The safety of sputum induction in adults with acute exacerbation of COPD
Induced sputum is a non-invasive method, and a useful tool to evaluate inflammatory cells and mediators in the airway lumen in the setting of acute exacerbation of chronic obstructive pulmonary disease (AECOPD). However, the inhalation of hypertonic saline solution to induce sputum may cause a bronchoconstrictive response, so it is important to evaluate the success and safety of sputum induction (SI).The aims of this study were to assess the safety and efficacy of SI in adults with AECOPD.Eighty-three AECOPD subjects and 26 healthy controls underwent a modified SI. The outcome measures included fall in lung function during induction and success of SI.Adults hospitalized with AECOPD had moderate to very severe airflow obstruction. SI was successful in over 80% of subjects. The percentage decrease in forced expiratory volume in 1s (FEV1 ) from baseline by the Global initiative for Chronic Obstructive Lung Disease (GOLD) category was median 1.2(interquartile range, 0.5-3.3)(GOLD II), 2.3(1.3-3.2)(GOLD III), 5.2(3.3-8.6)(GOLD IV) and 1.4(0.5-3.2)(control), respectively. A fall in FEV1 of >20% occurred in only one subject with AECOPD who was in GOLD category III. The decrease in percentage of FEV1 from baseline was greatest in the second stage of induction, and correlated with that of the final stage (r=0.589; P=0.01). The fall in FEV1 during induction increased with GOLD category (P<0.05).SI can be safely and successfully performed in patients with moderate to very severe chronic obstructive pulmonary disease who experience an exacerbation using this modified induction protocol. The early decrease in FEV1 can be used to predict the maximum fall.