The tolerability, safety, and success of sputum induction and combined hypertonic saline challenge in children

Induced sputum using hypertonic saline (HS) is a useful research tool to st udy airway inflammation (AI). HS provocation testing can also be used to me asure airway hyperresponsiveness (AHR). A combined HS challenge and sputum induction procedure has been developed to permit assessment of Al and AHR i n a single test. The aim of this study is to report the success and tolerab ility of sputum induction alone, and in combination with a HS bronchial pro vocation challenge. Sputum induction alone was performed with beta (2)-agon ist pretreatment. In the combined challenge, no beta (2)-agonist pretreatme nt was used. A high-output ultrasonic nebulizer with valve box and tubing w ere used to deliver 4.5% saline in doubling time periods from 0.5 s to 4 mi n. Outcomes assessed were completion of the test protocol, adequacy of sput um samples, decrease in FEV1, and adverse effects during the procedure. Fif ty-three children who underwent a sputum induction alone, and 182 children who underwent a combined sputum induction and bronchial provocation using H S. Sputum induction alone was well tolerated, with 98% of children completi ng the procedure and only 4% experiencing a significant (> 15%) fall in FEV 1. An adequate sample of sputum was obtained in 92% of children. The combin ed challenge was completed by 90% of children. A distressing cough occurred in 13% of children and irritation of the mucosa in 1% of children. In the combined challenge an adequate sample of sputum was obtained in significant ly fewer children than with sputum induction alone (70% versus 92%, p < 0.0 5). Sputum cellular changes reflected the shorter nebulization time with sp utum induction alone. We conclude that induction of sputum using HS after p retreatment with bronchodilator is well tolerated with a high success rate in children. Combining the HS challenge with sputum induction provides addi tional information and is a useful means of comparing AHR and Al simultaneo usly, but at the expense of having a reduced success rate in obtaining an a dequate sample of sputum, as well as increased side effects.