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 cellularity in induced sputum (IS) samples. However, there have been few studies employing sputum induction (SI) in pediatric patients. Objective: To assess the success rate, safety and tolerability of SI, as well as IS sample cellularity, in pediatric PSA patients. Methods: We conducted a cross-sectional study involving 44 pediatric PSA patients. We collected IS samples using inhalations 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, although 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. Conclusion: In our sample of pediatric patients with PSA, sputum induction was safe and generally well tolerated, suggesting that it could be useful in the assessment of inflammatory processes in such patients.