ELEVATED LEVELS OF EXHALED NITRIC-OXIDE IN BRONCHIECTASIS

Bronchiectasis is characterized by chronic inflammation in one or more bronchi, but the extent of inflammation is difficult to monitor. The concentration of nitric oxide (NO) in exhaled air is increased in asth matic patients, possibly as a result of the chronic inflammatory proce ss. We have measured exhaled NO in patients with documented bronchiect asis and investigated whether the concentration of exhaled NO is relat ed to the extent of disease as defined by computed tomography (CT) and lung function. In 20 patients with bronchiectasis who were not taking inhaled steroids, the peak concentration of NO in exhaled air, measur ed by a modified chemiluminescence analyzer, was significantly elevate d (285 +/- 49.0 ppb) as compared with values for 79 normal subjects(89 +/- 2.7 ppb, p < 0.01) and 19 patients with bronchiectasis treated wi th inhaled steroids (88 +/- 13.4 ppb, p < 0.01). Thin-section CT was u sed to quantify the extent of bronchiectasis in the 19 patients. There was a significant correlation between the CT score and FEV, (r = 0.73 , p < 0.01). In patients not treated with inhaled steroids there was a significant relationship between CT score and peak exhaled NO fr = 0. 81, n = 12, p < 0.02), but this was not the case for patients treated with regular inhaled steroids (n = 7). We conclude that untreated bron chiectasis is associated with an increase in exhaled NO, and that this is correlated with disease severity, whereas patients treated with in haled steroids have levels of exhaled NO within the normal range. The increase in exhaled NO in bronchiectasis, as in asthma, may reflect cy tokine-mediated chronic inflammation in the respiratory tract, and exh aled NO may represent a way of monitoring disease activity and assessi ng the effects of therapy.