Radiographic findings in severe bronchopulmonary dysplasia (BPD)To the editor,A 460g infant was born via cesarian-section at 26 weeks and 4 days gestation. The mother’s prenatal labs were unremarkable. The mother received magnesium phosphate for five doses prior to delivery. The infant was intubated at delivery and started on assist control volume guarantee (AC/VG) mode of ventilation. He received two doses of surfactant.Chest x-ray obtained on day of life (DOL) 1 showed granular airspace opacities throughout both lungs, suggestive of surfactant deficiency (Figure 1.). Serial radiographs throughout his neonatal intensive care unit stay re-demonstrated diffuse pulmonary opacities. He was intubated until DOL 47. He required a protracted course of mechanical ventilation. Echocardiogram demonstrated pulmonary hypertension, requiring initiation of inhaled nitric oxide. Echocardiogram showed right ventricular dilation with increased wall thickness. His right ventricular systolic pressure to be 60mmHg plus the right atrial pressure with interventricular septal flattening.Given his requirement for invasive ventilation at greater than 36 weeks post-menstrual age, he met criteria for severe bronchopulmonary dysplasia (BPD)1. A non-contrasted computed tomography (CT) scan was performed on DOL 180 to further characterize his lung disease. It showed diffuse bilateral coarse interlobular septal thickening and coarse band-shaped opacities likely representing areas of intermittent discoid atelectasis. In addition, it showed intermittent cystic lucencies suggestive of BPD (Figures 2-4). These findings are consistent with a profoundly severe case of BPD in an extremely preterm infant. He underwent a tracheostomy and continued synchronized intermittent mandatory ventilation/pressure regulated volume control plus pressure support (SIMV/PRVC + PS) using established BPD ventilator strategies. His ventilator settings have been progressively weaned to final discharge settings of PEEP of 10, TV of 10mL/kg, and PS of 30.BPD is a chronic lung disease of prematurity due to arrest of alveolarization in normal lung development, leading to the development of fewer, larger alveoli with less capacity for gas exchange2. While not standard in all cases, imaging can be useful in the characterization of certain severe cases of BPD. Chest x-ray is typically the first modality used. CT can be used in more complex cases. CT often demonstrates regions of decreased attenuation, emphysema-like change, linear and subpleural opacities, and bronchial wall thickening3.

To the Editor,Children’s interstitial lung disease (chILD) is an umbrella term that encompasses a heterogeneous group of complex, ultra-rare diffuse lung diseases affecting infants and children with a prevalence of <1 per 100,000 patients.5 There are over 200 disease conditions collectively grouped into chILD. Most conditions involve inflammation and secondary damage to the lungs which impacts gas exchange and may result in failure to thrive and respiratory failure in the most severe cases. The epidemiology of chILD is difficult to define given the low incidence and varying case definitions of disease. Prevalence is estimated to be likely <1 per 100,000 patients as compared to 60-80 per 100,000 in adults.3 Many European academic centers see between one and five new chILD cases each year.4 Diagnosing chILD is multi-faceted and complex not only including clinical assessment of symptoms and imaging, but possible need for lung biopsy and genetic testing. As chILD can result in impaired gas exchange, increased work of breathing, hypoxemia and/or hypercapnia, patients with chILD are at higher risk for sleep disordered breathing (SDB).2 As SDB may increase the risk of complications of chILD such as impaired growth and pulmonary hypertension, both might interplay and exacerbate one another.Prior studies have looked at SDB in chILD diagnoses such as neuroendocrine cell hyperplasia of infancy (NEHI) which is a rare pediatric disorder in which the abnormal growth of neuroendocrine cells in the lung parenchyma leads to hypoxemia and chronic respiratory distress. A study performed at Children’s Hospital Colorado has found a high incidence of sleep related breathing disorders in a NEHI cohort with 57% diagnosed with OSA, 3% with central sleep apnea (CSA), and 71% with nocturnal hypoxemia.1 As the prevalence of SDB was shown to be high in the NEHI cohort from Colorado, the aim of our study was to investigate SDB in a cohort of patients with a diverse spectrum of chILD diagnoses at our center.Methods :We performed a single-center retrospective chart review study approved by the Weill Cornell Medicine Institutional Review Board (IRB Protocol #21-11024168). Institutional IRB approved of waiver of informed consent given retrospective chart review study design. Study was conducted in accordance with Helsinki Declaration. We queried the electronic medical record to identify children age 0-21 years old who have ever received ICD-10 codes for chILD from 2012 to 2022 (Supplemental table 1). We performed a manual retrospective validation protocol to include only the patients who met criteria for chILD syndrome or a specific chILD diagnosis.6 We identified the children who were referred and underwent nocturnal polysomnogram (PSG), and analyzed demographic information, chILD diagnosis, clinical symptoms, reason for referral, and PSG data. Patients underwent standard level I PSG attended and reviewed by a registered polysomnography technologist using Natus system (Natus Medical Incorporation, San Carlos, CA, USA). Studies were interpreted by board-certified sleep physicians with sleep parameters based on American Academy of Sleep Medicine (AASM) guidelines. Obstructive sleep apnea (OSA) was defined by the presence of snoring, apnea, increased work of breathing, daytime sleepiness, behavioral problems, or learning problems combined with PSG findings of