Information Based Similarity Analysis of Oxygen Saturation Recordings to Detect Pulmonary Hypertension in Preterm Infants.

Pulmonary hypertension (PH) is a complex cardiovascular condition associated with multiple morbidities and mortality risk in preterm infants. PH often complicates the clinical course of infants who have bronchopulmonary dysplasia (BPD), a more common lung disease in these neonates, causing respiratory deterioration and an even higher risk of mortality. While risk factors and prevalence of PH are not yet well defined, early screening and management of PH in infants with BPD are recommended by consensus guidelines from the American Heart Association. In this study, we propose a screening method for PH by applying a signal analysis technique to oxygen saturation in infants. Oxygen saturation data from infant groups with BPD (41 with and 60 without PH), recorded prior to their clinical PH diagnosis were analyzed in this study. An information-based similarity approach was applied to quantify the regularity of SpO2 fluctuations represented as binary words between adjacent five-minute segments. Similarity indices (SI) were observed to be lower in subjects with PH compared to those with BPD alone (p<0.001). These measures were also assessed for performance in screening for PH. SI of 7-bit words, exhibited 80% detection accuracy, 76% sensitivity and specificity of 83%. This index also exhibited a cross-validated mean (SD) F1-score of 0.80 (0.08) ensuring that sensitivity and recall of the screening were balanced. Similarity analysis of oxygen saturation patterns is a novel technique that can be potentially developed into a signal based early PH detection method to support clinical decision and care in this vulnerable population.

Heterogeneity of Treatment Effects of Hydrocortisone by Risk of Bronchopulmonary Dysplasia or Death Among Extremely Preterm Infants in the National Institute of Child Health and Human Development Neonatal Research Network Trial: A Secondary Analysis of a Randomized Clinical Trial.

Importance: Extremely preterm infants who develop bronchopulmonary dysplasia (BPD) are at a higher risk for adverse pulmonary and neurodevelopmental outcomes. In the National Institute of Child Health and Human Development Neonatal Research Network (NICHD NRN) Hydrocortisone Trial, hydrocortisone neither reduced rates of BPD or death nor increased rates of neurodevelopmental impairment (NDI) or death. Objective: To determine whether estimated risk for grades 2 to 3 BPD or death is associated with the effect of hydrocortisone on the composite outcomes of (1) grades 2 to 3 BPD or death and (2) moderate or severe NDI or death. Design, Setting, and Participants: This secondary post hoc analysis used data from the NICHD NRN Hydrocortisone Trial, which was a double-masked, placebo-controlled, randomized clinical trial conducted in 19 US academic centers. The NICHD HRN Hydrocortisone Trial enrolled infants born at a gestational age of less than 30 weeks who received mechanical ventilation for at least 7 days, including at the time of enrollment, and who were aged 14 to 28 postnatal days. Infants were enrolled between August 22, 2011, and February 4, 2018, with follow-up between 22 and 26 months of corrected age completed on March 29, 2020. Data were analyzed from September 13, 2021, to March 25, 2023. Intervention: Infants were randomized to 10 days of hydrocortisone or placebo treatment. Main Outcomes and Measures: Infants' baseline risk of grades 2 to 3 BPD or death was estimated using the NICHD Neonatal BPD Outcome Estimator. Differences in absolute and relative treatment effects by baseline risk were evaluated using interaction terms in models fitted to the efficacy outcome of grades 2 to 3 BPD or death and the safety outcome of moderate or severe NDI or death by follow-up. Results: Among the 799 infants included in the analysis (421 boys [52.7%]), the mean (SD) gestational age was 24.9 (1.5) weeks, and the mean (SD) birth weight was 715 (167) g. The mean estimated baseline risk for grades 2 to 3 BPD or death was 54% (range, 18%-84%) in the study population. The interaction between treatment group and baseline risk was not statistically significant on a relative or absolute scale for grades 2 to 3 BPD or death; the size of the effect ranged from a relative risk of 1.13 (95% CI, 0.82-1.55) in quartile 1 to 0.94 (95% CI, 0.81-1.09) in quartile 4. Similarly, the interaction between treatment group and baseline risk was not significant on a relative or absolute scale for moderate or severe NDI or death; the size of the effect ranged from a relative risk of 1.04 (95% CI, 0.80-1.36) in quartile 1 to 0.99 (95% CI, 0.80-1.22) in quartile 4. Conclusions and Relevance: In this secondary analysis of a randomized clinical trial, the effect of hydrocortisone vs placebo was not appreciably modified by baseline risk for grades 2 to 3 BPD or death. Trial Registration: ClinicalTrials.gov Identifier: NCT01353313.

