Airway Problems in Neonates-A Review of the Current Investigation and Management Strategies

Higher versus lower nasal continuous positive airway pressure for extubation of extremely preterm infants in Australia (ÉCLAT): a multicentre, randomised, superiority trial

BACKGROUND

Extremely preterm infants often require invasive mechanical ventilation, and clinicians aim to extubate these infants as soon as possible. However, extubation failure occurs in up to 60% of extremely preterm infants and is associated with increased mortality and morbidity. Nasal continuous positive airway pressure (nCPAP) is the most common post-extubation respiratory support, but there is no consensus on the optimal nCPAP level to safely avoid extubation failure in extremely preterm infants. We aimed to determine if higher nCPAP levels compared with standard nCPAP levels would decrease rates of extubation failure in extremely preterm infants within 7 days of their first extubation.

METHODS

In this multicentre, randomised, open-label controlled trial done at three tertiary perinatal centres in Australia, we assigned extremely preterm infants to extubation to either higher nCPAP (10 cmH2O) or standard nCPAP (7 cmH2O). Infants were eligible if they were born at less than 28 weeks' gestation, were receiving mechanical ventilation via an endotracheal tube, and were being extubated for the first time to nCPAP. Eligible infants must have received previous treatment with exogenous surfactant and caffeine. Infants were ineligible if they were planned to be extubated to a mode of respiratory support other than nCPAP, if they had a known major congenital anomaly that might affect breathing, or if ongoing intensive care was not being provided. Parents or guardians provided prospective, written, informed consent. Infants were maintained within an assigned nCPAP range for a minimum of 24 h after extubation (higher nCPAP group 9-11 cmH2O and standard nCPAP group 6-8 cmH2O). Randomisation was stratified by both gestation (22-25 completed weeks or 26-27 completed weeks) and recruiting centre. The primary outcome was extubation failure within 7 days and analysis was by intention to treat. This trial was prospectively registered with the Australian New Zealand Clinical Trials Registry, number ACTRN12618001638224.

FINDINGS

Between March 3, 2019, and July 31, 2022, 483 infants were born at less than 28 weeks and admitted to the recruiting centres. 92 infants were not eligible, 172 were not approached, 65 families declined to participate, and 15 consented but were not randomly assigned. 139 infants were enrolled and randomly assigned, 70 to the higher nCPAP group and 69 to the standard nCPAP group. One infant in the higher nCPAP group was excluded from the analysis because consent was withdrawn after randomisation. 104 (75%) of 138 mothers were White. The mean gestation was 25·7 weeks (SD 1·3) and the mean birthweight was 777 grams (201). 70 (51%) of 138 infants were female. Extubation failure occurred in 24 (35%) of 69 infants in the higher nCPAP group and in 39 (57%) of 69 infants in the standard nCPAP group (risk difference -21·7%, 95% CI -38·5% to -3·7%). There were no significant differences in rates of adverse events between groups during the primary outcome period. Three patients died (two in the higher nCPAP group and one in the standard nCPAP group), pneumothorax occurred in one patient from each group, spontaneous intestinal perforation in three patients (two in the higher nCPAP group and one in the standard nCPAP group) and there were no events of pulmonary interstitial emphysema.

INTERPRETATION

Extubation of extremely preterm infants to higher nCPAP significantly reduced extubation failure compared with extubation to standard nCPAP, without increasing rates of adverse effects. Future larger trials are essential to confirm these findings in terms of both efficacy and safety.

FUNDING

National Health and Medical Research Council Centre for Research Excellence in Newborn Medicine, number 1153176.

Acoustic Cry Characteristics of Infants as a Marker of Neurological Dysfunction: A Systematic Review and Meta-Analysis

BACKGROUND

Atypical cries have been identified in infants with neurological dysfunction. The aim of this study was to conduct a systematic review and meta-analysis to appraise existing evidence for associations between acoustic cry characteristics and neurological dysfunction in infants aged 18 months or less.

METHODS

PubMed/MEDLINE, PsycINFO, CINAHL, and Embase were searched for original, peer-reviewed studies published in English reporting cry variables in infants aged 18 months or less with or at risk of neurological dysfunction. Studies without a nonneurologically impaired control sample were excluded. Pooled effect sizes were estimated using standardized mean difference (SMD) and odds ratio (OR). I² indicated study heterogeneity, and the risk of bias was assessed using the Newcastle-Ottawa Scale.

