Speed of lung inflation at birth influences the initiation of lung injury in preterm lambs.

Gas flow is fundamental for driving tidal ventilation and thus the speed of lung motion, but current bias flow settings to support the preterm lung after birth are without an evidence base. We aimed to determine the role of gas bias flow rates to generate positive pressure ventilation in initiating early lung injury pathways in the preterm lamb. Using slower speeds to inflate the lung during tidal ventilation (gas flow rates 4-6 L/min) did not impact lung mechanics, mechanical power or gas exchange compared to those currently used in clinical practice (8-10 L/min). Speed of pressure and volume change during inflation were faster with higher flow rates. Lower flow rates resulted in less bronchoalveolar fluid protein, better lung morphology and fewer detached epithelial cells. Overall, relative to unventilated fetal controls, there was greater protein change using 8-10 L/min, which was associated with enrichment of acute inflammatory and innate responses. Slowing the speed of lung motion by supporting the preterm lung from birth with lower flow rates than currently used clinically resulted in less lung injury without compromising tidal ventilation or gas exchange.

Plasma Proteome Profiles Associated with Early Development of Lung Injury in Extremely Preterm Infants.

The biological mediators which initiate lung injury in extremely preterm infants during early postnatal life remain largely unidentified, limiting opportunities for early treatment and diagnosis. This exploratory study used SWATH-mass spectrometry to identify bronchopulmonary dysplasia (BPD)-specific changes in protein abundance in plasma samples obtained in the first 72 hours of life from extremely preterm infants and bioinformatic analysis to identify BPD-related biological categories and pathways. Lasty, binary logistic regression analysis was used to test the BPD predictive potential of a base model alone (gestational age, birth weight, sex) and with the protein biomarker added, with bootstrap resampling used to internally validate protein predictors and adjust for overoptimism. We observed disturbance of key processes including coagulation, complement activation, development and extracellular matrix organisation in the first days of life in extremely preterm infants who were later diagnosed with BPD. In the BPD prediction analysis, 49 plasma proteins were identified which when each singularly was combined with birth characteristics had a C-index of 0.65-0.84 (optimism-adjusted C-index) suggesting predictive potential for BPD outcomes. Taken together, this study demonstrates that alterations in plasma proteins can be detected from 4 hours of age in extremely preterm infants who later develop BPD and that protein biomarkers when combined with three birth characteristics have the potential to predict BPD development within the first 72 hours of life.

Top 10 research priorities for congenital diaphragmatic hernia in Australia: James Lind Alliance Priority Setting Partnership.

OBJECTIVES: The Gaps in the Congenital Diaphragmatic Hernia (CDH) Journey Priority Setting Partnership (PSP) was developed in collaboration with CDH Australia, James Lind Alliance (JLA) and the Murdoch Children's Research Institute to identify research priorities for people with CDH, their families and healthcare workers in Australasia. DESIGN: Research PSP in accordance with the JLA standardised methodology. SETTING: Australian community and institutions caring for patients with CDH and their families. PATIENTS: CDH survivors, families of children born with CDH (including bereaved) and healthcare professionals including critical care physicians and nurses (neonatal and paediatric), obstetric, surgical, allied health professionals (physiotherapists, speech pathologists and speech therapists) and general practitioners. MAIN OUTCOME MEASURE: Top 10 research priorities for CDH. RESULTS: 377 questions, from a community-based online survey, were categorised and collated into 50 research questions. Through a further prioritisation process, 21 questions were then discussed at a prioritisation workshop where they were ranked by 21 participants (CDH survivors, parents of children born with CDH (bereaved and not) and 11 multidisciplinary healthcare professionals) into their top 10 research priorities. CONCLUSION: Stakeholders' involvement identified the top 10 CDH-related research questions, spanning from antenatal care to long-term functional outcomes, that should be prioritised for future research to maximise meaningful outcomes for people with CDH and their families.

Mechanical power made simple: validating a simplified calculation of mechanical power in preterm lungs.

