Oxygen desaturations in the early neonatal period predict development of bronchopulmonary dysplasia

Impact of Pharmacologic Patent Ductus Arteriosus Treatment on Acute Respiratory and Oxygenation Metrics in Very Low Birth Weight Infants

Hypoxemia and respiratory compromise occur in very low birth weight (VLBW, <1,500 g) infants and may be associated with shunting across patent ductus arteriosus (PDA). The impact of pharmacologic PDA treatment on acute hypoxemia and respiratory metrics is unclear. This study aimed to determine whether pharmacologic PDA treatment is associated with acute improvement in hypoxemia and respiratory metrics in VLBW infants.At a single center (2012-2022), all VLBW infants with echocardiographic evidence of PDA and without exclusions were classified as having received or not received pharmacologic PDA treatment (PDA-T and PDA-NT). Mean daily fraction of inspired oxygen (FIO2) and Respiratory Acuity Score (RAS, PMID 30374050) were compared at baseline (day 0) and 3 days after the start of treatment. For PDA-T infants with archived 0.5 Hz (every 2-second) oxygen saturation (SpO2) data, mean daily SpO2 and the percentage of time with severe hypoxemia (SpO2 <80%) were compared before and after treatment. Severe hypoxemia was further analyzed after stratification by clinical variables (sex, medication, gestational age, and postnatal age).We analyzed 125 VLBW infants with PDA, of whom 66 received pharmacologic PDA treatment. We analyzed a subgroup of 43 PDA-T infants with every 2-second SpO2 data available. PDA-T infants had higher baseline FiO2 and RAS and lower SpO2 than PDA-NT infants (p < 0.05). Compared to baseline, RAS decreased from a median of 258 (interquartile range [IQR]: 171, 348) to 254 (IQR: 174, 419), 3 days after the start of treatment (p = 0.012), but median FiO2 increased from 37% (IQR: 28, 46) to 40% (IQR: 29, 52; p = 0.008). SpO2 and the percent time with severe hypoxemia were unchanged.In this 10-year, retrospective, single-center analysis, pharmacologic PDA treatment in VLBW infants was not associated with a major improvement in acute measures of oxygenation or level of respiratory support. · Infants with pharmacologically treated PDA had worse baseline respiratory and oxygenation metrics.. · RAS decreased but FiO2 increased 3 days after pharmacologic PDA treatment.. · Pharmacologic PDA treatment did not acutely improve SpO2 or severe hypoxemia..

Tachycardia-Desaturation Episodes in Neonatal Intensive Care Unit Patients with and without Bronchopulmonary Dysplasia

Much attention has been paid to measuring physiological episodes of bradycardia-oxygen desaturation (BDs) in the neonatal intensive care unit (NICU). NICU patients also have spells of tachycardia-desaturation (TDs), but these have not been well-characterized. We hypothesized that TDs would be more common among infants with bronchopulmonary dysplasia (BPD). We aimed to quantify daily TDs compared to BDs in NICU patients across a range of gestational and postmenstrual ages (GA and PMA) and determine whether TDs are associated with BPD.We analyzed every 2-second heart rate (HR) and peripheral saturation of oxygen (SpO2) throughout the NICU stay of all infants with 24 to 39 weeks GA admitted to a single, level IV NICU from 2012 to 2015. BDs were defined in our prior work (HR <100 bpm for ≥4 seconds with concurrent SpO2 <80% for ≥10 seconds) and TDs as a 20% increase in HR from the previous 2-hour mean baseline and concurrent SpO2 <80% for ≥10 seconds. We calculated the median daily BDs and TDs across a range of GAs and PMAs. For infants ≤32 weeks GA, we compared TDs for those with and without BPD at 36 weeks PMA and discharge on supplemental oxygen.We analyzed 782,424 hours of HR and SpO2 data from 1,718 neonates, with a median of 271 hours analyzed per infant. TDs frequency increased with increasing PMA across all GAs. BDs occurred most frequently in infants <29 weeks GA and decreased as infants approached term equivalent age. For infants with ≤32 weeks GA, one or more TD per day from 33 to 35 weeks PMA was associated with BPD and home oxygen.Episodes of TD at the thresholds defined in this analysis occurred more frequently at later PMA and were more common in infants with BPD and those requiring home oxygen. · Desaturation episodes occur often in preterm infants.. · Bradycardia or tachycardia can coincide with desaturation.. · TD occurs later and with BPD..

Reimagining apnea monitoring in the neonatal ICU

PURPOSE OF REVIEW

This review outlines the prevalence and complications of apneas and intermittent hypoxemic events in preterm infants, examines current monitoring limitations in neonatal ICUs (NICUs), and explores emerging technologies addressing these challenges.

RECENT FINDINGS

New evidence from the Prematurity-Related Ventilatory Control (Pre-Vent) study, which analyzed cardiorespiratory data from 717 extremely preterm infants, exposes the varying frequency, duration, and severity of apneas, intermittent hypoxemia, bradycardias, and periodic breathing during hospitalization, and highlights the negative impact of intermittent hypoxemia on pulmonary outcomes at discharge. Although traditional monitoring methods cannot differentiate between apnea types and quantify their burden, recent advancements in sensor technologies and data integration hold promise for improving real-time detection and evaluation of apneas in the NICU. Notably, small wearable mechano-acoustic sensors could improve apnea monitoring through continuous detection of airflow and respiratory efforts. Additionally, integrating bedside physiological data with modalities such as near-infrared spectroscopy, diaphragmatic activity, and electrical impedance tomography could help predict adverse outcomes by monitoring regional oxygen saturation and lung function in relation to apneas.

SUMMARY

Enhancing our understanding of neonatal apneas and overcoming the current limitations in apnea monitoring through advanced sensor technologies and data integration could lead to more personalized management and improved outcomes for preterm infants.

Energy Utilization in Premature Neonates Undergoing Screening for Retinopathy of Prematurity

BACKGROUND/OBJECTIVES

Premature neonates are at risk for retinopathy of prematurity (ROP) and routinely undergo screening exams that involve substantial physical manipulation, often causing significant signs of pain, despite pain-relieving interventions. It remains unclear whether these exams affect energy utilization, cellular hypoxia, and clinically significant events, and whether receiving supplemental oxygen affects these relationships. This work examines the effects of ROP screening on (1) urinary uric acid-to-creatinine concentration ratios ([UA]/[Cr]), a known marker of ATP degradation, hypoxia, and oxidative stress; and (2) clinically significant events (apnea, bradycardia, gastric residuals, and oxygen desaturations) in premature neonates on room air or oxygen support.

METHODS

This prospective pilot study included premature neonates requiring ROP screening examinations at Loma Linda University's NICU. Urinary [UA]/[Cr], measured by high-performance liquid chromatography, and clinical events, documented by prospective medical chart review, were analyzed pre- and post-exam in subjects on room air (n = 18) or on oxygen support (n = 20). Statistical analyses included a generalized linear mixed model for urinary [UA]/[Cr] and Wilcoxon signed rank tests for clinical events.

RESULTS

A significant time effect (p = 0.010) was observed for urinary [UA]/[Cr], with higher levels at 0-12 (p = 0.023) and 12-24 (p = 0.023) hours post-exam. Subjects receiving oxygen support had more total (p = 0.028) and more severe (p = 0.026) oxygen desaturations.

CONCLUSIONS

ROP examinations may increase energy utilization in premature neonates, with those receiving oxygen support being particularly susceptible to oxygen desaturations post-exam. Further research is needed to clarify the full impact of the procedure and to identify strategies to minimize stress associated with these screening examinations.

Neonatal intermittent hypoxemia events are associated with later systemic hypertension

BACKGROUND

Approximately 5% of very premature infants delivered at less than 30 weeks' gestation have systemic hypertension. In adult human and animal models, intermittent hypoxemia events are associated with systemic hypertension. In neonates, intermittent hypoxemia events are associated with adverse outcomes, but it is unknown if they are a risk factor for hypertension. We hypothesize that early intermittent hypoxemia events in very preterm neonates are associated with systemic hypertension at 34-36 weeks' postmenstrual age.

METHODS

Secondary analysis of a single-center cohort study of 164 infants, <31 weeks' gestational age. Intermittent hypoxemia events were continuously recorded during the first 21 days of age.

