Permissive hypercapnia in extremely low birthweight infants (PHELBI): a randomised controlled multicentre trial

Effectiveness of corticosteroids and epinephrine use in neonates for the first extubation attempt: A retrospective study

BACKGROUND

This study aimed to analyze the use of corticosteroids and epinephrine in neonates for the first extubation attempt and compared clinical characteristics of infants with successful and failed extubation events.

METHODS

This was a retrospective cohort study conducted at a single level III neonatal intensive care unit in Taiwan. The study included 215 infants born between 2020 and 2021 who had been intubated for more than 48 h before their first extubation attempt. We compared perinatal and peri-extubation characteristics and outcomes between the two groups. Successful extubation was defined as freedom from invasive ventilatory support 72 h after extubation. The relationship between corticosteroids, local epinephrine, and successful extubation was determined using multivariate logistic regression analysis.

RESULTS

In the univariate analysis, the failed extubation group received a significantly higher proportion of intravenous dexamethasone (p = 0.006) than the successful extubation group. Furthermore, the failed extubation group had a longer duration of nebulized epinephrine (p = 0.034) and more episodes of local application of epinephrine to the superior larynx (p = 0.003) than the successful extubation group. Multivariate analysis revealed that the absence of lung atelectasis, tachycardia 72 h after extubation, and lower post-extubation PCO2 were the key factors associated with successful extubation.

CONCLUSIONS

There were trends toward systemic dexamethasone, local application of epinephrine to the superior larynx, and longer duration of nebulized epinephrine in the reintubation group. However, corticosteroid or local epinephrine use was not significantly associated with successful extubation. Lung atelectasis, elevated levels of carbon dioxide, and tachycardia were identified as risk factors for extubation failure.

Weaning from mechanical ventilation and assessment of extubation readiness

Tremendous advancements in neonatal respiratory care have contributed to the improved survival of extremely preterm infants (gestational age ≤ 28 weeks). While mechanical ventilation is often considered one of the most important breakthroughs in neonatology, it is also associated with numerous short and long-term complications. For those reasons, clinical research has focused on strategies to avoid or reduce exposure to mechanical ventilation. Nonetheless, in the extreme preterm population, 70-100% of infants born 22-28 weeks of gestation are exposed to mechanical ventilation, with nearly 50% being ventilated for ≥ 3 weeks. As contemporary practices have shifted towards selectively reserving mechanical ventilation for those patients, mechanical ventilation weaning and extubation remain a priority yet offer a heightened challenge for clinicians. In this review, we will summarize the evidence for different strategies to expedite weaning and assess extubation readiness in preterm infants, with a particular focus on extremely preterm infants.

Hypercapnia Causes Injury of the Cerebral Cortex and Cognitive Deficits in Newborn Piglets

In critically ill newborns, exposure to hypercapnia (HC) is common and often accepted in neonatal intensive care units to prevent severe lung injury. However, as a "safe" range of arterial partial pressure of carbon dioxide levels in neonates has not been established, the potential impact of HC on the neurodevelopmental outcomes in these newborns remains a matter of concern. Here, in a newborn Yorkshire piglet model of either sex, we show that acute exposure to HC induced persistent cortical neuronal injury, associated cognitive and learning deficits, and long-term suppression of cortical electroencephalogram frequencies. HC induced a transient energy failure in cortical neurons, a persistent dysregulation of calcium-dependent proapoptotic signaling in the cerebral cortex, and activation of the apoptotic cascade, leading to nuclear deoxyribonucleic acid fragmentation. While neither 1 h of HC nor the rapid normalization of HC was associated with changes in cortical bioenergetics, rapid resuscitation resulted in a delayed onset of synaptosomal membrane lipid peroxidation, suggesting a dissociation between energy failure and the occurrence of synaptosomal lipid peroxidation. Even short durations of HC triggered biochemical responses at the subcellular level of the cortical neurons resulting in altered cortical activity and impaired neurobehavior. The deleterious effects of HC on the developing brain should be carefully considered as crucial elements of clinical decisions in the neonatal intensive care unit.

Mechanical ventilation in special populations

Optimal respiratory support can only be achieved if the ventilator strategy utilized for each individual patient at any given point in the evolution of their disease process is tailored to the underlying pathophysiology. The critically ill newborn infant requires individualized patient care when it comes to mechanical ventilation. This can only occur if the clinician has a good understanding of the different pathophysiologies of a variety of conditions that can lead to respiratory failure. In this chapter we describe the key pathophysiological features of bronchopulmonary dysplasia, meconium aspiration syndrome and lung hypoplasia syndromes with emphasis on congenital diaphragmatic hernia. We review available evidence to guide management an provide specific recommendations for pathophysiologically-based mechanical ventilation support.

Permissive hypercapnia and oxygenation impairment in premature ventilated infants

AIM

In permissive hypercapnia high levels of carbon dioxide (CO2) are tolerated in ventilated preterm infants to minimise lung injury, but hypercapnia could directly impair oxygenation. We aimed to quantify the association of elevated CO2 with oxygenation impairment in preterm infants by measuring the right-to-left shunt and the ventilation/perfusion (VA/Q) ratio.

METHODS

Pre-existing datasets from preterm infants during the acute phase of respiratory distress syndrome or with evolving or established bronchopulmonary dysplasia were analysed. Non-invasive paired measurements of the fraction of inspired oxygen (FIO2) and transcutaneous oxygen saturation (SpO2) were used to calculate the degree of right-to-left shunt, right shift of the FIO2 versus SpO2 curve and the VA/Q.

RESULTS

A total of 75 infants (43 male) with a median (IQR) gestational age of 26.4 (24.7-27.7) weeks were studied at 7 (2-31) days. Thirty-six infants (48 %) had an arterial partial pressure of CO2 (PaCO2) above 6 kPa. The PaCO2 was independently associated with the right shift of the curve [adjusted p < 0.001, unstandardised coefficient; 2.26, 95 % CI: 1.51-2.95] and the right-to-left shunt [adjusted p = 0.016, unstandardised coefficient; 1.86, 95 % CI: 0.36-3.36] after adjusting for confounders. An increase of the PaCO2 from 5 to 8 kPa, corresponded to a right shift of the curve of 20.2 kPa or a decrease in the VA/Q from 0.66 to 0.24.

CONCLUSIONS

Increased carbon dioxide levels were significantly associated with impaired oxygenation in preterm infants with respiratory distress syndrome or bronchopulmonary dysplasia.

Late permissive hypercapnia and respiratory stability among very preterm infants: a pilot randomised trial

OBJECTIVE

Determine if targeting higher transcutaneous carbon dioxide improves respiratory stability among very preterm infants on ventilatory support.

DESIGN

Single-centre pilot randomised clinical trial.

SETTING

The University of Alabama at Birmingham.

PATIENTS

Very preterm infants on ventilatory support after postnatal day 7.

INTERVENTIONS

Infants were randomised to two different transcutaneous carbon dioxide levels targeting 5 mm Hg (0.67 kPa) changes with four sessions each lasting 24 hours for 96 hours: baseline-increase-baseline-increase or baseline-decrease-baseline-decrease.

MAIN OUTCOME MEASURES

We collected cardiorespiratory data evaluating episodes of intermittent hypoxaemia (oxygen saturations (SpO2)<85% for ≥10 s), bradycardia (<100 bpm for ≥10 s), and cerebral and abdominal hypoxaemia on near-infrared spectroscopy.

