Air leak syndrome in animals: definition and pathogenesis

Air leak syndrome (ALS) is described in human medicine as a constellation of clinical disorders including pneumomediastinum, pneumopericardium, pulmonary interstitial emphysema, pneumothorax, pneumoperitoneum, pneumoretroperitoneum and subcutaneous emphysema. The pathogenesis of ALS depends on the anatomy of the mediastinum and its associations with thoracic, abdominal and cervical connective tissues, as well as a physical phenomenon referred to as the Macklin effect. Various animal species develop diverse combinations of these lesions, although ALS has not been recognized in animals. However, this term aids pathologists in addressing this disease compilation. The aim of this retrospective study is to illustrate examples of ALS in animals by arbitrarily selecting 13 cases in dogs, cats, pinnipeds, sea otters and harbour porpoises. ALS can be classified into three groups based on aetiology: iatrogenic, secondary or spontaneous. Iatrogenic ALS was diagnosed in two cats with tracheal laceration following endotracheal intubation. Secondary ALS was identified in two dogs, one with acute respiratory distress syndrome and the other due to grass awn migration. Secondary ALS in pinnipeds was diagnosed following severe pulmonary parasitism, uraemic pneumonia and oesophageal perforation. The other marine mammals developed ALS following trauma. Spontaneous ALS was also diagnosed in one cat and one dog without any apparent predisposing causes.

Risk factors and neonatal outcomes of pulmonary air leak syndrome in extremely preterm infants: A nationwide descriptive cohort study

Most extremely preterm infants (EPIs), who were born before 28 weeks of gestation, with pulmonary air leak syndrome (ALS) are symptomatic, often severe, and require drainage. EPIs with severe air leak syndrome (sALS) that require tube drainage or needle aspiration are at high risk of morbidities and mortality. This study aimed to investigate perinatal characteristics, morbidities, and mortality in EPIs with sALS, and to estimate the risk of mortality according to gestational age (GA). A prospective cohort study conducted from 2013 to 2020 compiled the Korean Neonatal Network database to evaluate the incidence, perinatal characteristics, and outcomes of sALS in EPIs born before 28 weeks of gestation. Among 5666 EPIs, the incidence of sALS was 9.4% and inversely related to GA. From this cohort, we compared 532 EPIs with sALS to 1064 EPIs without sALS as controls, matching the subjects by GA and birth weight. Preterm premature rupture of membranes, oligohydramnios, resuscitation after birth, low Apgar scores, repeated surfactant administration, persistent pulmonary hypertension of the newborn, and pulmonary hemorrhage were associated with the development of pneumothorax. The sALS group required a higher fraction of inspired oxygen and more invasive respiratory support at both 28 days of life and 36 weeks of postmenstrual age. The sALS group had a higher incidence of bronchopulmonary dysplasia and major brain injury. The mortality rate was higher in the sALS group than in the control group (55.3% vs 32.5%, P < .001), and the ALS group had a 1.7 times risk of mortality than the control group. More attention should be paid to sALS in EPIs because the frequency of sALS increased as GA decreased, and the risk of mortality was more significant at lower GA.

Incidence of Air Leak Syndrome in Pediatric Patients With SARS-COV-2 Pneumonia and Respiratory Failure: A Single-Center Retrospective Study

