Central venous blood oxygen saturation monitoring in patients with chronic pulmonary arterial hypertension treated with continuous IV epoprostenol: correlation with measurements of hemodynamics and plasma brain natriuretic peptide levels.

Background: IV epoprostenol is a highly effective therapy for pulmonary arterial hypertension (PAH). However, monitoring the efficacy and adjusting the dose of epoprostenol often requires serial invasive hemodynamic measurements. This study investigated whether superior vena cava (SVC) oxygen saturation measured from the indwelling catheter and brain natriuretic peptide (BNP) level would predict right heart catheterization markers associated with lower survival rates (right atrial pressure [RAP], > 10 mm Hg; pulmonary artery [PA] oxygen saturation, < 62%) in epoprostenol-treated patients with PAH.
Methods: Twenty-seven epoprostenol-treated PAH patients had a BNP level and SVC oxygen saturation measured from their indwelling central venous catheters. The results were compared with cardiac catheterization results.
Results: SVC oxygen saturation and BNP level both showed significant correlation with hemodynamic variables. BNP level correlated best with RAP (r = 0.66; p < 0.001), while SVC oxygen saturation correlated most closely with PA oxygen saturation (r = 0.91; p < 0.001). All patients with a BNP level of >or= 117 pg/mL had an elevated RAP (specificity, 100% [defined as a RAP of > 10 mm Hg]), but sensitivity was only 65%. An SVC oxygen saturation of < 64% showed a sensitivity of 89% and a specificity of 78% in predicting a PA oxygen saturation of < 62%.
Conclusions: SVC oxygen saturation and BNP level predict hemodynamics associated with lower survival rates and may be useful as "noninvasive" markers of prognosis in epoprostenol-treated PAH patients. BNP levels have a lower sensitivity relative to specificity, and a normal BNP level did not exclude a high RAP or low PA oxygen saturation.