[Shuttle test in severe COPD patients]

The shuttle test (ST) is a maximal exercise field test with scarcely used in Argentina. Our objective was to compare different variables of exercise response to ST vs. other exercise tests such as six minute walking test (SMWT) and cardiopulmonary with maximal oxygen consumption (VO2max) in severe COPD patients. A total of 21 stable severe COPD patients (GOLD III and IV stages) were evaluated with SMWT, ST and VO2max test. In all patients spirometry was performed with bronchodilator response, arterial gas and chronic respiratory questionnaire to evaluate quality of life. Cardiac frequency, oxygen saturation and dyspnea scale by Borg in response to exercise tests were evaluated. Paired T Student and Pearson tests were used, defining p < 0.05 as significant. COPD patients were 65.27 +/- 12.72 years old and had severe airflow obstruction (FEV1: 33.23 +/- 4.94%). The exercise response to SMWT was 297.85 +/- 173.24 meters; ST: 318.8 +/- 42.42 meters and VO2max test: 14.7 +/- 5.44 ml/kg/min. The correlation between SMWT and ST was: r: 0.52(p < 0.00085); between ST and VO2max (l/min): r: 0.78 (p < 0.00079), and ST and VO2max (ml/kg/min): r: 0.81 (p < 0.00065). Moderate correlation was observed in final heart rate (r: 0.41, p < 0.00091), maximal Borg dyspnea scale (r: 0.47, p < 0.00099) and high correlation with final oxygen saturation (r: 0.81, p < 0.00087) between ST and VO2max. There was no correlation between ST and FEV1 and ST and quality of life. OUR CONCLUSION: The ST is a maximal, simple and low cost test. It has high correlation with cardiopulmonary test with VO2max measurement. It is a useful tool in those laboratories for pulmonary evaluations without possible availability of expensive tests.