Air leak syndrome (ALS) is defined as the extrusion of air from an aerated compartment into an unaerated compartment with associated symptoms of respiratory distress. This syndrome can occur as a consequence of trauma, iatrogenic causes, or spontaneously. Retrospective investigations conducted in the adult population have demonstrated an elevated risk of spontaneous ALS development in patients with coronavirus disease 2019 (COVID-19) pneumonia, along with its correlation with mortality. However, no studies have yet explored this phenomenon within the pediatric population. In light of this knowledge gap, we conducted a retrospective chart review comprising 128 pediatric patients ranging in age from one month to 18 years. The primary objective was to assess the incidence of ALS in two distinct groups: patients diagnosed with COVID-19 pneumonia and those with non-COVID-19 viral pneumonia. The groups were compared using Fisher's exact test for sex, the presence of ALS, the requirement of extracorporeal membrane oxygenation (ECMO), and death. The modified Wald method was used to calculate the 95% confidence interval for the mortality rate in patients with COVID-19 pneumonia in the presence of ALS. Our findings revealed a higher prevalence of ALS in patients with COVID-19 pneumonia compared to the non-COVID-19 viral pneumonia group, with a statistically significant P-value of 0.02 and an odds ratio (OR) of 6.72. In terms of mortality rates, there was a statistically significant difference between the two groups (P = 0.025, OR = 1.083). In addition, in patients with ALS in the presence of COVID-19 pneumonia, the mortality rate was 37.5%. However, the requirement of ECMO was not statistically significant (P = 0.16, OR = 1.04). These results suggest that patients with COVID-19 pneumonia have an increased mortality rate and a heightened risk of developing ALS compared to individuals with other viral pneumonias. Furthermore, the presence of ALS was associated with a high mortality rate in COVID-19 pneumonia patients. However, it is crucial to note that obtaining a larger patient sample and involving multiple institutions would be necessary to obtain more consistent and robust data.

Organizing Pneumonia and Ulcerative Colitis: A Relationship To Remember

Ulcerative colitis (UC) is a chronic inflammatory bowel disease characterised by relapsing and remitting mucosal inflammation of the colon. Despite primarily affecting the gastrointestinal tract, UC has various extraintestinal manifestations that often affect other organs and systems. Although pulmonary involvement is uncommon, organising pneumonia (OP), which affects the lung parenchyma, is one of the potential extraintestinal manifestations of UC. We report a case of OP in a 35-year-old male with a longstanding history of UC, well-medicated with sulfasalazine (SSZ). He presented to the emergency department (ED) with complaints of fatigue, coughing, myalgia, thoracalgia and dyspnoea. A chest X-ray showed parenchymal infiltrates and computed tomography revealed bilateral consolidation. Under a preliminary diagnosis of atypical pneumonia, he was treated with an empirical broad-spectrum antimicrobial agent, which did not lead to any clinical, laboratory or imaging improvement. Furthermore, the diagnostic work-up excluded any malignancy or infectious cause. A probable diagnostic hypothesis was OP as an extraintestinal manifestation of UC or as an adverse effect of SSZ therapy. Hence, SSZ was discontinued, and he was successfully treated with corticosteroids, exhibiting significant improvements and recovering completely during the follow-up period. Despite lung involvement in UC being rare, we present this case to emphasise the importance of a thorough differential diagnosis when treating acute respiratory illness in patients with UC, including extraintestinal manifestations of UC, especially OP, even during a period of remission. We also emphasise the importance of early initiation of corticosteroid therapy to prevent major complications and promote recovery.

Pneumomediastinum and Pneumopericardium as Uncommon Complications of COVID-19 Infection: A Review Article

There is an emerging body of literature describing an increasing incidence of pneumomediastinum and, to a lesser extent, pneumopericardium as a complication of COVID-19. However, the literature lacks information regarding patients' characteristics and a general view of this unusual condition. The purpose of this paper is to summarize the current literature on this phenomenon. In this study, we summarize the risk factors/etiology, imaging modalities, management, and prognosis of known cases in the literature. In total, 48 articles were included in the study, ranging from case reports to case series. Most patients were male (83.3%). The overall mortality rate was 27.1% and the recovery rate was 62.5%.

Air-Leak Syndrome with Spontaneous Tension Pneumothorax and Pneumomediastinum Caused by Bleomycin-Induced Organizing Pneumonia

Teaching Point: The appearance of pneumatoceles in a patient with organizing pneumonia is an early sign of leak syndrome and is a significant finding as its rupture can lead to a life-threatening tension pneumothorax. Air leak syndrome (ALS), consisting of pneumothorax, subcutaneous emphysema and pneumomediastinum, is a rare complication of organizing pneumonia (OP). We report a case of a patient with bleomycin-induced OP who develops a tension pneumothorax due to a ruptured pneumatocele caused by ALS and correlate with histopathological analysis. This is the third case in the literature with these findings and the first with a tension pneumothorax.

