Mechanical Ventilation and Bronchopulmonary Dysplasia

Impact of severity and age with variable definitions of bronchopulmonary dysplasia on neurodevelopmental outcomes

BACKGROUND

Bronchopulmonary dysplasia (BPD) is associated with neurodevelopmental impairment (NDI).

METHODS

To compare the ability of NICHD 2001 and Jensen 2019 definitions of BPD and respiratory support at 40 weeks postmenstrual age (PMA) to predict NDI, a retrospective study (1/2010-12/2020) was conducted in infants with gestational age <32 weeks and birth weight <1500 g. The primary outcome measure was NDI at 18-24 months corrected age.

RESULTS

Of 1119 infants, 227 (20.7%) met the inclusion criteria and had adequate follow-up data. Multivariate regression analysis showed that the NICHD 2001 definition was not predictive of NDI. Infants with Grade 2 or 3 BPD (Jensen 2019) had 4.75 (95% CI: 1.282-17.563) times greater odds of having NDI than infants without BPD. Infants requiring respiratory support at 40 weeks PMA had 4.95 (95% CI: 1.490-16.47) times greater odds of having NDI. Receiver operating characteristic curves demonstrated that the 2 definitions of BPD and the need for respiratory support at 40 weeks PMA were similar in their ability to predict NDI.

CONCLUSION

There is no significant difference in the ability of the NICHD 2001 and Jensen 2019 BPD definitions, as well as the need for respiratory support at 40 weeks, for predicting NDI.

IMPACT STATEMENT

Current bronchopulmonary dysplasia (BPD) definitions may not effectively predict neurodevelopmental impairment (NDI) in preterm infants. Grades 2/3 BPD (Jensen 2019 criteria) significantly associate with NDI. Infants requiring respiratory support at 40 weeks post-menstrual age (PMA) have 5 times higher odds of NDI than those on room air at 40 weeks PMA. The NICHD 2001, Jensen 2019 definitions, and the requirement for respiratory support at 40 weeks PMA, do not differ in their ability to predict NDI. Future studies should include multiple centers, with level III-IV NICUs, catering to socioeconomic, culturally, and racially diverse populations.

Toward Optimal High Continuous Positive Airway Pressure as Postextubation Support in Preterm Neonates: A Retrospective Cohort Study

OBJECTIVE

This study aimed to evaluate whether the initial pressure level on high continuous positive airway pressure (CPAP; ≥9 cm H2O), in relation to preextubation mean airway pressure (Paw), influences short-term clinical outcomes in preterm neonates.

STUDY DESIGN

In this retrospective cohort study, preterm neonates <29 weeks' gestational age (GA) extubated from mean Paw ≥9 cm H2O and to high CPAP (≥9 cm H2O) were classified into "higher level CPAP" (2-3 cm H2O higher than preextubation Paw) and "equivalent CPAP" (-1 to +1 cm H2O in relation to preextubation Paw). Only the first eligible extubation per infant was analyzed. The primary outcome was failure within ≤7 days of extubation, defined as any one or more of (1) need for reintubation, (2) escalation to an alternate noninvasive respiratory support mode, or (3) use of CPAP >preextubation Paw + 3 cm H2O. Secondary outcomes included individual components of the primary outcome, along with other clinical and safety outcomes.

RESULTS

Over a 10-year period (Jan 2011-Dec 2020), 175 infants were extubated from mean Paw >9 cm H2O to high CPAP pressures. Twenty-seven patients (median GA = 24.7, [interquartile range (IQR)]: (24.0-26.4) weeks and chronological age = 31, IQR: [21-40] days) were classified into the "higher level CPAP" group while 148 infants (median GA = 25.4, IQR: [24.6-26.6] weeks and chronological age = 26, IQR: [10-39] days) comprised the "equivalent CPAP" group. There was no difference in the primary outcome (44 vs. 51%; p = 0.51), including postadjustment for confounders (adjusted OR [aOR] = 0.47 [95% confidence interval (CI): 0.17-1.29; p = 0.14]). However, reintubation risk within 7 days was lower with higher level CPAP (7 vs. 37%; p < 0.01), including postadjustment (aOR = 0.07; 95% CI: 0.02-0.35; p < 0.01).

CONCLUSION

In this cohort, use of initial distending CPAP pressures 2 to 3 cm H2O higher than preextubation Paw did not alter the primary outcome of failure but did lower the risk of reintubation. The latter is an interesting hypothesis-generating finding that requires further confirmation.

KEY POINTS

· Use of high CPAP pressures (≥9 cm H2O) is gradually increasing in the care of preterm neonates.. · This study compares higher level versus equivalent CPAP in relation to preextubation Paw.. · The findings demonstrate no difference in failure as defined with use of higher level CPAP pressures..

Volume-targeted ventilation

Despite strong evidence of important benefits of volume-targeted ventilation, many high-risk extremely preterm infants continue to receive traditional pressure-controlled ventilation in the United States and elesewhere. Reluctance to abandon one's comfort zone, lack of suitable equipment and a lack of understanding of the subtleties of volume-targeted ventilation appear to contribute to the relatively slow uptake of volume-targeted ventilation. This review will underscore the benefits of using tidal volume as the primary control variable, to improve clinicians' understanding of the way volume-targeted ventilation interacts with the awake, breathing infant and to provide information about evidence-based tidal volume targets in various circmstances. Focus on underlying lung pathophysiology, individualized ventilator settings and tidal volume targets are essential to successful use of this approach thereby improving important clinical outcomes.

Caffeine pharmacokinetics following umbilical vein injection during delayed cord clamping in preterm lambs

BACKGROUND

Spontaneous breathing during and after delayed cord clamping (DCC) stabilizes cardiopulmonary transition at birth. Caffeine stimulates breathing and decreases apnea in premature newborns. We evaluated the pharmacokinetics and physiological effects of early caffeine administration-direct injection into the umbilical vein (UV) during DCC or administered through a UV catheter (UVC) after delivery.

METHODS

Eighteen extremely premature lambs (125-127d, term gestation 145d) were exteriorized and instrumented. Lambs received caffeine-citrate at high (40 mg/kg) or standard-dose (20 mg/kg) via direct UV (DUV) injection during DCC, or via the UVC.

RESULTS

Mean peak plasma caffeine concentrations were lower with high-dose DUV compared to UVC (18 ± 4.3 vs. 46 ± 12 mg/L, p < 0.05). With standard-dose caffeine, mean peak plasma levels were 7.48 ± 2.6 with DUV and 28.73 ± 9.4 mg/L with UVC. The volume of distribution was higher in the DUV group compared to UVC (2.5 ± 1.0 vs. 0.69 ± 0.15 L/kg) with an estimated 39 ± 18% entering the maternal circulation. Maternal peak concentrations were 0.79 ± 0.71 and 1.43 ± 0.74 mg/L with standard and high-dose DUV, respectively.

CONCLUSIONS

Caffeine injected directly into the UV during DCC is feasible but achieves lower concentrations due to high volume of distribution including maternal circulation. Further trials evaluating DUV caffeine injection should use higher caffeine doses.

IMPACT

Respiratory stimulation with early caffeine may reduce the need for intubation in preterm infants. In the preterm lambs, caffeine injection directly into the umbilical vein during delayed cord clamping is feasible. Plasma caffeine concentrations are less than half when administered directly into the umbilical vein during delayed cord clamping compared to administration via an umbilical venous catheter following birth likely attributed to a larger volume of distribution or injection site leak. There were no significant hemodynamic alterations following caffeine injection.

Peri-extubation settings in preterm neonates: a systematic review and meta-analysis

OBJECTIVE

To systematically review: 1) peri-extubation settings; and 2) association between peri-extubation settings and outcomes in preterm neonates.

STUDY DESIGN

In this systematic review, studies were eligible if they reported patient-data on peri-extubation settings (objective 1) and/or evaluated peri-extubation levels in relation to clinical outcomes (objective 2). Data were meta-analyzed when appropriate using random-effects model.

RESULTS

Of 9681 titles, 376 full-texts were reviewed and 101 included. The pooled means of peri-extubation settings were summarized. For objective 2, three experimental studies were identified comparing post-extubation CPAP levels. Meta-analyses revealed lower odds for treatment failure [pooled OR 0.46 (95% CI 0.27-0.76); 3 studies, 255 participants] but not for re-intubation [pooled OR 0.66 (0.22-1.97); 3 studies, 255 participants] with higher vs. lower CPAP.

CONCLUSIONS

Summary of peri-extubation settings may guide clinicians in their own practices. Higher CPAP levels may reduce extubation failure, but more data on peri-extubation settings that optimize outcomes are needed.

