Safety of Sputum Induction in Moderate-to-Severe Smoking-Related Chronic Obstructive Pulmonary Disease

BACKGROUND: Investigation of the safety of sputum induction in patients with moderate-to-severe chronic obstructive pulmonary disease (COPD) has been limited. OBJECTIVE: to evaluate this issue in 100 patients with a mean FEV1 of 1.2 (0.4) L. After 200 microg inhaled salbutamol, sputum induction was performed with inhaled saline in increasing and tailored concentrations (0.9% to 5%) until an adequate sample of sputum was obtained or the FEV1 fell by >20%. MAIN FINDINGS: Sputum induction was successful in 92% of occasions. The mean (SD) fall in FEV1 was 13.5 (8.6)%. Five patients had a fall >20% but all recovered to 10% of baseline after inhaled salbutamol. The magnitude of fall in FEV1 correlated weakly with salbutamol reversibility (r = 0.37, p < 0.001), baseline FEV1/VC (r = -0.32, p = 0.001) and baseline FEV1% predicted (r = -0.36, p = 0.003) but not with age, smoking history or post-Salbutamol FEV1. Principle CONCLUSION: Sputum induction can be performed safely using a patient-tailored approach in patients with moderate-to-severe COPD, supporting its use in research and clinical practice.