants born at week 32; the latter present higher HRV values throughout the follow-up period. No significant change over time was noted for the parasympathetic HRV measures while a significant increase was found in the sympathetic system. Moreover, a significant interaction effect of time and system was found, the increase in values of the sympathetic system over time was significantly larger than the change noted in the vagal HRV measures.

CONCLUSIONS

Given the beneficial influence of vagal tone on health and developmental outcomes in preterm infants, the findings of the current study highlight the need for further studies on the impact of specifics gestational age on vagal development and later assessing interventions associate with its continue development and maturation at these specific periods.

Heart rate variability as possible marker of brain damage in neonates with hypoxic ischemic encephalopathy: a systematic review

Heart rate variability (HRV) is currently considered the most valuable non-invasive test to investigate the autonomic nervous system function, based on the fact that fast fluctuations might specifically reflect changes of sympathetic and vagal activity. An association between abnormal values of HRV and brain impairment has been reported in the perinatal period, although data are still fragmentary. Considering such association, HRV has been suggested as a possible marker of brain damage also in case of hypoxic-ischemic encephalopathy following perinatal asphyxia. The aim of the present manuscript was to review systematically the current knowledge about the use of HRV as marker of cerebral injury in neonates suffering from hypoxic-ischemic encephalopathy. Findings reported in this paper were based on qualitative analysis of the reviewed data. Conclusion: A growing body of research supports the use of HRV as non-invasive, bedside tool for the monitoring of hypoxic-ischemic encephalopathy. The currently available data about the role of HRV as prognostic tool in case of hypoxic ischemic encephalopathy are promising but require further validation by future studies. What is Known: • Heart rate variability (HRV) is a non-invasive monitoring technique to assess the autonomic nervous system activity. • A correlation between abnormal HRV and cerebral injury has been reported in the perinatal period, and HRV has been suggested as possible marker of brain damage in case of hypoxic-ischemic encephalopathy. What is New: • HRV might provide precocious information about the entity of brain injury in asphyxiated neonates and be of help to design early, specific, and personalized treatments according to severity. • Further investigations are required to confirm these preliminary data.

Doppler ultrasound assessment of splanchnic perfusion and heart rate for the detection of necrotizing enterocolitis

PURPOSE

Monitoring disease progression is crucial to improve the outcome of necrotizing enterocolitis (NEC). A previous study indicates that intestinal wall flow velocity was reduced in NEC pups from the initial stages of the disease. This study aims to investigate whether splanchnic perfusion via the superior mesenteric artery (SMA) (i) is altered during NEC development and (ii) can be used as a monitoring tool to assess disease progression.

METHODS

NEC was induced in C57BL/6 mice via gavage feeding of formula, hypoxia, and oral lipopolysaccharide, from postnatal day 5 (P5) to P9 (AUP: 32,238). Breastfed littermates served as controls. Doppler ultrasound (U/S) of bowel loops was performed daily. Intestinal wall perfusion was calculated as average flow velocity (mm/s) of multiple abdominal regions. Groups were compared using one-way ANOVA.

RESULTS

The SMA flow velocity was not altered during the initial stage of NEC development, but become significantly reduced at P8 when the intestinal disease was more advanced. These changes occurred concomitantly with an increase in heart rate.

CONCLUSIONS

NEC is associated with intestinal hypo-perfusion at the periphery and flow in the SMA is reduced during the later stages of disease indicating the presence of intestinal epithelium damage. This study contributes to understanding NEC pathophysiology and illustrates the value of Doppler U/S in monitoring disease progression.