RESULTS

We enrolled 25 infants with a gestational age of 24 w 6 d±11 d (mean±SD) and birth weight 645±142 g on postnatal day 14±3. Continuous transcutaneous carbon dioxide values (56.8±6.9 in the higher group vs 54.5±7.8 in the lower group; p=0.36) did not differ significantly between groups during the intervention days. There were no differences in intermittent hypoxaemia (126±64 vs 105±61 per 24 hours; p=0.30) or bradycardia (11±16 vs 15±23 per hour; p=0.89) episodes between groups. The proportion of time with SpO2<85%, SpO2<80%, cerebral hypoxaemia or abdominal hypoxaemia did not differ (all p>0.05). There was moderate negative correlation between mean transcutaneous carbon dioxide and bradycardia episodes (r=-0.56; p<0.001).

CONCLUSION

Targeting 5 mm Hg (0.67 kPa) changes in transcutaneous carbon dioxide did not improve respiratory stability among very preterm infants on ventilatory support but the intended carbon dioxide separation was difficult to achieve and maintain.

TRIAL REGISTRATION NUMBER

NCT03333161.

Strengthening Reporting of Neonatal Trials

BACKGROUND AND OBJECTIVES

There is variability in the selection and reporting of outcomes in neonatal trials with key information frequently omitted. This can impact applicability of trial findings to clinicians, families, and caregivers, and impair evidence synthesis. The Neonatal Core Outcomes Set describes outcomes agreed as clinically important that should be assessed in all neonatal trials, and Consolidated Standards of Reporting Trials (CONSORT)-Outcomes 2022 is a new, harmonized, evidence-based reporting guideline for trial outcomes. We reviewed published trials using CONSORT-Outcomes 2022 guidance to identify exemplars of neonatal core outcome reporting to strengthen description of outcomes in future trial publications.

METHODS

Neonatal trials including >100 participants per arm published between 2015 to 2020 with a primary outcome included in the Neonatal Core Outcome Set were identified. Primary outcome reporting was reviewed using CONSORT 2010 and CONSORT-Outcomes 2022 guidelines by assessors recruited from Cochrane Neonatal. Examples of clear and complete outcome reporting were identified with verbatim text extracted from trial reports.

RESULTS

Thirty-six trials were reviewed by 39 assessors. Examples of good reporting for CONSORT 2010 and CONSORT-Outcomes 2022 criteria were identified and subdivided into 3 outcome categories: "survival," "short-term neonatal complications," and "long-term developmental outcomes" depending on the core outcomes to which they relate. These examples are presented to strengthen future research reporting.

CONCLUSIONS

We have identified examples of good trial outcome reporting. These illustrate how important neonatal outcomes should be reported to meet the CONSORT 2010 and CONSORT-Outcomes 2022 guidelines. Emulating these examples will improve the transmission of information relating to outcomes and reduce associated research waste.

Interventions to Reduce Severe Brain Injury Risk in Preterm Neonates: A Systematic Review and Meta-analysis

Importance

Interventions to reduce severe brain injury risk are the prime focus in neonatal clinical trials.

Objective

To evaluate multiple perinatal interventions across clinical settings for reducing the risk of severe intraventricular hemorrhage (sIVH) and cystic periventricular leukomalacia (cPVL) in preterm neonates.

Data Sources

MEDLINE, Embase, CENTRAL (Cochrane Central Register of Controlled Trials), and CINAHL (Cumulative Index to Nursing and Allied Health Literature) databases were searched from inception until September 8, 2022, using prespecified search terms and no language restrictions.

Study Selection

Randomized clinical trials (RCTs) that evaluated perinatal interventions, chosen a priori, and reported 1 or more outcomes (sIVH, cPVL, and severe brain injury) were included.

Data Extraction and Synthesis

Two co-authors independently extracted the data, assessed the quality of the trials, and evaluated the certainty of the evidence using the Cochrane GRADE (Grading of Recommendations, Assessment, Development, and Evaluation) approach. Fixed-effects pairwise meta-analysis was used for data synthesis.

Main Outcomes and Measures

The 3 prespecified outcomes were sIVH, cPVL, and severe brain injury.

Results

A total of 221 RCTs that assessed 44 perinatal interventions (6 antenatal, 6 delivery room, and 32 neonatal) were included. Meta-analysis showed with moderate certainty that antenatal corticosteroids were associated with small reduction in sIVH risk (risk ratio [RR], 0.54 [95% CI, 0.35-0.82]; absolute risk difference [ARD], -1% [95% CI, -2% to 0%]; number needed to treat [NNT], 80 [95% CI, 48-232]), whereas indomethacin prophylaxis was associated with moderate reduction in sIVH risk (RR, 0.64 [95% CI, 0.52-0.79]; ARD, -5% [95% CI, -8% to -3%]; NNT, 20 [95% CI, 13-39]). Similarly, the meta-analysis showed with low certainty that volume-targeted ventilation was associated with large reduction in risk of sIVH (RR, 0.51 [95% CI, 0.36-0.72]; ARD, -9% [95% CI, -13% to -5%]; NNT, 11 [95% CI, 7-23]). Additionally, early erythropoiesis-stimulating agents (RR, 0.68 [95% CI, 0.57-0.83]; ARD, -3% [95% CI, -4% to -1%]; NNT, 34 [95% CI, 22-67]) and prophylactic ethamsylate (RR, 0.68 [95% CI, 0.48-0.97]; ARD, -4% [95% CI, -7% to 0%]; NNT, 26 [95% CI, 13-372]) were associated with moderate reduction in sIVH risk (low certainty). The meta-analysis also showed with low certainty that compared with delayed cord clamping, umbilical cord milking was associated with a moderate increase in sIVH risk (RR, 1.82 [95% CI, 1.03-3.21]; ARD, 3% [95% CI, 0%-6%]; NNT, -30 [95% CI, -368 to -16]).

Conclusions and Relevance

Results of this study suggest that a few interventions, including antenatal corticosteroids and indomethacin prophylaxis, were associated with reduction in sIVH risk (moderate certainty), and volume-targeted ventilation, early erythropoiesis-stimulating agents, and prophylactic ethamsylate were associated with reduction in sIVH risk (low certainty) in preterm neonates. However, clinicians should carefully consider all of the critical factors that may affect applicability in these interventions, including certainty of the evidence, before applying them to clinical practice.

Respiratory Management of the Preterm Infant: Supporting Evidence-Based Practice at the Bedside

Extremely preterm infants frequently require some form of respiratory assistance to facilitate the cardiopulmonary transition that occurs in the first hours of life. Current resuscitation guidelines identify as a primary determinant of overall newborn survival the establishment, immediately after birth, of adequate lung inflation and ventilation to ensure an adequate functional residual capacity. Any respiratory support provided, however, is an important contributing factor to the development of bronchopulmonary dysplasia. The risks correlated to invasive ventilatory techniques increase inversely with gestational age. Preterm infants are born at an early stage of lung development and are more susceptible to lung injury deriving from mechanical ventilation. Any approach aiming to reduce the global burden of preterm lung disease must implement lung-protective ventilation strategies that begin from the newborn’s first breaths in the delivery room. Neonatologists today must be able to manage both invasive and noninvasive forms of respiratory assistance to treat a spectrum of lung diseases ranging from acute to chronic conditions. We searched PubMed for articles on preterm infant respiratory assistance. Our narrative review provides an evidence-based overview on the respiratory management of preterm infants, especially in the acute phase of neonatal respiratory distress syndrome, starting from the delivery room and continuing in the neonatal intensive care unit, including a section regarding exogenous surfactant therapy.

