Ventilatory assessment of asthmatic patients incremental shuttle walk test: A pilot study

Background: Exercise intolerance in asthmatics occurs by reduced ventilatory capacity and dyspnea as well as the occurrence of exercise-induced bronchoconstriction (EIB). Aims: 1) assess ventilatory responses at the peak of the Incremental Shuttle Walk Test (ISWT) and constant cardiopulmonary exercise test (CCPET); 2) determine the presence of EIB in patients with asthma ISWT. Methods : 20 asthmatic (28±8 years; FEV1 98±20% predictive, FEV1/FVC 75±20%) were evaluated. In two non-consecutive days, a CCPET test on a treadmillwith intensity at 40% of ventilatory demand (VE/MVV) in incremental CPET and an ISWT test with ventilation uptake (VE) (Oxycon) and VE/VCO 2 were performed. Three maneuvers of FVC were performed before the tests and at the end, a FVC maneuver every 5 minutes until 30 minutes of recovery (fall of FEV1≥ 10%, BIE was considered). Results: In ISWT, distance traveled was 540±83 meters, reaching 73±8% pred. In CCPET, the peak speed reached was 5.6±1.4 km / h, the slope of 8.5±4% and the time of 10±1 minute test. The values for peak ISWT and CCPET respectively were: VE/VCO 2 = 32±8 vs. 29±7, no significant difference was found and in the VE/MVV= 0.5±0.2 vs. 0.4±0.2 significant difference was found (p=0,032). Out of 20 asthmatic patients, 15 presented in BIE ISWT (Δ=-17±4) and CCPET (Δ=-12±2%). Conclusion : The ventilatory efficiency was similar in both tests and ventilatory demand was higher in ISWT. The ISWT can be a tool to assess the presence of EIB in this specific population. Financial support: no2011/23771-7 Sao Paulo Research Foundation (FAPESP) .