Comprehensive Analysis of Risk Factors for Bronchopulmonary Dysplasia in Preterm Infants in Taiwan: A Four-Year Study

Bronchopulmonary dysplasia (BPD) is a major respiratory condition mainly affecting premature infants. Although its occurrence is global, risk factors may differ regionally. This study, involving 3111 infants with birth weight ≤ 1500 gm or gestational age (GA) < 30 weeks, aimed to identify risk factors for BPD and BPD/mortality in Taiwan using data from the Taiwan Neonatal Network. The BPD criteria were based on the National Institute of Child Health and Human Development standards. Average GA was 27.5 weeks, with 23.7% classified as small for GA (SGA). Multivariate analysis highlighted low GA, low birth weight, and other perinatal factors as significant risk indicators for BPD. For moderate-to-severe BPD, additional risk factors included male gender and SGA, endotracheal intubation (ETT) or cardiopulmonary cerebral resuscitation (CPCR) in initial resuscitation. In the moderate-to-severe BPD/death group, SGA and ETT or CPCR in initial resuscitation remained the only additional risk factors. The study pinpoints male gender, SGA and ETT or CPCR as key risk factors for moderate-to-severe BPD/death in low-birth-weight infants in Taiwan, offering a basis for focused interventions and further research.

CircABPD1 alleviates oxidative lung injury of bronchopulmonary dysplasia through regulating miR-330-3p/HIF1α axis

In the NICU, bronchopulmonary dysplasia (BPD) is a concerning common respiratory complication in preterm and low birth-weight infants. Clinical studies have confirmed that human milk has an important nutritional role for children with BPD, therefore, dentification of beneficial components in human milk that prevent BPD is urgently needed. Our previous work showed that human milk exosomes (HM-Exos) could inhibit apoptosis of alveolar type II epithelial cells (AT II), and the circular RNA (circRNA)-circABPD1 were highly expressed in preterm colostrum milk exosomes. Exosomes transport circRNAs that are stable and may exert anti-inflammatory and immune effects attracted the attention of researchers, but the role and mechanism of human milk exosome-derived circABPD1 in BPD remains unclear. Here, we constructed BPD in vivo and in vitro models through exposure to hyperoxia, verified the effect of circABPD1 and revealed its mechanism through rescue experiments. We found that circABPD1 had circRNA properties, and overexpression of circABPD1 could improve reduced alveolar number, enlarged the alveolar linear intercept in vivo models of BPD, promote cell proliferation, reduce oxidative stress levels and alleviate lung epithelial cell damage in vivo and in vitro models. Mechanistically, circABPD1 targets miR-330-3p and regulates the expression of HIF1α. These results suggest that circABPD1 can improve the pathologoical changes of bronchopulmonary dysplasia, promote cell proliferation, inhibit oxidative stress level, and alleviate lung injury by targeting the miR-330-3p/HIF1α axis, which provides a new idea for the prevention and treatment of bronchopulmonary dysplasia.

Volume-targeted ventilation vs pressure-controlled ventilation for very low birthweight infants: a protocol of a randomized controlled trial

BACKGROUND

Mechanical ventilation (MV) is essential in the management of critically ill neonates, especially preterm infants. However, inappropriate or prolonged use of invasive MV may result in ventilator-associated lung injury. A systemic review comparing pressure control ventilation (PCV) with volume-targeted ventilation mode (VTV) approved that VTV reduces the incidence of death or bronchopulmonary dysplasia (BPD) in neonates; however, this study did not analyze subgroups of very low birthweight (VLBW) infants. Therefore, the aim of this study was to compare the use of VTV and PCV in VLBW infants and to provide clinical evidence for reducing mortality and complications of MV in VLBW infants.

METHOD

A single-center randomized controlled trial will be performed. All eligible infants will be randomized and assigned to either VTV or PCV group with 1:1 ratio using sealed envelopes. Death or BPD at 36 weeks' postmenstrual age will be used as the primary outcome. Secondary outcomes include BPD, death, length of invasive MV, noninvasive mechanical ventilation, and oxygen use, length of hospital stay, failure of conventional MV, rate of using high-frequency oscillatory ventilation (HFOV) as rescue therapy, rate of reintubation within 48 h, and hospital expenses.

DISCUSSION

Systemic review suggested that VTV decreases the incidence of death or BPD in neonates compared to PLV; however, this study did not specifically analyze subgroups of VLBW infants. We designed this single-center randomized controlled trials (RCT) to add a significant contribution regarding the benefits of VTV for VLBW patients.

Two-stage learning-based prediction of bronchopulmonary dysplasia in very low birth weight infants: a nationwide cohort study

Introduction

The aim of this study is to develop an enhanced machine learning-based prediction models for bronchopulmonary dysplasia (BPD) and its severity through a two-stage approach integrated with the duration of respiratory support (RSd) using prenatal and early postnatal variables from a nationwide very low birth weight (VLBW) infant cohort.

Methods

We included 16,384 VLBW infants admitted to the neonatal intensive care unit (NICU) of the Korean Neonatal Network (KNN), a nationwide VLBW infant registry (2013-2020). Overall, 45 prenatal and early perinatal clinical variables were selected. A multilayer perceptron (MLP)-based network analysis, which was recently introduced to predict diseases in preterm infants, was used for modeling and a stepwise approach. Additionally, we applied a complementary MLP network and established new BPD prediction models (PMbpd). The performances of the models were compared using the area under the receiver operating characteristic curve (AUROC) values. The Shapley method was used to determine the contribution of each variable.

Results

We included 11,177 VLBW infants (3,724 without BPD (BPD 0), 3,383 with mild BPD (BPD 1), 1,375 with moderate BPD (BPD 2), and 2,695 with severe BPD (BPD 3) cases). Compared to conventional machine learning (ML) models, our PMbpd and two-stage PMbpd with RSd (TS-PMbpd) model outperformed both binary (0 vs. 1,2,3; 0,1 vs. 2,3; 0,1,2 vs. 3) and each severity (0 vs. 1 vs. 2 vs. 3) prediction (AUROC = 0.895 and 0.897, 0.824 and 0.825, 0.828 and 0.823, 0.783, and 0.786, respectively). GA, birth weight, and patent ductus arteriosus (PDA) treatment were significant variables for the occurrence of BPD. Birth weight, low blood pressure, and intraventricular hemorrhage were significant for BPD ≥2, birth weight, low blood pressure, and PDA ligation for BPD ≥3. GA, birth weight, and pulmonary hypertension were the principal variables that predicted BPD severity in VLBW infants.

Conclusions

We developed a new two-stage ML model reflecting crucial BPD indicators (RSd) and found significant clinical variables for the early prediction of BPD and its severity with high predictive accuracy. Our model can be used as an adjunctive predictive model in the practical NICU field.

Bronchopulmonary dysplasia and carbon dioxide retention

AIM

The aim of this study was to determine the pre-discharge carbon dioxide (CO2 ) levels of preterm neonates with bronchopulmonary dysplasia (BPD) requiring ongoing nasal cannulae oxygen therapy and who were ready for discharge home.

METHODS

We studied a retrospective cohort of infants born <30 weeks gestational age (GA) at ≥36 weeks corrected GA who had established BPD requiring ongoing nasal cannulae oxygen therapy and were ready for discharge home. Neonates were born and admitted between May 2014 and December 2018. Demographic data at the time of birth and at the time of the last blood gas sampled were collected.

RESULTS

One hundred five neonates had median GA of 26.1 weeks and birth weight of 775 g. Median (IQR) CO2 level was 54 (49-58) mmHg. Ninety-nine (94%) neonates had CO2 levels exceeding the normal range and 91 (87%) neonates had a CO2 between 45 and 65 mmHg.

CONCLUSION

Ninety-four per cent of neonates <30 weeks GA at ≥36 weeks corrected GA requiring ongoing nasal cannulae oxygen therapy for established BPD, who were ready for discharge home, have CO2 levels outside of normocapnia (35-45 mmHg), with 87% having CO2 levels between 45 and 65 mmHg.

Automated prediction of extubation success in extremely preterm infants: the APEX multicenter study

BACKGROUND

Extremely preterm infants are frequently subjected to mechanical ventilation. Current prediction tools of extubation success lacks accuracy.

METHODS

Multicenter study including infants with birth weight ≤1250 g undergoing their first extubation attempt. Clinical data and cardiorespiratory signals were acquired before extubation. Primary outcome was prediction of extubation success. Automated analysis of cardiorespiratory signals, development of clinical and cardiorespiratory features, and a 2-stage Clinical Decision-Balanced Random Forest classifier were used. A leave-one-out cross-validation was done. Performance was analyzed by ROC curves and determined by balanced accuracy. An exploratory analysis was performed for extubations before 7 days of age.

RESULTS

A total of 241 infants were included and 44 failed (18%) extubation. The classifier had a balanced accuracy of 73% (sensitivity 70% [95% CI: 63%, 76%], specificity 75% [95% CI: 62%, 88%]). As an additional clinical-decision tool, the classifier would have led to an increase in extubation success from 82% to 93% but misclassified 60 infants who would have been successfully extubated. In infants extubated before 7 days of age, the classifier identified 16/18 failures (specificity 89%) and 73/105 infants with success (sensitivity 70%).

CONCLUSIONS

Machine learning algorithms may improve a balanced prediction of extubation outcomes, but further refinement and validation is required.