Refractory Pulmonary Interstitial Emphysema in Extreme Premature Newborn

Pulmonary interstitial emphysema (PIE) occurs when air leaks into the pulmonary interstitium due to overdistension of distal airways, it occurs mainly in neonates with respiratory distress syndrome who need positive pressure ventilation but has also been reported in spontaneously breathing infants. Herein, we report on an extremely low birth weight infant with severe persistent PIE, while on invasive mechanical ventilation (high-frequency oscillatory ventilation, high-frequency jet ventilation, and neurally adjust ventilator assist) managed successfully with 2 weeks of selective right lung ventilation after failure of more conservative measures, including shorter periods of right mainstem intubation, before the prolonged trial that was successful.

COVID-19 Pneumomediastinum: Possible Role of Transesophageal Echo in Bedside Percutaneous Bicaval Double-Lumen ECMO Cannulation in Children. A Case Report

COVID-19 is generally uneventful in children. Only 8% of severe acute respiratory distress syndrome corona virus 2 pediatric patients require intensive care; of these, 1% may need extracorporeal membrane oxygenation. Preexisting medical conditions are an independent risk factor for pediatric intensive care unit admission. We describe the case of an 11-year-old girl with adenosine deaminase 2 deficiency who presented severe COVID-19 acute respiratory distress syndrome, complicated by a massive air leak syndrome. The respiratory failure, refractory to conventional support, required veno-venous extracorporeal membrane oxygenation. To prevent viral diffusion, bicaval double-lumen cannulation was performed percutaneously at the bedside under exclusive echo guidance. Because of pneumomediastinum, pneumothorax, and subcutaneous emphysema, ultrasound visualization of the heart was possible only with transesophageal echo. To our knowledge, this is the first description of a transesophageal echo guided bedside percutaneous bicaval double-lumen extracorporeal membrane oxygenation cannulation in a pediatric patient. Pitfalls of the technique are highlighted.

Predictive Factors for Pneumomediastinum During Management of Connective Tissue Disease-related Interstitial Lung Disease: A Retrospective Study

Objective To identify factors associated with pneumomediastinum during management of connective tissue disease (CTD)-related interstitial lung disease (ILD). Methods Patients diagnosed with pneumomediastinum after the initiation of corticosteroid therapy for their CTD-ILD were enrolled. The baseline characteristics of patients who developed pneumomediastinum after the initiation of corticosteroid therapy (n=13, all occurring within 120 days) were compared to those of patients who did not develop pneumomediastinum (n=49). A multivariate logistic regression analysis was performed to identify factors associated with pneumomediastinum. A receiver operating characteristic (ROC) curve analysis was also performed to assess the predictive performance. Results The body mass index (BMI) [odds ratio (OR) (95% confidence interval (CI)) 0.482 (0.272-0.853)] and serum lactate dehydrogenase (LDH) [OR (95% CI) 1.013 (1-1.025)] levels at baseline were identified as independent factors associated with pneumomediastinum after corticosteroid initiation. The optimal cut-off points of the BMI and LDH levels for predicting pneumomediastinum development, as estimated by the Youden index, were 20.2 kg/m² and 378 U/L, respectively. LDH showed a sensitivity of 61.5% and the highest specificity of 87.8%. Importantly, combining these markers resulted in the highest sensitivity of 100% and a specificity of 71.4%. Conclusion A low BMI and high serum LDH levels at baseline are useful predictive factors for pneumomediastinum development in CTD-ILD patients.

Association between ventilatory settings and pneumothorax in extremely preterm neonates

OBJECTIVES

Pneumothorax is a catastrophic event associated with high morbidity and mortality, and it is relatively common in neonates. This study aimed to investigate the association between ventilatory parameters and the risk of developing pneumothorax in extremely low birth weight neonates.

METHODS

This single-center retrospective cohort study analyzed 257 extremely low birth weight neonates admitted to a neonatal intensive care unit between January 2012 and December 2017. A comparison was carried out to evaluate the highest value of positive end-expiratory pressure (PEEP), peak inspiratory pressure (PIP), and driving pressure (DP) in the first 7 days of life between neonates who developed pneumothorax and those who did not. The primary outcome was pneumothorax with chest drainage necessity in the first 7 days of life. A matched control group was created in order to adjust for cofounders associated with pneumothorax (CRIB II score, birth weight, and gestational age).