RESULTS

There was a significant association between the number of intermittent hypoxemia events (per 100) and systemic hypertension (OR (95% CI) = 1.08 (1.01-1.15)), and both the number of intermittent hypoxemia events (per 100 β (95% CI) = 0.22 (0.10-0.34)) and percent of time with hypoxemia (β (95% CI) = 0.10 (0.01-0.19)) and systolic blood pressure at 34-36 weeks' postmenstrual age.

CONCLUSION

This study demonstrated a higher incidence of early intermittent hypoxemia events in preterm infants with hypertension. Decreasing intermittent hypoxemia during this critical period may reduce incidence of later vascular stress in this population.

IMPACT

Intermittent hypoxemia events are very common in premature infants and increased frequency of intermittent hypoxemia events is associated with morbidity. Intermittent hypoxemia events in adult human as well as adult and neonatal animal models are associated with systemic hypertension. This study demonstrated an association between early intermittent hypoxemia events and systemic hypertension in very preterm neonates, adding to the body of literature of possible morbidities caused by intermittent hypoxemia events. This study addresses the common, though under-recognized, issue of neonatal hypertension, and suggests increased intermittent hypoxemia events may be contributory.

Apnea, Intermittent Hypoxemia, and Bradycardia Events Predict Late-Onset Sepsis in Infants Born Extremely Preterm

OBJECTIVE

The objective of this study was to examine the association of cardiorespiratory events, including apnea, periodic breathing, intermittent hypoxemia (IH), and bradycardia, with late-onset sepsis for extremely preterm infants (<29 weeks of gestational age) on vs off invasive mechanical ventilation.

STUDY DESIGN

This is a retrospective analysis of data from infants enrolled in Pre-Vent (ClinicalTrials.gov identifier NCT03174301), an observational study in 5 level IV neonatal intensive care units. Clinical data were analyzed for 737 infants (mean gestational age: 26.4 weeks, SD 1.71). Monitoring data were available and analyzed for 719 infants (47 512 patient-days); of whom, 109 had 123 sepsis events. Using continuous monitoring data, we quantified apnea, periodic breathing, bradycardia, and IH. We analyzed the relationships between these daily measures and late-onset sepsis (positive blood culture >72 hours after birth and ≥5-day antibiotics).

RESULTS

For infants not on a ventilator, apnea, periodic breathing, and bradycardia increased before sepsis diagnosis. During times on a ventilator, increased sepsis risk was associated with longer events with oxygen saturation <80% (IH80) and more bradycardia events before sepsis. IH events were associated with higher sepsis risk but did not dynamically increase before sepsis, regardless of ventilator status. A multivariable model including postmenstrual age, cardiorespiratory variables (apnea, periodic breathing, IH80, and bradycardia), and ventilator status predicted sepsis with an area under the receiver operator characteristic curve of 0.783.

CONCLUSION

We identified cardiorespiratory signatures of late-onset sepsis. Longer IH events were associated with increased sepsis risk but did not change temporally near diagnosis. Increases in bradycardia, apnea, and periodic breathing preceded the clinical diagnosis of sepsis.

Heart Rate and Pulse Oximetry Dynamics in the First Week after Birth in Neonatal Intensive Care Unit Patients and the Risk of Cerebral Palsy

OBJECTIVE

Infants in the neonatal intensive care unit (NICU) are at high risk of adverse neuromotor outcomes. Atypical patterns of heart rate (HR) and pulse oximetry (SpO2) may serve as biomarkers for risk assessment for cerebral palsy (CP). The purpose of this study was to determine whether atypical HR and SpO2 patterns in NICU patients add to clinical variables predicting later diagnosis of CP.

STUDY DESIGN

This was a retrospective study including patients admitted to a level IV NICU from 2009 to 2017 with archived cardiorespiratory data in the first 7 days from birth to follow-up at >2 years of age. The mean, standard deviation (SD), skewness, kurtosis and cross-correlation of HR and SpO2 were calculated. Three predictive models were developed using least absolute shrinkage and selection operator regression (clinical, cardiorespiratory and combined model), and their performance for predicting CP was evaluated.

RESULTS

Seventy infants with CP and 1,733 controls met inclusion criteria for a 3.8% population prevalence. Area under the receiver operating characteristic curve for CP prediction was 0.7524 for the clinical model, 0.7419 for the vital sign model, and 0.7725 for the combined model. Variables included in the combined model were lower maternal age, outborn delivery, lower 5-minute Apgar's score, lower SD of HR, and more negative skewness of HR.

CONCLUSION

In this study including NICU patients of all gestational ages, HR but not SpO2 patterns added to clinical variables to predict the eventual diagnosis of CP. Identification of risk of CP within the first few days of life could result in improved therapy resource allocation and risk stratification in clinical trials of new therapeutics.

KEY POINTS

· SD and skewness of HR have some added predictive value of later diagnosis of CP.. · SpO2 measures do not add to CP prediction.. · Combining clinical variables with early HR measures may improve the prediction of later CP..

Effects of bradycardia, hypoxemia and early intubation on bronchopulmonary dysplasia in very preterm infants: An observational study

BACKGROUND

Bronchopulmonary dysplasia (BPD) is the most common pulmonary complication in preterm infants.

OBJECTIVES

The study aimed to explore the effects of bradycardia, hypoxemia, and early intubation on BPD in very preterm infants.

METHODS

This is a prospective observational cohort study. Preterm infants with a mean gestational age of 28.67 weeks were recruited from two level III neonatal intensive care units (NICUs) in Taiwan. Continuous electrocardiography was used to monitor heart rates and oxygen saturation (SpO2). Infants were monitored for heart rates of <100 beats per minute and SpO2 levels of <90 % lasting for 30 s. Generalized estimating equations were used to analyze the effects of bradycardia, hypoxemia, and early intubation on BPD in very preterm infants. Model fit was visually assessed using receiver operating characteristic curve analysis.

RESULTS

Bradycardia, hypoxemia, and early intubation significantly increased the odds of BPD among the preterm infants (N = 39) during NICU stay; the odds ratios for bradycardia, hypoxemia, and early intubation for BPD versus non-BPD were 1.058, 1.013, and 29.631, respectively (all p < 0.05). A model combining bradycardia, hypoxemia, and early intubation accurately predicted BPD development (area under the curve = 0.919).

CONCLUSIONS

Bradycardia, hypoxemia, and early intubation significantly increased the odds of BPD among very preterm infants during NICU stay. The model combining bradycardia, hypoxemia, and early intubation accurately predicted BPD development.

Oxygenation Instability during Bolus versus Continuous Feeding among Very Low Birth Weight Premature Infants, Supported by Noninvasive Ventilation: A Randomized Prospective Study

OBJECTIVE

This study aimed to compare oxygenation instability, as documented by the oxygen saturation (SpO2) histograms, during bolus (over 30 minutes) versus continuous (over 2 hours) feeding among very low birth weight (VLBW) premature infants, supported with noninvasive ventilation (NIV).

STUDY DESIGN

This was a randomized prospective study. VLBW infants supported with NIV received three consecutive feeds in a random order of bolus-continuous-bolus or continuous-bolus-continuous. During each feed, 30 minutes and 2 hours histograms were documented.

RESULTS

Twenty-four infants (birth weight [mean ± standard deviation, SD] 820 ± 168 g, gestational age [mean ± SD] 27.0 ± 1.6 weeks) were included in our study (12 infants started with bolus feeding and 12 with continuous feeding) and 72 histograms were obtained (36 during bolus feeding and 36 during continuous feeding). No differences in mean fraction of inspired oxygen (FiO2), and number of apnea events were observed between the two feeding modes. Oxygenation instability as assessed by time spent in different SpO2 ranges and histogram types (stable or unstable) was comparable during bolus and continuous feedings. Changing feeding mode from bolus to continuous or vice versa did not significantly change the oxygenation instability of the group, though individual infants did show a consistence response to feeding length changes.

CONCLUSION

Among VLBW infants supported with NIV, oxygenation instability, as documented by SpO2 histograms, was comparable between bolus and continuous feedings. Individual infants may benefit from specific feeding length, and this can be easily demonstrated by the SpO2 histograms.

KEY POINTS

· Feeding length did not affect oxygenation instability of preterm infants on noninvasive respiratory Support.. · Oxygen saturation histograms allow objective quantification of oxygenation instability at the bedside.. · Individual infants benefit from specific feeding length, as demonstrated by SpO2 histograms..

