M. Heringlake1, M. Wernerus1, J. Grünefeld1, J. Schön1, L. Dibbelt2, T. Hanke3, M. Bechtel3, M. Misfeld3, F. Eberhardt4, H. Heinze1
1Department of Anesthesiology, 2Institute of Clinical Chemistry, 3Department of Cardiac and Thoracic Vascular Surgery, 4Medical Clinic II, University of Lübeck, Lübeck, Germany
[Applied Cardiopulmonary Pathophysiology 12: 47-52, 2008]
Introduction: The N-terminal-prohormone of the B-type-natriuretic-peptide (NTproBNP) is an accepted marker of acute heart failure in medical patients. It is not known if the plasma levels of this peptide may also be useful to detect a low-cardiac-output-syndrome (LCOS) in postoperative cardiac surgery patients.
Materials and methods: A posthoc analysis of a prospective, randomized trial investigating the effects of different inotropes on metabolism and renal function in patients presenting with a LCOS upon ICU-admission in comparison with a group of patients not needing inotropes after coronary artery bypass grafting (CABG) surgery was performed. LCOS was defined as a cardiac index (CI) < 2.2 l/min/m2 despite optimization of filling pressures and mean arterial pressure. 18 patients fulfilled the LCOS-criteria (LCOS-group) and underwent 14h treatment with adrenaline or milrinone aimed to achieve a CI > 3.0 l/min/m2, 20 patients served as controls (CON-group). Plasma levels of NTproBNP and hemodynamics were determined at 0, 2, 6, 10, 14, and 48 hours after ICU-admission.
Results: Baseline NTproBNP levels in the LCOS- and the CON group were 462 ± 404 pg/ml and 296 ± 259 pg/ml, and increased to 2411 ± 1592 pg/ml and 2321 ± 1375 pg/ml respectively, at t=48h. No significant between-group differences in NTproBNP were observed. CI in the LCOS-group was 1.9 ± 0.2 l/min/m2 at t0, increased to 2.9 ± 0.5 l/min/m2 at t2, and was maintained at 3.0 to 3.4 l/min/m2 thereafter. Cardiac index in the CON-group was 3.1±0.4 l/min/m2 at t0 (p<0.001 vs. LCOS) and increased to 3.8 ± 1.0 l/min/m2 (p=0.019) during the treatment period.
Conclusions: Postoperative plasma levels of NTproBNP do not discriminate between patients with a short-lasting LCOS or a normal myocardial function. This questions the usefulness of determining plasma NTproBNP levels for guiding hemodynamic treatment in the immediate postoperative period after CABG surgery.
Key words: natriuretic peptides, low-cardiac output syndrom, acute heart failure, cardiac surgery
Address for corresponding: Matthias Heringlake, M.D., Department of Anesthesiology, University of Lübeck, Ratzeburger Allee 160, D-23538 Lübeck, Germany, E-Mail: Heringlake@bitte-keinen-spamt-online.de