on two consecutive beeps. The test takes on average 25 minutes to complete. Results Data was available on 277 children with negative bronchial reactivity. The M;F was 1.27:1. The mean age was 10 years old (range 5-15).The number of patients per age in years ranged from 14 to 33 (mean 25). The line of best fit indicates that the mean exercise distance reached in meters was given by the formula Y = (54.7×Age) + 404. The study noted that the main reasons for test cessation related to fatigue and shortness of breath.Abstract GP282 Table 1 Conclusions This study defines normative data for children's exercise capacity as measured by the MST. It provides a frame of reference for parents in discussing their child's exercise tolerance and the modified formula is easy to use (distance travelled = 55x Age + 400m).

Objective: This study aims to evaluate clinical and radiological findings and treatment outcomes of the patients with PIBO. Methods: One hundred fourteen children were enrolled. Initial demographic and clinical findings were evaluated.Pre-and post-treatment symptoms, radiological findings and scores, the number of admissions to the hospital and PICU were compared. Results: Seventy-three patients were male. The median age of the patients at initial pulmonary injury was 7.2 months, the median age at diagnosis was 17.5 months and the median interval from initial injury to diagnosis was 8.5 months. Thirty-five patients had mechanical ventilation history. Persistent wheezing was the most common complaints. The most common radiological findings were peribronchial thickening and air-trapping. Sixty-eight patients were treated with inhaled corticosteroid (IC), systemic corticosteroid (SC) and azithromycin (AZT) combination. 25 patients were treated with only IC, 14 with IC and AZT, and 7 with IC and SC. 82,5% of patients had clinical improvement. Chronic respiratory failure occurred in 11 patients, and three patients died. Bronchiectasis, atelectasis, hyperinflation and air trapping in HRCT improved significantly. Bhalla scores decreased from 8.3 to 6.5 (p= 0,001). IC, SC and AZT combination was effective than the other treatments. Conclusions: This study is one of the largest studies in the literature and one of the few studies that evaluate clinical and radiological outcomes. We found that IC, AZT and SC combination is clinically and radiologically effective in patients with PIBO.