BACKGROUND: The incidence of chronic lung disease is increasing, suggesting a need to explore novel ways to understand ventilator induced lung injury (VILI) in preterm infants. Mechanical power (MP) is a unifying measure of energy transferred to the respiratory system and a proposed determinant of VILI. The gold-standard method for calculating MP (geometric method) is not feasible in the clinical setting. This has prompted the derivation of simplified equations for calculating MP. OBJECTIVE: To validate the agreement between a simplified calculation of MP (MPSimple) and the true MP calculated using the geometric method (MPRef). METHODS: MPSimple and MPRef was calculated in mechanically ventilated preterm lambs (n = 71) and the agreement between both measures was determined using intraclass correlation coefficients (ICC), linear regression, and Bland-Altman analysis. RESULTS: A strong linear relationship (adjusted R2 = 0.98), and excellent agreement (ICC = 0.99, 95% CI = 0.98-0.99) between MPSimple and MPRef was demonstrated. Bland-Altman analysis demonstrated a negligible positive bias (mean difference = 0.131 J/min·kg). The 95% limits of agreement were -0.06 to 0.32 J/min·kg. CONCLUSIONS: In a controlled setting, there was excellent agreement between MPSimple and gold-standard calculations. MPSimple should be validated and explored in preterm neonates to assess the cause-effect relationship with VILI and neonatal outcomes. IMPACT STATEMENT: Mechanical power (MP) unifies the individual components of ventilator induced lung injury (VILI) and provides an estimate of total energy transferred to the respiratory system during mechanical ventilation. As gold-standard calculations of mechanical power at the bedside are not feasible, alternative simplified equations have been proposed. In this study, MP calculated using a simplified equation had excellent agreement with true MP in mechanically ventilated preterm lambs. These results lay foundations to explore the role of MP in neonatal VILI and determine its relationship with short and long term respiratory outcomes.

Endotracheal Tube Size Adjustments Within Seven Days of Neonatal Intubation.

BACKGROUND AND OBJECTIVES: Neonatal endotracheal tube (ETT) size recommendations are based on limited evidence. We sought to determine data-driven weight-based ETT sizes for infants undergoing tracheal intubation and to compare these with Neonatal Resuscitation Program (NRP) recommendations. METHODS: Retrospective multicenter cohort study from an international airway registry. We evaluated ETT size changes (downsizing to a smaller ETT during the procedure or upsizing to a larger ETT within 7 days) and risk of procedural adverse outcomes associated with first-attempt ETT size selection when stratifying the cohort into 200 g subgroups. RESULTS: Of 7293 intubations assessed, the initial ETT was downsized in 5.0% of encounters and upsized within 7 days in 1.5%. ETT downsizing was most common when NRP-recommended sizes were attempted in the following weight subgroups: 1000 to 1199 g with a 3.0 mm (12.6%) and 2000 to 2199 g with a 3.5 mm (17.1%). For infants in these 2 weight subgroups, selection of ETTs 0.5 mm smaller than NRP recommendations was independently associated with lower odds of adverse outcomes compared with NRP-recommended sizes. Among infants weighing 1000 to 1199 g: any tracheal intubation associated event, 20.8% with 2.5 mm versus 21.9% with 3.0 mm (adjusted OR [aOR] 0.62, 95% confidence interval [CI] 0.41-0.94); severe oxygen desaturation, 35.2% with 2.5 mm vs 52.9% with 3.0 mm (aOR 0.53, 95% CI 0.38-0.75). Among infants weighing 2000 to 2199 g: severe oxygen desaturation, 41% with 3.0 mm versus 56% with 3.5mm (aOR 0.55, 95% CI 0.34-0.89). CONCLUSIONS: For infants weighing 1000 to 1199 g and 2000 to 2199 g, the recommended ETT size was frequently downsized during the procedure, whereas 0.5 mm smaller ETT sizes were associated with fewer adverse events and were rarely upsized.

Making respiratory care safe for neonatal and paediatric intensive care unit staff: mitigation strategies and use of filters.

