SMOKING CESSATION IS ASSOCIATED WITH AN INCREASE IN EXHALED NITRIC-OXIDE

Study objectives: Nitric oxide (NO), a gas produced by cells lining th e respiratory tract, has been reported to be decreased in the exhaled air of cigarette smokers. We hypothesized that smoking cessation would result in an increase in exhaled NO. Design: Comparison of exhaled NO measured from nonsmokers, cigarette smokers, and smokers after smokin g cessation. Setting: University outpatient smoking cessation clinic. Patients or participants: Twenty-five cigarette smokers and 23 normal, nonsmokers. Interventions: Exhaled NO was measured by three technique s: (1) a peak oral method; (2) a mean oral method; and (3) a nasal met hod. The smokers were given nicotine patches and instructed to return after 1 and 8 weeks. The exhaled NO determinations were repeated on ea ch visit. Measurements and results: Compared with nonsmokers, smokers had decreased NO levels measured by all three methods (p<0.05, each co mparison). Nineteen smokers returned after 1 week. Fourteen were succe ssfully abstinent. from cigarettes and their exhaled NO increased comp ared with baseline (p<0.01 for each method) but not in the five subjec ts who had not successfully quit smoking (p>0.05 for each method). Ten subjects returned after a weeks. The exhaled NO levels increased furt her and were not significantly different from the normal nonsmokers fo r the peak oral and nasal NO methods (p>0.2), but-were still lower tha n the normal nonsmoker mean oral NO (p=0.018). Conclusions: These data demonstrate that smoking cessation is associated with an increase in exhaled NO.