Intermittent Hypoxemia and Bronchopulmonary Dysplasia with Pulmonary Hypertension in Preterm Infants.

Rationale: Bedside biomarkers that allow early identification of infants with bronchopulmonary dysplasia-associated pulmonary hypertension (BPD-PH) are critically important, given the higher risk of death in these infants. Objectives: We hypothesized that infants with BPD-PH have patterns of intermittent hypoxemia (IH) that differ from infants with BPD without PH. Methods: We conducted a matched case-control study of extremely preterm infants from 22 weeks 0 days to 28 weeks 6 days born between 2018 and 2020 at the University of Alabama at Birmingham. BPD-PH status was determined using echocardiographic data performed after postnatal Day 28. Physiologic data were compared between infants with BPD-PH (cases) and BPD alone (control subjects). Receiver operating characteristic (ROC) analysis estimated the predictive ability of cumulative hypoxemia, desaturation frequency, and duration of intermittent hypoxemic events in the week preceding echocardiography to discriminate between cases and control subjects. Measurements and Main Results: Forty infants with BPD-PH were compared with 40 infants with BPD alone. Infants with and without PH had a similar frequency of IH events, but infants with PH had more prolonged hypoxemic events for desaturations below 80% (7 s vs. 6 s; P = 0.03) and 70% (105 s vs. 58 s; P = 0.008). Among infants with BPD-PH, infants who died had longer hypoxemic events below 70% (145 s vs. 72 s; P = 0.01). Using the duration of hypoxemic events below 70%, the areas under the ROC curves for diagnosis of BPD-PH and death in BPD-PH infants were 0.71 and 0.77, respectively. Conclusions: Longer duration of intermittent hypoxemic events was associated both with a diagnosis of BPD-PH and with death among infants with BPD-PH.

Patent Ductus Arteriosus and Development of Bronchopulmonary Dysplasia-associated Pulmonary Hypertension.

Rationale: Extremely preterm infants with evolving bronchopulmonary dysplasia (BPD) are at risk for development of BPD-associated pulmonary hypertension (BPD-PH). A patent ductus arteriosus (PDA) shunt may be a modifiable risk factor for BPD-PH development. Objective: To determine whether the presence and duration of ductus arteriosus patency differs between extremely preterm infants with and without BPD-PH. Methods: We conducted a retrospective case-control study among preterm infants of gestational age 22 weeks, 0 days, to 28 weeks, 6 days, who remained on respiratory support on postnatal day 28 at the University of Alabama at Birmingham from 2017 to 2020. Infants who were diagnosed with PH (cases) by echocardiography were compared with infants without PH (control subjects). Data from echocardiograms performed during the hospitalization after postnatal day 28 were included. Logistic regression adjusted for covariates that differed significantly between groups. A probit analysis related the duration of ductal patency to the development of BPD-PH. Measurements and Main Results: A total of 138 infants developed BPD alone, and 82 infants developed BPD-PH. After adjustment for differing covariates between groups, both PDA (adjusted odds ratio, 4.29; 95% confidence interval, 1.89-9.77) and moderate to large PDA (adjusted odds ratio, 4.15; 95% confidence interval, 1.78-9.64) remained significantly related to BPD-PH at discharge. By probit analysis, each additional month of PDA and hemodynamically significant PDA exposure was associated with an increased probability for the composite outcome of BPD-PH at discharge or death with coefficients of 0.40 (P < 0.001) and 0.45 (P < 0.001), respectively. Conclusions: In extremely preterm infants on respiratory support on postnatal day 28, both the presence of and a longer duration of ductus arteriosus patency were associated with the development of BPD-PH.

Improving birth certificate data accuracy in Alabama.