Background: Many medical devices in pediatric and newborn intensive care units can potentially expose healthcare workers (HCWs) and others to transmission of respiratory and other viruses and bacteria. Such fomites include ventilators, nebulizers, and monitoring equipment. Approach: We report the general, novel approach we have taken to identify and mitigate these risks and to protect HCWs, visitors and patients from exposure while maintaining the optimal performance of such respiratory equipment. Findings: The approach combined a high level of personal protective equipment (PPE), strict hand hygiene, air filtration and air conditioning and other relevant viral risk mitigation guidelines. This report describes the experiences from the SARS-CoV-2 pandemic to provide a reference framework that can be applied generally. The steps we took consisted of auditing our equipment and processes to identify risk through sources of potentially contaminated gas that may contain aerosolized virus, seeking advice and liaising with suppliers/manufacturers, devising mitigation strategies using indirect and direct approaches (largely filtering), performing tests on equipment to verify proper function and the absence of negative impacts and the development and implementation of relevant procedures and practices. We had a multidisciplinary team to guide the process. We monitored daily for hospital-acquired infections among staff caring for SARS-CoV-2 patients. Conclusion: Our approach was successful as we have continued to offer optimal intensive care to our patients, and we did not find any healthcare worker who was infected through the course of caring for patients at the bedside. The lessons learnt will be of benefit to future local outbreaks or pandemics.

Factors that impact second attempt success for neonatal intubation following first attempt failure: a report from the National Emergency Airway Registry for Neonates.

OBJECTIVE: To determine the factors associated with second attempt success and the risk of adverse events following a failed first attempt at neonatal tracheal intubation. DESIGN: Retrospective analysis of prospectively collected data on intubations performed in the neonatal intensive care unit (NICU) and delivery room from the National Emergency Airway Registry for Neonates (NEAR4NEOS). SETTING: Eighteen academic NICUs in NEAR4NEOS. PATIENTS: Neonates requiring two or more attempts at intubation between October 2014 and December 2021. MAIN OUTCOME MEASURES: The primary outcome was successful intubation on the second attempt, with severe tracheal intubation-associated events (TIAEs) or severe desaturation (≥20% decline in oxygen saturation) being secondary outcomes. Multivariate regression examined the associations between these outcomes and patient characteristics and changes in intubation practice. RESULTS: 5805 of 13 126 (44%) encounters required two or more intubation attempts, with 3156 (54%) successful on the second attempt. Second attempt success was more likely with changes in any of the following: intubator (OR 1.80, 95% CI 1.56 to 2.07), stylet use (OR 1.65, 95% CI 1.36 to 2.01) or endotracheal tube (ETT) size (OR 2.11, 95% CI 1.74 to 2.56). Changes in stylet use were associated with a reduced chance of severe desaturation (OR 0.74, 95% CI 0.61 to 0.90), but changes in intubator, laryngoscope type or ETT size were not; no changes in intubator or equipment were associated with severe TIAEs. CONCLUSIONS: Successful neonatal intubation on a second attempt was more likely with a change in intubator, stylet use or ETT size.

Factors that determine first intubation attempt success in high-risk neonates.

BACKGROUND: Approximately 50% of all neonatal endotracheal intubation attempts are unsuccessful and associated with airway injury and cardiorespiratory instability. The aim of this study was to describe intubation practice at a high-risk Neonatal Intensive Care Unit (NICU) and identify factors associated with successful intubation at the first attempt. METHODS: Retrospective cohort study of all infants requiring intubation within the Royal Children's Hospital NICU over three years. Data was collected from the National Emergency Airway Registry for Neonates (NEAR4NEOS). Outcomes were number of attempts, level of operator training, equipment used, difficult airway grade, and clinical factors. Univariate and multivariate analysis were performed to determine factors independently associated with first attempt success. RESULTS: Three hundred and sixty intubation courses, with 538 attempts, were identified. Two hundred and twenty-five (62.5%) were successful on first attempt, with similar rates at subsequent attempts. On multivariate analysis, increasing operator seniority increased the chance of first attempt success. Higher glottic airway grades were associated with lower chance of first attempt success, but neither a known difficult airway nor use of a stylet were associated with first attempt success. CONCLUSION: In a NICU with a high rate of difficult airways, operator experience rather than equipment was the greatest determinant of intubation success. IMPACT: Neonatal intubation is a high-risk lifesaving procedure, and this is the first report of intubation practices at a quaternary surgical NICU that provides regional referral services for complex medical and surgical admissions. Our results showed that increasing operator seniority and lower glottic airway grades were associated with increased first attempt intubation success rates, while factors such as gestational age, weight, stylet use, and known history of difficult airway were not. Operator factors rather than equipment factors were the greatest determinants of first attempt success, highlighting the importance of team selection for neonatal intubations in a high-risk cohort of infants.