Weaning and extubation from neonatal mechanical ventilation: an evidenced-based review

Mechanical ventilation is a lifesaving treatment used to treat critical neonatal patients. It facilitates gas exchange, oxygenation, and CO2 removal. Despite advances in non-invasive ventilatory support methods in neonates, invasive ventilation (i.e., ventilation via an endotracheal tube) is still a standard treatment in NICUs. This ventilation approach may cause injury despite its advantages, especially in preterm neonates. Therefore, it is recommended that neonatologists consider weaning neonates from invasive mechanical ventilation as soon as possible. This review examines the steps required for the neonate's appropriate weaning and safe extubation from mechanical ventilation.

Efficacy and safety of permissive hypercapnia in preterm infants: A systematic review

CONTEXT

In adults, permissive hypercapnia reduces mortality and ventilation duration. However, in preterm infants, the findings from past research regarding the efficacy and safety of permissive hypercapnia are controversial.

OBJECTIVE

To evaluate the efficacy and safety of permissive hypercapnia versus normocapnia in preterm infants on mechanical ventilation.

DATA SOURCES

MEDLINE, EMBASE, CENTRAL, and CINAHL STUDY SELECTION: Published randomized controlled trials (RCTs), non-RCTs, interrupted time series, cohort studies, case-control studies, and controlled before-and-after studies were included.

DATA EXTRACTION

Two reviewers independently screened the title, abstract, and full text, extracted data, assessed the risk of bias, and evaluated certainty of evidence (CoE) according to the Grading of Recommendations Assessment and Development and Evaluation approach. A meta-analysis of RCTs was performed using the random-effects model.

RESULTS

Four RCTs (693 infants) and one cohort study (371 infants) were included. No significant differences existed between the permissive hypercapnia and normocapnia groups for bronchopulmonary dysplasia (BPD) (risk ratio [RR], 0.94; 95% confidence interval [CI], 0.74-1.18; very low CoE) and a composite outcome of death or BPD (RR, 1.05; 95% CI, 0.90-1.23; very low CoE). Permissive hypercapnia may increase necrotizing enterocolitis (RR, 1.69; 95% CI, 0.98-2.91; very low CoE), but the null or trivial effect cannot be excluded. No significant differences existed between the two groups for any other outcome assessed (very low-to-low CoE).

LIMITATIONS

The sample sizes were less than the optimal sizes for all outcomes assessed, indicating the need for further trials.

CONCLUSIONS

Permissive hypercapnia did not have any significant benefit or harm in preterm infants.

Diagnosis and management of pulmonary hypertension in infants with bronchopulmonary dysplasia

Chronic pulmonary hypertension of infancy (cPHi) is a heterogeneous disease process that contributes to morbidity and mortality in preterm infants. cPHi is most commonly associated with chronic lung disease of prematurity and represents a unique phenotype of bronchopulmonary dysplasia. It is characterized by persistently elevated or newly rising pulmonary vascular resistance and pulmonary artery pressure beyond the first weeks of age. The high-pressure afterload on the right ventricle may or may not be tolerated, depending upon additional cardiovascular shunting and co-morbidities. A comprehensive clinical evaluation combined with advanced hemodynamic assessment by echocardiography and other cardiac imaging modalities help decipher the etiopathologies of disease, identify cardiopulmonary compromise earlier and guide individualized therapeutic intervention tailored by the phenotype. This review summarizes the underlying etiologies, risk factors for development, hemodynamic assessment, management, and follow-up of cPHi in preterm infants. We offer an algorithm for early detection of cPHi and outline research priorities.

Respiratory support of infants born at 22-24 weeks of gestational age

Lung immaturity and acute respiratory failure are the major problems in the care of extremely preterm infants. Most infants with gestational age (GA) 22-24 weeks will need mechanical ventilation and many will depend on some type of respiratory support, invasive and non-invasive for extended periods. There is ongoing gap in knowledge regarding optimal respiratory support and applying strategies that are effective in more mature populations is not easy or even suitable because lung maturation differs in smaller infants. Better strategies on how to avoid lung damage and to promote growth and development of the immature lung are warranted since increased survival is accompanied by increasing rates of bronchopulmonary dysplasia and concerns over long-standing reductions in lung function. This review focuses on some aspects of respiratory care of infants born at 22-24 weeks of GA.

A Quality Improvement Bundle to Improve Outcomes in Extremely Preterm Infants in the First Week

OBJECTIVES

Our objective with this quality improvement initiative was to reduce rates of severe intracranial hemorrhage (ICH) or death in the first week after birth among extremely preterm infants.

METHODS

The quality improvement initiative was conducted from April 2014 to September 2020 at the University of Alabama at Birmingham's NICU. All actively treated inborn extremely preterm infants without congenital anomalies from 22 + 0/7 to 27 + 6/7 weeks' gestation with a birth weight ≥400 g were included. The primary outcome was severe ICH or death in the first 7 days after birth. Balancing measures included rates of acute kidney injury and spontaneous intestinal perforation. Outcome and process measure data were analyzed by using p-charts.

RESULTS

We studied 820 infants with a mean gestational age of 25 + 3/7 weeks and median birth weight of 744 g. The rate of severe ICH or death in the first week after birth decreased from the baseline rate of 27.4% to 15.0%. The rate of severe ICH decreased from a baseline rate of 16.4% to 10.0%. Special cause variation in the rate of severe ICH or death in the first week after birth was observed corresponding with improvement in carbon dioxide and pH targeting, compliance with delayed cord clamping, and expanded use of indomethacin prophylaxis.

CONCLUSIONS

Implementation of a bundle of evidence-based potentially better practices by using specific electronic order sets was associated with a lower rate of severe ICH or death in the first week among extremely preterm infants.

Carbon dioxide levels in neonates: what are safe parameters?

There is no consensus on the optimal pCO₂ levels in the newborn. We reviewed the effects of hypercapnia and hypocapnia and existing carbon dioxide thresholds in neonates. A systematic review was conducted in accordance with the PRISMA statement and MOOSE guidelines. Two hundred and ninety-nine studies were screened and 37 studies included. Covidence online software was employed to streamline relevant articles. Hypocapnia was associated with predominantly neurological side effects while hypercapnia was linked with neurological, respiratory and gastrointestinal outcomes and Retinpathy of prematurity (ROP). Permissive hypercapnia did not decrease periventricular leukomalacia (PVL), ROP, hydrocephalus or air leaks. As safe pCO₂ ranges were not explicitly concluded in the studies chosen, it was indirectly extrapolated with reference to pCO₂ levels that were found to increase the risk of neonatal disease. Although PaCO₂ ranges were reported from 2.6 to 8.7 kPa (19.5-64.3 mmHg) in both term and preterm infants, there are little data on the safety of these ranges. For permissive hypercapnia, parameters described for bronchopulmonary dysplasia (BPD; PaCO₂ 6.0-7.3 kPa: 45.0-54.8 mmHg) and congenital diaphragmatic hernia (CDH; PaCO₂ ≤ 8.7 kPa: ≤65.3 mmHg) were identified. Contradictory findings on the effectiveness of permissive hypercapnia highlight the need for further data on appropriate CO₂ parameters and correlation with outcomes. IMPACT: There is no consensus on the optimal pCO₂ levels in the newborn. There is no consensus on the effectiveness of permissive hypercapnia in neonates. A safe range of pCO₂ of 5-7 kPa was inferred following systematic review.