IMPACT

A machine learning-derived predictive model combining clinical data with automated analyses of individual cardiorespiratory signals may improve the prediction of successful extubation and identify infants at higher risk of failure with a good balanced accuracy. Such multidisciplinary approach including medicine, biomedical engineering and computer science is a step forward as current tools investigated to predict extubation outcomes lack sufficient balanced accuracy to justify their use in future trials or clinical practice. Thus, this individualized assessment can optimize patient selection for future trials of extubation readiness by decreasing exposure of low-risk infants to interventions and maximize the benefits of those at high risk.

Instrumental dead space: A glass ceiling for extremely low birth weight preterm infants? A dead space washout bench study

BACKGROUND

When ventilating extremely low birth weight infants, clinicians face the problem of instrumental dead space, which is often larger than tidal volume. Hence, aggressive ventilation is necessary to achieve CO₂ removal. Continuous tracheal gas insufflation can wash out CO₂ from dead space and might also have an impact on O₂ and water vapor transport. The objective of this bench study is to test the impact of instrumental dead space on the transport of CO₂ , O₂ , and water vapor and the ability of continuous tracheal gas insufflation to remedy this problem during small tidal volume ventilation.

METHODS

A test-lung located in an incubator at 37°C was ventilated with pressure levels needed to reach different tidal volumes from 1.5 to 5 mL. End-tidal CO₂ at the test-lung exit, O₂ concentration, and relative humidity in the test-lung were measured for each tidal volume with and without a 0.2 L/min continuous tracheal gas insufflation flow.

RESULTS

CO₂ clearance was improved by continuous tracheal gas insufflation allowing a 28%-44% of tidal volume reduction. With continuous tracheal gas insufflation, time to reach desired O₂ concentration was reduced from 20% to 80% and relative humidity was restored. These results are inversely related to tidal volume and are particularly critical below 3 mL.

CONCLUSION

For the smallest tidal volumes, reduction of instrumental dead space seems mandatory for CO₂ , O₂ , and water vapor transfer. Continuous tracheal gas insufflation improved CO₂ clearance, time to reach desired O₂ concentration and humidification of airways and, thus, may be an option to protect lung development.

Can amniotic fluid protect developing fetal lungs against the harmful effects of oxidative stress?

BACKGROUND

Preterm births cause fetuses to be born without completing the development of their organs. Due to this undesirable situation, it is the pulmonary tissue which has to be most exposed to harmful effects of extrauterine environment. Early disappearance of the prophylactic and constructive effects of amniotic fluid (AF) on developing tissues, such as pulmonary tissue, facilitates the formation of pulmonary morbidities resulting from oxygen. Setting out from this knowledge, we wanted, in addition to assessing the beneficent effects of AF on pulmonary tissue, to study the importance of AF in morbidities of this tissue thought to originate from oxygen.

METHODS

In this experimental study, while the study group was made up of the fetuses of pregnant rats exposed to hyperbaric oxygen, (hyperoxic pregnant rat fetuses-HPRF), the control group was formed of the fetuses of the rats pregnant in the usual room setting (normoxic pregnant rat fetuses-NPRF). The pulmonary and hepatic tissues taken from the fetuses of these pregnant rats on the 21st day of their pregnancy were compared biochemically and histologically. For biochemical assessment, total glutathione (tGSH), catalase (CAT), malondialdehyde (MDA), tumor necrosis factor-alpha (TNF-α) values and for histopathological assessment, apoptosis, alveolar wall count (AWC), vena centralis count (VCC) were included.

RESULTS

Statistical significance was found in the pulmonary tissue values of tGSH on behalf of NPRF, and MDA on behalf of HPRF (p < 0.05). In liver tissue, statistical significance was detected in tGSH and CAT values in favor of NPRF and in MDA, and TNF-α values in favor of HPRF (p < 0.05).

DISCUSSION

: Our study has demonstrated that AF protects the pulmonary tissue from the harmful effects of oxygen in the intrauterine period. In addition, our data have suggested that the pulmonary tissue's being deprived of the useful effects of AF owing to premature birth may be an important trigger in the occurrence of the pulmonary morbidities thought to result from oxygen.

Duration of mechanical ventilation and clinical outcomes in very low birth weight infants: A single center 10-years cohort study

BACKGROUND

Despite the important role of MV in reducing mortality in very preterm infants, its use is often associated with complications. The study was aimed to determine the duration of mechanical ventilation (MV), which significantly increased the risk of adverse outcomes in very low birth weight (VLBW) infants.

METHODS

Data obtained from a prospectively created computer database were used in a retrospective cohort study. The database included information about 1980 VLBW infants <32 weeks of gestation who were cared for at the tertiary care center between January 2010 and December 2020.

RESULTS

Out of 1980 VLBW infants, 1086 (55%) were ventilated sometime during the hospital stay. 678 (62.43%) of ventilated babies survived until discharge. With ROC analysis, it was identified that MV duration of 60.5 hours had 79.3% sensitivity and 64.6% specificity for the prediction of BPD with the AUC of 0.784 (95% CI 0.733-0.827; p < 0.0001). The duration of MV above 60.5 hours was a significant risk factor for bronchopulmonary dysplasia (aOR 6.005, 95% CI 3.626-9.946), death (aOR 3.610, 95% CI 2.470-5.276), bronchopulmonary dysplasia/death (aOR 4.561, 95% CI 3.328-6.252), sepsis (aOR 1.634, 95% CI 1.168-2.286), necrotizing enterocolitis (aOR 2.606, 95% CI 1.364-4.980), and periventricular leukomalacia (aOR 2.191, 95% CI 1.241-3.867).

CONCLUSIONS

Duration of MV longer than 60.5 hours is an independent risk factor for adverse outcomes in VLBW infants. It is essential to increase and optimize efforts to avoid MV or extubate very preterm infants as soon as possible, before reaching the established threshold duration of invasive respiratory support.

Short-term pulmonary and systemic effects of hydrocortisone initiated 7-14 days after birth in ventilated very preterm infants: a secondary analysis of a randomised controlled trial

OBJECTIVE

Observational studies in preterm infants suggest that systemic hydrocortisone improves pulmonary condition but may also lead to systemic adverse effects. We report the short-term pulmonary and systemic effects of hydrocortisone initiated in the second week.

DESIGN

Randomised placebo-controlled trial.

SETTING

Dutch and Belgian neonatal intensive care units.

PATIENTS

Infants born <30 weeks' gestation and/or birth weight <1250 g, and ventilator dependent in the second week of life.

INTERVENTION

Infants were randomly assigned to a 22-day course of systemic hydrocortisone (cumulative dose 72.5 mg/kg; n=182) or placebo (n=190).

MAIN OUTCOME MEASURES

Data on extubation, ventilator settings, glucose levels, and blood pressure were recorded daily and analysed during the first 7 days of treatment using linear mixed-effects models.

RESULTS

Infants in the hydrocortisone group (24.3%) failed extubation less often compared with placebo (38.6%, crude risk difference: -14.3% (95% CI: -23.4% to -4.8%)). The estimated difference in daily rate of change between hydrocortisone and placebo was -0.42 cmH₂O (95% CI: -0.48 to -0.36) for mean airway pressure, -0.02 (95% CI: -0.02 to -0.01) for fraction of inspired oxygen, -0.37 (95% CI: -0.44 to -0.30) for respiratory index, 0.14 mmol/L (95% CI: 0.08 to 0.21) for blood glucose levels and 0.83 mm Hg (95% CI: 0.58 to 1.09) for mean blood pressure.

CONCLUSIONS

Systemic hydrocortisone initiated between 7 and 14 days after birth in ventilated preterm infants improves pulmonary condition, thereby facilitating weaning and extubation from invasive ventilation. The effects of hydrocortisone on blood glucose levels and blood pressure were mild and of limited clinical relevance.

TRIAL REGISTRATION NUMBER

Netherlands Trial Register (NTR2768; https://www.trialregister.nl/trial/2640) and European Union Clinical Trials Register (EudraCT, 2010-023777-19).

[Risk factors for moderate/severe bronchopulmonary dysplasia in preterm infants with a gestational age of <32 weeks: a multicenter retrospective analysis]

OBJECTIVES

To investigate the risk factors for moderate/severe bronchopulmonary dysplasia (BPD) in preterm infants with a gestational age of <32 weeks.

METHODS

A retrospective analysis was performed on the medical data of preterm infants with a gestational age of <32 weeks and a length of hospital stay of ≥28 days who were admitted to the neonatal intensive care unit (NICU) of 17 institutions of Jiangsu Neonatal Perinatal Cooperation Network from January 1, 2019 to December 31, 2020 and were diagnosed with BPD. The preterm infants were grouped according to gestational age and severity of BPD. A multivariate logistic regression analysis was used to investigate the risk factors for moderate/severe BPD in various gestational age groups.