Heart Rate Variability in the Perinatal Period: A Critical and Conceptual Review

Neonatal intensive care units (NICUs) greatly expand the use of technology. There is a need to accurately diagnose discomfort, pain, and complications, such as sepsis, mainly before they occur. While specific treatments are possible, they are often time-consuming, invasive, or painful, with detrimental effects for the development of the infant. In the last 40 years, heart rate variability (HRV) has emerged as a non-invasive measurement to monitor newborns and infants, but it still is underused. Hence, the present paper aims to review the utility of HRV in neonatology and the instruments available to assess it, showing how HRV could be an innovative tool in the years to come. When continuously monitored, HRV could help assess the baby’s overall wellbeing and neurological development to detect stress-/pain-related behaviors or pathological conditions, such as respiratory distress syndrome and hyperbilirubinemia, to address when to perform procedures to reduce the baby’s stress/pain and interventions, such as therapeutic hypothermia, and to avoid severe complications, such as sepsis and necrotizing enterocolitis, thus reducing mortality. Based on literature and previous experiences, the first step to efficiently introduce HRV in the NICUs could consist in a monitoring system that uses photoplethysmography, which is low-cost and non-invasive, and displays one or a few metrics with good clinical utility. However, to fully harness HRV clinical potential and to greatly improve neonatal care, the monitoring systems will have to rely on modern bioinformatics (machine learning and artificial intelligence algorithms), which could easily integrate infant’s HRV metrics, vital signs, and especially past history, thus elaborating models capable to efficiently monitor and predict the infant’s clinical conditions. For this reason, hospitals and institutions will have to establish tight collaborations between the obstetric, neonatal, and pediatric departments: this way, healthcare would truly improve in every stage of the perinatal period (from conception to the first years of life), since information about patients’ health would flow freely among different professionals, and high-quality research could be performed integrating the data recorded in those departments.

Reproducibility of 24-h heart rate variability measures in preterm infants born at 28-32 weeks of gestation

AIMS

To determine the reproducibility and minimum detectable change (MDC) of heart rate variability (HRV) measures during two sequential 24-h periods, at week 32 of gestation, in preterm infants born between 28 and 32 weeks, hospitalized in the neonatal intensive care unit (NICU). The second aim is to assess postnatal changes in HRV measures between 32 and 35 weeks.

STUDY DESIGN

32 preterm infants born between 28 and 32 weeks of gestation were recruited. For each infant 48 h of recordings of RR interval were performed at week 32 and week 35. HRV parameters included time and frequency parameters.

RESULTS

At week 32, the intra-class correlation coefficient (ICC) of all HRV values was statistically significant with high correlation coefficients (ICC = 0.83-0.97). At week 35, a significant increase was noted in the HRV parameters, characterize mainly the sympathetic tone, with over half the infants showing an increase greater than the MDC for these parameters.

CONCLUSIONS

Using 24-h recording at week 32 of gestation during NICU routine is reliable, feasible, not costly and may have important implications for an early identification of premature in a state of stress such as sepsis, or as a follow-up measure.

Continuous vital sign analysis for predicting and preventing neonatal diseases in the twenty-first century: big data to the forefront

In the neonatal intensive care unit (NICU), heart rate, respiratory rate, and oxygen saturation are vital signs (VS) that are continuously monitored in infants, while blood pressure is often monitored continuously immediately after birth, or during critical illness. Although changes in VS can reflect infant physiology or circadian rhythms, persistent deviations in absolute values or complex changes in variability can indicate acute or chronic pathology. Recent studies demonstrate that analysis of continuous VS trends can predict sepsis, necrotizing enterocolitis, brain injury, bronchopulmonary dysplasia, cardiorespiratory decompensation, and mortality. Subtle changes in continuous VS patterns may not be discerned even by experienced clinicians reviewing spot VS data or VS trends captured in the monitor. In contrast, objective analysis of continuous VS data can improve neonatal outcomes by allowing heightened vigilance or preemptive interventions. In this review, we provide an overview of the studies that have used continuous analysis of single or multiple VS, their interactions, and combined VS and clinical analytic tools, to predict or detect neonatal pathophysiology. We make the case that big-data analytics are promising, and with continued improvements, can become a powerful tool to mitigate neonatal diseases in the twenty-first century.

Influence of nasal CPAP on cardiorespiratory control in healthy neonate

The present study aimed to further unravel the effects of nasal continuous positive airway pressure (nCPAP) on the cardiovascular and respiratory systems in the neonatal period. Six-hour polysomnographic recordings were first performed in seven healthy newborn lambs, aged 2-3 days, without and with nCPAP application at 6 cmH₂O (nCPAP-6), in randomized order. The effects of nCPAP-6 on heart rate variability, respiratory rate variability, and cardiorespiratory interrelations were analyzed using a semiautomatic signal processing approach applied to ECG and respiration recordings. Thereafter, a cardiorespiratory mathematical model was adapted to the experimental conditions to gain further physiological interpretation and to simulate higher nCPAP levels (8 and 10 cmH₂O). Results from the signal processing approach suggest that nCPAP-6 applied in newborns with healthy lungs: 1) increases heart rate and decreases the time and frequency domain indices of heart rate variability, especially those representing parasympathetic activity, while increasing the complexity of the RR-interval time series; 2) prolongs the respiratory cycle and expiration duration and decreases respiratory rate variability; and 3) slightly impairs cardiorespiratory interrelations. Model-based analysis revealed that nCPAP-6 increases the heart rate and decreases respiratory sinus arrhythmia amplitude, in association with a reduced parasympathetic efferent activity. These results were accentuated when simulating an increased CPAP level. Overall, our results provide a further understanding of the effects of nCPAP in neonates, in the absence of lung disease.NEW & NOTEWORTHY Application of nasal continuous positive airway pressure (CPAP) at 6 cmH₂O, a level very frequently used in newborns, alters heart and respiratory rate variability, as well as cardiorespiratory interrelations in a full-term newborn model without lung disease. Moreover, whereas nasal CPAP at 6 cmH₂O decreases parasympathetic efferent activity, there is no change in sympathetic efferent activity.