Lung Protection During Mechanical Ventilation in the Premature Infant

Mechanical ventilation can be life-saving for the premature infant, but is often injurious to immature and underdeveloped lungs. Lung injury is caused by atelectrauma, oxygen toxicity, and volutrauma. Lung protection must include appropriate lung recruitment starting in the delivery suite and throughout mechanical ventilation. Strategies include open lung ventilation, positive end-expiratory pressure, and volume-targeted ventilation. Respiratory function monitoring, such as capnography and ventilator graphics, provides clinicians with continuous real-time information and an adjunct to optimize lung-protective ventilatory strategies. Further research is needed to assess which lung-protective strategies result in a decrease in long-term respiratory morbidity.

Outcomes of multiple gestation births compared to singleton: analysis of multicenter KID database

Background

The available data regarding morbidity and mortality associated with multiple gestation births is conflicting and contradicting.

Objective

To compare morbidity, mortality, and length of stay (LOS) outcomes between multiple gestation (twin, triplet and higher-order) and singleton births.

Methods

Data from the national multicenter Kids’ Inpatient Database of the Healthcare Cost and Utilization Project from the years 2000, 2003, 2006, 2009, 2012, and 2016 were analyzed using a complex survey design using Statistical Analysis System (SAS) 9.4 (SAS Institute, Cary NC). Neonates with ICD9 and ICD10 codes indicating singletons, twins or triplets, and higher-order multiples were included. Mortality was compared between these groups after excluding transfer outs to avoid duplicate inclusion. To analyze LOS, we included inborn neonates and excluded transfers; who died inpatient and any neonates who appear to have been discharged less than 33 weeks PMA. The LOS was compared by gestational age groups.

Results

A total of 22,853,125 neonates were analyzed for mortality after applying inclusion-exclusion criteria; 2.96% were twins, and 0.13% were triplets or more. A total of 22,690,082 neonates were analyzed for LOS. Mean GA, expressed as mean (SD), for singleton, twins and triplets, were 38.30 (2.21), 36.39 (4.21), and 32.72 (4.14), respectively. The adjusted odds for mortality were similar for twin births compared to singleton (aOR: 1.004, 95% CI:0.960–1.051, p = 0.8521). The adjusted odds of mortality for triplet or higher-order gestation births were higher (aOR: 1.33, 95% CI: 1.128–1.575, p = 0.0008) when compared to the singleton births. Median LOS (days) was significantly longer in multiple gestation compared to singleton births overall (singletons: 1.59 [1.13, 2.19] vs. twins 3.29 [2.17, 9.59] vs. triplets or higher-order multiples 19.15 [8.80, 36.38], p < .0001), and this difference remained significant within each GA category.

Conclusion

Multiple gestation births have higher mortality and longer LOS when compared to singleton births. This population data from multiple centers across the country could be useful in counseling parents when caring for multiple gestation pregnancies.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40748-021-00135-5.

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.

The Intertemporal Role of Respiratory Support in Improving Neonatal Outcomes: A Narrative Review

Defining improvements in healthcare can be challenging due to the need to assess multiple outcomes and measures. In neonates, although progress in respiratory support has been a key factor in improving survival, the same degree of improvement has not been documented in certain outcomes, such as bronchopulmonary dysplasia. By exploring the evolution of neonatal respiratory care over the last 60 years, this review highlights not only the scientific advances that occurred with the application of invasive mechanical ventilation but also the weakness of the existing knowledge. The contributing role of non-invasive ventilation and less-invasive surfactant administration methods as well as of certain pharmacological therapies is also discussed. Moreover, we analyze the cost-benefit of neonatal care-respiratory support and present future challenges and perspectives.

Eligibility Criteria and Representativeness of Randomized Clinical Trials That Include Infants Born Extremely Premature: A Systematic Review

OBJECTIVE

To assess the eligibility criteria and trial characteristics among contemporary (2010-2019) randomized clinical trials (RCTs) that included infants born extremely preterm (<28 weeks of gestation) and to evaluate whether eligibility criteria result in underrepresentation of high-risk subgroups (eg, infants born at <24 weeks of gestation).

STUDY DESIGN

PubMed and Scopus were searched January 1, 2010, to December 31, 2019, with no language restrictions. RCTs with mean or median gestational ages at birth of <28 weeks of gestation were included. The study followed the PRISMA guidelines; outcomes were registered prospectively. Data extraction was performed independently by multiple observers. Study quality was evaluated using a modified Jadad scale.

RESULTS

Among RCTs (n = 201), 32 552 infants were included. Study participant characteristics, interventions, and outcomes were highly variable. A total of 1603 eligibility criteria were identified; rationales were provided for 18.8% (n = 301) of criteria. Fifty-five RCTs (27.4%) included infants <24 weeks of gestation; 454 (1.4%) infants were identified as <24 weeks of gestation.

CONCLUSIONS

The present study identifies sources of variability across RCTs that included infants born extremely preterm and reinforces the critical need for consistent and transparent policies governing eligibility criteria.

Rates of Bronchopulmonary Dysplasia Following Implementation of a Novel Prevention Bundle

IMPORTANCE

Bronchopulmonary dysplasia (BPD) rates in the United States remain high and have changed little in the last decade.

OBJECTIVE

To develop a consistent BPD prevention bundle in a systematic approach to decrease BPD.

DESIGN, SETTING, AND PARTICIPANTS

This quality improvement study included 484 infants with birth weights from 501 to 1500 g admitted to a level 3 neonatal intensive care unit in the Kaiser Permanente Southern California system from 2009 through 2019. The study period was divided into 3 periods: 1, baseline (2009); 2, initial changes based on ongoing cycles of Plan-Do-Study-Act (2010-2014); and 3, full implementation of successive Plan-Do-Study-Act results (2015-2019).

INTERVENTIONS

A BPD prevention system of care bundle evolved with a shared mental model that BPD is avoidable.

MAIN OUTCOMES AND MEASURES

The primary outcome was BPD in infants with less than 33 weeks' gestational age (hereafter referred to as BPD <33). Other measures included adjusted BPD <33, BPD severity grade, and adjusted median postmenstrual age (PMA) at hospital discharge. Balancing measures were adjusted mortality and adjusted mortality or specified morbidities.

RESULTS

The study population included 484 infants with a mean (SD) birth weight of 1070 (277) g; a mean (SD) gestational age of 28.6 (2.9) weeks; 252 female infants (52.1%); and 61 Black infants (12.6%). During the 3 study periods, BPD <33 decreased from 9 of 29 patients (31.0%) to 3 of 184 patients (1.6%) (P < .001 for trend); special cause variation was observed. The standardized morbidity ratio for the adjusted BPD <33 decreased from 1.2 (95% CI, 0.7-1.9) in 2009 to 0.4 (95% CI, 0.2-0.8) in 2019. The rates of combined grades 1, 2, and 3 BPD decreased from 7 of 29 patients (24.1%) to 17 of 183 patients (9.3%) (P < .008 for trend). Grade 2 BPD rates decreased from 3 of 29 patients (10.3%) to 5 of 183 patients (2.7%) (P = .02 for trend). Adjusted median PMA at home discharge decreased by 2 weeks, from 38.2 (95% CI, 37.3-39.1) weeks in 2009 to 36.8 (95% CI, 36.6-37.1) weeks during the last 3 years (2017-2019) of the full implementation period. Adjusted mortality was unchanged, whereas adjusted mortality or specified morbidities decreased significantly.

