Current guidelines recommend measurement of pulmonary artery wedge pressure (PAWP) at end-expiration. However, this recommendation is not universally followed and may not be physiologically appropriate. We investigated the performance of end-expiratory wedge pressure (eePAWP) in the evaluation of precapillary pulmonary hypertension patients. Three hundred and twenty-nine spontaneously breathing patients undergoing right heart catheterization were retrospectively classified as having precapillary, postcapillary, or mixed phenotype based on standardized clinical criteria. Tracings were reviewed to compare eePAWP with PAWP averaged throughout the respiratory cycle; these values were correlated with the clinical classifications. Predictors of large respirophasic excursion in PAWP were determined. Elevated eePAWP (>15 mm Hg) occurred in 29.0% of subjects with precapillary phenotype. There were no differences in demographics or clinical history between those with elevated and normal eePAWP. Those with elevated eePAWP had greater right atrial pressure and respirophasic PAWP variation. Among all subjects, the magnitude of respirophasic variation in PAWP was positively correlated with body mass index and respirophasic variation in left ventricular end diastolic pressure. A significant proportion of precapillary pulmonary hypertension patients have eePAWP >15 mm Hg. Spontaneous positive end-expiratory intrathoracic pressure may contribute; in those cases, PAWP averaged throughout respiration may be a more accurate measurement.

Prostacyclin is an endogenous eicosanoid produced by endothelial cells; through actions on vascular smooth-muscle cells, it promotes vasodilation. Pulmonary arterial hypertension (PAH) is characterized by elevated mean pulmonary artery pressure due to a high pulmonary vascular resistance state. A relative decrease in prostacyclin presence has been associated with PAH; this pathway has thus become a therapeutic target. Epoprostenol, the synthetic equivalent of prostacyclin, was first utilized as short-term or bridging therapy in the 1980s. Further refinement of its long-term use via continuous intravenous infusion followed. A randomized controlled trial by Barst et al in 1996 demonstrated functional, hemodynamic, and mortality benefits of epoprostenol use. This work was a groundbreaking achievement in the management of PAH and initiated a wave of research that markedly altered the dismal prognosis previously associated with PAH. Analogs of prostacyclin, including iloprost and treprostinil, exhibit increased stability and allow for an extended array of parenteral and non-parenteral (inhaled and oral) therapeutic options. This review further examines the pharmacology and clinical use of epoprostenol and its analogs in PAH.

When overt pulmonary hypertension arises in interstitial lung disease (ILD), it contributes to exercise intolerance. We sought to determine the functional significance of abnormal pulmonary arterial pressure (PAP) responses to exercise in ILD.27 ILD patients and 11 age-matched controls underwent invasive cardiopulmonary exercise testing (iCPET). Mean PAP (mPAP) was indexed to cardiac output (Q´T) during exercise, with a mPAP-Q´T slope ⩾3 mmHg·min·L −1 defined as an abnormal pulmonary vascular response. All control subjects had mPAP-Q´T slopes <3 mmHg·min·L −1 (mean±SEM 1.5±0.1 mmHg·min·L −1 ). 15 ILD patients had mPAP-Q´T slopes ⩾3 mmHg·min·L −1 (4.1±0.2 mmHg·min·L) and were labelled as having ILD plus pulmonary vascular dysfunction (PVD). Subjects without pulmonary hypertension and with mPAP-Q´T slopes <3 mmHg·min·L −1 (1.9±0. 2 mmHg·min·L −1) were labelled as ILD minus PVD (n=12). ILD+PVD and ILD−PVD patients did not differ in terms of age, sex, body mass index, pulmonary function testing or degree of exercise oxygen desaturation. Peak oxygen consumption was lower in ILD+PVD than in ILD−PVD (13.0±0.9 versus 17±1.1 mL·kg , p=0.003). ILD+PVD patients had increased dead space volume (VD)/tidal volume (VT) and minute ventilation/carbon dioxide production at the anaerobic threshold.In ILD, mPAP-Q´T slope ⩾3 mmHg·min·L −1 is associated with lower peak oxygen consumption, increased VD/VT and inefficient ventilation. While noninvasive parameters were unable to predict those with abnormal pulmonary vascular responses to exercise, iCPET-derived mPAP-Q´T slope may aid in identifying physiologically significant, early pulmonary vascular disease in ILD.@ERSpublications PAP responses to exercise may help to refine resting phenotypes related to pulmonary vascular dysfunction in ILD http://ow.ly/M0nMa

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