Necrotizing enterocolitis attenuates developmental heart rate variability increases in newborn rats

BACKGROUND

We have shown previously that a decreased high-frequency spectrum of heart rate variability (HF-HRV), indicative of reduced vagal tone, shows promise in predicting neonates likely to develop necrotizing enterocolitis (NEC) before its clinical onset. We hypothesized that NEC induction in rat pups decreases HF-HRV power; subdiaphragmatic vagotomy worsens the severity of the NEC phenotype, increases levels of pro-inflammatory cytokines, and alters the myenteric phenotype.

METHODS

Newborn Sprague-Dawley rats, representative of preterm human neonates, were subjected to 7-8 days of brief periods of cold stress and hypoxia to induce NEC with or without unilateral subdiaphragmatic vagotomy. HRV was measured at postnatal days one and five, pups were sacrificed at day 8/9, and gastrointestinal tissues and blood were collected for immunohistochemical, corticosterone, and cytokine analysis.

KEY RESULTS

Compared to control, NEC-induced rats showed the following: (a) typical histological signs of grade 2 NEC, which were more severe in rats that underwent vagotomy; (b) reduced developmental increases in time (RMSSD) and frequency (HF) HRV spectra when combined with the stress of laparotomy/vagotomy; (c) increases in nitric oxide synthase-immunoreactivity in the myenteric plexus of jejunum and ileum; furthermore, compared to mild NEC and controls, vagotomized NEC rats had increased plasma values of pro-inflammatory cytokines IL-1β and IL-6.

CONCLUSIONS AND INFERENCES

Our data suggest that in rodents, similar to neonatal observations, NEC induction attenuated developmental HF-HRV increases, furthermore, subdiaphragmatic vagotomy worsened the histological severity, increased pro-inflammatory cytokines, and altered the nitrergic myenteric phenotype, suggesting a role of the vagus in the development of NEC pathology.

An update on biomarkers of necrotizing enterocolitis

Necrotizing enterocolitis (NEC) remains a devastating surgical emergency with high morbidity and mortality in preterm infants. Slow but steady progress has been made in past years searching for novel biomarkers of NEC, for both surveillance and diagnostic purposes. This review primarily focuses on recent discoveries: clinical applications of different categories of biomarkers for surveillance, early diagnosis, and predicting severity and prognosis; and understanding of pathophysiological mechanisms as a basis to rationalize the search for 'gut-associated specific biomarkers' of NEC. An important next step is to collaborate with our industrial partners to develop point-of-care tests, and to discover novel and gut-associated specific biomarkers that can be used for surveillance and early diagnosis of NEC in routine clinical settings.

Caffeine Treatment for Apnea of Prematurity and the Influence on Dose-Dependent Postnatal Weight Gain Observed Over 15 Years

Background and Aim: To analyze the influence on weight gain of infants exposed to two dosage regimens of oral caffeine citrate (CC) for apnea of prematurity.

Methods: Retrospective descriptive observational study of an eligible very low birth weight cohort over a 15-year period in an Irish University hospital. Data were analyzed between two distinct postnatal ages: 14–28 and 29–56 days.