RESULTS

From March 2018 to February 2019, 28,294 studies were retrieved. Eight were meta-analyzed. Infants with or at risk of neurological dysfunction exhibited higher mean (SMD = 0.11 [95% confidence interval, 0.00 to 0.23]) and minimum (SMD = 0.93 [0.64 to 1.23]) fundamental frequency; higher odds of hyperphonation (OR = 13.17 [1.05 to 165.87]), biphonation (OR = 10.62 [1.53 to 73.59]), rise-fall-rise melodies (OR = 4.66 [1.16 to 18.66]), and flat melodies (OR = 4.47 [1.27 to 15.68]); and lower odds of fall-rise-fall melodies (OR = 0.21 [0.05 to 0.83]).

CONCLUSIONS

Infants with underlying neuropathology have unique cries characterized by higher fundamental frequency, dysphonation, and atypical melodies, although study heterogeneity and imprecision of effect size estimates limited our interpretation. Assessment of acoustic cry characteristics offers the potential for noninvasive, rapid, point-of-care screening for neurologically high-risk infants.

Clinical survey and predictors for the development of tracheobronchomalacia in preterm infants

BACKGROUND

Tracheobronchomalacia (TBM) contributes to the increased morbidity and mortality observed in preterm infants. Effective strategies for the prevention of TBM are necessary to achieve better outcomes. We sought to identify risk factors associated with the development of TBM in preterm infants. Optimal cut-off values for each risk factor were also determined.

METHODS

A total of 80 infants who were born at 36 week's gestation or earlier and underwent flexible bronchoscopy were included in our study sample. A comparison of demographic and clinical risk factors between those with TBM (n = 35, 44%) and those without TBM (n = 45, 56%) was conducted using multivariate logistic regression analysis. Receiver operating characteristic curve analysis was performed to determine the appropriate cut-off values for predicting the development of TBM.

RESULTS

In the multivariate analysis, only peak inspiratory pressure (PIP) and the number of intubation days remained significantly different between infants with and without TBM. Preterm infants with TBM received higher PIP (odds ratio: [OR], 1.067; 95% confidence interval [CI], 1.010-1.128; p = .020) and were intubated for longer (odds ratio [OR], 1.019; 95% CI, 1.003-1.035; p = .016) than those without TBM. Infants who received PIP > 19.5 cmH₂ O or were intubated for >79.5 days were associated with a significantly higher risk of presence of TBM.

CONCLUSION

High PIP and prolonged intubation were major risk factors for the development of TBM in premature infants. Those who require PIP > 19.5 cmH₂ O or intubation >79.5 days warrant bronchoscopy examination for early diagnosis and management of TBM.

Bronchial stenting in infants with severe bronchomalacia: Technique and outcomes

OBJECTIVES

To report the first use of a balloon expandable bare metal stent for treating infant bronchomalacia.

BACKGROUND

Infant bronchomalacia often requires prolonged mechanical ventilation and can be life-threatening. Effective treatment for severe infant bronchomalacia continues to be elusive. We present three cases of bronchial stenting for no-option or treatment refractory infant bronchomalacia.

METHODS

Three consecutive cases of stenting to relieve conservative treatment refractory severe infant bronchomalacia were performed between February 2019 and December 2020. Initial diagnosis was confirmed with Computed Tomography (CT) angiography. Patients underwent rigid micro laryngoscopy, bronchoscopy, and flexible bronchoscopy to evaluate the airway. Initial conservative management strategies were pursued. Patients failing initial conservative management strategies were considered for rescue bronchial stenting.

RESULTS

Our initial clinical experience with a coronary bare metal stent for these procedures has been favorable. The stent was easy to deploy with precision. We did not encounter stent embolization or migration. There was sufficient stent radial strength to relieve bronchomalacia without causing restenosis or erosion. There was no significant granulation tissue formation. In one patient, the stent was removed after 12 months of somatic growth; this was uneventful and bronchial patency was maintained. There were no complications in any of our patients regarding stent placement and reliability.

CONCLUSION

In cases of three infants with severe bronchomalacia, we found that bronchial stenting with the bare metal coronary stent was effective in relieving bronchial stenosis.