CONCLUSIONS AND RELEVANCE

A sustained low rate of BPD was observed in infants after the implementation of a detailed BPD system of care.

Evidence for the Management of Bronchopulmonary Dysplasia in Very Preterm Infants

Background: Very preterm birth often results in the development of bronchopulmonary dysplasia (BPD) with an inverse correlation of gestational age and birthweight. This very preterm population is especially exposed to interventions, which affect the development of BPD. Objective: The goal of our review is to summarize the evidence on these daily procedures and provide evidence-based recommendations for the management of BPD. Methods: We conducted a systematic literature research using MEDLINE/PubMed on antenatal corticosteroids, surfactant-replacement therapy, caffeine, ventilation strategies, postnatal corticosteroids, inhaled nitric oxide, inhaled bronchodilators, macrolides, patent ductus arteriosus, fluid management, vitamin A, treatment of pulmonary hypertension and stem cell therapy. Results: Evidence provided by meta-analyses, systematic reviews, randomized controlled trials (RCTs) and large observational studies are summarized as a narrative review. Discussion: There is strong evidence for the use of antenatal corticosteroids, surfactant-replacement therapy, especially in combination with noninvasive ventilation strategies, caffeine and lung-protective ventilation strategies. A more differentiated approach has to be applied to corticosteroid treatment, the management of patent ductus arteriosus (PDA), fluid-intake and vitamin A supplementation, as well as the treatment of BPD-associated pulmonary hypertension. There is no evidence for the routine use of inhaled bronchodilators and prophylactic inhaled nitric oxide. Stem cell therapy is promising, but should be used in RCTs only.

Ventilation Strategies in Severe Bronchopulmonary Dysplasia

Bronchopulmonary dysplasia (BPD) is an acquired, developmental chronic lung disease that is a consequence of premature birth. In the most severe form of the disease, infants may require prolonged periods of positive pressure ventilation. BPD is a heterogeneous disease with lung mechanics that differ from those in respiratory distress syndrome; strategies to manage the respiratory support in infants with severe BPD should take this into consideration. When caring for these infants, practitioners need to shift from the acute care ventilation strategies that use frequent blood gases and support adjustments designed to minimize exposure to positive pressure. Infants with severe BPD benefit from a chronic care model that uses less frequent ventilator adjustments and provides the level of positive support that will achieve the longer-term goal of ongoing lung growth and repair.

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.

Is Anesthesia Bad for the Brain? Current Knowledge on the Impact of Anesthetics on the Developing Brain

There are compelling preclinical data that common general anesthetics cause increased neuroapoptosis in juvenile animals. Retrospective studies demonstrate that young children exposed to anesthesia have school difficulties, which could be caused by anesthetic neurotoxicity, perioperative hemodynamic and homeostatic instability, underlying morbidity, or the neuroinflammatory effects of surgical trauma. Unnecessary procedures should be avoided. Baseline measures of blood pressure are important in determining perioperative blood pressure goals. Inadvertent hypocapnia or moderate hypercapnia and hyperoxia or hypoxia should be avoided. Pediatric patients should be maintained in a normothermic, euglycemic state with neutral positioning. Improving outcomes of infants and children requires the collaboration of anesthesiologists, surgeons, pediatricians and neonatologists.

Beyond Anesthesia Toxicity: Anesthetic Considerations to Lessen the Risk of Neonatal Neurological Injury

Infants who undergo surgical procedures in the first few months of life are at a higher risk of death or subsequent neurodevelopmental abnormalities. Although the pathogenesis of these outcomes is multifactorial, an understanding of the nature and pathogenesis of brain injury in these infants may assist the anesthesiologist in consideration of their day-to-day practice to minimize such risks. This review will summarize the main types of brain injury in preterm and term infants and their key pathways. In addition, the review will address key potential pathogenic pathways that may be modifiable including intraoperative hypotension, hypocapnia, hyperoxia or hypoxia, hypoglycemia, and hyperthermia. Each of these conditions may increase the risk of perioperative neurological injury, but their long-term ramifications are unclear.

Comparison of brain microstructure after prenatal spina bifida repair by either laparotomy-assisted fetoscopic or open approach

OBJECTIVE

To compare prenatal and postnatal brain microstructure between infants that underwent fetoscopic myelomeningocele (MMC) repair and those that had open-hysterotomy repair.

METHODS

This was a longitudinal retrospective cohort study of 57 fetuses that met the Management of Myelomeningocele Study (MOMS) trial criteria and underwent prenatal MMC repair, by a fetoscopic (n = 27) or open-hysterotomy (n = 30) approach, at 21.4-25.9 weeks' gestation. Fetoscopic repair was performed under CO₂ insufflation, according to our protocol. Diffusion-weighted magnetic resonance imaging (MRI) was performed before surgery in 30 cases (14 fetoscopic and 16 open), at 6 weeks postsurgery in 48 cases (24 fetoscopic and 24 open) and within the first year after birth in 23 infants (five fetoscopic and 18 open). Apparent diffusion coefficient (ADC) values from the basal ganglia, frontal, occipital and parietal lobes, mesencephalon and genu as well as splenium of the corpus callosum were calculated. ADC values at each of the three timepoints (presurgery, 6 weeks postsurgery and postnatally) and the percentage change in the ADC values between the timepoints were compared between the fetoscopic-repair and open-repair groups. ADC values at 6 weeks after surgery in the two prenatally repaired groups were compared with those in a control group of eight healthy fetuses that underwent MRI at a similar gestational age (GA). Comparison of ADC values was performed using the Student's t-test for independent samples (or Mann-Whitney U-test if non-normally distributed) and multivariate general linear model analysis, adjusting for GA or age at MRI and mean ventricular width.

RESULTS

There were no differences in GA at surgery or GA/postnatal age at MRI between the groups. No significant differences were observed in ADC values in any of the brain areas assessed between the open-repair and fetoscopic-repair groups at 6 weeks after surgery and in the first year after birth. No differences were detected in the ADC values of the studied areas between the control and prenatally repaired groups, except for significantly increased ADC values in the genu of the corpus callosum in the open-hysterotomy and fetoscopic-repair groups. Additionally, there were no differences between the two prenatally repaired groups in the percentage change in ADC values at any of the time intervals analyzed.

CONCLUSIONS

Fetoscopic MMC repair has no detectable effect on brain microstructure when compared to babies repaired using an open-hysterotomy technique. CO₂ insufflation of the uterine cavity during fetoscopy does not seem to have any isolated deleterious effects on fetal brain microstructure. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

How to ventilate preterm infants with lung compliance close to circuit compliance: real-time simulations on an infant hybrid respiratory simulator

Circuit compliance close to lung compliance can create serious problems in effective and safe mechanical ventilation of preterm infants. We considered what ventilation technique is the most beneficial in this case. A hybrid (numerical-physical) simulator of infant respiratory system mechanics, the Bennett Ventilator and NICO apparatus were used to simulate pressure-controlled ventilation (PC) and volume-controlled ventilation with constant flow (VCV_CF) and descending flow (VCV_DF), under permissive hypercapnia (PHC) (6 ml kg^-1) and normocapnia (SV) (8 ml kg^-1) conditions. Respiratory rate (RR) was 36 or 48 min^-1 and PEEP was 0.3 or 0.6 kPa. Peak inspiratory pressure (PIP), mean airway pressure (MAP), and work of breathing by the ventilator (WOB) were lower (P < 0.01, 1 - β = 0.9) using the PHC strategy compared to the SV strategy. The WOB increased (P < 0.01; 1 - β = 0.9) when the RR increased. The PC, VCV_CF, and VCV_DF modes did not differ in minute ventilation produced by the ventilator (MV_V), but the PC mode delivered the highest minute ventilation to the patient (MV_T) (P < 0.01; 1 - β = 0.9) at the same PIP, MAP, and WOB. The most beneficial ventilation technique appeared to be PC ventilation with the PHC strategy, with lower RR (36 min^-1). Graphical abstract The effectiveness of an infant ventilation depending on circuit compliance to lung compliance ratio (C_v C_L ^-1) and inspiration time (T_i). V_V, V_T, tidal volume set on the ventilator and delivered to patient, respectively.