Results: During the 15-year study, 457 infants were prescribed caffeine. Among the 14–28-day group, after applying exclusion criteria, 418 infants qualified. Two hundred forty-eight infants received 5 mg/(kg·day) and 170 received 10 mg/(kg·day) of CC. Among the 29–56-day group, 362 infants were identified and after applying exclusions, 332 fulfilled entry criteria [214 on 5 mg/(kg·day) and 118 on 10 mg/(kg·day) regimen]. Baseline characteristics of infants were comparable between groups without statistically significant differences. Mean daily weight gain (MDWG) in grams from day 14 to 28 showed a higher rate of increase for the 5 mg/(kg·day) group compared with the 10 mg/(kg·day) group (17.2 ± 12 g vs. 13.0 ± 10.2 g [p = 0.04]). From day 29 to 56, also MDWG was higher among infants on 5 mg/(kg·day) of CC compared with 10 mg/(kg·day) group (15.6 ± 10.8 g vs. 10.2 ± 9.8 g [p = 0.011]).

Conclusion: While a variety of measures are optimized to promote postnatal weight gain of premature infants close to an ideal intrauterine growth curve, not paying sufficient attention to one of the most widely used catabolic agents in neonatology is questionable and warrants vigilance. Additional nutritional measures could be offered to those with prolonged caffeine exposure.

Autonomic Dysfunction in Neonates with Hypoxic Ischemic Encephalopathy Undergoing Therapeutic Hypothermia Impairs Physiological Responses to Routine Care Events

OBJECTIVE

To evaluate whether infants with hypoxic-ischemic encephalopathy and evidence of autonomic dysfunction have aberrant physiological responses to care events that could contribute to evolving brain injury.

STUDY DESIGN

Continuous tracings of heart rate (HR), blood pressure (BP), cerebral near infrared spectroscopy, and video electroencephalogram data were recorded from newborn infants with hypoxic-ischemic encephalopathy who were treated with hypothermia. Videos between 16 and 24 hours of age identified 99 distinct care events, including stimulating events (diaper changes, painful procedures), and vagal stimuli (endotracheal tube manipulations, pupil examinations). Pre-event HR variability was used to stratify patients into groups with impaired versus intact autonomic nervous system (ANS) function. Postevent physiological responses were compared between groups with the nearest mean classification approach.

RESULTS

Infants with intact ANS had increases in HR/BP after stimulating events, whereas those with impaired ANS showed no change or decreased HR/BP. With vagal stimuli, the HR decreased in infants with intact ANS but changed minimally in those with impaired ANS. A pupil examination in infants with an intact ANS led to a stable or increased BP, whereas the BP decreased in the group with an impaired ANS. Near infrared spectroscopy measures of cerebral blood flow/blood volume increased after diaper changes in infants with an impaired ANS, but were stable or decreased in those with an intact ANS.

CONCLUSION

HR variability metrics identified infants with impaired ANS function at risk for maladaptive responses to care events. These data support the potential use of HR variability as a real-time, continuous physiological biomarker to guide neuroprotective care in high-risk newborns.

Serum Markers of Necrotizing Enterocolitis: A Systematic Review

OBJECTIVE

The aim of the study was to systematically review the diagnostic utility of serum biomarkers for the diagnosis of necrotizing enterocolitis (NEC).

METHODS

We conducted an electronic and manual search of the available evidence. We included studies reporting data on the diagnostic accuracy of "serum" biomarkers for the diagnosis of NEC, available until January 2016.

RESULTS

We selected 22 studies from the 1296 articles retrieved. Only S100 A8/A9 protein and apolipoprotein-CII showed high sensitivity (100% and 96.4%, respectively) and specificity (90% and 95%, respectively) in the studies using Bell stage II NEC as target condition. High sensitivity and specificity were reported for interleukin-10 (100% and 90%), interleukin1-receptor antagonist (100% and 91.7%), intestinal fatty acid-binding protein (100% and 91%) and ischemia-modified albumin (94.7% and 92%), when tested to predict the evolution from definite to advanced NEC. Given the amount of uncertainty, the limited availability of data and heterogeneity among the populations in the different studies, we were unable to perform a meta-analysis. Major concerns about the applicability stemmed from the spectrum of patients enrolled and the inclusion of diseases different from Bell stage ≥2 NEC as target conditions.

CONCLUSIONS

We identified only few markers with good diagnostic accuracy and found an overall low quality of the studies on serum NEC biomarkers. In conclusion, data supporting their use are insufficient.

Chorioamnionitis following preterm premature rupture of membranes and fetal heart rate variability

Introduction

The objective of this study was to identify prenatal markers of histological chorioamnionitis (HC) during pPROM using fetal computerized cardiotocography (cCTG).

