This study examines the Clinical Decision Support Systems (CDSS) in healthcare, in particular about the prevention, diagnosis and treatment of respiratory diseases, such as Asthma and Chronic Obstructive Pulmonary Disease (COPD). The empirical pulmonology study of a representative sample (n=132), attempts to identify the major factors that contribute to the diagnosis of these diseases. Our machine learning results show that in COPD’s case, SVM outperform other techniques with 96.7% precision, while the most prominent attributes for diagnosis are: smoking, FEV1, age and FVC. In asthma’s case, the best precision, 84.8%, is achieved with the Random Forest classifier, while the most prominent attributes are: MEF2575, smoking, age and wheeze. Finally, the prediction model is integrated in a mobile-web app ready to be used by doctors and patients