one or more obstructive apnea, mixed apnea, or hypopnea per hour of sleep (oAHI > 1/hr). Sleep related hypoxemia was defined as Descriptive statistics were used for categorical and continuous variables.Results :14 of the 52 children identified with a diagnosis of chILD had undergone a PSG. Their age ranged from one month to 19 years (median age of eight years). Four had a diagnosis of chILD associated with rheumatologic disease, four with bronchiolitis obliterans, two with ABCA3, one with NEHI, one with pulmonary interstitial glycogenesis and two with chILD of unknown etiology (Figure 1). The reasons for referral were symptoms of snoring (43%), restless sleep (7%), daytime sleepiness (7%) and assessment for nocturnal hypoxemia (71%). The PSG was diagnostic for OSA in 50% of patients with an oAHI range from 1.4 to 11.2 (median oAHI of 3.1) events/hr. Sleep related hypoxemia was diagnosed in in three patients (21%), one of them had OSA as well. No patients had central sleep apnea (Table 1). This led to an overall prevalence of OSA of 13% and a prevalence of SDB (OSA and/or hypoxemia) of 17% in our cohort of patients with chILD.Discussion :This study demonstrates a high prevalence of sleep disordered breathing (SDB) in a cohort of children with a spectrum of chILD diagnoses. We demonstrated that the prevalence of OSA is higher than that of the general pediatric population (1-4%).6 Sleep related breathing disorders in children with chronic lung disease are not well studied and may go undetected. Possible explanations might be under-recognition of SDB by physicians or parents given the medical complexity of the underlying chILD diagnosis, attributing respiratory symptoms in sleep to the underlying lung disease, and underreporting of sleep symptoms by parents unless specifically asked. In this study, not all patients with chILD systematically underwent PSG. Those that were referred were because they presented with symptoms. This might have led to an under-diagnosis of SDB. In our institution, however all patients with chILD are followed by pulmonologists who screen for sleep related breathing disorders at each visit and have a low threshold for PSG referral. This finding underscores the recommendation by the American Academy of Pediatrics to screen all pediatric patients for SDB as well as considering referring complex, high risk patients with chronic lung disease for further evaluation by a sleep specialist.There is a paucity of research in the field of pediatric sleep in chILD in comparison to the adult population.1 Previous studies in children found a high prevalence of OSA of 57% in a cohort of NEHI patients, and other studies identified the range to be anywhere from 33% to 61% in chILD.1,2 One study found that only 10% of their chILD population were observed to have mild or moderate OSA, and therefore they concluded that OSA seems uncommon in patients with chILD.2 The strength of our study was that we were able to evaluate the presence of SDB in diverse spectrum of chILD diagnoses which allows for increased recognition of comorbid sleep disorders. A limitation of our study is the small sample size. Considering how rare chILD is, a prospective multi-center study evaluating chILD patients by PSGs is needed to determine the prevalence and potential health outcomes.The impact of SDB on healthcare outcomes in patients with chILD is not well studied. We know that repeated collapse of the airway during sleep, increased respiratory effort, and impaired gas exchange with intermittent and/or sustained hypoxemia with concomitant hypercapnia activates the sympathetic nervous system leading to cardiovascular and endocrine morbidities. Neurobehavioral development has been linked to synaptic remodeling that occurs during sleep, and with the disruption in sleep associated with SDB, deficits in neurocognition have been well recognized.2 We know there is a critical relationship between untreated OSA and development of pulmonary hypertension, of which patients with chILD are already at risk for given their underlying lung disease. To improve outcomes and avoid detrimental effects on the cardiovascular system and child development, it is important to identify and treat comorbid SDB to improve outcomes in chILD.Conclusion/Summary :The aim of our study was to investigate the spectrum of sleep disordered breathing in a cohort of patients with children’s interstitial lung disease at our center. We performed a single-center retrospective chart review using ICD-10 codes for children’s interstitial lung disease from 2012-2022. For those who had a polysomnogram performed, we identified and analyzed demographic information, diagnosis, clinical symptoms, reason for referral, and the polysomnogram data. Of the patients in our cohort who received a sleep study, seven patients met diagnostic criteria for obstructive sleep apnea while 3 patients met criteria for sleep related hypoxemia. The prevalence of obstructive sleep apnea was 13% in our cohort. The overall prevalence of sleep disordered breathing in our cohort was 17%. This study demonstrates an increased prevalence of sleep disordered breathing in a cohort of children with spectrum of children’s interstitial lung disease diagnoses. We demonstrated that the prevalence of obstructive sleep apnea is higher than that of the general pediatric population. Sleep related breathing disorders in children with chronic lung disease are not well studied and may go undetected resulting in increased morbidity. Previous studies have evaluated sleep disordered breathing in specific chILD diagnoses such as neuroendocrine cell hyperplasia of infancy, so we aimed to expand to a larger spectrum of chILD diagnoses. This study expands our knowledge base surrounding comorbid sleep conditions in complex, ultra rare lung disease and advocates for early identification of sleep disorders to potentially improve health outcomes in patients with chILD.