Lung ultrasound detects regional aeration inhomogeneity in ventilated preterm lambs.

BACKGROUND: Inhomogeneous lung aeration is a significant contributor to preterm lung injury. EIT detects inhomogeneous aeration in the research setting. Whether LUS detects inhomogeneous aeration is unknown. The aim was to determine whether LUS detects regional inhomogeneity identified by EIT in preterm lambs. METHODS: LUS and EIT were simultaneously performed on mechanically ventilated preterm lambs. LUS images from non-dependent and dependent regions were acquired and reported using a validated scoring system and computer-assisted quantitative LUS greyscale analysis (Q-LUSMGV). Regional inhomogeneity was calculated by observed over predicted aeration ratio from the EIT reconstructive model. LUS scores and Q-LUSMGV were compared with EIT aeration ratios using one-way ANOVA. RESULTS: LUS was performed in 32 lambs (~125d gestation, 128 images). LUS scores were greater in upper anterior (non-dependent) compared to lower lateral (dependent) regions of the left (3.4 vs 2.9, p = 0.1) and right (3.4 vs 2.7, p < 0.0087). The left and right upper regions also had greater LUS scores compared to right lower (3.4 vs 2.7, p < 0.0087) and left lower (3.7 vs 2.9, p = 0.1). Q-LUSMGV yielded similar results. All LUS findings corresponded with EIT regional differences. CONCLUSION: LUS may have potential in measuring regional aeration, which should be further explored in human studies. IMPACT: Inhomogeneous lung aeration is an important contributor to preterm lung injury, however, tools detecting inhomogeneous aeration at the bedside are limited. Currently, the only tool clinically available to detect this is electrical impedance tomography (EIT), however, its use is largely limited to research. Lung ultrasound (LUS) may play a role in monitoring lung aeration in preterm infants, however, whether it detects inhomogeneous lung aeration is unknown. Visual LUS scores and mean greyscale image analysis using computer assisted quantitative LUS (Q-LUSMGV) detects regional lung aeration differences when compared to EIT. This suggests LUS reliably detects aeration inhomogeneity warranting further investigation in human trials.

Surfactant status assessment and personalized therapy for surfactant deficiency or dysfunction.

Surfactant is a pivotal neonatal drug used both for respiratory distress syndrome due to surfactant deficiency and for more complex surfactant dysfunctions (such as in case of neonatal acute respiratory distress syndrome). Despite its importance, indications for surfactant therapy are often based on oversimplified criteria. Lung biology and modern monitoring provide several diagnostic tools to assess the patient surfactant status and they can be used for a personalized surfactant therapy. This is desirable to improve the efficacy of surfactant treatment and reduce associated costs and side effects. In this review we will discuss these diagnostic tools from a pathophysiological and multi-disciplinary perspective, focusing on the quantitative or qualitative surfactant assays, lung mechanics or aeration measurements, and gas exchange metrics. Their biological and technical characteristics are described with practical information for clinicians. Finally, available evidence-based data are reviewed, and the diagnostic accuracy of the different tools is compared. Lung ultrasound seems the most suitable tool for assessing the surfactant status, while some other promising tests require further research and/or development.

The neonatal airway.

Safe and effective management of the neonatal airway requires knowledge, teamwork, preparation and experience. At baseline, the neonatal airway can present significant challenges to experienced neonatologists and paediatric anaesthesiologists, and increased difficulty can be due to anatomical abnormalities, physiological instability or increased situational stress. Neonatal airway obstruction is under recognised, and should be considered an emergency until the diagnosis and physiological implications are understood. When multiple types of difficulties are present or there are multiple levels of anatomical obstruction, the challenge increases exponentially. In these situations, preparation, multi-disciplinary teamwork and a consistent hospital-wide approach will help to reduce errors and morbidity.