Maturation of cardioventilatory physiological trajectories in extremely preterm infants

BACKGROUND

In extremely preterm infants, persistence of cardioventilatory events is associated with long-term morbidity. Therefore, the objective was to characterize physiologic growth curves of apnea, periodic breathing, intermittent hypoxemia, and bradycardia in extremely preterm infants during the first few months of life.

METHODS

The Prematurity-Related Ventilatory Control study included 717 preterm infants <29 weeks gestation. Waveforms were downloaded from bedside monitors with a novel sharing analytics strategy utilized to run software locally, with summary data sent to the Data Coordinating Center for compilation.

RESULTS

Apnea, periodic breathing, and intermittent hypoxemia events rose from day 3 of life then fell to near-resolution by 8-12 weeks of age. Apnea/intermittent hypoxemia were inversely correlated with gestational age, peaking at 3-4 weeks of age. Periodic breathing was positively correlated with gestational age peaking at 31-33 weeks postmenstrual age. Females had more periodic breathing but less intermittent hypoxemia/bradycardia. White infants had more apnea/periodic breathing/intermittent hypoxemia. Infants never receiving mechanical ventilation followed similar postnatal trajectories but with less apnea and intermittent hypoxemia, and more periodic breathing.

CONCLUSIONS

Cardioventilatory events peak during the first month of life but the actual postnatal trajectory is dependent on the type of event, race, sex and use of mechanical ventilation.

IMPACT

Physiologic curves of cardiorespiratory events in extremely preterm-born infants offer (1) objective measures to assess individual patient courses and (2) guides for research into control of ventilation, biomarkers and outcomes. Presented are updated maturational trajectories of apnea, periodic breathing, intermittent hypoxemia, and bradycardia in 717 infants born <29 weeks gestation from the multi-site NHLBI-funded Pre-Vent study. Cardioventilatory events peak during the first month of life but the actual postnatal trajectory is dependent on the type of event, race, sex and use of mechanical ventilation. Different time courses for apnea and periodic breathing suggest different maturational mechanisms.

Prediction of bronchopulmonary dysplasia in very preterm infants: competitive risk model nomogram

Objective

To develop predictive clinical models of bronchopulmonary dysplasia (BPD) through competing risk analysis.

Methods

Retrospective observational cohort study, including preterm newborns ≤32 weeks gestational age, conducted between January 1, 2013 and September 30, 2022 in a third-level Neonatal Intensive Care Unit in Spain. A prediction study was carried out using competing risk models, where the event of interest was BPD and the competing event was death. A multivariate competing risk model was developed separately for each postnatal day (days 1, 3, 7 and 14). Nomograms to predict BPD risk were developed from the coefficients of the final models and internally validated.

Results

A total of 306 patients were included in the study, of which 73 (23.9%) developed BPD and 29 (9.5%) died. On day 1, the model with the greatest predictive capacity was that including birth weight, days since rupture of membranes, and surfactant requirement (area under the receiver operating characteristic (ROC) curve (AUC), 0.896; 95% CI, 0.792-0.999). On day 3, the final predictive model was based on the variables birth weight, surfactant requirement, and Fraction of Inspired Oxygen (FiO2) (AUC, 0.891; 95% CI, 0.792-0.989).

Conclusions

Competing risk analysis allowed accurate prediction of BPD, avoiding the potential bias resulting from the exclusion of deceased newborns or the use of combined outcomes. The resulting models are based on clinical variables measured at bedside during the first 3 days of life, can be easily implemented in clinical practice, and can enable earlier identification of patients at high risk of BPD.

Apnea, Intermittent Hypoxemia, and Bradycardia Events Predict Late-Onset Sepsis in Extremely Preterm Infants

Objectives

Detection of changes in cardiorespiratory events, including apnea, periodic breathing, intermittent hypoxemia (IH), and bradycardia, may facilitate earlier detection of sepsis. Our objective was to examine the association of cardiorespiratory events with late-onset sepsis for extremely preterm infants (<29 weeks' gestational age (GA)) on versus off invasive mechanical ventilation.

Study Design

Retrospective analysis of data from infants enrolled in Pre-Vent (ClinicalTrials.gov identifier NCT03174301), an observational study in five level IV neonatal intensive care units. Clinical data were analyzed for 737 infants (mean GA 26.4w, SD 1.71). Monitoring data were available and analyzed for 719 infants (47,512 patient-days), of whom 109 had 123 sepsis events. Using continuous monitoring data, we quantified apnea, periodic breathing, bradycardia, and IH. We analyzed the relationships between these daily measures and late-onset sepsis (positive blood culture >72h after birth and ≥5d antibiotics).

Results

For infants not on a ventilator, apnea, periodic breathing, and bradycardia increased before sepsis diagnosis. During times on a ventilator, increased sepsis risk was associated with longer IH80 events and more bradycardia events before sepsis. IH events were associated with higher sepsis risk, but did not dynamically increase before sepsis, regardless of ventilator status. A multivariable model predicted sepsis with an AUC of 0.783.

Conclusion

We identified cardiorespiratory signatures of late-onset sepsis. Longer IH events were associated with increased sepsis risk but did not change temporally near diagnosis. Increases in bradycardia, apnea, and periodic breathing preceded the clinical diagnosis of sepsis.

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.

Clinical usefulness of reintubation criteria in extremely preterm infants: a cohort study

OBJECTIVE

To describe the thresholds of instability used by clinicians at reintubation and evaluate the accuracy of different combinations of criteria in predicting reintubation decisions.

DESIGN

Secondary analysis using data obtained from the prospective observational Automated Prediction of Extubation Readiness study (NCT01909947) between 2013 and 2018.

SETTING

Multicentre (three neonatal intensive care units).

PATIENTS

Infants with birth weight ≤1250 g, mechanically ventilated and undergoing their first planned extubation were included.

INTERVENTIONS

After extubation, hourly O2 requirements, blood gas values and occurrence of cardiorespiratory events requiring intervention were recorded for 14 days or until reintubation, whichever came first.

MAIN OUTCOME MEASURES

Thresholds at reintubation were described and grouped into four categories: increased O2, respiratory acidosis, frequent cardiorespiratory events and severe cardiorespiratory events (requiring positive pressure ventilation). An automated algorithm was used to generate multiple combinations of criteria from the four categories and compute their accuracies in capturing reintubated infants (sensitivity) without including non-reintubated infants (specificity).

RESULTS

55 infants were reintubated (median gestational age 25.2 weeks (IQR 24.5-26.1 weeks), birth weight 750 g (IQR 640-880 g)), with highly variable thresholds at reintubation. After extubation, reintubated infants had significantly greater O2 needs, lower pH, higher pCO2 and more frequent and severe cardiorespiratory events compared with non-reintubated infants. After evaluating 123 374 combinations of reintubation criteria, Youden indices ranged from 0 to 0.46, suggesting low accuracy. This was primarily attributable to the poor agreement between clinicians on the number of cardiorespiratory events at which to reintubate.

CONCLUSIONS

Criteria used for reintubation in clinical practice are highly variable, with no combination accurately predicting the decision to reintubate.

Hypoxemia events in preterm neonates are associated with urine oxidative biomarkers

BACKGROUND

Intermittent hypoxemia (IH) events are common in preterm neonates and are associated with adverse outcomes. Animal IH models can induce oxidative stress. We hypothesized that an association exists between IH and elevated peroxidation products in preterm neonates.

METHODS

Time in hypoxemia, frequency of IH, and duration of IH events were assessed from a prospective cohort of 170 neonates (<31 weeks gestation). Urine was collected at 1 week and 1 month. Samples were analyzed for lipid, protein, and DNA oxidation biomarkers.

RESULTS

At 1 week, adjusted multiple quantile regression showed positive associations between several hypoxemia parameters with various individual quantiles of isofurans, neurofurans, dihomo-isoprostanes, dihomo-isofurans, and ortho-tyrosine and a negative correlation with dihomo-isoprostanes and meta-tyrosine. At 1 month, positive associations were found between several hypoxemia parameters with quantiles of isoprostanes, dihomo-isoprostanes and dihomo-isofurans and a negative correlation with isoprostanes, isofurans, neuroprostanes, and meta-tyrosine.

CONCLUSIONS

Preterm neonates experience oxidative damage to lipids, proteins, and DNA that can be analyzed from urine samples. Our single-center data suggest that specific markers of oxidative stress may be related to IH exposure. Future studies are needed to better understand mechanisms and relationships to morbidities of prematurity.

