Journal: J Anesth 21(3):304-310, 2007
Reprint: Dept of Anesthesiology and Intensive Care Medicine, Medical Center Cologne-Merheim, Osterheimerstrasse 200, D-51109, Cologne, Germany (SG Sakka, MD)
Faculty Disclosure: Abstracted by J. Joyce, who has nothing to disclose.
Myoglobin is present only in heart and skeletal muscle tissue. All of its biochemical functions are not yet entirely clear; however, myoglobin is considered a participant in the muscular intracellular oxygen transfer cycle. Detectable myoglobin in the serum can be derived from either the cardiac muscle or the skeletal muscular system or both. In any scenario, myoglobin and other intracellular components are thought to reach the circulation due to disruption of cellular integrity. One major clinical point of interest is that myoglobin reaches its peak serum levels hours before other heart muscle specific markers. Conse¬quently, serum myoglobin has found its place in clinical routine as a determinant in diagnosing acute myocardial infarction or acute coronary syndromes. The purpose of this study was to determine and com¬pare the prognostic value of serum myoglobin with other parameters, in terms of ICU mortality and need for renal replacement therapy (RRT) in patients after cardiac surgery.
The results of this study demonstrate that serum myoglobin is of similar prognostic value to serum creatinine in cardiac surgery patients. By using the most pathological values within the first 24 hours after ICU admission, creatinine and myoglobin showed significantly better predictive values for outcomes than serum CK. In general, myoglobin, CK, and troponin are intracellular components with their origin in muscle, but they are not specific to myocardial muscle. Different causes of muscle damage can lead to different time courses of the production and elimination of these components. So far, CK-MB has been described to be superior to myoglobin with respect to diagnostic value.
For the interpretation of the data presented in this study, a general issue which should be considered is the elimination kinetics of myoglobin from the blood. The relatively short period of time between muscle injury and the consecutive peak serum concentration may be the most convincing benefit of myoglobin as an early marker. This fact may be disadvantageous, in so far as the serum myoglobin concentration decreases quite rapidly. It is not surprising that some authors report that in early-type infarction cases, sole screening for myoglobin is positive and in late-type infarctions, serum myoglobin has returned to normal values at the time of investigation. |
