[Noninvasive diagnosis of pulmonary arterial hypertension in chronic respiratory insufficiency].

A precise assessment of pulmonary arterial hypertension (HTAP) in chronic lung disorders is not possible without right heart catheterisation. In spite of technological advances (floating catheters with or without balloons) the examination remains invasive, at least to a certain degree, in addition it is not currently practiced in respiratory function laboratories or in services specialising in thoracic medicine. The diagnosis of HTAP is important when considering both the prognosis and the therapeutic approach notably in chronic airflow obstruction (BPCO) and thus the interest in non-invasive diagnostic methods for HTAP. Do current methods offer such a diagnosis? It is this question that the authors endeavour to answer in analysing the possibilities of the principle methods available, from the most standard (eg ECG, chest radiographs) to the most recent (right heart echo-cardiography, myocardial scintigraphy, isotopic measurement of the right heart function). The reference factor is usually the mean pulmonary artery pressure at rest (PAP) supplied by right heart catheterisation. The ideas of sensibility and specificity of a method are defined and the importance of the correlation between the numerical results obtained by a given method and right heart catheterisation is emphasized: only a very strong correlation could assure the possibility of a correct prediction of the level of PAP. Individually no current methods allow such a prediction in a satisfactory manner. Right heart echo-cardiography is "a priori" the most tempting, but it is unfortunately difficult to accomplish in patients with BPCO. Bidimensional echo-cardiography and the Doppler have given very promising results, which need to be confirmed in patients with BPCO. By combining the results of several methods (eg. ECG, radiological measurements, echocardiography) to those of respiratory function (FEV1, PaO2, PaCO2) one can predict in a satisfactory manner the existence (or the absence) of HTAP but not the precise level of the PAP. An approach of this kind may help to limit the indications for right heart catheterisation which remains irreplaceable for the precise knowledge of pulmonary hemodynamic parameters.