Characterization of adolescents with functional respiratory disorders and prior history of SARS-CoV-2

Abstract

Background: The SARS-CoV-2 pandemic has caused significant pulmonary morbidity and mortality in the adult population. Children and adolescents typically show milder symptoms; however, a relevant proportion of them report persistent pulmonary symptoms even after mild SARS-CoV-2 infection. Functional respiratory disorders may be relevant differential diagnoses of persistent dyspnea. This study aims at characterizing functional respiratory disorders that may arise after SARS-CoV-2 infection regarding their clinical presentation and pulmonary function tests as well as gaining insights into the clinical course after initiation of appropriate therapy.

Methods: This study retrospectively identified all patients referred to an outpatient clinic for pediatric pulmonology with functional respiratory disorders manifesting after proven SARS-CoV-2 infection between January 1, 2022, and October 31, 2022. Clinical history, thorough clinical examination regarding breathing patterns, and pulmonary function tests (PFTs) were taken into consideration to diagnose functional respiratory disorders.

Results: Twenty-five patients (44% female) with mean (m) age = 12.73 years (SD ± 1.86) who showed distinctive features of functional respiratory disorders after SARS-CoV-2 infection (onset at m = 4.15 (± 4.24) weeks after infection) were identified. Eleven patients showed thoracic dominant breathing with insufficient ventilation, and 4 patients mainly had symptoms of inducible laryngeal obstruction. The rest (n = 10) showed overlap of these two etiologies. Most patients had a flattened inspiratory curve on spirometry and slightly elevated residual volume on body plethysmography, but values of PFTs were normal before and after standardized treadmill exercise testing. Patients were educated about the benign nature of the condition and were offered rebreathing training. All patients with follow-up (n = 5) showed normalization of the breathing pattern within 3 months.

Conclusions: Functional respiratory disorders are important differential diagnoses in persisting post-SARS-CoV-2 dyspnea in adolescents. A combination of clinical history, detailed examination of breathing patterns, and pulmonary function tests are helpful to correctly diagnose these conditions. Reassurance and rebreathing training are the mainstay of the therapy. The clinical course is favorable.

Keywords: Dysfunctional breathing; Exercise-induced laryngeal obstruction; Functional respiratory disorder; Hyperventilation; Long-COVID syndrome.

Fig. 1

No differences in z-scores of forced expiratory volume in 1 s (FEV-1), resistance (Rtot), residual volume (RV), and peak inspiratory flow (PIF, in liters) while resting (n = 25) and after standardized treadmill exercise (n = 20) as well as during follow-up (n = 5). Mean, 25–75% quartiles and 95% confidence interval depicted

Fig. 2

Mildly increased residual volume and slightly flattened inspiratory curve on spirometry in a 14-year-old boy with functional respiratory symptoms of thoracic dominant breathing (with insufficient ventilation) 8 weeks after SARS-CoV-2 infection. FRC, functional residual capacity; RV, residual volume; TLC, total lung capacity