RESULTS

During the two-year period, a total of 2 603 preterm infants with a gestational age of <32 weeks were admitted to the NICU of the 17 institutions, among whom 961 were diagnosed with BPD, and the incidence rates of BPD and moderate/severe BPD were 36.92% (961/2 603) and 8.64% (225/2 603), respectively. The incidence rate of moderate/severe BPD was 56.5% (26/46) in preterm infants with a gestational age of 24⁺⁰-25⁺⁶ weeks, 31.0% (66/213) in those with a gestational age of 26⁺⁰-27⁺⁶ weeks, 16.9% (75/445) in those with a gestational age of 28⁺⁰-29⁺⁶ weeks, and 22.6% (58/257) in those with a gestational age of 30⁺⁰-31⁺⁶ weeks. The multivariate logistic regression analysis showed that there were different risk factors for moderate/severe BPD in preterm infants with different gestational ages: patent ductus arteriosus requiring treatment as risk factors in preterm infants with a gestational age of 24⁺⁰-25⁺⁶ weeks; premature rupture of membranes ≥18 hours, positive pressure ventilation for resuscitation, clinical sepsis, and duration of mechanical ventilation ≥14 days as risk factors in preterm infants with a gestational age of 26⁺⁰-27⁺⁶ weeks; duration of mechanical ventilation ≥14 days, neonatal pneumonia, and patent ductus arteriosus requiring treatment as risk factors in preterm infants with a gestational age of 28⁺⁰-29⁺⁶ weeks; positive pressure ventilation for resuscitation, neonatal pneumonia, and anemia of prematurity as risk factors in preterm infants with a gestational age of 30⁺⁰-31⁺⁶ weeks (P<0.05).

CONCLUSIONS

The development of moderate/severe BPD is multifactorial in preterm infants with a gestational age of <32 weeks, and there are different risk factors in different gestational age groups. Targeted preventive measures for preterm infants of different gestational ages may be useful to reduce the severity of BPD.

Natural evolution of the patent ductus arteriosus in the extremely premature newborn and respiratory outcomes

OBJECTIVE

Evaluate spontaneous closure of the patent ductus arteriosus (PDA) in extremely preterm infants and their respiratory outcomes, especially at <26 weeks gestational age (GA).

STUDY DESIGN

Retrospective study in <29 weeks, admitted within 24 h after birth (Feb 2015 and Dec 2019). Infants without any intervention to promote ductal closure, ≥1 echocardiography, and alive at discharge were included.

RESULTS

Two hundred and fourteen infants (average GA 26.3 ± 1.5 weeks) were included; 84 (39%) <26 weeks. PDA closed spontaneously in 194 (91%); 76/84 (90%) for infants <26 weeks. PDA closure was ascertained on an echocardiography performed at a median age of 36.4 [34.4-40.1] weeks. Rate of moderate-to-severe bronchopulmonary dysplasia decreased throughout the study period (OR for year of birth: 0.70 [95% CI: 0.57-0.87], p = 0.001).

CONCLUSION

Majority of extremely preterm infants, including <26 weeks, had spontaneous closure of the ductus before term corrected age. There was a concomitant improvement of respiratory outcomes.

Moving Bronchopulmonary Dysplasia Research from the Bedside to the Bench

Although advances in the respiratory management of extremely preterm infants have led to improvements in survival, this progress has not yet extended to a reduction in the incidence of bronchopulmonary dysplasia (BPD). BPD is a complex multifactorial condition that primarily occurs due to disturbances in the regulation of normal pulmonary airspace and vascular development. Preterm birth and exposure to invasive mechanical ventilation also compromises large airway development, leading to significant morbidity and mortality. Although both predisposing and protective genetic and environmental factors have been frequently described in the clinical literature, these findings have had limited impact on the development of effective therapeutic strategies. This gap is likely because the molecular pathways that underlie these observations are yet not fully understood, limiting the ability of researchers to identify novel treatments that can preserve normal lung development and/or enhance cellular repair mechanisms. In this review article, we will outline various well-established clinical observations whilst identifying key knowledge gaps that need to be filled with carefully designed pre-clinical experiments. We will address these issues by discussing controversial topics in the pathophysiology, the pathology and the treatment of BPD, including an evaluation of existing animal models that have been used to answer important questions.

Evaluation of the applicability of the current CDC pediatric ventilator-associated events (PedVAE) surveillance definition in the neonatal intensive care unit population

Background

There is limited data on pediatric ventilator-associated events (PedVAE) in the neonatal intensive care unit (NICU) setting, since the CDC mandated state reporting of these events in January 2019. This study sought to describe PedVAE rates and characteristics in the NICU population.

Methods

Single-center case-control study of infants requiring mechanical ventilation in a 39-bed level IV NICU between January 1, 2018 and December 31, 2020. Baseline infant demographic, respiratory support and antibiotic use data was obtained and comparisons were performed between patients with potential PedVAEs and those without events.

Result

Two hundred and nine infants were mechanically ventilated. Two of the 126 patients ventilated for ≥4 days met CDC criteria for PedVAEs with a total of 3 events, and 32 (25%) received antibiotics with escalation of respiratory support, primarily for tracheitis.

Conclusion

NICU-specific data on PedVAE is limited. Only 2 infants in the study period met the current CDC criteria for PedVAE with a rate of 0.9 events per 1000 ventilator days. The current CDC PedVAE definition might be inadequate to identify actionable VAEs to inform prevention efforts in the NICU population, and alternate indices could better characterize these events.

Factors associated with successful extubation following the first course of systemic dexamethasone in ventilator-dependent preterm infants with or at risk of developing bronchopulmonary dysplasia

OBJECTIVES

We aimed to identify factors present at the start of an initial course of systemic dexamethasone that would be associated with successful extubation in mechanically ventilated neonates <30 weeks gestational age (GA) with or at risk of developing bronchopulmonary dysplasia (BPD).

METHODS

We studied a retrospective cohort of neonates (23⁺⁰ -29⁺⁶ weeks GA), with or at risk of developing BPD, prescribed their first course of systemic dexamethasone to aid in extubation from mechanical ventilation. The data collected only pertained to the first course of dexamethasone. Neonates given dexamethasone for airway edema were not included. The primary outcome of interest was successful extubation (i.e., extubated within 14 days of starting dexamethasone and remaining extubated for at least 7 days). Binary logistic regression was employed.

RESULTS

A total of 287 neonates were included. Each additional week of GA at birth led to a 1.53 increase in the odds of successful extubation (95% CI: 1.122-2.096, p < 0.01). Higher average fraction of inspired oxygen (FiO₂ ) requirements in the preceding 24 h resulted in a 0.94 decrease in the odds of successful extubation (p < 0.05) and higher mean airway pressure (MAP) resulted in 0.76 decrease in odds of successful extubation (p < 0.01).

CONCLUSIONS

Mechanically ventilated neonates with or at risk of developing BPD, born at <30 week GA and initiated on dexamethasone to facilitate extubation, had a lower likelihood of successful extubation by Day 14 if they had younger GA at birth, and at the time of commencing steroids had higher MAPs and had higher oxygen requirements.

Positive versus negative pressure during removal of endotracheal-tube on prevention of post-extubation atelectasis in ventilated neonates: A randomized controlled trial

Background

Post-extubation-atelectasis (PEA) is a common problem after the removal of an endotracheal tube in neonates which increases the rate of extubation failure. Different techniques have been introduced for the prevention of PEA. One technique is the removal of the endotracheal tube by negative or positive gradients of pressure. No RCT has yet been done to compare the use of these two methods in neonates. So this study aimed to compare the role of positive and negative pressure during extubation of neonates on the prevention of PEA.

Materials and methods

We enrolled 100 newborns in this RCT that required at least 24 h of mechanical ventilation. The endotracheal tube in one group was removed by a T-Piece resuscitator at a PEEP level of 5 CmH2o while in another group extubation was done applying suction pressure of 100 mmHg by random selection. Prevalence of PEA in CXRs after extubation was compared between the two groups.

Results

The prevalence of PEA in the extubation of the positive pressure group (24%) was significantly lower than that of the negative pressure group (46%) (p = 0.024). Extubation failure was found to be lower in the positive pressure group (6% versus 20% P = 0.037). No significant difference was observed between the two groups in the prevalence of apnea, pneumothorax, and death at 3 days after extubation.

Conclusion

The use of positive pressure during removal of the endotracheal tube in newborn infants reduced the rate of PEA compared with the negative pressure so extubation by a positive pressure is recommended in neonates.

•

Post extubation atelectasis (PEA) is a common problem after the removal of an endotracheal tube in neonates.

•

This study compares two different extubation methods for the prevention of PEA in neonates.

•

The prevalence of PEA in the extubation with positive pressure method was significantly lower than the negative pressure.

•

Extubation by a positive pressure method is recommended in neonates.

Novel Ventilation Strategies to Reduce Adverse Pulmonary Outcomes

Extremely preterm infants who must suddenly support their own gas exchange with lungs that are incompletely developed and lacking adequate amount of surfactant and antioxidant defenses are susceptible to lung injury. The decades-long quest to prevent bronchopulmonary dysplasia has had limited success, in part because of increasing survival of more immature infants. The process must begin in the delivery room with gentle assistance in establishing and maintaining adequate lung aeration, followed by noninvasive support and less invasive surfactant administration. Various modalities of invasive and noninvasive support have been used with varying degree of effect and are reviewed in this article.