Continuous Noninvasive Carbon Dioxide Monitoring in Neonates: From Theory to Standard of Care

Ventilatory support may affect the short- and long-term neurologic and respiratory morbidities of preterm infants. Ongoing monitoring of oxygenation and ventilation and control of adequate levels of oxygen, pressures, and volumes can decrease the incidence of such adverse outcomes. Use of pulse oximetry became a standard of care for titrating oxygen delivery, but continuous noninvasive monitoring of carbon dioxide (CO₂) is not routinely used in NICUs. Continuous monitoring of CO₂ level may be crucial because hypocarbia and hypercarbia in extremely preterm infants are associated with lung and brain morbidities, specifically bronchopulmonary dysplasia, intraventricular hemorrhage, and cystic periventricular leukomalacia. It is shown that continuous monitoring of CO₂ levels helps in maintaining stable CO₂ values within an accepted target range. Continuous monitoring of CO₂ levels can be used in the delivery room, during transport, and in infants receiving invasive or noninvasive respiratory support in the NICU. It is logical to hypothesize that this will result in better outcome for extremely preterm infants. In this article, we review the different noninvasive CO₂ monitoring alternatives and devices, their advantages and disadvantages, and the available clinical data supporting or negating their use as a standard of care in NICUs.

Turkish Neonatal Society guideline on prevention and management of bronchopulmonary dysplasia

Scientific and technological advances in perinatology and neonatology have led to an increased rate of survival and decreased incidences of various neonatal morbidities. However, the incidence of bronchopulmonary dysplasia has remained almost the same for years in very-low-birth-weight preterm infants. Although bronchopulmonary dysplasia is the leading cause of chronic respiratory morbidity in small preterms, no substantial improvement has been achieved in prevention and treatment strategies to date. Currently, postnatal very-low-dose corticosteroids, caffeine, and vitamin A seem to be the drugs of choice, and stem cell therapy appears to be the most promising treatment modality for the future. In this guideline, which was prepared by the Turkish Neonatal Society, recent evidence-based recommendations for the prevention and treatment of bronchopulmonary dysplasia are summarized.

Noninvasive high-frequency oscillatory ventilation as respiratory support in preterm infants: a meta-analysis of randomized controlled trials

BACKGROUND

Noninvasive high-frequency oscillatory ventilation (nHFOV), a relatively new modality, is gaining popularity despite scarce evidence. This meta-analysis was designed to evaluate the efficacy and safety of nHFOV as respiratory support in premature infants.

METHODS

We searched MEDLINE, EMBASE, CINAHL, and Cochrane CENTRAL from inception of the database to January 2019. All published randomized controlled trials (RCTs) evaluating the effect of nHFOV therapy with nasal continuous positive airway pressure (nCPAP) or biphasic nCPAP (BP-CPAP) in newborns for respiratory support were included. All meta-analyses were performed using Review Manager 5.3.

RESULTS

A total of 8 RCTs involving 463 patients were included. The meta-analysis estimated a lower risk of intubation (relative risk = 0.50, 95% confidence interval of 0.36 to 0.70) and more effective clearance of carbon dioxide (weighted mean difference = - 4.61, 95% confidence interval of - 7.94 to - 1.28) in the nHFOV group than in the nCPAP/BP-CPAP group.

CONCLUSIONS

Our meta-analysis of RCTs suggests that nHFOV, as respiratory support in preterm infants, significantly remove carbon dioxide and reduce the risk of intubation compared with nCPAP/BP-CPAP. The appropriate parameter settings for different types of noninvasive high-frequency ventilators, the effect of nHFOV in extremely preterm infants, and the long-term safety of nHFOV need to be assessed in large trials.

Carbon dioxide and retinopathy of prematurity in extremely low birth weight infants

Objective: To evaluate the relationship between partial pressure of carbon dioxide (PCO₂) during the first 3 days of life and retinopathy of prematurity (ROP) in extremely low birthweight (ELBW) infants.Patients and methods: A retrospective evaluation of data on ELBW infants were collected over a period of 4 years. Data during the first 72 hours of life was divided into six, 12-hour epochs. The average highest and overall means of PCO₂, PO₂, FiO_2, and glucose were calculated for each epoch. Logistic regression analysis was used to determine the association between PCO₂ and ROP after controlling for covariables.Results: A total of 78 neonates were included: birth weight (BW) (703 ± 157 g) and gestational age (25 ± 1.4 weeks). A total of 45 out of 78 had ROP: stage 1 (N = 8), stage 2 (N = 26), stage 3 (N = 14), and plus (N = 4). The overall mean PCO₂ correlated with ROP in the first 72 hours of life (R = 0.31, p = .0069). This correlation was significant in epochs 2 (p = .049), 4 (p = .008) and 6 (p = .038). The average of the highest PCO₂ also correlated with ROP in the first 72 hours of life (R = 0.38, p = .0007). This correlation was significant in epochs 2 (p = .0115), 4 (p = .0011), 5 (p = .028) and 6 (p = .037). The correlation between the stage of ROP and PCO₂ was significant after controlling for PO₂ and glucose concentrations. Other variables that correlated with ROP were the overall means of FiO₂ (R = 0.23, p = .04), PO₂ (R = 0.39, p = .0005) and glucose (R = 0.39, p = .0004) as well as the average highest concentrations of FiO₂ (R = 0.26, p = .025), PO₂ (R = 0.38, p = .0008) and glucose (R = 0.34, p = .007).Conclusion: After controlling for confounding variables, ROP correlated with the overall means and average highest PCO₂. ROP also correlated with FiO₂, PO₂ and glucose concentrations. Further studies are needed to define the safe PCO₂ range and the effect of PCO₂ on the normal development of the retina.

European Consensus Guidelines on the Management of Respiratory Distress Syndrome - 2019 Update

As management of respiratory distress syndrome (RDS) advances, clinicians must continually revise their current practice. We report the fourth update of "European Guidelines for the Management of RDS" by a European panel of experienced neonatologists and an expert perinatal obstetrician based on available literature up to the end of 2018. Optimising outcome for babies with RDS includes prediction of risk of preterm delivery, need for appropriate maternal transfer to a perinatal centre and timely use of antenatal steroids. Delivery room management has become more evidence-based, and protocols for lung protection including initiation of CPAP and titration of oxygen should be implemented immediately after birth. Surfactant replacement therapy is a crucial part of management of RDS, and newer protocols for its use recommend early administration and avoidance of mechanical ventilation. Methods of maintaining babies on non-invasive respiratory support have been further developed and may cause less distress and reduce chronic lung disease. As technology for delivering mechanical ventilation improves, the risk of causing lung injury should decrease, although minimising time spent on mechanical ventilation using caffeine and, if necessary, postnatal steroids are also important considerations. Protocols for optimising general care of infants with RDS are also essential with good temperature control, careful fluid and nutritional management, maintenance of perfusion and judicious use of antibiotics all being important determinants of best outcome.

