Evaluation problems of a long-term study on evolving pulmonary arterial hypertension in chronic non specific lung disease.

After having collected a sufficient number of standardized data checked for reliability from patients with chronic non specific lung disease, the following subgroups of pulmonary arterial mean pressure were defined: A = PAP less than 2.7 kPa [= 20 mmHg]; B = 2.7 less than PAP less than 4 kPa; C = PAP greater than 4 kPa [= 30 mmHg].