Neutrophil-Derived IL-17 Promotes Ventilator-Induced Lung Injury via p38 MAPK/MCP-1 Pathway Activation

Ventilator-induced lung injury (VILI) is one of the most common complications of mechanical ventilation and can severely affect health. VILI appears to involve excessive inflammatory responses, but its pathogenesis has not yet been clarified. Since interleukin-17 (IL-17) plays a critical role in the immune system and the development of infectious and inflammatory diseases, we investigated here whether it plays a role in VILI. In a mouse model of VILI, mechanical ventilation with high tidal volume promoted the accumulation of lung neutrophils, leading to increased IL-17 levels in the lung, which in turn upregulated macrophage chemoattractant protein-1 via p38 mitogen-activated protein kinase. Depletion of neutrophils decreases the production IL-17 in mice and inhibition of IL-17 significantly reduced HTV-induced lung injury and inflammatory response. These results were confirmed in vitro using RAW264.7 macrophage cultures. Our results suggest that IL-17 plays a pro-inflammatory role in VILI and could serve as a new target for its treatment.

Ventilation-Induced Lung Injury (VILI) in Neonates: Evidence-Based Concepts and Lung-Protective Strategies

Supportive care with mechanical ventilation continues to be an essential strategy for managing severe neonatal respiratory failure; however, it is well known to cause and accentuate neonatal lung injury. The pathogenesis of ventilator-induced lung injury (VILI) is multifactorial and complex, resulting predominantly from interactions between ventilator-related factors and patient-related factors. Importantly, VILI is a significant risk factor for developing bronchopulmonary dysplasia (BPD), the most common chronic respiratory morbidity of preterm infants that lacks specific therapies, causes life-long morbidities, and imposes psychosocial and economic burdens. Studies of older children and adults suggest that understanding how and why VILI occurs is essential to developing strategies for mitigating VILI and its consequences. This article reviews the preclinical and clinical evidence on the pathogenesis and pathophysiology of VILI in neonates. We also highlight the evidence behind various lung-protective strategies to guide clinicians in preventing and attenuating VILI and, by extension, BPD in neonates. Further, we provide a snapshot of future directions that may help minimize neonatal VILI.

Sphingosine Kinase 1 Plays an Important Role in Atorvastatin-Mediated Anti-Inflammatory Effect against Acute Lung Injury

Atorvastatin is a 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMG-CoA reductase) inhibitor and inhibits cholesterol synthesis. Recently, atorvastatin also showed anti-inflammatory effect in acute lung injury, ameliorating pulmonary gas-blood exchanging function. Sphingosine kinase 1 plays a central role in endothelial (EC) cytoskeleton rearrangement and EC barrier integrity regulation. In this study, the role of sphingosine kinase 1 in atorvastatin anti-inflammatory effect against acute lung injury was investigated. Both wild-type (WT) and SphK1^-/- mice were challenged with high tidal volume ventilation (40 ml/kg body weight, 65 breathing/min, 4 hours). The acute lung injury was evaluated and the mechanisms were explored. In WT mice, atorvastatin treatment significantly decreased acute lung injury responding to high tidal volume ventilation (HT), including protein, cellular infiltration, and cytokine releasing; comparing to WT mice, SphK1^-/- mice showed significantly worsen pulmonary injuries on HT model. Moreover, the atorvastatin-mediated anti-inflammatory effect was diminished in SphK1^-/- mice. To further confirm the role of SphK1 in VILI, we then compared the inflammatory response of endothelial cells that were isolated from WT and SphK1^-/- mice to cyclic stretching. Similarly, atorvastatin significantly decreased cytokine generation from WT EC responding to cyclic stretching. Atorvastatin also significantly preserved endothelial junction integrity in WT EC against thrombin challenge. However, the inhibitory effect of atorvastatin on cytokine generation induced by cyclic stretching was abolished on SphK1^-/- mice EC. The endothelial junction integrity effects of atorvastatin also diminished on SphK1^-/- mouse EC. Signal analysis indicated that atorvastatin inhibited JNK activation induced by cyclic stretch. SphK1 knockout also blocked atorvastatin-mediated VE-cadherin junction enhancement. In summary, by inhibition of MAPK activity and maintenance of EC junction homeostasis, SphK1 plays a critical role in atorvastatin-mediated anti-inflammatory effects in both cellular and in vivo model. This study also offers an insight into mechanical stress-mediated acute lung injury and potential therapy in the future.

Respiratory support strategies in the management of severe, longstanding bronchopulmonary dysplasia

Despite efforts to minimize ventilator-induced lung injury, some preterm infants require positive pressure support after 36 weeks' post-menstrual age. Infants with severe BPD typically experience progressive mismatch of ventilation and perfusion, which manifests as respiratory distress, hypoxemia in room air, hypercarbia, and growth failure. Lung compliance varies, but lung resistance generally increases with prolonged exposure to positive pressure ventilation and other sources of inflammation. Serial lung radiographs reveal a heterogeneous pattern, with areas of both hyperinflation and atelectasis; in extreme cases, macrocystic changes may be noted. Efforts to wean the respiratory support are often unsuccessful, and trials of high frequency ventilation, exogenous corticosteroids, and diuretics are common. The incidence of pulmonary hypertension increases with the severity of BPD, as does the mortality rate. Therefore, periodic screening and efforts to mitigate the risk of PH is fundamental to the management of longstanding BPD. Failure of conventional, lung-protective strategies (e.g., high rate/low tidal-volume and/or high frequency ventilation) warrants consideration of ventilatory strategies individualized to the disease physiology. Non-invasive modes of respiratory support may be successful in infants with mild to moderate BPD phenotypes. However, infants with moderate to severe BPD phenotypes often require invasive respiratory support, and pressure-limited or volume-targeted conventional ventilation may be better suited to the physiology than high-frequency ventilation. The consistent provision of adequate support is fundamental to the management of longstanding BPD and is best achieved with a stepwise increase in ventilator support until comfortable spontaneous respirations are achieved. Adequately supported infants typically experience improvements in both oxygenation and ventilation, which, if sustained, may arrest and generally reverses the course of a potentially lethal lung disease. Care should be individualized to address the most likely pulmonary mechanics, including variable lung compliance, elevated airway resistance, and variable airway obstruction.

Diagnosis and management of bronchopulmonary dysplasia

Bronchopulmonary dysplasia (BPD) is the most common chronic lung disease in infants and is associated with increased mortality, respiratory morbidity, neurodevelopmental impairment, and increased healthcare costs. In parallel with advances made in the field of neonatal intensive care, the phenotype of BPD has evolved from a fibrocystic disease affecting late preterm infants to one of impaired parenchymal development and dysregulated vascular growth predominantly affecting infants born before 29 weeks' gestational age. BPD has been shown to have significant lifelong consequences. Adults with BPD have been found to have abnormal lung function tests, reduced exercise tolerance, and may be at increased risk for developing chronic obstructive pulmonary disease. Evidence shows that BPD occurs secondary to genetic-environmental interactions in an immature lung. In this review, we evaluate the various clinical definitions, imaging modalities, and biomarker data that are helpful in making an early diagnosis of BPD. In addition, we evaluate recent evidence about the prevention and treatment of BPD. We discuss the invasive and non-invasive ventilation strategies and pharmacological agents used in the early, evolving, and established phases of BPD.

Prediction Model for Bronchopulmonary Dysplasia in Preterm Newborns

OBJECTIVE: To develop a multifactorial model that allows the prediction of bronchopulmonary dysplasia (BPD) in preterm newborns. MATERIALS AND METHODS: A single-center retrospective study of infants born below 32 + 0 weeks gestational age. We created a receiver operating characteristic curve to assess the multifactorial BPD risk and calculate the BPD risk accuracy using the area under the curve (AUC). BPD risk was categorized using a multifactorial predictive model based on the weight of the evidence. RESULTS: Of the 278 analyzed preterm newborns, 127 (46%) developed BPD. The significant risk factors for BPD in the multivariate analysis were gestational age, number of red blood cell concentrate transfusions, number of surfactant administrations, and hemodynamically significant patent ductus arteriosus. The combination of these factors determined the risk of developing BPD, with an AUC value of 0.932. A multifactorial predictive model based on these factors, weighted by their odds ratios, identified four categories of newborns with mean BPD risks of 9%, 59%, 82%, and 100%. CONCLUSION: A multifactorial model based on easily available clinical factors can predict BPD risk in preterm newborns and inform potential preventive measures.

Nasal high flow oxygen therapy in hospitalised neonatal foals

BACKGROUND

Respiratory disease is common in critically ill neonatal foals. Traditional oxygen therapy (TOT) with nasal insufflation of oxygen is often used to provide first-line respiratory support. Mechanical ventilation is used in foals which require a greater level of support but requires specialist expertise and can be associated with significant complications. Non-invasive ventilation (NIV) enables a greater level of respiratory support without the need for intubation. High flow oxygen therapy (HFOT) is a mode of NIV commonly used in human intensive care.