Risk Factors for Tracheobronchomalacia in Preterm Infants With Bronchopulmonary Dysplasia

Aim: To identify the risk factors associated with the development of tracheobronchomalacia (TBM) in preterm infants with bronchopulmonary dysplasia (BPD). Methods: This was a retrospective cohort study using chart reviews of preterm infants born at ≤ 36 week's gestation who underwent flexible fiberoptic bronchoscopy in a tertiary pediatric referral center between January 2015 and January 2020. Indications for the bronchoscopy examination included lobar atelectasis on plain chest film, persistent CO₂ retention, recurrent extubation failure, or abnormal breathing sounds such as wheeze or stridor. Optimal cutoff values for each risk factor were also determined. Results: Fifty-eight preterm infants with BPD were enrolled, of whom 29 (50%) had TBM. There were no significant differences in gestational age and birth weight between those with and without TBM. Significantly more of the patients with TBM had severe BPD compared to those without TBM (68.9 vs. 20.6%, p < 0.001). Clinical parameters that were significantly different between the two groups were included in multivariate analysis. Among these factors, severe BPD was the most powerful risk factor for the development of TBM (odds ratio 5.57, 95% confidence interval 1.32-23.5, p = 0.019). The areas under the receiver operating characteristic curves for peak inspiratory pressure (PIP) and the duration of intubation were 0.788 and 0.75, respectively. The best predictive cutoff values of PIP and duration of intubation for TBM were 18.5 mmHg and 82 days, respectively. Conclusion: Preterm infants with severe BPD are at high risk for the development of TBM, and the risk is even higher in those who receive a higher PIP or are intubated for longer. Bronchoscopy examinations should be considered for the early diagnosis and management of TBM in infants with these risk factors.

Prematurity and associated future paediatric airway pathology: experience from a single tertiary paediatric ENT centre

PURPOSE

Enhanced management of the pre-term patient has resulted in improved survival rates in increasingly premature patients. Although prematurity predisposes to congenital airway pathology, there is also increased risk of endotracheal intubation, and therefore acquired subglottic pathology. We sought to evaluate airway pathology in children outside the neonatal period with a history of prematurity to explore the relationship between prematurity and upper airway pathologies.

METHODS

Data for patients undergoing elective microlaryngobronchoscopy (MLB) at our centre were collected prospectively over a 5-year period. Patients identified as premature were sub-classified by the grade of prematurity.

RESULTS

339 patients over 1 month of age underwent MLB, of which 56 (16.5%) were born prematurely. Of those with identified airway pathology, 49 (23.4%) were born prematurely, accounting for 32.6% of subglottic stenosis (n = 30), 24% of laryngomalacia (n = 13) and 19% of laryngeal cleft diagnoses (n = 16). 49 premature patients (87.5%) had one or more airway pathologies diagnosed. Multi-level airway pathology was seen in twelve premature infants (21.4%), demonstrating a statistically significant association (odds ratio 3.396; 95% CI 1.697-6.842; p value < 0.0016). Incidence of airway pathology, the severity of airway disease and multi-level airway pathology were not related to the grade of prematurity.

CONCLUSIONS

Premature patients account for a significant proportion of the workload within our tertiary centre due to improving neonatal care and survival in pre-term infants. We suggest early paediatric ENT evaluation for ex-premature patients with symptoms of airway pathology, with a low threshold for MLB. Improving neonatal survival rates in ever-increasing prematurity will require the further provision of specialist paediatric ENT services to manage their ongoing care.

Tracheal opening manoeuvre (PEEP-20) in a patient with bronchopulmonary dysplasia and severe tracheobronchomalacia with neurally adjusted ventilatory assist (NAVA)

Bronchopulmonary dysplasia (BPD) is occasionally associated with tracheobronchomalacia, and it is this combination that can lead to serious outcomes. The most severe cases require tracheostomies, ventilatory support and eventually even tracheal stents or surgery. Ventilation in patients with tracheomalacia is complicated without a good patient-ventilator synchrony; the neurally adjusted ventilatory assist (NAVA) mode is potentially beneficial in these cases. This case report presents a patient affected by BPD and severe tracheobronchomalacia who was tracheostomised and ventilated 24 hours a day and who suffered from episodes of airway collapse despite using the NAVA mode. It was necessary to increase the positive end-expiratory pressure to 20 cmH₂O (the PEEP-20 manoeuvre) for several minutes during an episode; this allowed the trachea to remain open and allowed us to optimise the patient's ventilation. This strategy has previously been described in a patient with tracheomalacia, reducing the frequency and need for sedation in the following episodes.

