Safety of sputum induction.

Abstract

One of the most important recent advances in the investigation of airway inflammation has been the introduction of sputum induction by inhalation of an aerosol of hypertonic saline, by Pin et al. 1 in 1992, to directly obtain airway secretions in asthma. This method has a number of advantages over invasive methods. Safety and practicality are the most obvious. The method of obtaining induced sputum is relatively noninvasive and can be carried out at random 2 and repeatedly in subjects with varying disease severity 3–13. Therefore, it is not surprising that the examination of induced sputum has become the most clinically applicable method for the assessment of airway inflammation. The induction procedure is simple and safe. The risks in patients with stable asthma or chronic obstructive pulmonary disease (COPD) with mild­to­moderate airflow limitation are acceptable 1, 3–5, 8, 12–14. It can also be safe in patients with more severe airflow limitation 6, 10, 11 provided that the induction is performed with caution using a modified procedure 6. The safety of sputum induction has been specifically addressed in several recent publications 3–5, 12, 14. To date, there have been no reports of death or need for hospital admission in patients undergoing sputum induction for the assessment of airway inflammation; the airway constriction caused by sputum induction with hypertonic saline is quickly reversed by treatment with an inhaled short­acting β2‐agonist. It is well known, however, that inhalation of hypertonic or even isotonic saline can cause airway constriction in asthmatic subjects and in COPD, particularly in those with associated airway hyperresponsiveness (AHR). In 1958, Bickerman et al. 15, using aerosols of saline generated by jet nebuliser with concentrations ranging 3.0–15%, observed …