OBJECTIVES

To describe the use of HFOT in hospitalised neonatal foals.

STUDY DESIGN

Retrospective case series.

METHODS

Hospital records of neonatal foals admitted between 2018 and 2019 that received treatment with HFOT were reviewed. Clinical data and complications were recorded.

RESULTS

Fourteen foals were identified and the median duration of use was 43 hours (range 2-93 hours) with a median flow rate of 0.7L/kg/min (range 0.42-1.67). Ten foals survived to discharge. No significant complications associated with the technique were recorded.

MAIN LIMITATIONS

A small study population which was retrospectively reviewed.

CONCLUSIONS

This study provides preliminary information about the clinical use of HFOT in neonatal foals. The technique was well tolerated and no significant adverse effects were noted. However, further study is required to evaluate efficacy.

Introducing Less-Invasive Surfactant Administration into a Level IV NICU: A Quality Improvement Initiative

Less-invasive surfactant administration (LISA), a newer technique of delivering surfactant via a thin catheter, avoids mechanical ventilation. LISA has been widely adopted in Europe but less so in the US. Our goal was to increase the percentage of surfactant delivered via LISA from 0% to 51% by 12/2020. Project planning and literature review started 12/2019, and included a standardized equipment kit and simulation training sessions. We began Plan–Do–Study–Act (PDSA) cycles in 6/2020. Initial exclusions for LISA were gestational age (GA) <28 weeks (w) or ≥36 w, intubation in the delivery room, or PCO2 >70 if known; GA exclusion is now <25 w. From 6 to 12/2020, 97 patients received surfactant, 35 (36%) via LISA. When non-LISA-eligible patients were excluded, 35/42 (83%) received LISA successfully. There were only 2/37 patients for whom LISA was not able to be performed. Three LISA infants required mechanical ventilation in the first week of life. Sedation remained an initial challenge but improved when sucrose was used routinely. LISA was safely and successfully introduced in our NICU.

Lung function trajectories in children with post-prematurity respiratory disease: identifying risk factors for abnormal growth

Background

Survivors of prematurity are at risk for abnormal childhood lung function. Few studies have addressed trajectories of lung function and risk factors for abnormal growth in childhood. This study aims to describe changes in lung function in a contemporary cohort of children born preterm followed longitudinally in pulmonary clinic for post-prematurity respiratory disease and to assess maternal and neonatal risk factors associated with decreased lung function trajectories.

Methods

Observational cohort of 164 children born preterm ≤ 32 weeks gestation followed in pulmonary clinic at Boston Children’s Hospital with pulmonary function testing. We collected demographics and neonatal history. We used multivariable linear regression to identify the impact of neonatal and maternal risk factors on lung function trajectories in childhood.

Results

We identified 264 studies from 82 subjects with acceptable longitudinal FEV₁ data and 138 studies from 47 subjects with acceptable longitudinal FVC and FEV₁/FVC data. FEV₁% predicted and FEV₁/FVC were reduced compared to childhood norms. Growth in FVC outpaced FEV₁, resulting in an FEV₁/FVC that declined over time. In multivariable analyses, longer duration of mechanical ventilation was associated with a lower rate of rise in FEV₁% predicted and greater decline in FEV₁/FVC, and postnatal steroid exposure in the NICU was associated with a lower rate of rise in FEV₁ and FVC % predicted. Maternal atopy and asthma were associated with a lower rate of rise in FEV₁% predicted.

Conclusions

Children with post-prematurity respiratory disease demonstrate worsening obstruction in lung function throughout childhood. Neonatal risk factors including exposure to mechanical ventilation and postnatal steroids, as well as maternal atopy and asthma, were associated with diminished rate of rise in lung function. These results may have implications for lung function trajectories into adulthood.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12931-021-01720-0.

[Epidemiology and risk factors for bronchopulmonary dysplasia in prematures infants born at or less than 32 weeks of gestation]

OBJECTIVES

To describe risk factors of bronchopulmonary dysplasia in very preterm infants in the first weeks of life.

MATERIAL AND METHODS

Retrospective cohort study of preterm infants ≤ 32 weeks of gestational age and birth weight ≤ 1500 g. A multivariate logistic regression analysis was performed to identify independent risk factors for bronchopulmonary dysplasia in the first weeks of life.

RESULTS

A total of 202 newborns were included in the study (mean gestational age 29.5 ± 2.1 weeks), 61.4% never received invasive mechanical ventilation. The incidence of bronchopulmonary dysplasia was 28.7%, and 10.4% of the patients were diagnosed with moderate-severe bronchopulmonary dysplasia. Bronchopulmonary dysplasia was independently associated with gestational age at birth (p < 0.001; OR = 0.44 [95% CI = 0.30-0.65]), the need for mechanical ventilation on the first day of life (p = 0.001; OR = 8.13 [95% CI = 2.41-27.42]), nosocomial sepsis (p < 0.001; OR = 9.51 [95% CI = 2.99-30.28]) and FiO2 on day 14 (p < 0.001; OR = 1.39 [95% CI = 1.16-1.66]). Receiving mechanical ventilation at the first day of life (p = 0.008; OR = 5.39 [95% CI = 1.54-18.89]) and at the third day of life (p = 0.001; OR = 9.99 [95% CI = 2.47-40.44]) and nosocomial sepsis (p = 0.001; OR = 9.87 [95% CI = 2.58-37.80]) were independent risk factors for moderate-severe bronchopulmonary dysplasia.

CONCLUSIONS

Gestational age at birth, mechanical ventilation in the first days of life and nosocomial sepsis are early risk factors for bronchopulmonary dysplasia. The analysis of simple and objective clinical data, allows us to select a group of patients at high risk of bronchopulmonary dysplasia in whom it could be justified to act more aggressively, and shows areas for improvement to prevent its development or reduce its severity.

The Predictive Value of Lung Ultrasound Scores in Developing Bronchopulmonary Dysplasia: A Prospective Multicenter Diagnostic Accuracy Study

BACKGROUND

Different lung ultrasound (LUS) scanning protocols have been used, and the results in terms of diagnostic accuracy are heterogeneous.

RESEARCH QUESTIONS

What is the diagnostic accuracy of the LUS score to predict moderate to severe bronchopulmonary dysplasia (msBPD)? Does scanning of posterior lung fields improve the diagnostic accuracy?

STUDY DESIGN AND METHODS

This was a multicenter prospective, observational study in six centers. Two LUS aeration scores, one involving only anterolateral lung fields and the other adding the posterior fields were obtained at birth, on the third day of life (DOL), on the seventh DOL, on the 14th DOL, and on the 21st DOL. The diagnostic accuracy of both scores to predict msBPD was assessed at each time point.

RESULTS

Eight hundred thirty-two LUS examinations in 298 infants were included. Both LUS score using anterolateral and posterior fields and LUS score using only anterolateral fields showed a similar moderate diagnostic accuracy to predict msBPD on the third DOL (area under the receiver operating characteristic curve [AUC] 95% CI, 0.68-0.85 vs 0.68-0.85; P = .97), seventh DOL (AUC 95% CI, 0.74-0.85 vs 0.74-0.84; P = .26), and 21st DOL (AUC 95% CI, 0.72-0.86 vs 0.74-0.88; P = .17). The LUS score using anterolateral and posterior fields was slightly more accurate at 14th DOL (AUC 95% CI, 0.69-0.83 vs 0.66-0.80; P = .01). A cutoff of 8 points in the LUS score using only anterolateral fields on the seventh DOL provided a sensitivity, specificity, positive likelihood ratio, and negative likelihood ratio of 70%, 79%, 3.3, and 0.38, respectively, to predict msBPD. Adding gestational age (GA) and sex improved the discriminative value without significant differences compared with a predictive model based on multiple clinical variables: AUC 95% CI, 0.77-0.88 vs 0.80-0.91 (P = .52).

INTERPRETATION

The LUS score is able to predict msBPD from the third DOL with a moderate diagnostic accuracy. Scanning posterior lung fields slightly improved diagnostic accuracy only at the 14th DOL. Adding GA and sex improves the diagnostic accuracy of the LUS scores. The LUS score is useful to stratify BPD risk early after birth.