IMPACT

Hypoxemia events are frequent in preterm infants and are associated with poor outcomes. The mechanisms by which hypoxemia events result in adverse neural and respiratory outcomes may include oxidative stress to lipids, proteins, and DNA. This study begins to explore associations between hypoxemia parameters and products of oxidative stress in preterm infants. Oxidative stress biomarkers may assist in identifying high-risk neonates.

Plasma serotonergic biomarkers are associated with hypoxemia events in preterm neonates

BACKGROUND

Hypoxemia is a physiological manifestation of immature respiratory control in preterm neonates, which is likely impacted by neurotransmitter imbalances. We investigated relationships between plasma levels of the neurotransmitter serotonin (5-HT), metabolites of tryptophan (TRP), and parameters of hypoxemia in preterm neonates.

METHODS

TRP, 5-HT, 5-hydroxyindoleacetic acid (5-HIAA), and kynurenic acid (KA) were analyzed in platelet-poor plasma at ~1 week and ~1 month of life from a prospective cohort of 168 preterm neonates <31 weeks gestational age (GA). Frequency of intermittent hypoxemia (IH) events and percent time hypoxemic (<80%) were analyzed in a 6 h window after the blood draw.

RESULTS

At 1 week, infants with detectable plasma 5-HT had fewer IH events (OR (95% CI) = 0.52 (0.29, 0.31)) and less percent time <80% (OR (95% CI) = 0.54 (0.31, 0.95)) compared to infants with undetectable 5-HT. A similar relationship occurred at 1 month. At 1 week, infants with higher KA showed greater percent time <80% (OR (95% CI) = 1.90 (1.03, 3.50)). TRP, 5-HIAA or KA were not associated with IH frequency at either postnatal age. IH frequency and percent time <80% were positively associated with GA < 29 weeks.

CONCLUSIONS

Circulating neuromodulators 5-HT and KA might represent biomarkers of immature respiratory control contributing to hypoxemia in preterm neonates.

IMPACT

Hypoxemia events are frequent in preterm infants and are associated with poor outcomes. Mechanisms driving hypoxemia such as immature respiratory control may include central and peripheral imbalances in modulatory neurotransmitters. This study found associations between the plasma neuromodulators serotonin and kynurenic acid and parameters of hypoxemia in preterm neonates. Imbalances in plasma biomarkers affecting respiratory control may help identify neonates at risk of short- and long-term adverse outcomes.

Prediction Models for Bronchopulmonary Dysplasia in Preterm Infants: A Systematic Review and Meta-Analysis

OBJECTIVE

To review systematically and assess the accuracy of prediction models for bronchopulmonary dysplasia (BPD) at 36 weeks of postmenstrual age.

STUDY DESIGN

Searches were conducted in MEDLINE and EMBASE. Studies published between 1990 and 2022 were included if they developed or validated a prediction model for BPD or the combined outcome death/BPD at 36 weeks in the first 14 days of life in infants born preterm. Data were extracted independently by 2 authors following the Critical Appraisal and Data Extraction for Systematic Reviews of Prediction Modelling Studies (ie, CHARMS) and PRISMA guidelines. Risk of bias was assessed using the Prediction model Risk Of Bias ASsessment Tool (ie, PROBAST).

RESULTS

Sixty-five studies were reviewed, including 158 development and 108 externally validated models. Median c-statistic of 0.84 (range 0.43-1.00) was reported at model development, and 0.77 (range 0.41-0.97) at external validation. All models were rated at high risk of bias, due to limitations in the analysis part. Meta-analysis of the validated models revealed increased c-statistics after the first week of life for both the BPD and death/BPD outcome.

CONCLUSIONS

Although BPD prediction models perform satisfactorily, they were all at high risk of bias. Methodologic improvement and complete reporting are needed before they can be considered for use in clinical practice. Future research should aim to validate and update existing models.

Care Bundle to Improve Oxygen Maintenance and Events

Prolonged periods spent outside the target range of oxygen saturation (SpO₂) in preterm infants, along with frequent desaturation events, predispose them to retinopathy of prematurity (ROP) and long-term neurodevelopmental impairment. The primary aim of this study was to increase the mean time spent within the target SpO₂ range (WTR) by 10% and to reduce the frequency of desaturation events by 5 events per patient day, respectively, within 18 months of implementing a care bundle.

Methods

This study was completed in a 46-bed neonatal intensive care unit (NICU), involving 246 staff members and led by a quality improvement team. The change interventions included implementing new practice guidelines, reviewing daily summaries of SpO₂ maintenance, daily infant wellness assessment, standardizing workflow, and responding to SpO₂ alarms. In addition, we collected staff satisfaction and compliance with change interventions, resource use, and morbidity and mortality data at discharge.

Results

The mean time spent WTR increased from 65.3% to 75.3%, and the frequency of desaturation events decreased from 25.1 to 16.5 events per patient day, respectively, with a higher magnitude of benefit in infants on days with supplemental oxygen. Postimplementation, the duration of high-frequency ventilation and supplemental oxygen were lower, but morbidity and mortality rates were similar. Staff satisfaction with training workshops, coaching, use of the infant wellness assessment tool, and SpO₂ alarm management algorithms were 74%, 82%, 80%, and 74%, respectively.

Conclusion

Implementing a care bundle to improve oxygen maintenance and reduce desaturation events increased the time spent WTR and reduced the frequency of desaturation events.

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.

Neonatal intermittent hypoxia persistently impairs lung vascular development and induces long-term lung mitochondrial DNA damage

Adults born preterm have an increased risk of pulmonary vascular disease. Extreme preterm infants often require supplemental oxygen but they also exhibit frequent intermittent hypoxemic episodes (IH). Here, we test the hypothesis that neonatal IH induces lung endothelial cell mitochondrial DNA (mitDNA) damage and contributes to long-term pulmonary vascular disease and pulmonary hypertension (PH). Newborn C57BL/6J mice were assigned to the following groups: 1) normoxia, 2) hyperoxia (O2 65%), 3) normoxia cycling with IH (O2 21% + O2 10%), and 4) hyperoxia cycling with IH (O2 65% + O2 10%) for 3 wk. IH episodes were initiated on postnatal day 7. Lung angiogenesis, PH, and mitDNA lesions were assessed at 3 wk and 3 mo. In vitro, the effect of IH on tubule formation and mitDNA lesions was evaluated in human pulmonary microvascular endothelial cells (HPMECs). Data were analyzed by ANOVA. In vitro, IH exposure reduced tubule formation and increased mitDNA lesions in HPMECs. This was most marked in HPMECs exposed to hyperoxia cycling with IH. In vivo, neonatal IH increased lung mitDNA lesions, impaired angiogenesis, and induced PH in 3-wk-old mice. These findings were pronounced in mice exposed to hyperoxia cycling with IH. At 3 mo follow-up, mice exposed to neonatal IH had persistently increased lung mitDNA lesions and impaired lung angiogenesis, even without concomitant hyperoxia exposure. Neonatal IH induces lung endothelial cell mitDNA damage and causes persistent impairment in lung angiogenesis. These findings provide important mechanistic insight into the pathogenesis of pulmonary vascular disease in preterm survivors.NEW & NOTEWORTHY Our current study demonstrates that neonatal intermittent hypoxia (IH) alters lung endothelial cell function, induces mitochondrial DNA lesions, and impairs lung vascular growth into adulthood. Moreover, when superimposed on hyperoxia, neonatal IH induces a severe lung vascular phenotype that is seen in preterm infants with PH. These findings suggest that neonatal IH contributes to PH in adults born preterm and importantly, that mitochondrial protection strategies may mitigate these deleterious effects.

Regional oxygenation, perfusion and body and/or head position: Are preterm infants adversely impacted? A systematic review

This review addresses regional oxygenation and perfusion changes for preterm infants and changes with body position, with or without head rotation. Future directions for improving neurodevelopmental and clinical outcomes are suggested. The MEDLINE, Embase and Scopus databases were searched up to July 2021. Fifteen out of 470 studies met the inclusion criteria. All were prospective, observational studies with a moderate risk of bias. Significant variation was found for the baseline characteristics of the cohort, postnatal ages, and respiratory support status at the time of monitoring. When placed in a non-supine position, preterm infants showed a transient reduction in cardiac output and stroke volume without changes to heart rate or blood pressure. No studies reported on long-term neurodevelopmental outcomes. Overall, side lying or prone position does not appear to adversely affect regional, and specifically cerebral, oxygenation or cerebral perfusion. The effect of head rotation on regional oxygenation and perfusion remains unclear.