RESULTS

There was no statistically significant difference in PEEP, PIP, and DP values in the first 7 days of life between extremely low birth weight neonates who had pneumothorax with chest drainage necessity and those who did not have pneumothorax, even after adjusting for potential cofounders.

CONCLUSIONS

Pressure-related ventilatory settings in mechanically ventilated extremely low birth weight neonates are not associated with a higher risk of pneumothorax in the first 7 days of life.

Unilateral neonatal pulmonary interstitial emphysema managed conservatively: A case report

BACKGROUND

Pulmonary interstitial emphysema (PIE) is a pathological state when air escapes from ruptured alveoli and is trapped along the sheaths surrounding the bronchovascular bundle. PIE is not uncommon in infants who require mechanical ventilation and even less common in infants on noninvasive ventilatory support; however, it is extremely unusual in infants in room air.

CASE PRESENTATION

A 2-week-old male infant developed worsening tachypnea in the special-care nursery. The patient was born at 33 weeks' gestation by induced vaginal delivery due to pre-eclampsia. He required positive pressure ventilation at birth and was admitted to the neonatal intensive care unit on nasal continuous positive airway pressure. On the second day of life, exogenous surfactant was administered via endotracheal tube due to increased oxygen requirement, and, soon after, he was weaned off all respiratory support. After 10 days of stability, he developed tachypnea with diminished air entry on the left side of the chest. Chest radiograph and chest computerized tomography confirmed left-sided unilateral PIE. The patient was treated conservatively with positional therapy alone. Significant clinical and radiographic improvement was noticed within 4 days; almost complete resolution by 10 days and the infant was discharged 23 days later. At follow-up at 7 months, the infant was found to be symptom-free with a normal chest radiograph.

CONCLUSIONS

Traditional management of unilateral PIE generally involves a combination of invasive ventilatory support and positional therapy to break the vicious cycle pathophysiology of PIE. This report focuses on the insidious progression of PIE in nonventilated neonates and describes a nontraditional conservative management strategy for the management of unilateral PIE.

Clinical and imaging characteristics of hematologic disease complicated by air leak syndrome: A STROBE-compliment observational study

There are limited systematic studies on hematologic disease complicated by air leak syndrome (ALS). Physicians in radiology departments and hematology departments have a limited awareness of ALS.The aim of this study was to explore the similarities and differences in clinical data between the clinical group and imaging group in patients with hematologic disease complicated by ALS.Clinical and CT data for 59 patients with hematologic disease complicated by ALS in our hospital were retrospectively reviewed. Patients were assessed by clinical grouping and image grouping. Data were compared between groups, and P < .05 was considered statistically significant.Dyspnea occurred more often in the allo-HSCT (allogeneic hematopoietic stem cell transplantation) group than that in the non-allo-HSCT group (68.8% vs 4.7%, P < .001), there were statistically significant differences in inducing factors between groups, and differences in other aspects were not statistically significant. Chest tightness and dyspnea occurred more often in the allo-HSCT with BO/BOOP (bronchiolitis Obliteran/bronchiolitis obliterans organizing pneumonia) group than those in the allo-HSCT without BO/BOOP group (80.0% vs 9.1%, P = .013), and differences in other aspects were not statistically significant. Chest pain occurred more often in the HPT (hydropneumothorax) group than that in the other 3 groups (pure pneumothorax [PT], pulmonary interstitial emphysema [PIE], complex ALS) (71.4% vs 11.1%, 0.0%, and 26.5%, P = .005); ALS thickness in the HPT group was greater than that in the other 2 groups (PIE and complex ALS) (19.7 vs 3.5 cm and 9.5 cm, P = .001); catheter drainage occurred more often in the HPT group than that in the other three groups (PT, PIE, complexALS) (64.3% vs 22.2%, 0.0%, and 2.9%, P = .001).ALS is a high risk in male patients who have a low BMI, have leukemia as a basic disease, and have basic lung diseases (eg, BO/BOOP). CT types are mainly complex ALS, HPT, and pure PT. In addition, clinical symptoms for patients in the HPT group are severe, and there is a high prevalence of catheter drainage.