Antenatal Endotoxin Impairs Lung Mechanics and Increases Sensitivity to Ventilator-Induced Lung Injury in Newborn Rat Pups

Perinatal inflammation due to chorioamnionitis and ventilator-induced lung injury (VILI) at birth is independent risk factors for the development of bronchopulmonary dysplasia (BPD). We have previously shown that antenatal endotoxin (ETX) causes abnormal lung structure and function in 2-week-old rats, but whether ETX impairs lung mechanics at birth and increases risk for VILI is unknown. Fetal rats were exposed to 10 μg endotoxin or saline via intra-amniotic injection. At birth (D0) or 7 days (D7), rats received 90 min of lung protective ventilation [PROTECT group; tidal volume (Vt) = 6 ml/kg with positive end expiratory pressure (PEEP) = 2 cmH₂O]; P20 ventilation [plateau pressure (Pplat) = 20 cmH₂O, PEEP = 0]; or P24 ventilation (Pplat = 24 cmH₂O, PEEP = 0, only applied to D7). Prior to prolonged ventilation at D0, endotoxin-exposed rats had decreased compliance and inspiratory capacity (IC) compared to controls. At D7, endotoxin was associated with reduced compliance. High-pressure ventilation (P20 and P24) tended to increase IC and compliance in all saline-treated groups. Ventilation at D0 with P20 increased IC and compliance when applied to saline-treated but not endotoxin-exposed pups. At D7, P24 ventilation of endotoxin-exposed pups increased elastance, bronchoalveolar lavage protein content, and IL-1b and TEN-C mRNA expression in comparison to the saline group. In summary, antenatal endotoxin exposure alters lung mechanics at birth and 1 week of life and increases susceptibility to VILI as observed in lung mechanics, alveolocapillary barrier injury, and inflammatory mRNA expression. We speculate that antenatal inflammation primes the lung for a more marked VILI response, suggesting an adverse synergistic effect of antenatal and postnatal exposures.

Non-invasive High-Frequency Oscillatory Ventilation as Initial Respiratory Support for Preterm Infants With Respiratory Distress Syndrome

Objectives: The aim of this study was to investigate the safety and feasibility of nHFOV as initial respiratory support in preterm infants with RDS. Methods: This study retrospectively analyzed the clinical data of 244 premature infants with RDS who were treated in our hospital from January 2016 to January 2019 and divided into the nHFOV group (n = 115) and the BiPAP group (n = 129) based on the initial respiratory support method. Results: Respiratory outcomes showed that the rate of NIV failure during the first 72 hours of life in the nHFOV group was significantly lower than that in the BiPAP group. The time of NIV in the nHFOV group was significantly shorter than that in the BiPAP group. The time of supplemental oxygen in the nHFOV group was significantly shorter than that in the BiPAP group. The incidence of air leakage syndrome in the nHFOV group was significantly lower than that in the BiPAP group, and the length of hospital stay of the nHFOV group was also significantly shorter than that in the BiPAP group. Although the rate of infants diagnosed with BPD was similar between the two groups, the rate of severe BPD in the nHFOV group was significantly lower than that in the BiPAP group. Conclusion: This study showed that nHFOV as initial respiratory support for preterm infants with RDS was feasible and safe compared to BiPAP. Furthermore, nHFOV can reduce the need for IMV and reduce the incidence of severe BPD and air leak syndrome.

Transcutaneous carbon dioxide pattern and trend over time in preterm infants

BACKGROUND

Chronic lung disease remains a burden for extremely preterm infants. The changes in ventilation over time and optimal ventilatory management remains unknown. Newer, non-invasive technologies provide insight into these patterns.

METHODS

This single-center prospective cohort study enrolled infants ≤32 0/7 weeks. We obtained epochs of transcutaneous carbon dioxide (TcCO₂) measurements twice each week to describe the pattern of hypercarbia throughout their hospitalization.

RESULTS

Patterns of hypercarbia varied based on birth gestational age and post-menstrual age (PMA) (p = 0.03), regardless of respiratory support. Infants receiving the most respiratory support had values 16-21 mmHg higher than those on room air (p < 0.001). Infants born at the youngest gestational ages had the greatest total change but the rate of change was slower (p = 0.049) compared to infants born at later gestational ages. All infants had TcCO₂ values stabilize by 31-33 weeks PMA, when values were not significantly different compared to discharge. No rebound was observed when infants weaned off invasive support.

CONCLUSIONS

Hypercarbia improves as infants approached 31-33 weeks PMA. Hypercarbia was the highest in the most immature infants and improved with age and growth despite weaning respiratory support.

IMPACT

This study describes the evolution of hypercarbia as very preterm infants grow and develop. The pattern of ventilation is significantly different depending on the gestational age at birth and post-menstrual age. Average transcutaneous carbon dioxide (TCO₂) decreased over time as infants became more mature despite weaning respiratory support. This improvement was most significant in infants born at the lowest gestational ages.

A Systematic Review of the Influence of Continuous Positive Airway Pressure on Fetal and Newborn Animal Models: Suggestions to Improve Neonatal Respiratory Care

INTRODUCTION

Prematurely born infants regularly develop respiratory distress syndrome and require assisted ventilation. Ventilation may injure the premature lung and increase the risk of bronchopulmonary dysplasia. Continuous positive airway pressure (CPAP), a form of noninvasive ventilation, is commonly used in modern neonatology. Limited clinical data are available on the acute and long-term effect of neonatal exposure to CPAP on the lung. Given the restricted clinical data, newborn animal models have been used to study the influence of CPAP on lung structure and function. The findings of animal studies can guide neonatal care and improve the use of CPAP.

METHODS

A systematic review of electronic databases (Medline, Embase, and Cinahl) was performed using the medical subject heading terms, "CPAP" or "continuous positive airway pressure" and "animals" and "newborn." Abstracts were screened for inclusion using predetermined eligibility criteria.

RESULTS

In total, 235 abstracts were identified and screened for inclusion. Of these, 21 papers were included. Large (N = 18) and small (N = 3) animal models investigated the effects of CPAP. Pulmonary outcomes included gas exchange, lung structure and function, surfactant metabolism, lung inflammation and injury, and the effect of intrapulmonary therapy. Compared to mechanical ventilation, CPAP improves lung function, evokes less lung injury, and does not disrupt alveolar development. Surfactant administration combined with CPAP further improves respiratory outcomes. Of concern are findings that CPAP may increase airway reactivity.

DISCUSSION/CONCLUSION

CPAP offers numerous advantages over mechanical ventilation for the immature lung. The combination of CPAP and exogenous surfactant administration offers further pulmonary benefit.

New BPD-prevalence and risk factors for bronchopulmonary dysplasia/mortality in extremely low gestational age infants ≤28 weeks

OBJECTIVE

To evaluate prevalence and risk factors of moderate-severe Bronchopulmonary dysplasia (BPD)/Death in extremely low gestation age neonates (ELGANs).

STUDY DESIGN

Study of 266 ELGANs born at gestational age (GA) ≤ 28 weeks (w). Primary Outcome measure-composite outcome of moderate-severe BPD/Death using the National Institute of Child Health and Human Development NICHD's (2001) BPD definition.

RESULT

Cohort's mean GA and birth-weight (BW) were 25.3 ± 1.4w and 724 ± 14 g respectively with an overall mortality of 19% and moderate-severe BPD of 67%. Prevalence of moderate-severe BPD/death decreased significantly with increasing GA (86-93%) at 23-24 w; to <60% at 27-28w (OR 0.63; 95% CI; 0.52-0.77). On univariate analysis, other risk factors included BW(OR 1.005; 95% CI; 1.003-1.007), Sepsis (OR 2.9; 95% CI, 1.3-6.4), PDA needing treatment (OR 2.2; 95% CI, 1.3-3.9); air leaks (OR 2.7; 95% CI; 1.02-7.3) FiO₂ requirement >25%(OR 1.06; 95% CI; 1.01-1.11); and mechanical ventilation(MV) on Day7 (OR5.5; 95% CI; 2.8-10.8). Only need for Day7 MV was independently predictive of composite outcome (OR1.97; 95% CI; 1.3-3.1).

CONCLUSION

Risk factor identification will enable initiatives to implement lung protective strategies and develop prospective models for BPD prediction and prognostication.

Development and Validation of a Nomogram for Predicting Bronchopulmonary Dysplasia in Very-Low-Birth-Weight Infants

Background: Bronchopulmonary dysplasia is a common pulmonary disease in newborns and is one of the main causes of death. The aim of this study was to build a new simple-to-use nomogram to screen high-risk populations. Methods: In this single-center retrospective study performed from January 2017 to December 2020, we reviewed data on very-low-birth-weight infants whose gestational ages were below 32 weeks. LASSO regression was used to select variables for the risk model. Then, we used multivariable logistic regression to build the prediction model incorporating these selected features. Discrimination was assessed by the C-index, and and calibration of the model was assessed by and calibration curve and the Hosmer-Lemeshow test. Results: The LASSO regression identified gestational age, duration of ventilation and serum NT-proBNP in the 1st week as significant predictors of BPD. The nomogram-illustrated model showed good discrimination and calibration. The C-index was 0.853 (95% CI: 0.851-0.854) in the training set and 0.855 (95% CI: 0.77-0.94) in the validation set. The calibration curve and Hosmer-Lemeshow test results showed good calibration between the predictions of the nomogram and the actual observations. Conclusion: We demonstrated a simple-to-use nomogram for predicting BPD in the early stage. It may help clinicians recognize high-risk populations.