Objective: Accurate vital statistics data are critical for monitoring population health and strategizing public health interventions. Previous analyses of statewide birth data have identified several factors that may reduce birth certificate accuracy including systematic errors and limited data review by clinicians. The aim of this initiative was to increase the proportion of hospitals in Alabama reporting accurate birth certificate data from 67% to 87% within 1 year. Methods: The Alabama Perinatal Quality Collaborative led this statewide collaborative effort. Process measures included monthly monitoring of 11 variables across 5-10 patient birth certificates per month per hospital. Accuracy determination, defined as ≥95% accuracy of the variables analyzed, was performed by health care specialists at each hospital by comparing birth certificate variables from vital statistics with data obtained from original hospital source materials. Three months of retrospective, baseline accuracy data were collected before project initiation from which actionable drivers and change ideas were identified at individual hospitals. Data were analyzed using statistical process control measures. Results: Thirty-one hospitals entered data throughout the course of the initiative, accounting for 850 chart analyses and 9350 variable assessments. The least accurately reported variables included birth weight, maternal hypertension, and antenatal corticosteroid exposure. At baseline, 67% of hospitals reported birth certificate accuracy rates ≥ 95%, which increased to 90% of hospitals within 2 months and was sustained for the remainder of the initiative. Conclusion: Statewide, multidisciplinary quality improvement efforts increased birth certificate accuracy vital to public health surveillance.

Improving Time to Independent Oral Feeding to Expedite Hospital Discharge in Preterm Infants.

BACKGROUND AND OBJECTIVES: Achievement of independent oral feedings remains the most common barrier to discharge in preterm infants. Early oral feeding initiation may be associated with a lower postmenstrual age (PMA) at independent oral feeding and discharge. In preterm infants born between 25 and 32 weeks' gestation, our aim was to decrease the PMA at independent oral feedings and discharge by 1 week between June 2019 and June 2020. METHODS: Following formation of a multidisciplinary team, the following plan-do-study-act cycles were targeted: (1) oral feeding initiation at <33 weeks' PMA, (2) cue-based feeding, and (3) practitioner-driven feeding in infants who had not yet achieved independent oral feedings by 36 weeks' PMA. Outcome measures included the PMA at independent oral feeding and discharge. Process measures included adherence to cue-based feeding assessments and PMA at oral feeding initiation. RESULTS: In total, 552 infants with a median gestational age of 30.3 weeks' (interquartile range 28.1-32.0) and birth weight of 1320 g (interquartile range 1019-1620) were included. The PMA at discharge decreased from 38.8 to 37.7 weeks during the first plan-do-study-act cycle, which coincided with an increase in the number of infants initiated on oral feeds at <33 weeks' PMA from 47% to 80%. The age at independent oral feeding decreased from 37.4 to 36.5 weeks' PMA. CONCLUSIONS: In preterm infants born between 25 and 32 weeks' gestation, earlier oral feeding initiation was associated with a decreased PMA at independent oral feeding and discharge.

Duration of noninvasive respiratory support and risk for bronchopulmonary dysplasia or death.

OBJECTIVE: To determine whether the duration of noninvasive respiratory support exposure is associated with bronchopulmonary dysplasia (BPD) or death in preterm infants. METHODS: Multicenter, retrospective study of infants born at <29 weeks' gestation. The association between days on noninvasive respiratory support and BPD or death was determined using instrumental variable techniques and generalized propensity score matching to account for potential confounding by illness severity. RESULTS: Among 6268 infants 36% developed BPD or died. The median duration of noninvasive respiratory support was 18 days. There was inconsistency in the association between noninvasive support and BPD or death when analyzed by instrumental variable techniques (Average Marginal Effect -0.37; 95% CI -1.23 to 0.50) and generalized propensity score matching (Average Marginal Effect 0.46; 95% CI 0.33 to 0.60). CONCLUSION: Findings on the association between duration of exposure to noninvasive respiratory support and the development of BPD or death were inconclusive. GOV ID: Generic Database:NCT00063063.

Early Skin-to-Skin Care with a Polyethylene Bag for Neonatal Hypothermia: A Randomized Clinical Trial.

