Limitación crónica al flujo aéreo en pacientes con secuelas de tuberculosis pulmonar: Caracterización y comparación con EPOC

Abstract

Chronic airway obstruction (CAO) resulting from tuberculosis (TB) sequelae (CAO-TB) is a frequent condition in our population. However the information in the medical literature is scarce. The management of these patients usually follows guidelines for other illnesses such as chronic obstructive pulmonary disease (COPD) or asthma. To better characterize CAO-TB, 25 patients with this condition that never smoked nor were diagnosed having asthma, were studied by means of spirometry, arterial blood gases and 6-minute walk test. Furthermore, they were compared with 12 COPD patients with similar FEV1 values. CAO-TB patients had history of tuberculosis 35 ± 11 years earlier, and all of them presented with lung scarring in one or both upper lobes. They were younger than COPD (58 ± 11 vs 69 ± 6 y.o.; p = 0.001) and females predominated over males (20/5 vs 2/10; p = 0.001). The FEV1/FVC ratio pre- and post-bronchodilator were higher in CAO-TB than in COPD patients (67% ± 12 vs 54% ± 9 pre; p = 0.001; 65% ± 14 vs 51% ± 7; p = 0.003 post, respectively). There were no differences in the remaining spirometric indices nor in arterial blood gases. The 6-min distance walked was comparable in both groups: 343 m (69%) in CAO-TB and 361 m (76%) in COPD. There were no differences in the oxygen saturation nor in heart rate neither at the beginning nor at the end of the 6-min walk test. However, CAO-TB patients had a higher respiratory rate at the beginning (22.7 ± 4.7 vs 19.8 ± 3.1 breath/min; p = 0.05) and at the end of the walk test (27.3 ± 6.7 vs 21.9 ± 3.3; p = 0.01) than COPD patients; although the Borg dyspnoea score was not different (1 ± 0,7 vs 1 ± 0.5 initial, 3 ± 1.5 vs 2.5 ± 0.8 final). Furthermore, a significant linear correlation between respiratory rate and Borg score was found both at the beginning (r = 0.747; p < 0.001) and at the end (r = 0.507; p = 0.01) of the walk test. In conclusion, CAO-TB patients are functionally comparable to COPD patients, although they have higher respiratory rate and develop more dyspnoea because of their added restrictive impairment. In addition to spirometry, tests for assessment of dyspnoea such as 6-minute walk test must be considered, to evaluate the response to treatment in CAO-TB patients