[Possibilities of using non-invasive techniques to predict pulmonary arterial pressure in chronic respiratory...

The value of non-invasive procedures for predicting pulmonary arterial pressure (PAP) was assessed in 297 patients with chronic obstructive lung disease (COLD) and in 73 patients with alveolitis in multicenter trials at 9 centres in 6 European countries. FEV1, blood gases, ECG, radiographic dimensions of the pulmonary artery, right ventricle dimensions measured with M-mode echocardiography, and 201Ta heart scintigraphy together with clinical examinations served the purpose. No single variable was correlated closely enough to allow precise prediction of PAP. In patients with COLD multiple stepwise analysis of regression explained 49% of the variance in PAP but was not useful for prediction. Discriminant analysis allowed patients allocation to PAP bands similarly to 2 non-parametric procedures in which decision trees were established with the aid of either Kolmogoroff-Smirnoff statistics or Fishers' exact test. Patients with PAP of 30 mm Hg or higher were identified with sensitivity of 83% and specificity of 91%. Non-parametric tests produced better results than discriminant functions. Additional 54 patients were tested to validate these functions. Ninety percent of them with PAP > 20 mm Hg, and 80% with PAP > 29 mm Hg were identified correctly. Similar results were achieved in patients with fibrosing alveolitis. These mathematical functions allow the use of non-invasive procedures combinations to select those individuals out the populations at risk of pulmonary hypertension in whom direct PAP measurements are required. These mathematical functions may further be widen by addition of other variables obtained from newer non-invasive techniques.