Turkish Neonatal Society guideline on the management of respiratory distress syndrome and surfactant treatment

Respiratory distress syndrome is the leading cause of respiratory failure in preterm infants. The incidence and severity of respiratory distress syndrome are inversely related to the gestational age of the newborn. The major underlying pathophysiologic mechanisms are surfactant deficiency and anatomic, structural immaturity of the lung. Recent improvements such as antenatal steroid treatment to enhance pulmonary maturity, appropriate resuscitation facilitated by placental transfusion and immediate use of continuous positive airway pressure for alveolar recruitment, early rescue administration of surfactant, ventilation with gentler modes to minimize damage to the immature lungs, and the other supportive therapies have significantly decreased respiratory distress syndrome-related morbidity and mortality. This guideline was addressed to overview the mentioned improvements in order to standardize respiratory distress syndrome management in neonatal intensive care units in Turkey.

Partial amniotic carbon dioxide insufflation for fetal surgery

Partial amniotic carbon dioxide insufflation (PACI) involves insufflating the amniotic sac with carbon dioxide (CO₂ ) and, in some cases, draining some of the amniotic fluid. The creation of a gaseous intra-amniotic compartment improves visualization, even in the presence of limited bleeding, and creates the work space required for complex fetoscopic procedures. Clinically, PACI is mostly used to perform fetoscopic myelomeningocele (MMC) repair, enabling a minimally invasive alternative to open fetal surgery. However, evidence of the fetal safety of PACI is limited. Previous animal experiments in sheep demonstrate that PACI induces fetal hypercapnia and acidosis with largely unknown short and longer term implications. In this review, we examine the literature for the physiological effects of intrauterine insufflation pressure, duration, humidity, and the role of maternal hyperventilation on fetal physiology and well-being.

Does prolonged severe hypercapnia interfere with normal cerebrovascular function in piglets?

BACKGROUND

Hypercapnia causes cerebral vasodilation and increased cerebral blood flow (CBF). During prolonged hypercapnia it is unknown whether cerebral vasodilation persists and whether cerebrovascular function is preserved. We investigated the effects of prolonged severe hypercapnia on pial arteriolar diameters (PAD) and cerebrovascular reactivity to vasodilators and vasoconstrictors.

METHODS

Piglets were anesthetized, intubated and ventilated. Closed cranial windows were implanted to measure PAD. Changes in PAD were documented during hypercapnia (PaCO₂ 75-80 mm Hg). Cerebrovascular reactivity was documented during normocapnia and at 30, 60, and 120 min of hypercapnia.

RESULTS

Cerebral vasodilation to hypercapnia was sustained over 120 min. Cerebrovascular responses to vasodilators and vasoconstrictors were preserved during hypercapnia. During hypercapnia, vasodilatory responses to second vasodilators were similar to normocapnia, while exposure to vasoconstrictors caused significant vasoconstriction.

CONCLUSIONS

Prolonged severe hypercapnia causes sustained vasodilation of pial arteriolar diameters indicative of hyperperfusion. During hypercapnia, cerebral vascular responses to vasodilators and vasoconstrictors were preserved, suggesting that cerebral vascular function remained intact. Of note, cerebral vessels during hypercapnia were capable of further dilation when exposed to additional cerebral vasodilators and, significant vasoconstriction when exposed to vasoconstrictors. Extrapolating these findings to infants, we suggest that severe hypercapnia should be avoided, because it could cause/increase cerebrovascular injury.

Evidence Regarding the Use of Bubble Continuous Positive Airway Pressure in the Extremely Low Birth-Weight Infant: Benefits, Challenges, and Implications for Nursing Practice

BACKGROUND

Gentle ventilation with optimal oxygenation is integral to prevention of chronic lung disease in the extremely low birth-weight (ELBW) infant. Various types of noninvasive ventilation are used in neonatal intensive care units worldwide. Bubble continuous positive airway pressure (BCPAP) has been in use in newborn intensive care since 1975.

PURPOSE

To synthesize the current evidence on the use of BCPAP in the ELBW infant and its relationship to outcomes, particularly morbidity and mortality.

METHODS/SEARCH STRATEGIES

A literature review was completed using PubMed, EMBASE, CINAHL, and Cochrane with a focus on BCPAP use in the ELBW population.

FINDINGS/RESULTS

No study found was exclusive to the ELBW population. All studies ranged from ELBW to full-term neonates. Studies supported the use of BCPAP in the ELBW, demonstrating decreased incidence of chronic lung disease and barotrauma through the use of oscillation and permissive hypercapnia.

IMPLICATIONS FOR PRACTICE

Literature supports the use of nasal bubble CPAP in the ELBW population. Barriers such as septal erosion, pneumothorax, inconsistent pressures, and air in the abdomen were identified and management recommendations were provided.

IMPLICATIONS FOR RESEARCH

Studies are needed comparing outcomes of nasal bubble CPAP use with other forms of CPAP in the ELBW infant, comparison of prongs to mask for nasal bubble CPAP, and comparing interventions to recommend optimal care bundles to prevent nasal septum injuries.

Influence of PCO2 Control on Clinical and Neurodevelopmental Outcomes of Extremely Low Birth Weight Infants

BACKGROUND

Levels or fluctuations in the partial pressure of CO2 (PCO2) may affect outcomes for extremely low birth weight infants.

OBJECTIVES

In an exploratory analysis of a randomized trial, we hypothesized that the PCO2 values achieved could be related to significant outcomes.

METHODS

On each treatment day, infants were divided into 4 groups: relative hypocapnia, normocapnia, hypercapnia, or fluctuating PCO2. Ultimate assignment to a group for the purpose of this analysis was made according to the group in which an infant spent the most days. Statistical analyses were performed with analysis of variance (ANOVA), the Kruskal-Wallis test, the χ2 test, and the Fisher exact test as well as by multiple logistic regression.

RESULTS

Of the 359 infants, 57 were classified as hypocapnic, 230 as normocapnic, 70 as hypercapnic, and 2 as fluctuating PCO2. Hypercapnic infants had a higher average product of mean airway pressure and fraction of inspired oxygen (MAP × FiO2). For this group, mortality was higher, as was the likelihood of having moderate/severe bronchopulmonary dysplasia (BPD), necrotizing enterocolitis (NEC), and poorer neurodevelopment. Multiple logistic regression analyses showed an increased risk for BPD or death associated with birth weight (p < 0.001) and MAP × FiO2 (p < 0.01). The incidence of adverse neurodevelopment was associated with birth weight (p < 0.001) and intraventricular hemorrhage (IVH; p < 0.01).

CONCLUSIONS

Birth weight and respiratory morbidity, as measured by MAP × FiO2, were the most predictive of death or BPD and NEC, whereas poor neurodevelopmental outcome was associated with low birth weight and IVH. Univariate models also identified PCO2. Thus, hypercapnia seems to reflect greater disease severity, a likely contributor to differences in outcomes.

Permissive Hypercapnia Results in Decreased Functional Vessel Density in the Skin of Extremely Low Birth Weight Infants

BACKGROUND

Ventilator-induced lung injury with subsequent bronchopulmonary dysplasia remains an important issue in the care of extremely low-birth-weight infants. Permissive hypercapnia has been proposed to reduce lung injury. Hypercapnia changes cerebral perfusion, but its influence on the peripheral microcirculation is unknown.