OBJECTIVE: To determine whether early polyethylene bag use with skin-to-skin care compared with skin-to skin care alone reduce hypothermia among infants born at term in resource-limited settings. STUDY DESIGN: Infants born at term in the tertiary referral center in Lusaka, Zambia, were randomized using sequentially numbered sealed opaque envelopes in 2 phases: after birth (phase 1) and at 1 hour after birth (phase 2) to either skin-to-skin care with polyethylene bags or skin-to-skin care alone. Infant and maternal temperatures were recorded at birth, 1 hour, and every 4 hours until discharge or 24 hours. RESULTS: We enrolled 423 infants from May 2017 to August 2017. The rate of moderate-severe hypothermia (temperature <36.0°C) at 1 hour was 72 of 208 (34.6%) in the skin-to-skin care with a polyethylene bag group compared with 101 of 213 (47.4%) in the skin-to-skin care alone group (relative risk, 0.71; 95% CI 0.56-0.90; P < .01; number needed to treat = 8). phase 1 treatment assignment significantly modified the effect of phase 2 treatment (P = .02 for interaction effect). Among infants randomized to skin-to-skin care with a polyethylene bag in phase 1, the risk of moderate-severe hypothermia was decreased in infants randomized to continue this intervention until discharge compared with infants randomized to skin-to-skin care alone. The rates of severe hypothermia, hyperthermia, and other adverse events did not differ significantly between groups. CONCLUSIONS: Low-cost polyethylene bags started after birth in combination with skin-to-skin care reduced moderate or severe hypothermia at 1 hour and at discharge among infants born at term in a resource-limited setting compared with skin-to-skin care alone. TRIAL REGISTRATION: ClinicalTrials.gov: NCT03141723.

Bronchopulmonary dysplasia is associated with reduced oral nitrate reductase activity in extremely preterm infants.

Oral microbiome mediated nitrate reductase (NR) activity regulates nitric oxide (NO) bioavailability and signaling. While deficits in NO-bioavailability impact several morbidities of extreme prematurity including bronchopulmonary dysplasia (BPD), whether oral NR activity is associated with morbidities of prematurity is not known. We characterized NR activity in extremely preterm infants from birth until 34 weeks' post menstrual age (PMA), determined whether changes in the oral microbiome contribute to changes in NR activity, and determined whether changes in NR activity correlated with disease. In this single center prospective cohort study (n = 28), we observed two surprising findings: (1) NR activity unexpectedly peaked at 29 weeks' PMA (p < 0.05) and (2) when infants were stratified for BPD status, infants who developed BPD had significantly less NR activity at 29 weeks' PMA compared to infants who did not develop BPD. Oral microbiota and NR activity may play a role in BPD development in extremely preterm infants, indicating potential for disease prediction and therapeutic targeting.

Airway nitrite is increased in extremely preterm infants with bronchopulmonary dysplasia.

RATIONALE: Bronchopulmonary dysplasia (BPD) is the most common complication of prematurity and significantly contributes to mortality and morbidity with few predictive biomarkers. Given that nitrites have been implicated in pathways associated with lung disease, we hypothesized that nitrite levels would be altered in the airways of premature infants diagnosed with BPD. METHODS: This was a prospective cohort study of extremely low birth infants (< 28 weeks' gestation) at the University of Alabama at Birmingham. Nitrite levels from tracheal aspirates (TAs) were compared between intubated and ventilated infants with BPD and gestation matched full term (FT) controls. TA derived nitrite levels from day one after birth were also compared between preterm infants who did and did not develop BPD. RESULTS: Infants with BPD were found to have significantly elevated nitrite levels in their tracheal aspirates compared to gestation matched FT controls (p < 0.05). There was a trend for increased nitrite levels on postnatal day one in infants that developed BPD compared to infants that did not develop BPD (p = 0.05). CONCLUSIONS: In conclusion, nitrite levels are significantly increased in airways of infants with BPD. Data from a larger cohort are needed to further support the utility of nitrite for BPD prediction. TRIAL REGISTRATION: Not applicable.

Association of Antenatal Corticosteroids and Magnesium Sulfate Therapy With Neurodevelopmental Outcome in Extremely Preterm Children.