Bronchopulmonary dysplasia requiring tracheostomy: A review of management and outcomes

Bronchopulmonary Dysplasia (BPD) is a pulmonary disease affecting newborns, commonly those with prematurity or low birth weight. Its pathogenesis involves underdevelopment of lung tissue with subsequent limitations in ventilation and oxygenation, resulting in impaired postnatal alveolarization. Despite advances in care with improved survival, BPD remains a prevalent comorbidity of prematurity. In severe cases, management may involve mechanical ventilation via tracheostomy. BPD's demand for multidisciplinary care compounds the challenges in management of this condition. Here, we review existing literature: the history of disease, criteria for diagnosis, pathogenesis, and modes of treatment with a focus on the severe subtype: that which is associated with pulmonary hypertension (PAH) for which tracheostomy is often required to facilitate long-term mechanical ventilation. We review the current recommendations for tracheostomy and decannulation.

Allogeneic administration of human umbilical cord-derived mesenchymal stem/stromal cells for bronchopulmonary dysplasia: preliminary outcomes in four Vietnamese infants

Background

Bronchopulmonary dysplasia (BPD) is a severe condition in premature infants that compromises lung function and necessitates oxygen support. Despite major improvements in perinatal care minimizing the devastating effects, BPD remains the most frequent complication of extreme preterm birth. Our study reports the safety of the allogeneic administration of umbilical cord-derived mesenchymal stem/stromal cells (allo-UC-MSCs) and the progression of lung development in four infants with established BPD.

Methods

UC tissue was collected from a healthy donor, followed by propagation at the Stem Cell Core Facility at Vinmec Research Institute of Stem Cell and Gene Technology. UC-MSC culture was conducted under xeno- and serum-free conditions. Four patients with established BPD were enrolled in this study between May 25, 2018, and December 31, 2018. All four patients received two intravenous doses of allo-UC-MSCs (1 million cells/kg patient body weight (PBW) per dose) with an intervening interval of 7 days. Safety and patient conditions were evaluated during hospitalization and at 7 days and 1, 6 and 12 months postdischarge.

Results

No intervention-associated severe adverse events or prespecified adverse events were observed in the four patients throughout the study period. At the time of this report, all patients had recovered from BPD and were weaned off of oxygen support. Chest X-rays and CT scans confirmed the progressive reductions in fibrosis.

Conclusions

Allo-UC-MSC administration is safe in preterm infants with established BPD.

Trial registration This preliminary study was approved by the Vinmec International Hospital Ethics Board (approval number: 88/2019/QĐ-VMEC; retrospectively registered March 12, 2019).

Effect of low-dose exogenous surfactant on infants with acute respiratory distress syndrome after cardiac surgery: a retrospective analysis

BACKGROUND

Acute respiratory distress syndrome (ARDS) in infants undergoing cardiac surgery is associated with significant mortality and prolonged ventilation; surfactant administration may be a useful therapy. The purpose of this study is to evaluate the effect of low-dose exogenous surfactant therapy on infants suffering ARDS after cardiac surgery.

METHODS

We conducted a case-control study of infants diagnosed with moderate-to-severe ARDS (PaO₂/FiO₂ < 150) after cardiac surgery. A case was defined as a patient that received surfactant and standard therapy, while a control was defined as a patient that underwent standard therapy. The primary endpoint was the improvement in oxygenation index (OI) after 24-h of surfactant treatment; and secondary endpoints were the ventilator time and PICU time.

RESULTS

Twenty-two infants treated with surfactant were matched with 22 controls. Early low-dose (20 mg/kg) surfactant treatment was associated with improved outcomes. After surfactant administration for 24-h, the surfactant group was much better compared with the control group at the 24-h in OI (difference in average change from baseline, - 6.7 [95% CI, - 9.3 to - 4.1]) (P < 0.01) and ventilation index (VI, mean difference, - 11.9 [95% CI, - 18.1 to - 5.7]) (P < 0.01). Ventilation time and PICU time were significantly shorter in the surfactant group compared with the control group (133.6 h ± 27.2 vs 218.4 h ± 28.7, P < 0.01; 10.7d ± 5.1 vs 17.5d ± 6.8, P < 0.01). Infants in the surfactant group under 3 months benefit more from OI and VI than the infants over 3 months in a preliminary exploratory analysis.

CONCLUSIONS

In infants with moderate-to-severe ARDS after cardiac surgery, early low-dose exogenous surfactant treatment could prominently improve oxygenation and reduce mechanical ventilation time and PICU time. Infants younger than 3 months may get more benefit of oxygenation than the older ones. Randomized controlled trials are needed to explore the effect of surfactant to ARDS of cardiac surgical infants.

Physiological Basis of Neonatal Aerodigestive Difficulties in Chronic Lung Disease

In the United States, preterm birth rates have steadily increased since 2014. Despite the recent advances in neonatal-perinatal care, more than 40% of very low-birth-weight infants develop chronic lung disease (CLD) and almost 25% have feeding difficulties resulting in delayed achievement of full oral feeds and longer hospital stay. Establishment of full oral feeds, a major challenge for preterm infants, becomes magnified among those on respiratory support and/or with CLD. The strategies to minimize aerodigestive disorders include supporting nonnutritive sucking, developing infant-directed feeding protocols, sensory oromotor stimulation, and early introduction of oral feeds.

Small Molecule Inhibitor Adjuvant Surfactant Therapy Attenuates Ventilator- and Hyperoxia-Induced Lung Injury in Preterm Rabbits

Background

Invasive mechanical ventilation (IMV) has become one of the mainstays of therapy in NICUs worldwide, as a result of which premature babies with extremely low birth weight have been able to survive. Although lifesaving, IMV can result in lung inflammation and injury. Surfactant therapy is considered a standard of care in preterm infants with immature lungs. Recently, small molecule inhibitors like siRNAs and miRNAs have been used for therapeutic purposes. Ddit3 (CHOP), Ang2 and miR34a are known to be upregulated in experimental lung injury. We wanted to test whether inhibitors for these molecules (CHOP siRNA, Ang2 siRNA, and miR34a antagomir) if used alone or with a combination with surfactant (Curosurf^®) would help in reducing ventilation and hyperoxia-induced injury in an experimental lung injury model.

Methods

Preterm rabbits born by cesarean section were intratracheally instilled with the three small molecule inhibitors with or without Curosurf^® prior to IMV and hyperoxia exposure. Prior to testing the inhibitors in rabbits, these small molecule inhibitors were transfected in mouse lung epithelial cells (MLE12 and AECII) and delivered to neonatal mouse pups intranasally as a proof of concept that surfactant (Curosurf^®) could be used as an effective vehicle for administration of such drugs. Survival, pulmonary function tests, histopathology, immunostaining, quantitative PCR and western blotting were done to see the adjuvant effect of surfactant with these three small molecule inhibitors.

Results

Our data shows that Curosurf^® can facilitate transfection of small molecules in MLE12 cells with the same and/or increased efficiency as Lipofectamine. Surfactant given alone or as an adjuvant with small molecule inhibitors increases survival, decreases IMV and hyperoxia-induced inflammation, improves pulmonary function and lung injury scores in preterm rabbit kits.

Conclusion

Our study shows that Curosurf^® can be used successfully as an adjuvant therapy with small molecule inhibitors for CHOP/Ang2/miR34a. In this study, of the three inhibitors used, miR34a inhibitor seemed to be the most promising compound to combat IMV and hyperoxia-induced lung injury in preterm rabbits.

Factors Associated with Neurodevelopmental Impairment in Bronchopulmonary Dysplasia

OBJECTIVE

To identify factors associated with neurodevelopmental impairment (NDI) in patients with bronchopulmonary dysplasia (BPD).

STUDY DESIGN

We identified 151 patients with moderate to severe BPD from 2010 to 2014 with complete Bayley Scales of Infant Development (BSID) scores at 24 months corrected age. We defined NDI as any diagnosis of cerebral palsy or ≥1 BSID composite scores of <80.

RESULTS

The mean corrected age at BSID was 23 ± 1 months; 18% had a cognitive score of <80, 37% had a communication score of <80, and 26% had a motor score of <80. Cerebral palsy was diagnosed in 22 patients (15%); 84 (56%) patients did not have NDI. Patients with NDI had lower birth weight, but there was no difference in gestational age at birth, severe intraventricular hemorrhage (IVH), necrotizing enterocolitis, or patent ductus arteriosus ligation compared with patients with no NDI. Ventilator days were greater in patients with NDI than in patients without NDI. More patients with NDI received furosemide and systemic corticosteroids and the hospital length of stay was longer than in patients with no NDI. Logistic regression modeling demonstrated that for every additional 100 g of birth weight the odds of NDI decreased by 35% and for every additional hospital day the odds of NDI increased by 1.3%.

CONCLUSIONS

In our cohort of patients with moderate to severe BPD, the majority had no NDI, and low birth weight and length of hospital stay were associated with increased risk of developing NDI. This finding suggests that there are potentially modifiable factors associated with better neurodevelopmental outcomes in patients with BPD that deserve further study.