PURPOSE: To assess impedance cardiography as a method for obtaining a non-invasive hemodynamic evaluation in patients with pulmonary hypertension (PH).
METHODS: A total of 39 patients (age 57± 14 years, 87% women) with presumed (23%) or confirmed PH (77%) of different etiologies who underwent right heart catheterization (RHC) at University of Florida from August 2009 to March 2010 agreed to be studied by impedance cardiography (PhysioFlow(r) PF-05, Manatec Biomedical, Macheren, France) immediately after RHC. PhysioFlow(r) measures cardiac output (CO) and end-diastolic volume (EDV), among other parameters.
RESULTS: The median pulmonary artery pressure was 36 (IQR 26-56)mm Hg. The CO (mean ± SD in l/m) by thermodilution (CO-T), Fick methodology (CO-F) and impedance cardiography (CO-IC) was 5.9 ± 2.2, 5.5 ± 1.6 and 5.6 ± 1.5, respectively. Bland-Altman analysis of CO-T versus CO-F showed mean of 0.4 L/min (95% limit of agreement (LoA) 3.4 and -2.6), CO-T versus CO-IC a mean of 0.3 L/min (95% LoA 2.8 and -2.2) and CO-F versus CO-IC a mean of -0.1 L/min (95% LoA 2.5 and -2.7). Correlation between CO-T and CO-IC was R2 = 0.7, p < 0.001. In patients with PH the correlation of CO-T and CO-IC had a mean of 0.4 L/min(95% LoA 2.9 and -2.2), R2 = 0.75, p < 0.001.Pulmonary artery occlusion pressure (PAOP) correlated with EDV (R2 = 0.2, p = 0.005). By ROC analysis EDV of ≥ 200 ml had a sensitivity of 53% and a specificity of 86% for PAOP > 15 mm Hg (AUC: 0.78).
CONCLUSION: Impedance cardiography allows a reliable and non-invasive measurement of cardiac output in patients with PH. End-diastolic volume correlated with pulmonary artery occlusion pressure.
CLINICAL IMPLICATIONS: Impedance cardiography reliably measures cardiac output in patients with pulmonary hypertension. This methodology may serve as a valid tool for the hemodynamic evaluation of this group of patients.
DISCLOSURE: Adriano Tonelli, No Financial Disclosure Information; No Product/Research Disclosure Information