OBJECTIVE: To test the primary hypothesis that extremely preterm children antenatally exposed to both magnesium sulfate and antenatal corticosteroids have a lower rate of severe neurodevelopmental impairment or death compared with those exposed to antenatal corticosteroids alone. METHODS: This was a prospective observational study of children born at 22 0/7-26 6/7 weeks of gestation from 2011 to 2014 at Eunice Kennedy Shriver National Institute of Child Health and Human Development Neonatal Research Network hospitals (N=3,093). The primary outcome was severe neurodevelopmental impairment or death at 18-26 months of corrected age follow-up based on exposure to antenatal corticosteroids and magnesium sulfate or antenatal corticosteroids alone. Secondary outcomes included components of severe neurodevelopmental impairment by exposure group and comparisons of severe neurodevelopmental impairment or death between children exposed to both antenatal corticosteroids and magnesium sulfate with those exposed to magnesium sulfate alone or to neither antenatal corticosteroids nor magnesium sulfate. Logistic regression models adjusted for background characteristics. RESULTS: Children exposed to both antenatal corticosteroids and magnesium sulfate had a lower rate of severe neurodevelopmental impairment or death (813/2,239, 36.3%) compared with those exposed to antenatal corticosteroids alone (225/508, 44.3%; adjusted odds ratio [aOR] 0.73; 95% CI 0.58-0.91), magnesium sulfate alone (47/89, 53%; aOR 0.49; 95% CI 0.29-0.82), or neither therapy (121/251; 48.2%; aOR 0.66, 95% CI 0.49-0.89). Similarly, children exposed to both antenatal corticosteroids and magnesium sulfate had a lower rate of death compared with either or neither therapy, but the rate of severe neurodevelopmental impairment among survivors did not differ between exposure groups. CONCLUSION: In children born between 22 0/7 and 26 6/7 weeks of gestation, exposure to both antenatal corticosteroids and magnesium sulfate was associated with lower rates of severe neurodevelopmental impairment or death and death compared with exposure to antenatal corticosteroids alone. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov, NCT00063063.

Neonatal comorbidities and gasotransmitters.

Hydrogen sulfide, nitric oxide, and carbon monoxide are endogenously produced gases that regulate various signaling pathways. The role of these transmitters is complex as constitutive production of these molecules may have anti-inflammatory, anti-microbial, and/or vasodilatory effects whereas induced production or formation of secondary metabolites may lead to cellular death. Given this fine line between friend and foe, therapeutic attenuation of these molecules' production has involved both inhibition of endogenous formation and therapeutic supplementation. All three gases have been implicated as regulators of critical aspects of neonatal physiology, and in turn, comorbidities including necrotizing enterocolitis, hypoxic ischemic encephalopathy, and pulmonary hypertension. In this review, we present current perspectives on these associations, highlight areas where insights remain sparse, and identify areas for potential for future investigations.

Oxygen saturation histograms predict nasal continuous positive airway pressure-weaning success in preterm infants.

BACKGROUND: Continuous positive airway pressure (CPAP) is widely used in preterm infants. Identification of readiness for weaning from CPAP can balance benefits with risks of CPAP exposure. We tested the hypothesis that preterm infants that successfully transition off CPAP have higher oxygen saturations prior to weaning compared with infants who fail weaning from CPAP. METHODS: This was a single-center-matched case-control study in infants ≤30 weeks' gestation receiving ≤30% FiO2 weaned off CPAP during the first postnatal week. Cases were infants placed back on CPAP within 7 days of being taken off CPAP, whereas control infants remained off CPAP for 7 consecutive days following CPAP discontinuation. Infants were matched on gestational age at birth (±10 days). Prospectively collected histograms detailing the distribution of oxygen saturations prior to CPAP discontinuation were compared between cases and controls. RESULTS: Over a 12-month monitoring period, 36 infants met inclusion criteria. Baseline characteristics, morbidities, and clinical variables did not differ between cases and controls. Controls achieved oxygen saturations of 95-97 and 97-100% for longer duration compared to cases (p < 0.05). CONCLUSIONS: In preterm infants with RDS receiving CPAP and ≤30% FiO2, infants with higher oxygen saturations had greater success in transitioning off CPAP.

Oxygen Therapy and Pulmonary Hypertension in Preterm Infants.