Corticosteroid response predicts bronchopulmonary dysplasia status at 36 weeks in preterm infants treated with dexamethasone: A pilot study

IMPORTANCE

A major barrier to therapeutic development in neonates is a lack of standardized drug response measures that can be used as clinical trial endpoints. The ability to quantify treatment response in a way that aligns with relevant downstream outcomes may be useful as a surrogate marker for new therapies, such as those for bronchopulmonary dysplasia (BPD).

OBJECTIVE

To construct a measure of clinical response to dexamethasone that was well aligned with the incidence of severe BPD or death at 36 weeks' postmenstrual age.

DESIGN

Retrospective cohort study.

SETTING

Level IV Neonatal Intensive Care Unit.

PARTICIPANTS

Infants treated with dexamethasone for developing BPD between 2010 and 2020.

MAIN OUTCOME(S) AND MEASURE(S)

Two models were built based on demographics, changes in ventilatory support, and partial pressure of carbon dioxide (pCO₂ ) after dexamethasone administration. An ordinal logistic regression and regularized binary logistic model for the composite outcome were used to associate response level to BPD outcomes defined by both the 2017 BPD Collaborative and 2018 Neonatal Research Network definitions.

RESULTS

Ninety-five infants were treated with dexamethasone before 36 weeks. Compared to the baseline support and demographic data at the time of treatment, changes in ventilatory support improved ordinal model sensitivity and specificity. For the binary classification, BPD incidence was well aligned with risk levels, increasing from 16% to 59%.

CONCLUSIONS AND RELEVANCE

Incorporation of response variables as measured by changes in ventilatory parameters and pCO₂ following dexamethasone administration were associated with downstream outcomes. Incorporating drug response phenotype into a BPD model may enable more rapid development of future therapeutics.

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..

Association between Intermittent Hypoxemia and Severe Bronchopulmonary Dysplasia in Preterm Infants

Rationale: Bronchopulmonary dysplasia increases the risk of disability in extremely preterm infants. Although the pathophysiology remains uncertain, prior exposure to intermittent hypoxemia may play a role in this relationship. Objectives: To determine the association between prolonged episodes of intermittent hypoxemia and severe bronchopulmonary dysplasia. Methods: A post hoc analysis of extremely preterm infants in the Canadian Oxygen Trial who survived to 36 weeks' postmenstrual age was performed. Oxygen saturations <80% for ⩾1 minute and the proportion of time per day with hypoxemia were quantified using continuous pulse oximetry data that had been sampled every 10 seconds from within 24 hours of birth until 36 weeks' postmenstrual age. The study outcome was severe bronchopulmonary dysplasia as defined in the 2001 NIH Workshop Summary. Measurements and Main Results: Of 1,018 infants, 332 (32.6%) developed severe bronchopulmonary dysplasia. The median number of hypoxemic episodes ranged from 0.8/day (interquartile range, 0.2-1.1) to 60.2/day (interquartile range, 51.4-70.3) among the least and most affected 10% of infants. Compared with the lowest decile of exposure to hypoxemic episodes, the adjusted relative risk of severe bronchopulmonary dysplasia increased progressively from 1.72 (95% confidence interval, 1.55-1.90) at the 2nd decile to 20.40 (95% confidence interval, 12.88-32.32) at the 10th decile. Similar risk gradients were observed for time in hypoxemia. Significant differences in the rates of hypoxemia between infants with and without severe bronchopulmonary dysplasia emerged within the first week after birth. Conclusions: Prolonged intermittent hypoxemia beginning in the first week after birth was associated with an increased risk of developing severe bronchopulmonary dysplasia among extremely preterm infants. Clinical trial registered with www.isrctn.com (ISRCTN62491227) and www.clinicaltrials.gov (NCT00637169).

Oxygen Toxicity to the Immature Lung-Part II: The Unmet Clinical Need for Causal Therapy

Oxygen toxicity continues to be one of the inevitable injuries to the immature lung. Reactive oxygen species (ROS) production is the initial step leading to lung injury and, subsequently, the development of bronchopulmonary dysplasia (BPD). Today, BPD remains the most important disease burden following preterm delivery and results in life-long restrictions in lung function and further important health sequelae. Despite the tremendous progress in the pathomechanistic understanding derived from preclinical models, the clinical needs for preventive or curative therapies remain unmet. This review summarizes the clinical progress on guiding oxygen delivery to the preterm infant and elaborates future directions of research that need to take into account both hyperoxia and hypoxia as ROS sources and BPD drivers. Many strategies have been tested within clinical trials based on the mechanistic understanding of ROS actions, but most have failed to prove efficacy. The majority of these studies were tested in an era before the latest modes of non-invasive respiratory support and surfactant application were introduced or were not appropriately powered. A comprehensive re-evaluation of enzymatic, antioxidant, and anti-inflammatory therapies to prevent ROS injury is therefore indispensable. Strategies will only succeed if they are applied in a timely and vigorous manner and with the appropriate outcome measures.

Lung ultrasound predicts the development of bronchopulmonary dysplasia: a prospective observational diagnostic accuracy study

This study aimed to evaluate the predictive ability of lung ultrasound (LU) in the development of bronchopulmonary dysplasia (BPD) in very low birth weight (VLBW) infants. A total of 130 VLBW infants with gestational age < 32 weeks were included; LU was performed at days 1, 2, 3, 6, 9, 12, and 15 postnatally. We calculated the LU score by 12-region, 10-region, and 6-region protocols. The incidence of BPD according to the National Institutes of Health (NIH) 2001 definition and 2019 criteria was 38.5% and 64.6%, respectively. By 12-region and 10-region protocols, LU predicted BPD from the 9^th to 15^th days of life (DOLs) regardless of the criteria used, with an area under the curve (AUC) ranging from 0.826 (95% confidence interval (CI): 0.750-0.887) to 0.877 (95% CI: 0.807-0.928). According to the 2019 BPD definition, the LU score incorporated gestational age, and invasive mechanical ventilation >6 days predicted BPD on the 6^th DOL with an AUC of 0.862 (95% CI: 0.790-0.916). The 6-region protocol had significantly smaller AUC values on the 6^th and 9^th DOLs than the other two protocols.Conclusion: The 12-region and 10-region LU scoring protocols are superior to the 6-region protocol in the prediction of BPD. LU can predict the development of BPD from the 9^th to 15^th DOLs. With the addition of clinical variables, the earliest prediction time was the 6^th DOL. What is Known: • Bronchopulmonary dysplasia is the most common and adverse complication of prematurity. Recent four studies found that lung ultrasound score or findings predicted the development of bronchopulmonary dysplasia. What is New: • We present analysis by classical 6-region and the other two lung ultrasound score (10-region and 12-region) which include an assessment of the posterior lung to allow to understand what is the best score to be used. In addition, we explore whether LU-incorporated clinical variables could improve the predictive value for BPD.

Immature control of breathing and apnea of prematurity: the known and unknown

This narrative review provides a broad perspective on immature control of breathing, which is universal in infants born premature. The degree of immaturity and severity of clinical symptoms are inversely correlated with gestational age. This immaturity presents as prolonged apneas with associated bradycardia or desaturation, or brief respiratory pauses, periodic breathing, and intermittent hypoxia. These manifestations are encompassed within the clinical diagnosis of apnea of prematurity, but there is no consensus on minimum criteria required for diagnosis. Common treatment strategies include caffeine and noninvasive respiratory support, but other therapies have also been advocated with varying effectiveness. There is considerable variability in when and how to initiate and discontinue treatment. There are significant knowledge gaps regarding effective strategies to quantify the severity of clinical manifestations of immature breathing, which prevent us from better understanding the long-term potential adverse outcomes, including neurodevelopment and sudden unexpected infant death.

Major cardiorespiratory events do not increase after immunizations, eye exams, and other stressors in most very low birth weight infants

BACKGROUND

Increased cardiorespiratory events with bradycardia and oxygen desaturation have been reported in very low birthweight (VLBW) infants following stressors such as immunizations. These events are difficult to quantify and may be mild. Our group developed an automated algorithm to analyze bedside monitor data from NICU patients for events with bradycardia and prolonged oxygen desaturation (BDs) and used this to compare BDs 24 hours before and after potentially stressful interventions.

