The role of arterial blood gases, exercise testing, and cardiac examination in asthma

The severity of bronchial asthma may not be assessed easily in some patients using the current evaluation methods. In this study, we aimed to obtain more objective and detailed data in evaluating patients with stable mild and moderate bronchial asthma and to validate the current parameters against more objective ones in determining the disease severity. One-hundred six stable patients with bronchial asthma were included in the study. These patients underwent spirometric and cardiological examination, 6-minute walk testing (6MWT) and arterial blood gas analysis. Continuous measurement of pulse oxymetry (SpO₂) was done during 6MWT. Dyspnea that developed during 6MWT was measured using the modified Borg category scale. Sixteen patients were found severely hypoxemic at rest, and 16 patients were severely desaturated at 6MWT. Nineteen patients had pulmonary hypertension on echocardiography. Patients with oxygenation problems were older and had longer disease duration, lower forced expiratory flow of 25–75%, higher Borg exercise rating, and higher pulmonary artery pressure (p < 0.05). Patients with pulmonary hypertension had earlier disease onset, lower forced expiratory flow of 25–75%, lower arterial oxygen tension and lower pre-6MWT SpO₂ (p < 0.05), older age, and lower SpO₂ at 6MWT (p < 0.01). Classic evaluation methods correctly operated only on the two-thirds of asthmatic patients. Cardiological examination, 6MWT, and arterial blood gas analysis were needed for the true evaluation of other patients who had potentially progressive disease. We think that evaluation of asthmatic patients with these more objective and detailed methods provides important additional clinical data.