[Clinical interpretation for the pressure-flow relationships in extrinsic allergic alveolitis and in interstitial lung disease pulmonary hypertension patients. Should we care for the lung, the pulmonary artery pressure or both?].

OBJECTIVES

We sought to analyze exercise-derived mean pulmonary artery pressure (mPAP)-cardiac index (CI) relationship to expand the concepts regarding its nature and to better identify pulmonary hemodynamic responders to acute oxygen breathing (AO2B-99.5%) and to hydralazine (H) in extrinsic allergic alveolitis (EAA) and chronic interstitial lung disease (CILD) pulmonary hypertension (PH) patients.

MATERIAL AND METHODS

mPAP/CI and extrapolated pressure (Pext) to zero flow were obtained while breathing room air (BRA) and under AO2B-99.5% in 38 stable (EAA (n = 14) and CILD (n = 24)) patients with resting and exercising PH. Hemodynamic characteristics were analyzed for the entire cohort and separate for EAA and CILD patients. AO2B-99.5% was tested in cohorts, H only in CILD and the effect of long-term corticosteroid treatment in EAA patients. Lung biopsies (LB) were obtained to evaluate the inflammatory-fibrosis stage and the degree of vascular lesion in the entire cohort.

RESULTS

LB studies reveal a predominant stage of inflammation associated with grade-I vascular lesion for EAA patients. A predominant stage for fibrosis (although moderate) over inflammation associated with grade-II vascular lesions were documented for CILD patients. mPAP/CI abnormal location were associated with hypoxemia/decreased mixed venous-PO2 and lung mechanics abnormalities for both cohorts. An abnormal slope (Sp: 4.13; 95% CI: 3.42-4.84 mmHg/L/min/m2) and a normal Pext value (7 +/- 1.9 mmHg) were found for EAA patients. On the contrary, a normal slope (Sp: 1.22; 95% CI: 0.47-1.99 mmHg/L/min/m2) and an abnormal Pext value (19.7 +/- 3.5 mmHg) were found for CILD patients. Hemodynamic conditions that did not change for the Sp (4.0; 95% CI: 3.18-4.82 mmHg/L/min/m2); however, were associated with a statistical significant decrease in parallel for mPAP/CI during AO2B-99.5% when compared to BRA (p < 0.01), although not to normal slope values (0.96; 95% CI: 0.41-1.37) or mPAP/CI location. For CILD patients, during AO2B-99.5% no change for the slope, for Pext and mPAP/CI location in relation to BRA were observed. Under the effect of H, no change for the previous mentioned hemodynamic findings were found in relation to the control condition for CILD patients. After long-term corticosteroid treatment, normalization for mPAP/CI location and for the slope value (1.6; 95% CI: 0.91-2.29 mmHg/L/min/m2) were associated with lung mechanics and blood-gas exchange normalization were documented in EAA patients.

CONCLUSIONS

When mPAP/CI exercise derived is analyzed, valuable information for linear-pulmonary vascular resistance-(LPVR) could be obtained for EAA and CILD-PH patients. mPAP/CI-r abnormalities not always reflect "pure arteriolar" increased LPVR for EAA and CILD patients. H is not useful as an adjunct vasodilator therapy for CILD-PH patients. AO2B-99.5% decrease right ventricular afterload for EAA patients, although not to normal. Complete reversibility for PH could result after long-term corticosteroid treatment. We conclude that treatment should focus mainly on the lung and not in the pulmonary artery pressure in interstitial lung disease PH patients.