Materials and methods

Retrospective review of medical records from pregnant women referred for pPROM between 26 and 34 weeks, in whom placental histology was available, in a tertiary level obstetric service over a 5-year period. Fetal heart rate variability was assessed using cCTG. Patients were included if they were monitored at least six times in the 72 hours preceding delivery. Clinical and biological cCTG parameters during the pPROM latency period were compared between cases with or without HC.

Results

In total, 222 pPROM cases were observed, but cCTG data was available in only 23 of these cases (10 with and 13 without HC) after exclusion of co-morbidities which may potentially perturb fetal heart rate variability measures. Groups were comparable for maternal age, parity, gestational age at pPROM, pPROM duration and neonatal characteristics (p>0.1). Baseline fetal heart rate was higher in the HC group [median 147.3 bpm IQR (144.2–149.2) vs. 141.3 bpm (137.1–145.4) in no HC group; p = 0.02]. The number of low variation episodes [6.4, (3.5–15.3) vs. 2.3 (1–5.2); p = 0.04] was also higher in the HC group, whereas short term variations were lower in the HC group [7.1 ms (6–7.4) vs. 8.1 ms (7.4–9); p = 0.01] within 72 hours before delivery. Differences were especially discriminant within 24 hours before delivery, with less short-term variation [5 ms (3.7–5.9) vs. 7.8 ms (5.4–8.7); p = 0.007] and high variation episodes [3.9 (4.9–3.2) vs. 0.8 (1.5–0.2); p < 0.001] in the HC group.

Conclusion

These results show differences in fetal heart rate variability, suggesting that cCTG could be used clinically to diagnoses chorioamnionitis during the pPROM latency period.

Heart Rate Variability in Newborns

Heart rate (HR) and heart rate variability (HRV) in newborns is influenced by genetic determinants, gestational and postnatal age, and other variables. Premature infants have a reduced HRV. In neonatal HRV evaluated by spectral analysis, a dominant activity can be found in low frequency (LF) band (combined parasympathetic and sympathetic component). During the first postnatal days the activity in the high frequency (HF) band (parasympathetic component) rises, together with an increase in LF band and total HRV. Hypotrophy in newborn can cause less mature autonomic cardiac control with a higher contribution of sympathetic activity to HRV as demonstrated by sequence plot analysis. During quiet sleep (QS) in newborns HF oscillations increase – a phenomenon less expressed or missing in premature infants. In active sleep (AS), HRV is enhanced in contrast to reduced activity in HF band due to the rise of spectral activity in LF band. Comparison of the HR and HRV in newborns born by physiological vaginal delivery, without (VD) and with epidural anesthesia (EDA) and via sectio cesarea (SC) showed no significant differences in HR and in HRV time domain parameters. Analysis in the frequency domain revealed, that the lowest sympathetic activity in chronotropic cardiac chronotropic regulation is in the VD group. Different neonatal pathological states can be associated with a reduction of HRV and an improvement in the health conditions is followed by changes in HRV what can be use as a possible prognostic marker. Examination of heart rate variability in neonatology can provide information on the maturity of the cardiac chronotropic regulation in early postnatal life, on postnatal adaptation and in pathological conditions about the potential dysregulation of cardiac function in newborns, especially in preterm infants.

Effect of unconjugated hyperbilirubinemia on neonatal autonomic functions: evaluation by heart rate variability

BACKGROUND

Serum bilirubin levels beyond the physiological limits, may lead to alterations in autonomic regulation in a newborn infant. Heart rate variability (HRV), is a noninvasive and quantitative marker of the activity of the autonomic nervous system (ANS). To date, few studies have demonstrated the undesirable effects of severe unconjugated hyperbilirubinemia (UHB) on autonomic functions, and only one study has used HRV as a marker of the autonomic activity. However, the relationship between altered cardiac autonomic functions and UHB by using the HRV derived from 24-hour Holter electrocardiography (ECG) recording has not been investigated previously.

OBJECTIVE

We aimed to assess whether a relationship exists between severe UHB and cardiac autonomic dysfunction by evaluating HRV via 24-hour Holter ECG recording.

METHODS

This single-center, prospective, case-control study was conducted on 50 full-term newborn infants with severe UHB requiring phototherapy and 50 healthy infants as controls. HRV assessment was performed by using 24-hour Holter ECG recording.

