Safety of sputum induction in moderate-to-severe chronic obstructive pulmonary disease

Abstract

This retrospective study was designed to evaluate the safety and efficacy of a bronchoprotective sputum induction protocol in moderate to severe chronic obstructive pulmonary disease (COPD). Forty-two adults with COPD (FEV1 = 51.7 ± 3.2% predicted (mean ± SEM)) underwent sputum induction using a protocol designed to minimize hypertonic saline-induced bronchoconstriction. Hypertonic (3%) saline was used for subjects with FEV1 ≥50%, and normal (0.9%) saline was used for subjects with FEV1 <50%. Primary outcomes were change in peak flow, FEV1 and oxygen saturation. Mean decline in peak flow during sputum induction was 13.2±2.1%. FEV1 fell by 11.4±23%, an absolute fall of 0.14±0.031. Oxygen saturation did not change. A fall in peak flow of ≥20% reliably predicted a fall in FEV1 of ≥20%, Thirty-five of 42 subjects (83.3%) produced an acceptable sputum sample. Sputum eosinophil and neutrophil percentages were 2.8±0.9 and 73.0±3.0%, respectively, and were not correlated with changes in peak flow, FEV1 or oxygen saturation. A protocol for sputum induction which restricts the use of hypertonic saline based on lung function is both safe and effective in subjects with moderate to severe COPD. © 2002 Elsevier Science Ltd. All rights reserved.