Serum biochemical determinants of peripheral congestion assessed by bioimpedance vector analysis in acute heart failure

Background: The pathophysiology of peripheral congestion is poorly investigated in patients with acute heart failure (AHF). Objectives: to evaluate the relative contribution of serum colloid osmotic pressure (COP), relative plasma volume status (PVS), biomarkers of renal function, electrolytes, haemoglobin, and brain natriuretic peptide (BNP)in peripheral fluid overload using bioimpedance vector analysis (BIVA). Methods: We retrospectively analysed data from 485 patients with AHF. Hydration status was evaluated by semiquantitative and quantitative approach using BIVA (R/Xc graph)and Hydration Index (HI), respectively. COP was calculated from albumin and total protein concentration, while relative PVS was calculated from validated equations. Results: Congestion assessed by BIVA was observed in 304 (63%)patients and classified as mild (30%), moderate (42%), and severe (28%). On univariate analysis, HI was inversely correlated with COP (P < 0.01), glomerular filtration rate (P < 0.01), and haemoglobin (P < 0.01), while positive correlations were found for relative PVS (P < 0.05), BNP (P < 0.01), and blood urea nitrogen (BUN; P < 0.01). On stepwise multivariate analysis, COP explained 12% of the total variability, while BUN, PVS, haemoglobin, and BNP added a further 6%, 4%, 2%, and 1%, respectively, to the final explanatory model. Conclusions: COP was the major determinant of the presence and entity of peripheral congestion assessed by BIVA. BUN, PVS, haemoglobin, and BNP revealed reduced influence on congestion as compared with COP. Routine laboratory testing could be useful in peripheral fluid accumulation. Future studies should evaluate the relationship between COP and pharmacological target therapies for the fluid management of AHF patients.