Interpretación de la relación presión-flujo en la hipertensión arterial pulmonar idiopática

objectives: we analyze exercise-derived mean pulmonary artery pressure/cardiac index relationship to expand the concepts regarding its nature and to better identify "responders" in idiopathic pulmonary arterial hypertension patients. methods: mean pulmonary artery pressure/cardiac index relationship and extrapolated pressure to zero flow were obtained in 40 patients' breathing room air, oxygen 99.5% and hydralazine. the hemodynamic characteristics were analyzed for the cohort and separate for responders (n = 20) and non responders (n = 20) according to the acute response to vasodilator. we tested this previous criteria versus the task force on diagnosis and treatment prescribed by the european society of cardiology. results: the mean pulmonary arterial pressure/cardiac index was located abnormally in the pressure-flow diagram of the total cohort (p < 0.01). no alterations in gas exchange or lung mechanics. for patients responders versus non-responders, the slope was abnormal 2.2 (95% ci:1.1-3.3) vs. 5.89 (95% ci: 4.69 - 7.11), mm hg/l min/m2 and increased extrapolated pressure to zero flow (38.2 ± 7.5 to 66.3 ± 7.5 mm hg, p <0.01). without difference with oxygen 99.5%. with vasodilator effect, mean pulmonary arterial pressure decreased (52.1 ± 9.5 to 40 ± 5.5 mm hg, p <0.01) versus it did not change (96.2 ± 8.5 versus 90 ± 7.5 mm hg, p=0.3), slope 1.15 (95% ci: 0.68 - 1.62) vs. 1.28 (95% ci: 0.78-1.78) mmhg/l min/m2, the extrapolated pressure to zero flow did not change (69.4 ± 7.8 to 85.1 ± 8.5 mm hg), p <0.01, compared to control. in non-responders with vasodilator, mean pulmonary arterial pressure/cardiac index (90 ± 7.5 mmhg, slope: 1.28, 95% ci :0.78 - 1.78 mm hg/l min/m2) was different between responders < or > 40 mmhg mean pulmonary arterial pressure. pressures were 34 ± 3 vs. 45 ± 4 mm hg and slopes 1.14 (95% ci: 0.67 - 1.61) vs. 2.22(95% ci: 1.35 - 3.09) mm hg/l min/m2, p <0.01, respectively.. conclusions: abnormalities of the mean pulmonary arterial pressu