METHODS

Data were collected from 12 infants, who were randomized to a permissive high PCO₂ target group (HTG) or a control group (CG). Inclusion criteria were birth weight between 400 and 1,000 g, gestational age from 23 to 28 6/7 weeks, intubation during the first 24 h of life, and no malformations. The PCO₂ target range was increased stepwise in both groups for weaning and was always 15 mmHg higher in the HTG than in the CG. Skin microvascular parameters were assessed non-invasively with sidestream dark field imaging on the inner side of the right arm every 24 h during the first week of life and on the 14th day of life.

RESULTS

Infants in the HTG had significantly higher max. PCO₂ exposure, which was associated with a significantly and progressively reduced functional vessel density (FVD, p < 0.01). Moreover, there were significant differences in the diameter distribution over time, with HTG subjects having fewer small vessels but more large vessels.

CONCLUSION

High PCO₂ levels significantly impaired peripheral microcirculation in preterm infants, as shown by a decreased FVD, presumably secondary to peripheral vasoconstriction.

ISRCTN

56143743.

Prevention of bronchopulmonary dysplasia: current strategies

Bronchopulmonary dysplasia (BPD) is one of the few diseases affecting premature infants that have continued to evolve since its first description about half a century ago. The current form of BPD, a more benign and protracted respiratory failure in extremely preterm infants, is in contrast to the original presentation of severe respiratory failure with high mortality in larger premature infants. This new BPD is end result of complex interplay of various antenatal and postnatal factors causing lung injury and subsequent abnormal repair leading to altered alveolar and vascular development. The change in clinical and pathologic picture of BPD over time has resulted in new challenges in developing strategies for its prevention and management. While some of these strategies like Vitamin A supplementation, caffeine and volume targeted ventilation have stood the test of time, others like postnatal steroids are being reexamined with great interest in last few years. It is quite clear that BPD is unlikely to be eliminated unless some miraculous strategy cures prematurity. The future of BPD prevention will probably be a combination of antenatal and postnatal strategies acting on multiple pathways to minimize lung injury and abnormal repair as well as promote normal alveolar and vascular development.

Lung-protective ventilatory strategies in intubated preterm neonates with RDS

This article provides a narrative review of lung-protective ventilatory strategies (LPVS) in intubated preterm infants with RDS. A description of strategies is followed by results on short-and long-term respiratory and neurodevelopmental outcomes. Strategies will include patient-triggered or synchronized ventilation, volume targeted ventilation, the technique of intubation, surfactant administration and rapid extubation to NCPAP (INSURE), the open lung concept, strategies of high-frequency ventilation, and permissive hypercapnia. Based on this review single recommendations on optimal LPVS cannot be made. Combinations of several strategies, individually applied, most probably minimize or avoid potential serious respiratory and cerebral complications like bronchopulmonary dysplasia and cerebral palsy.

Hemodynamic effects of sodium bicarbonate administration

OBJECTIVE

To describe the hemodynamic changes that occur with sodium bicarbonate (NaHCO₃) administration in premature neonates.

STUDY DESIGN

This retrospective study included premature neonates 23 to 31+6 weeks of gestational age who underwent continuous cardiac and cerebral monitoring as participants in prospective trials at our institution, and who received NaHCO₃ infused over 30 min in the first 24 h of life. Blood pressure (BP), heart rate, cardiac output (CO), SpO₂ and cerebral oximetry (StO₂) were captured every 2 s. A baseline was established for all continuous data and averaged over the 10 min before NaHCO₃ administration. Baseline was compared with measurements over 10 min epochs until 80 min after administration. Arterial blood gases before and within 1 h of administration were also compared. Significance was set at P<0.05.

RESULTS

A total of 36 subjects received NaHCO₃ (1.3±0.3 mEq kg^-1) in the first 24 h (14±8.5 h) of life. NaHCO₃ administration increased pH (7.23 vs 7.28, P<0.01) and decreased base deficit (-8.9 vs -6.8, P<0.01) and PaCO₂ (45 vs 43 mm Hg, P<0.05). There was a transient but significant (P<0.05) decrease in systemic BP coinciding with an increase in cerebral oxygenation without an increase in oxygen extraction. CO did not change.

CONCLUSION

Early postnatal NaHCO₃ administration does not acutely improve CO but does cause transient fluctuations in cerebral and cardiovascular hemodynamics in extremely premature infants.

The role and limitations of Cochrane reviews at the bedside: a systematic synopsis of five pediatric subspecialties

BACKGROUND

Cochrane meta-analyses provide the physician at the bedside with the most relevant, up-to-date clinical information. However, implementation of evidence-based medicine (EBM) at the bedside may be difficult for a variety of reasons. The aim of this study was to assess relevant issues and obstacles related to implementing EBM in pediatrics in real life at the bedside/cotside.

METHODS

We performed five systematic literature reviews of all published Cochrane reviews in neonatology (1996-2010), pediatric neurology (1996-2010), pediatric gastroenterology (1993-2012), pediatric cardiology (2001-2015), and complementary and alternative medicine (1996-2012; CAM) in children and neonates. In all five analyses, the main outcome variables were percentage of reviews concluding that a certain intervention provides a benefit, percentage of reviews concluding that a certain intervention should not be performed, and percentage of studies concluding that the current level of evidence is inconclusive.

RESULTS

In all five areas of pediatrics, a substantial number of Cochrane reviews yielded inconclusive data (neonatology: 46.6%; neuropediatrics: 26.8%; pediatric gastroenterology: 27.9%; pediatric cardiology: 42.9%; complementary and alternative medicine: 66.9%).

CONCLUSIONS

Our up-dated systematic synopsis reiterates the need for high-quality, sophisticated research to reduce the number of inconclusive meta-analyses in the field of pediatrics-most importantly in the field of complementary and alternative medicine (CAM), neonatology, and pediatric cardiology. The realization of high-quality, clinically driven research will in turn yield more systematic reviews with a clear conclusion (e. g., in favor or against a certain intervention, or treatment modality), thus, substantively decreasing the proportion of inconclusive reviews.

Bronchopulmonary Dysplasia: Chronic Lung Disease of Infancy and Long-Term Pulmonary Outcomes

Bronchopulmonary dysplasia (BPD) is a chronic lung disease most commonly seen in premature infants who required mechanical ventilation and oxygen therapy for acute respiratory distress. While advances in neonatal care have resulted in improved survival rates of premature infants, limited progress has been made in reducing rates of BPD. Lack of progress may in part be attributed to the limited therapeutic options available for prevention and treatment of BPD. Several lung-protective strategies have been shown to reduce risks, including use of non-invasive support, as well as early extubation and volume ventilation when intubation is required. These approaches, along with optimal nutrition and medical therapy, decrease risk of BPD; however, impacts on long-term outcomes are poorly defined. Characterization of late outcomes remain a challenge as rapid advances in medical management result in current adult BPD survivors representing outdated neonatal care. While pulmonary disease improves with growth, long-term follow-up studies raise concerns for persistent pulmonary dysfunction; asthma-like symptoms and exercise intolerance in young adults after BPD. Abnormal ventilatory responses and pulmonary hypertension can further complicate disease. These pulmonary morbidities, combined with environmental and infectious exposures, may result in significant long-term pulmonary sequalae and represent a growing burden on health systems. Additional longitudinal studies are needed to determine outcomes beyond the second decade, and define risk factors and optimal treatment for late sequalae of disease.