Safety of sputum induction in chronic obstructive pulmonary disease

The aim of the present study was to evaluate the safety of sputum induction in patients with varying severity of chronic obstructive pulmonary disease. The subjects were 28 smokers with baseline forced expiratory volume in one second (FEV1) of (mean and range) 1.8 (0.8-2.9) L that is 53 (28-69)% of the predicted and reversibility of 2.5 (-7.4-9.9)%. Sputum was induced after premedication with 200 microg salbutamol at increasing concentrations (0.9, 3, 4, and 5%) of hypertonic saline nebulized by an ultrasonic nebulizer. The procedure was well tolerated, and none of the patients reported major side-effects. However, the mean change from prebronchodilator FEV1 during induction was -8.5 (-23-11)%, p=0.001, and from postbronchodilator FEV1 -10.7 (-25-5)%, p<0.0001. Three (11%) of the patients had a fall in FEV1 from the prebronchodilator baseline of >20%, and a further 10 (36%) had a fall of 10-20%. Patients with greater reversibility in airway obstruction seemed to get the best benefit from the bronchodilator pretreatment, since there was an inverse relationship between reversibility in FEV1 and fall in FEV1 during induction (r=-0.4, p=0.03). It is concluded that sputum induction by hypertonic saline inhalation can cause meaningful bronchoconstriction in patients with chronic obstructive pulmonary disease, despite pretreatment with an inhaled beta2-agonist. The results highlight the importance of monitoring spirometry during sputum induction to detect bronchoconstriction.