The goal of oxygen therapy and oxygen saturation targeting in extremely preterm infants is to improve outcomes and balance the risks associated with both hypoxemia and hyperoxemia. Although the NeOProM trials addressed whether low or high oxygen saturation targets affect the most important outcomes of extreme prematurity including death and other co-morbidities, the trials did not evaluate infants for pulmonary hypertension. There is limited evidence for the optimal oxygen saturation targets in extremely preterm infants that can be used to prevent the development of pulmonary hypertension and manage pulmonary hypertension once developed.

Predicting BPD: Lessons Learned From the Airway Microbiome of Preterm Infants.

Bronchopulmonary dysplasia (BPD) is the chronic lung disease of prematurity with an operational definition, various different clinical phenotypes, and a complex, multifactorial etiology. Newer unbiased systems biology approaches have identified various "omic" factors associated with the pathogenesis and prediction of BPD. Recent microbi "omic" studies have discovered that airways of newborns harbor a low biomass but distinct microbiome signature as early as at the time of birth. This early airway microbiome may serve to prime the host immune system and may play a role in modulating the infant's future susceptibility to severe BPD development. Temporal changes are observed in airway microbiome of preterm infants from birth to the diagnosis of BPD, with an overall decrease in bacterial diversity, and development of a relative dysbiosis marked by increased Gammaproteobacteria and decreased Lactobacilli abundance. This review will summarize previous investigations of the airway microbiome in preterm infants, appraise the utility of using the airway microbiome to predict BPD development, discuss possible molecular mechanisms involved, and speculate on future microbiome-mediated therapeutics for BPD.

Environmental or Nasal Cannula Supplemental Oxygen for Preterm Infants: A Randomized Cross-Over Trial.

OBJECTIVE: To test the hypothesis that environmental compared with nasal cannula oxygen decreases episodes of intermittent hypoxemia (oxygen saturations <85% for ≥10 seconds) in preterm infants on supplemental oxygen by providing a more stable hypopharyngeal oxygen concentration. STUDY DESIGN: This was a single center randomized crossover trial with a 1:1 parallel allocation to order of testing. Preterm infants on supplemental oxygen via oxygen environment maintained by a servo-controlled system or nasal cannula with flow rates ≤1.0 L per kg per minute were crossed over every 24 hours for 96 hours. Data were collected electronically to capture real time numeric and waveform data from patient monitors. RESULTS: Twenty-five infants with gestational age of 27 ± 2 weeks (mean ± SD) and a birth weight of 933 ± 328 g were studied at postnatal day 36 ± 26. The number of episodes of intermittent hypoxemia per 24 hours was 117 ± 77 (median, 98; range, 4-335) with oxygen environment vs 130 ± 63 (median, 136; range, 16-252) with nasal cannula (P = .002). Infants on oxygen environment compared with nasal cannula also had decreased episodes of severe intermittent hypoxemia (P = .005). Infants on oxygen environment compared with nasal cannula had a lower proportion of time with oxygen saturations <85% (.05 ± .03 vs .06 ± .03, P < .001), and a lower coefficient of variation of oxygen saturation (P = .02). CONCLUSIONS: In preterm infants receiving supplemental oxygen, servo-controlled oxygen environment decreases hypoxemia compared with nasal cannula. TRIAL REGISTRATION: ClinicalTrials.gov: NCT02794662.

Caffeine controversies.

PURPOSE OF REVIEW: Caffeine use in preterm infants has endured several paradigms: from standard of care to possible neurotoxin to one of the few medications for which there is evidence of bronchopulmonary dysplasia (BPD) risk reduction. The purpose of the review is to analyze this dynamic trajectory and discuss controversies that still remain after decades of caffeine use. RECENT FINDINGS: Following concerns for caffeine safety in preterm infants, a large randomized controlled trial demonstrated a reduction in BPD and treatment for patent ductus arteriosus. The lower rate of death or neurodevelopmental impairment noted at 18-21 months was not statistically different at later timepoints; however, infants in the caffeine group had lower rates of motor impairment at 11-year follow-up. The time of caffeine therapy initiation is now substantially earlier, and doses used are sometimes higher that previously used, but there are limited data to support these practices. SUMMARY: Caffeine therapy for apnea of prematurity (AOP) remains one of the pillars of neonatal care, although more evidence to support dosing and timing of initiation and discontinuation are needed.