287 Nasal Nitric Oxide Levels after Lysine Aspirin Nasal Challenge in Subjects with Aspirin Induced Asthma

BACKGROUND: Changes in nasal nitric oxide (nNO) levels after nasal lysine aspirin (lys-ASA) challenge have not been determined. METHODS: Fourteen patients with aspirin induced asthma (AIA) with or without nasal polyps with aspirin were included to the study. Hypersensitivity had to be confirmed by positive result of oral aspirin challenge Ten healthy subjects served as the control group. 12 mg of lys-ASA were applied unilaterally. Nasal symptoms were assessed using visual analogue scale (VAS) and nNO and peak nasal inspiratory flow (PNIF) measurements were performed before and 1, 2, 4 and 24 hours after the challenge. The result of the challenge was considered as positive when at least 20% fall of PNIF as well as 20% increase of total VAS score were observed. RESULTS: Ten patients (71.4%) had clinically positive result of the challenge. We observed significant fall in nNO levels in AIA patients after 1 and 2 hours after the challenge (653. 1 ± 420. 2 at baseline versus 490. 3 ± 456. 0; P = 0.0029 and 439. 9 ± 556. 4 ppb; P = 0.0076; respectively). The decrease in nNO level was more pronounced in patients with clinically positive result of the challenge (510. 1 ± 212. 5 at baseline versus 283. 3 ± 173. 4; P = 0.005; 159, 6 ± 166,1; P = 0.005 and 331. 0 ± 312.0 ppb; P = 0.037 after 1, 2 and 3 hours, respectively). In 4 subjects with clinically negative result of the challenge we noticed a trend towards higher nNO concentrations after lys-ASA challenge (1010. 8 ± 625. 2 at baseline vs 1341. 3 ± 670. 5 ppb after 4 hours). No significant changes in nNO levels after the challenge were observed in healthy controls. CONCLUSIONS: NO levels decrease after lys-ASA nasal challenge in subjects with AIA and clinically positive nasal provocation. An unexpected trend towards increase in nNO levels was observed in subjects with AIA and clinically negative provocation Potential usefulness of nNO measurement in aspirin nasal provocation needs further evaluation.