Open Access Sputum Induction in Children and Adolescents with Problematic Severe Asthma: Success Rate, Safety and Tolerability

Abstract: Background: In problematic severe asthma (PSA), inflammatory phenotypes can by identified by assessing cel-lularity in induced sputum (IS) samples. However, there have been few studies employing sputum induction (SI) in pedi-atric patients. Objective: To assess the success rate, safety and tolerability of SI, as well as IS sample cellularity, in pediatric PSA pa-tients. Methods: We conducted a cross-sectional study involving 44 pediatric PSA patients. We collected IS samples using inha-lations of nebulized saline solution. On the basis of the post-bronchodilator forced expiratory volume in one second (FEV1, % of predicted), we administered nebulization with 4.5 % hypertonic saline (for patients with an FEV1 60%) or 0.9 % isotonic saline (for those with an FEV1 < 60%). We classified IS samples as satisfactory if there was 20% squamous cell contamination and cell viability was> 50%. Results: The observed success rate was 75 % (95 % CI: 60-86). Most of the patients provided satisfactory samples, al-though multiple SI sessions were required in some cases (27%). In comparison with the IS samples containing> 20% squamous cells, those containing 20 % showed significantly more neutrophils (P = 0.02) and eosinophils (P = 0.03). The most common adverse events were mild wheezing (in 14%) and salty taste (in 9%). In 8 % of the sessions, there was a 20 % decrease in FEV1