METHODS

We included VLBW infants from 2012-2017 with data available around at least one of four interventions: two-month immunizations, retinopathy of prematurity (ROP) examinations, ROP therapy, and inguinal hernia surgery. We used a validated algorithm to analyze electrocardiogram heart rate and pulse oximeter saturation data (HR, SpO2) to quantify BD events of HR <  100 beats/minute for≥4 seconds with oxygen desaturation <  80%SpO2 for≥10 seconds. BDs were analyzed 24 hours before and after interventions using Wilcoxon rank-sum tests.

RESULTS

In 354 of 493 (72%) interventions, BD frequency stayed the same or decreased in the 24 hours after the event. An increase of at least five BD's occurred in 17/146 (12%) after immunizations, 85/290 (29%) after ROP examinations, 4/33 (12%) after ROP therapy, and 3/25 (12%) after hernia surgery. Infants with an increase in BDs after interventions had similar demographics compared to those without. More infants with an increase in BDs following immunizations were on CPAP or caffeine than those without.

CONCLUSIONS

Most VLBW infants in our cohort had no increase in significant cardiorespiratory events in the 24 hours following potentially stressful interventions.

Vital sign metrics of VLBW infants in three NICUs: implications for predictive algorithms

BACKGROUND

Continuous heart rate (HR) and oxygenation (SpO₂) metrics can be useful for predicting adverse events in very low birth weight (VLBW) infants. To optimize the utility of these tools, inter-site variability must be taken into account.

METHODS

For VLBW infants at three neonatal intensive care units (NICUs), we analyzed the mean, standard deviation, skewness, kurtosis, and cross-correlation of electrocardiogram HR, pulse oximeter pulse rate, and SpO₂. The number and durations of bradycardia and desaturation events were also measured. Twenty-two metrics were calculated hourly, and mean daily values were compared between sites.

RESULTS

We analyzed data from 1168 VLBW infants from birth through day 42 (35,238 infant-days). HR and SpO₂ metrics were similar at the three NICUs, with mean HR rising by ~10 beats/min over the first 2 weeks and mean SpO₂ remaining stable ~94% over time. The number of bradycardia events was higher at one site, and the duration of desaturations was longer at another site.

CONCLUSIONS

Mean HR and SpO₂ were generally similar among VLBW infants at three NICUs from birth through 6 weeks of age, but bradycardia and desaturation events differed in the first 2 weeks after birth. This highlights the importance of developing predictive analytics tools at multiple sites.

IMPACT

HR and SpO₂ analytics can be useful for predicting adverse events in VLBW infants in the NICU, but inter-site differences must be taken into account in developing predictive algorithms. Although mean HR and SpO₂ patterns were similar in VLBW infants at three NICUs, inter-site differences in the number of bradycardia events and duration of desaturation events were found. Inter-site differences in bradycardia and desaturation events among VLBW infants should be considered in the development of predictive algorithms.

Response to first dose of inhaled albuterol in mechanically ventilated preterm infants

BACKGROUND

Bronchodilator responses among preterm infants are heterogeneous. Bedside measurements may identify responders.

STUDY DESIGN

Respiratory measurements (Resistance, Compliance, FiO2) and pulse oximetry (SpO2) patterns were downloaded from infants <30 weeks gestational age during the first 2 months of life. Mechanically ventilated infants who received albuterol were included (n = 33). Measurements were compared before and after first albuterol. Secondary analyses assessed subsequent doses.

RESULTS

Median gestation and birthweight were 25 3/7 weeks and 730 g, respectively. Mean Resistance decreased post-albuterol (p = 0.007). Sixty-eight percent of infants were responders based on decreased Resistance. Compliance and FiO2 did not significantly differ. Percent time in hypoxemia (SpO2 < 85%) decreased post albuterol (p < 0.02). In responders, Resistance changes diminished with subsequent administration (all p = 0.01).

CONCLUSIONS

Ventilator resistance decreased in two-thirds of preterm infants, consistent with studies that utilized formal pulmonary function testing. Albuterol had a variable effect on delivered FiO2; however, hypoxemia may be useful in evaluating albuterol response.

Are we over-treating hypoxic spells in preterm infants?

A frequent challenge in Neonatology is the high frequency of spontaneously occurring hypoxemic events, a majority of which are associated with apnea or hypoventilation. These episodes present a challenge for caregivers and families as they frequently delay discharge of preterm infants. Supplemental oxygen, respiratory support, and caffeine therapy are widely used as therapeutic approaches, but challenges remain regarding their precise indications. Future clinical practice should be directed by an evidence-based approach including automated supplemental oxygen, minimizing the use of medications for gastroesophageal reflux, optimal timing and dosage of caffeine therapy, and standardization of alarm limits and discharge monitoring protocols.

Hypoxemia in infants with trisomy 21 in the neonatal intensive care unit

OBJECTIVE

Newborns with trisomy 21 (T21) often require NICU hospitalization. Oxygen desaturations are frequently observed in these infants, even in the absence of congenital heart defects (CHD). We hypothesized that NICU patients with T21 have more hypoxemia than those without T21.

DESIGN

All infants with T21 without significant CHD discharged home from the NICU between 2009 and 2018 were included (n = 23). Controls were matched 20:1 for gestational age and length of stay. We compared daily severe hypoxemia events (SpO₂ < 80% for ≥10 s) for the whole NICU stay and the pre-discharge week.

RESULTS

Infants with T21 showed significantly more daily hypoxemia events during their entire NICU stay (median 10 versus 7, p = 0.0064), and more so in their final week (13 versus 7, p = 0.0008).

CONCLUSION

NICU patients with T21 without CHD experience more severe hypoxemia events than controls, particularly in the week before discharge. Whether this hypoxemia predicts or contributes to adverse outcomes is unknown.

Integrating Physiological Data Artifacts Detection With Clinical Decision Support Systems: Observational Study

BACKGROUND

Clinical decision support systems (CDSS) have the potential to lower the patient mortality and morbidity rates. However, signal artifacts present in physiological data affect the reliability and accuracy of the CDSS. Moreover, patient monitors and other medical devices generate false alarms while processing physiological data, further leading to alarm fatigue because of increased noise levels, staff disruption, and staff desensitization in busy critical care environments. This adversely affects the quality of care at the patient bedside. Hence, artifact detection (AD) algorithms play a crucial role in assessing the quality of physiological data and mitigating the impact of these artifacts.

OBJECTIVE

The aim of this study is to evaluate a novel AD framework for integrating AD algorithms with CDSS. We designed the framework with features that support real-time implementation within critical care. In this study, we evaluated the framework and its features in a false alarm reduction study. We developed static framework component models, followed by dynamic framework compositions to formulate four CDSS. We evaluated these formulations using neonatal patient data and validated the six framework features: flexibility, reusability, signal quality indicator standardization, scalability, customizability, and real-time implementation support.

METHODS

We developed four exemplar static AD components with standardized requirements and provisions interfaces that facilitate the interoperability of framework components. These AD components were mixed and matched into four different AD compositions to mitigate the artifacts' effects. We developed a novel static clinical event detection component that is integrated with each AD composition to formulate and evaluate a dynamic CDSS for peripheral oxygen saturation (SpO2) alarm generation. This study collected data from 11 patients with diverse pathologies in the neonatal intensive care unit. Collected data streams and corresponding alarms include pulse rate and SpO2 measured from a pulse oximeter (Masimo SET SmartPod) integrated with an Infinity Delta monitor and the heart rate derived from electrocardiography leads attached to a second Infinity Delta monitor.

RESULTS

A total of 119 SpO2 alarms were evaluated. The lowest achievable SpO2 false alarm rate was 39%, with a sensitivity of 80%. This demonstrates the framework's utility in identifying the best possible dynamic composition to serve the clinical need for false SpO2 alarm reduction and subsequent alarm fatigue, given the limitations of a small sample size.

CONCLUSIONS

The framework features, including reusability, signal quality indicator standardization, scalability, and customizability, allow the evaluation and comparison of novel CDSS formulations. The optimal solution for a CDSS can then be hard-coded and integrated within clinical workflows for real-time implementation. The flexibility to serve different clinical needs and standardized component interoperability of the framework supports the potential for a real-time clinical implementation of AD.

