Abstract Background Asthma is the most common chronic illness in the pediatric population. Objective evidence of reversible airway obstruction is recommended in the appropriate age group. Failure to respond to standard therapy should prompt reconsideration of the diagnosis. Missing subtle physiological clues can cause delays in identifying airway diseases.1 Case Presentation A 4-year-old girl presented for chronic cough and wheezing. Her physical exam showed normal vital signs (HR 133bpm, Temp 36.8 °C (98.2 °F), Resp 26, SpO2 99%) and normal pulmonary auscultation. Initial pulmonary function test (PFTs) showed flattening of the flow-volume loop but did not meet the American Thoracic Society testing standards. She was treated with inhaled corticosteroids and bronchodilators for persistent asthma with mild improvement. On follow up visit, the patient had reproducible PFTs (showing reproducible flattening of the flow-volume loop) with continued suboptimal technique. Review of her chest Xray (showing right perihilar consolidation versus atelectasis) along with her PFT results warranted further investigations. A computed tomography (CT) of the chest revealed tracheal compression secondary to pulmonary artery sling. She underwent vascular translocation surgery successfully with significant improvement in her respiratory symptoms and PFT. Discussion Vascular rings and pulmonary artery slings are uncommon congenital anomalies that can present with cough, wheezing, and recurrent respiratory infections, often leading to an initial diagnosis of asthma. The 2020 NHLBI Asthma Management Guidelines recommend incorporating objective testing, such as spirometry, to support the diagnosis of asthma whenever feasible. However, normal spirometry does not exclude structural airway disease, and even technically suboptimal studies may provide valuable diagnostic clues. In this case, the child’s spirometry efforts did not meet full acceptability criteria, yet the persistent flattening of the flow-volume loop across visits suggested a fixed central airway obstruction rather than the variable obstruction characteristic of asthma. Recognizing and interpreting this subtle but reproducible abnormality prompted further imaging, which confirmed a pulmonary artery sling as the underlying cause. This case underscores the importance of carefully evaluating flow-volume loop morphology when available, even when spirometry values alone appear limited, as early identification of structural airway anomalies allows timely surgical intervention and prevents prolonged morbidity. Conclusion This case highlights the importance of utilizing flow volume loops in considering structural airway anomalies in children with persistent or atypical respiratory symptoms unresponsive to asthma therapy. Early recognition of vascular rings can prevent morbidity and guide appropriate surgical management. 1CT scan with pulmonary artery sling and flattening of the flow volume loops This abstract is funded by: None
Chikhani et al. (Fri,) studied this question.