RESULTS

There was no significant difference in terms of mean average heart rate, mean maximum heart rate and mean RR duration between the groups. However, mean minimum heart rate was significantly lower in the study group. When 24-hour time and frequency domain parameters were compared, time and frequency domain parameters rMSDD as well as high frequency (HF), which represent parasymphathetic activity, were significantly higher in the study group. Furthermore, low frequency to high frequency (LF/HF) ratio, that serves as an indicator of sympathovagal balance, was significantly lower in the study group.

CONCLUSION

Severe UHB may cause cardiac autonomic dysfunction in favor of parasympathetic predominance in jaundiced neonates.

Cerebral modulation of the autonomic nervous system in term infants

OBJECTIVE

Central topography of autonomic nervous system (ANS) function has yet to be fully deciphered. In adults it has been shown to lateralize sympathetic and parasympathetic influence predominantly to the right and left cerebral hemispheres, respectively. We examined functional topography of central ANS in newborn subjects utilizing spectral analysis of heart rate variability (HRV), an established measure of ANS function.

STUDY DESIGN

We studied newborns with hypoxic-ischemic encephalopathy participating in a prospective study undergoing a therapeutic hypothermia protocol.We included subjects with continuous heart rate data over the first 3 h of normothermia (post rewarming) and brain magnetic resonance imaging, which was reviewed and scored according to a 4 region scheme. HRV was evaluated by spectral analysis in the low-frequency (0.05 to 0.25 Hz) and high-frequency (0.3 to 1 Hz) ranges. The relationship between injured brain regions and HRV was studied using multiple regressions.

RESULTS

Forty eight newborns were included. When examined in isolation, right hemisphere injury had a significant negative effect on HRV (-0.088; 95% CI: -0.225,-0.008). The combination of posterior fossa region injury with right hemispheric injury or left hemispheric injury demonstrated significant positive (0.299; 95% CI: 0.065, 0.518) and negative (-0.475; 95% CI: -0.852, -0.128) influences on HRV, respectively. The association between brain injury location and HRV in the high-frequency range did not reach significance.

CONCLUSION

Our data support the notion that lateralized cerebral modulation of the ANS, specifically of its sympathetic component, is present in the term newborn, and suggest complex modulation of these tracts by components of the posterior fossa.

Early-onset neonatal sepsis is associated with a high heart rate during automatically selected stationary periods

AIM

This study examined the heart rate variability characteristics associated with early-onset neonatal sepsis in a prospective, observational controlled study.

METHODS

Eligible patients were full-term neonates hospitalised with clinical signs that suggested early-onset sepsis and a C-reactive protein of >10 mg/L. Sepsis was considered proven in cases of symptomatic septicaemia, meningitis, pneumonia or enterocolitis. Heart rate variability parameters (n = 16) were assessed from five-, 15- and 30-minute stationary sequences automatically selected from electrocardiographic recordings performed at admission and compared with a control group using the U-test with post hoc Benjamini-Yekutieli correction. Stationary sequences corresponded to the periods with the lowest changes of heart rate variability over time.

RESULTS

A total of 40 full-term infants were enrolled, including 14 with proven sepsis. The mean duration of the cardiac cycle length was lower in the proven sepsis group than in the control group (n = 11), without other significant changes in heart rate variability parameters. These durations, measured in five-minute stationary periods, were 406 (367-433) ms in proven sepsis group versus 507 (463-522) ms in the control group (p < 0.05).

CONCLUSION

Early-onset neonatal sepsis was associated with a high mean heart rate measured during automatically selected stationary periods.

Effect of Temperature on Heart Rate Variability in Neonatal ICU Patients With Hypoxic-Ischemic Encephalopathy

OBJECTIVE

To determine whether measures of heart rate variability are related to changes in temperature during rewarming after therapeutic hypothermia for hypoxic-ischemic encephalopathy.

DESIGN

Prospective observational study.

SETTING

Level 4 neonatal ICU in a free-standing academic children's hospital.

PATIENTS

Forty-four infants with moderate to severe hypoxic-ischemic encephalopathy treated with therapeutic hypothermia.

INTERVENTIONS

Continuous electrocardiogram data from 2 hours prior to rewarming through 2 hours after completion of rewarming (up to 10 hr) were analyzed.

MEASUREMENTS AND MAIN RESULTS

Median beat-to-beat interval and measures of heart rate variability were quantified including beat-to-beat interval SD, low and high frequency relative spectral power, detrended fluctuation analysis short and long α exponents (αS and αL), and root mean square short and long time scales. The relationships between heart rate variability measures and esophageal/axillary temperatures were evaluated. Heart rate variability measures low frequency, αS, and root mean square short and long time scales were negatively associated, whereas αL was positively associated, with temperature (p < 0.01). These findings signify an overall decrease in heart rate variability as temperature increased toward normothermia.