The relationship between intermittent hypoxemia events and neural outcomes in neonates

This brief review examines 1) patterns of intermittent hypoxemia in extremely preterm infants during early postnatal life, 2) the relationship between neonatal intermittent hypoxemia exposure and outcomes in both human and animal models, 3) potential mechanistic pathways, and 4) future alterations in clinical care that may reduce morbidity. Intermittent hypoxemia events are pervasive in extremely preterm infants (<28 weeks gestation at birth) during early postnatal life. An increased frequency of intermittent hypoxemia events has been associated with a range of poor neural outcomes including language and cognitive delays, motor impairment, retinopathy of prematurity, impaired control of breathing, and intraventricular hemorrhage. Neonatal rodent models have shown that exposure to short repetitive cycles of hypoxia induce a pathophysiological cascade. However, not all patterns of intermittent hypoxia are deleterious and some may even improve neurodevelopmental outcomes. Therapeutic interventions include supplemental oxygen, pressure support and pharmacologic drugs but prolonged hyperoxia and pressure exposure have been associated with cardiopulmonary morbidity. Therefore, it becomes imperative to distinguish high risk from neutral and/or even beneficial patterns of intermittent hypoxemia during early postnatal life. Identification of such patterns could improve clinical care with targeted interventions for high-risk patterns and minimal or no exposure to treatment modalities for low-risk patterns.

Understanding hydrogen sulfide signaling in neonatal airway disease

INTRODUCTION

Airway dysfunction leading to chronic lung disease is a common consequence of premature birth and mechanisms responsible for early and progressive airway remodeling are not completely understood. Current therapeutic options are only partially effective in reducing the burden of neonatal airway disease and premature decline of lung function. Gasotransmitter hydrogen sulfide (H2S) has been recently recognized for its therapeutic potential in lung diseases.

AREAS COVERED

Contradictory to its well-known toxicity at high concentrations, H2S has been characterized to have anti-inflammatory, antioxidant, and antiapoptotic properties at physiological concentrations. In the respiratory system, endogenous H2S production participates in late lung development and exogenous H2S administration has a protective role in a variety of diseases such as acute lung injury and chronic pulmonary hypertension and fibrosis. Literature searches performed using NCBI PubMed without publication date limitations were used to construct this review, which highlights the dichotomous role of H2S in the lung, and explores its promising beneficial effects in lung diseases.

EXPERT OPINION

The emerging role of H2S in pathways involved in chronic lung disease of prematurity along with its recent use in animal models of BPD highlight H2S as a potential novel candidate in protecting lung function following preterm birth.

Clinical and vital sign changes associated with late-onset sepsis in very low birth weight infants at 3 NICUs

BACKGROUND

In premature infants, clinical changes frequently occur due to sepsis or non-infectious conditions, and distinguishing between these is challenging. Baseline risk factors, vital signs, and clinical signs guide decisions to culture and start antibiotics. We sought to compare heart rate (HR) and oxygenation (SpO2) patterns as well as baseline variables and clinical signs prompting sepsis work-ups ultimately determined to be late-onset sepsis (LOS) and sepsis ruled out (SRO).

METHODS

At three NICUs, we reviewed records of very low birth weight (VLBW) infants around their first sepsis work-up diagnosed as LOS or SRO. Clinical signs prompting the evaluation were determined from clinician documentation. HR-SpO2 data, when available, were analyzed for mean, standard deviation, skewness, kurtosis, and cross-correlation. We used LASSO and logistic regression to assess variable importance and associations with LOS compared to SRO.

RESULTS

We analyzed sepsis work-ups in 408 infants (173 LOS, 235 SRO). Compared to infants with SRO, those with LOS were of lower GA and BW, and more likely to have a central catheter and mechanical ventilation. Clinical signs cited more often in LOS included hypotension, acidosis, abdominal distension, lethargy, oliguria, and abnormal CBC or CRP(p <  0.05). HR-SpO2 data were available in 266 events. Cross-correlation HR-SpO2 before the event was associated with LOS after adjusting for GA, BW, and postnatal age. A model combining baseline, clinical and HR-SpO2 variables had AUC 0.821.

CONCLUSION

In VLBW infants at 3-NICUs, we describe the baseline, clinical, and HR-SpO2 variables associated with LOS versus SRO.

Oxygenation Instability Assessed by Oxygen Saturation Histograms during Supine vs Prone Position in Very Low Birthweight Infants Receiving Noninvasive Respiratory Support

OBJECTIVE

To evaluate the effect of prone vs supine position on the oxygenation instability among very low birth weight (VLBW) infants receiving noninvasive respiratory support, as assessed by the average oxygen saturation (SpO₂) histograms.

STUDY DESIGN

Sixty-nine histograms from 23 VLBW infants were studied prospectively. Each infant was studied during 3 consecutive 3-hour periods of alternating positions; 12 infants started the study while prone and 11 infants started supine, by random order. Histogram classification system was used to quantify oxygenation stability and time spent in different SpO₂ ranges.

RESULTS

The fraction of inspired oxygen values were similar in both positions. Unstable histograms were more common in supine vs prone position (20/34 [59%] vs 10/35 [29%]; P = .02, respectively). Analyzing oxygenation stability as per position change revealed that a change from prone to supine increased oxygenation instability, and supine to prone decreased instability (P = .02). In the supine vs prone position, percent of time spent in SpO₂ ≤80% and <90% was higher (5.0 ± 4.2 vs 2.4 ± 3.4 [P < .001] and 24.1 ± 13.7 vs 13.2 ± 10.0 [P < .001], respectively), and percent of time in SpO₂ >94% was lower (39.7 ± 26.0 vs 52.4 ± 23.4 [P = .04]).

CONCLUSIONS

Prone positioning decreased oxygenation instability and resulted in higher oxygenation among VLBW premature infants on noninvasive respiratory support. SpO₂ histograms allow easy bedside assessment of oxygenation instability, and quantification of the time spent at different SpO₂ ranges.

Body temperature instability and respiratory morbidity in the very low birth weight infant: a multiple case, intensive longitudinal study

Background

Very low birth weight (VLBW) infant thermal instability upon neonatal intensive care unit admission has been associated with respiratory morbidity; however, the association between ongoing thermal instability and respiratory morbidity remains unclear.

Methods

A longitudinal data analysis was conducted on 12 VLBW infants. Chronic respiratory morbidity risk was defined as supplemental oxygen requirement (FiO₂) or scheduled diuretic dosing at 36 weeks post-menstrual age. Acute respiratory morbidity was quantified as desaturations (SpO₂<90%), bradycardia with desaturations (HR<100 and SpO₂<90%), apnea, increase in FiO₂ requirement, or increase in respiratory support. Multi-level, mixed-effects models and regression analysis examined the relationships between body temperature over the first 14 days of life and respiratory morbidities.

Results

Body temperature was not associated with chronic respiratory morbidity risk (p=0.2765). Desaturations, bradycardia with desaturations, increased FiO₂ requirement, and increased respiratory support were associated with decreased body temperature (p<0.05). Apnea was associated with increased body temperature (p<0.05). The covariate-adjusted risk of desaturations (aOR=1.3), bradycardia with desaturations (aOR=2.2), increase in FiO₂ requirement (aOR=1.2), and increase in respiratory support (aOR=1.2) were significantly greater during episodes of hypothermia.

Conclusion

VLBW infants are dependent on a neutral thermal environment for optimal growth and development. Therefore, the significant associations between hypothermia and symptoms of acute respiratory morbidity require further study to delineate if these are causal relationships that could be attenuated with clinical practice changes, or if these are concurrent symptoms that cluster during episodes of physiological instability.

Effect of Blood Transfusions on Intermittent Hypoxic Episodes in a Prospective Study of Very Low Birth Weight Infants

OBJECTIVES

To compare the number of intermittent hypoxia events before and after packed red blood cell (pRBC) and non-pRBC transfusions in very low birth weight infants, and to compare the time spent with saturations of ≤85% before and after transfusions in the same population.

STUDY DESIGN

This prospective observational study was conducted from April 2014 to August 2017. It included 92 transfusions (81 pRBC, 11 non-pRBC) from 41 very low birth weight infants between 23^0/7 and 28^6/7 weeks of gestation. The primary outcome was number of intermittent hypoxia events. Secondary outcomes included the percent time of Peripheral capillary oxygen saturation (SpO2)of ≤85%, ≤80%, and ≤75%. A mixed ANOVA model was used to examine the relationship between event rate and covariates.