ERS statement on tracheomalacia and bronchomalacia in children

Tracheomalacia and tracheobronchomalacia may be primary abnormalities of the large airways or associated with a wide variety of congenital and acquired conditions. The evidence on diagnosis, classification and management is scant. There is no universally accepted classification of severity. Clinical presentation includes early-onset stridor or fixed wheeze, recurrent infections, brassy cough and even near-death attacks, depending on the site and severity of the lesion. Diagnosis is usually made by flexible bronchoscopy in a free-breathing child but may also be shown by other dynamic imaging techniques such as low-contrast volume bronchography, computed tomography or magnetic resonance imaging. Lung function testing can provide supportive evidence but is not diagnostic. Management may be medical or surgical, depending on the nature and severity of the lesions, but the evidence base for any therapy is limited. While medical options that include bronchodilators, anti-muscarinic agents, mucolytics and antibiotics (as well as treatment of comorbidities and associated conditions) are used, there is currently little evidence for benefit. Chest physiotherapy is commonly prescribed, but the evidence base is poor. When symptoms are severe, surgical options include aortopexy or posterior tracheopexy, tracheal resection of short affected segments, internal stents and external airway splinting. If respiratory support is needed, continuous positive airway pressure is the most commonly used modality either via a face mask or tracheostomy. Parents of children with tracheobronchomalacia report diagnostic delays and anxieties about how to manage their child's condition, and want more information. There is a need for more research to establish an evidence base for malacia. This European Respiratory Society statement provides a review of the current literature to inform future study.

Evaluation of Acellular Bilayer Silk Fibroin Grafts for Onlay Tracheoplasty in a Rat Defect Model

OBJECTIVE

To assess the efficacy of acellular bilayer silk fibroin (BLSF) grafts to repair full-thickness tracheal defects and to compare the performance with conventional porcine small intestinal submucosa (SIS) implants.

STUDY DESIGN

A prospective controlled animal trial in a rat model of onlay tracheoplasty.

SETTING

Pediatric medical center.

SUBJECTS AND METHODS

Tracheal reconstruction of adult Sprague-Dawley rats was performed with BLSF (n = 38) or SIS (n = 32) matrices for up to 3 months of implantation. Functional evaluations of repaired conduits as well as histologic, immunohistochemical, and histomorphometric analyses of neotissues were assessed.

RESULTS

Prior to scheduled euthanasia, survival rates of rats receiving BLSF or SIS grafts were ≥94%, with no clinical signs of airway obstruction observed over the course of the study. Micro-computed tomography analysis revealed that the mean percentage of stenosis was <20% in both implant groups. BLSF and SIS grafts supported formation of pseudostratified ciliated columnar epithelium by 1 week postoperatively; however, each matrix failed to promote de novo chondrogenesis by 3 months following repair.

CONCLUSIONS

BLSF scaffolds can be used for reconstruction of rat tracheal patch defects with functional outcomes comparable to those of SIS matrices.

The wound healing capacity of undifferentiated and differentiated airway epithelial cells in vitro

INTRODUCTION

Congenital or acquired tracheal lesions alter airway epithelial structure and can lead to long-segment tracheal defects. Tissue engineered tracheal grafts (TETG) have the potential to cure such defects; however, clinical applications have been plagued with numerous complications including delayed graft epithelialization. The knowledge that epithelial cells migrate from native tissue to the TETG raises the possibility that TETG performance can be improved by increasing the rate of epithelialization.

OBJECTIVES

We developed a model that can be used quantify epithelial migration in clinically-relevant conditions.

METHODS

Existing histological analyses determined the differentiation status of the normal and injured human tracheal epithelium and were used to identify in vitro culture conditions that mimic these parameters. The classical scratch assay was adapted to permit analysis of migratory velocity as a function of differentiation status. Migration of undifferentiated (UD), partially-differentiated (PD), and well-differentiated (WD) epithelia was quantified.

RESULTS

The normal and injured epithelium can be modeled using human cells that are cultured using a modified air-liquid-interface culture system. PD cell cultures are similar to the remodeled epithelium; whereas; WD cultures are similar to the normal epithelium. Preliminary results indicate that PD cells migrate more rapidly than WD cells and that PD and WD cells migrate more rapidly than UD cells.

CONCLUSION

Pending verification of these results, we suggest that epithelial migration is significantly altered by differentiation status. Thus, efforts to improve TETG epithelialization should use model systems that faithfully-represent the differentiation state of the native tissue.