CONCLUSIONS

Measures of heart rate variability are temperature dependent in the range of therapeutic hypothermia to normothermia. Core body temperature needs to be considered when evaluating heart rate variability metrics as potential physiologic biomarkers of illness severity in hypoxic-ischemic encephalopathy infants undergoing therapeutic hypothermia.

A critical question for NEC researchers: Can we create a consensus definition of NEC that facilitates research progress?

In the last decades the reported incidence of preterm necrotizing enterocolitis (NEC) has been declining in large part due to implementing comprehensive NEC prevention initiatives, including breast milk feeding, standardized feeding protocols, transfusion guidelines, and antibiotic stewardship and improving the rigor with which non-NEC cases are excluded from NEC data. However, after more than 60 years of NEC research in animal models, the promise of a "magic bullet" to prevent NEC has yet to materialize. There are also serious issues involving clinical NEC research. There is a lack of a common, comprehensive definition of NEC. National datasets have their own unique definition and staging definitions. Even within academia, randomized trials and single center studies have widely disparate definitions. This makes NEC metadata of very limited value. The world of neonatology needs a comprehensive, universal, consensus definition of NEC. It also needs a de-identified, international data warehouse.

Surgical necrotizing enterocolitis

Although currently available data are variable, it appears that the incidence of surgical necrotizing enterocolitis (NEC) has not decreased significantly over the past decade. Pneumoperitoneum and clinical deterioration despite maximal medical therapy remain the most common indications for operative treatment. Robust studies linking outcomes with specific indications for operation are lacking. Promising biomarkers for severe NEC include fecal calprotectin and S100A12; serum fatty acid-binding protein; and urine biomarkers. Recent advances in ultrasonography make this imaging modality more useful in identifying surgical NEC and near-infrared spectroscopy (NIRS) is being actively studied. Another fairly recent finding is that regionalization of care for infants with NEC likely improves outcomes. The neurodevelopmental outcomes after surgical treatment are known to be poor. A randomized trial near completion will provide robust data regarding neurodevelopmental outcomes after laparotomy versus drainage as the initial operative treatment for severe NEC.

Dexamethasone effect on heart rate variability in preterm infants on mechanical ventilation

BACKGROUND

Dexamethasone is administered to some preterm infants with chronic lung disease to facilitate weaning from mechanical ventilation. Heart rate characteristics (HRC), including heart rate variability (HRV), may be impacted by glucocorticoids and may predict extubation readiness. A commercially available monitor developed for sepsis detection continuously calculates HRV and an HRC index, which are inversely related.

OBJECTIVES

Determine the impact of dexamethasone on HRV and the HRC index, in relation to extubation success.

METHODS

We identified 109 preterm infants who received dexamethasone while on mechanical ventilation and had HRC index monitoring data available. Average hourly HRV and HRC index were compared the day before and the day after initiation of dexamethasone in three groups: infants who remained on mechanical ventilation, those who were successfully extubated, and those who were extubated and required reintubation in < 3 days.

RESULTS

There was a significant increase in HRV and decrease in the HRC index the day after dexamethasone was started (HRV 16.2±0.5 vs 27.6±1.1 ms; HRC index 1.51±0.11 vs. 0.79±0.06 mean SE, p < 0.001). The 63 infants who were extubated within a day of starting dexamethasone had significantly higher HRV compared to those who remained on mechanical ventilation. There was no difference in HRV or its change with dexamethasone in the 45 infants who remained successfully extubated compared to the 18 infants who required reintubation within 3 days.

CONCLUSION

Dexamethasone improves HRV and lowers the HRC index in preterm infants with chronic lung disease on mechanical ventilation.

Current Research on the Epidemiology, Pathogenesis, and Management of Necrotizing Enterocolitis

Despite decades of research on necrotizing enterocolitis, we still do not fully understand the pathogenesis of the disease, or how to prevent or how to treat it. However, as a result of recent significant advances in the microbiology, molecular biology, and cell biology of the intestine of preterm infants and infants with necrotizing enterocolitis, there is some hope that research into this devastating disease will yield some important translation into effective prevention, more rapid diagnosis, and novel therapies.