RESULTS

The mean number of intermittent hypoxia events per hour decreased from 5.27 ± 5.02 events per hour before pRBC transfusion to 3.61 ± 3.17 per hour after pRBC transfusions (P < .01) and intermittent hypoxia did not change after non-RBC transfusions (before, 4.45 ± 3.19 vs after, 4.47 ± 2.78; P = NS). The percent time with saturations of ≤80% and ≤75% significantly decreased after pRBC transfusions (P = .01). The time with saturations of ≤85% did not significantly change after non-pRBC transfusion.

CONCLUSIONS

In very low birth weight infants with a hematocrit of 20%-42%, pRBC transfusions are associated with decreased frequency of intermittent hypoxia. No such diminution of intermittent hypoxia events was observed in infants who had received a non-pRBC transfusion. This finding suggests that the observed beneficial effects of RBC transfusions on apnea and its clinical manifestations of intermittent hypoxia are mediated through an enhanced oxygen carrying capacity.

Cardiorespiratory Events in Infants Born Preterm during the Transitional Period

OBJECTIVE

To investigate the features of cardiorespiratory events in infants born preterm during the transitional period, and to evaluate whether different neonatal characteristics may correlate with event type, duration, and severity.

STUDY DESIGN

Infants with gestational age (GA) <32 weeks and/or birth weight <1500 g were enrolled in this observational prospective study. Heart rate (HR) and peripheral oxygen saturation (SpO₂) were recorded continuously over the first 72 hours. Cardiorespiratory events of ≥10 seconds were clustered into isolated desaturation (SpO₂ <85%), isolated bradycardia (HR <100 bpm or <70% of baseline), or combined desaturation/bradycardia and classified as mild, moderate, or severe. The daily incidences of isolated desaturation, isolated bradycardia, and combined desaturation and bradycardia were analyzed. The effects of relevant clinical variables on cardiorespiratory event type and severity were assessed using generalized estimating equations.

RESULTS

Among the 1050 events analyzed, isolated desaturations were the most frequent (n = 625) and isolated bradycardias the least common (n = 171). The number of cardiorespiratory events increased significantly from day 1 to day 2 (P = .028). One in 5 events had severe characteristics; event severity was highest for combined desaturation and bradycardia (P < .001). Compared with other event types, the incidence of combined desaturation and bradycardia was inversely correlated with GA (P = .029) and was higher with the use of continuous positive airway pressure (P = .002). The presence of a hemodynamically significant patent ductus arteriosus was associated with the occurrence of isolated desaturations (P = .001) and with a longer duration of cardiorespiratory events (P = .003).

CONCLUSIONS

Cardiorespiratory events during transition exhibit distinct types, duration, and severity. Neonatal characteristics are associated with the clinical features of these events, indicating that a tailored clinical approach may reduce the hypoxic burden in preterm infants aged 0-72 hours.

Clinical quantification of SpO2 instability using a new histogram classification system: a clinical study

BACKGROUND

Oxygenation instability is not quantified or documented despite being common and correlated with neonatal morbidities, retinopathy of prematurity, and adverse 18-month outcomes.

METHODS

We developed a five-type SpO₂ histogram classification system based on the SpO₂ difference within the 10-90th cumulative time percentile (A) and the time percentage with SpO₂ ≤80% (B). In type 1, A is <5% and in type 5, A and B are ≥10%. We then studied consecutive 12-h SpO₂ frequency histograms in all infants ≤34 weeks gestation receiving respiratory support on day 1, over 6 months.

RESULTS

Six thousand and sixteen histograms were obtained in 73 infants, 28.9 ± 3.0 weeks gestation, and birth weight (BW) 1318.5 ± 495 g. All types were common and did not overlap. Type 3-5 ("unstable") histograms were more common in oxygen or any intubated support. Time in SpO₂ <85% and <80% progressively increased in types 3-5. Among histograms in oxygen, the mean (±SD) of SpO₂ medians was 92.8 ± 1.9. Infants ≤28 weeks exhibited three phases of SpO₂ instability (stable-unstable-stable). Those developing unstable histograms during the first week received longer ventilatory support (median [IQR], 101 [66] vs. 62 [28] days) and supplemental oxygen (62.5 [72] vs. 40.5 [40] days), and more were on ventilatory support at 40 weeks (7/15 vs. 0/10).

CONCLUSIONS

Classified SpO₂ histograms quantify and document SpO₂ instability and identify early infants at risk of prolonged respiratory support, while median SpO₂ does not.

Intermittent hypoxia and bronchial hyperreactivity

The premature neonate is at high risk for childhood airway hyperreactivity and episodes of wheezing. Intermittent hypoxic events are frequently observed during the first weeks and months of life in these infants. Intermittent hypoxemia has been associated with adverse outcomes in extremely premature infants; including the diagnosis of bronchopulmonary dysplasia, reported wheezing, and use of prescription asthma medications. We review the incidence of intermittent hypoxia, their potential role in short and longer term respiratory morbidity, and the translational newborn models now being used to investigate common pathways by which intermittent hypoxia contributes to respiratory disease.

Predictive Monitoring of Critical Cardiorespiratory Alarms in Neonates Under Intensive Care

We aimed at reducing alarm fatigue in neonatal intensive care units by developing a model using machine learning for the early prediction of critical cardiorespiratory alarms. During this study in over 34,000 patient monitoring hours in 55 infants 278,000 advisory (yellow) and 70,000 critical (red) alarms occurred. Vital signs including the heart rate, breathing rate, and oxygen saturation were obtained at a sampling frequency of 1 Hz while heart rate variability was calculated by processing the ECG - both were used for feature development and for predicting alarms. Yellow alarms that were followed by at least one red alarm within a short post-alarm window constituted the case-cohort while the remaining yellow alarms constituted the control cohort. For analysis, the case and control cohorts, stratified by proportion, were split into training (80%) and test sets (20%). Classifiers based on decision trees were used to predict, at the moment the yellow alarm occurred, whether a red alarm(s) would shortly follow. The best performing classifier used data from the 2-min window before the occurrence of the yellow alarm and could predict 26% of the red alarms in advance (18.4s, median), at the expense of 7% additional red alarms. These results indicate that based on predictive monitoring of critical alarms, nurses can be provided a longer window of opportunity for preemptive clinical action. Further, such as algorithm can be safely implemented as alarms that are not algorithmically predicted can still be generated upon the usual breach of the threshold, as in current clinical practice.

Predicting the likelihood of bronchopulmonary dysplasia in premature neonates

Introduction: Bronchopulmonary dysplasia (BPD) is the most common serious pulmonary morbidity in premature infants. Despite ongoing advances in neonatal care, the incidence of BPD has not improved. A potential explanation for this phenomenon is the limited ability for accurate early prediction of the risk of BPD. BPD continues to represent a therapeutic challenge and no single effective therapy exists for this condition. Areas covered: Here, we review risk factors of BPD derived from clinical data, biological fluid biomarkers, respiratory management data, and scientific advancements using 'omics' technologies, and their ability to predict the pathogenesis of BPD in preterm neonates. Risk factors and biomarkers were identified via literature search with a focus on the last 5 years of data. Expert opinion: The most accurate predictive tools utilize risk factors that encompass a variety of categories. Numerous predictive models have been proposed but suffer from a lack of adequate validation. An ideal model should include multiple, easily measurable variables validated across a heterogeneous population. In addition to evaluating recent BPD prediction models, we suggest approaches to enhance future models.

Vulnerability of the developing airway

Longer term respiratory morbidity is a frequent concern for former preterm infants. Increased airway reactivity and wheezing disorders are extremely common in this population, both in infants who meet diagnostic criteria for bronchopulmonary dysplasia [BPD], and in the absence of this diagnosis. It is, therefore, imperative to gain a better understanding of normal and abnormal postnatal development of the immature airway. Airway hyperreactivity may be secondary to abnormal bronchoalveolar attachments in the face of parenchymal lung injury, or secondary to an imbalance between constrictor and dilator neural pathways. Finally, the airway itself may undergo functional and/or structural changes, including increased airway smooth muscle mass, and changes in airway extracellular matrix which may, in turn, modulate downstream signaling pathways to hyperoxia or pressure exposed vulnerable airways.

Rodent models of respiratory control and respiratory system development-Clinical significance

The newborn infant's respiratory system must rapidly adapt to extra-uterine life. Neonatal rat and mouse models have been used to investigate early development of respiratory control and reactivity in both health and disease. This review highlights several rodent models of control of breathing and respiratory system development (including pulmonary function), discusses their translational strengths and limitations, and underscores the importance of creating clinically relevant models applicable to the human infant.