Ischemia-modified albumin increases after skeletal muscle ischemia during arthroscopic knee surgery.
BACKGROUND
Ischemia can alter the ability of albumin to bind free metal atoms. Based on these biochemical changes, methods to quantify ischemia modified albumin (IMA) were developed to assist in the evaluation of patients with symptoms of cardiac ischemia. Since ischemia can occur in any vascular bed, the specificity of IMA for cardiac muscle ischemia is unclear and requires further investigation.


METHODS
We evaluated the specificity of an IMA test in patients with skeletal muscle ischemia during arthroscopic knee surgery. A pressurized thigh cuff was continuously inflated to 300 mm Hg on the operative leg, in order to arrest blood flow during the procedure. Samples were collected before surgery, 15 min after surgery, and prior to discharge.


RESULTS
Twenty-three patients were enrolled in the study. Median tourniquet time was 29 min (range 19-108). Median pre-operative IMA was 90.2 KU/l (range 77-101.6). Statistically significant (p<0.05) increases in IMA and myoglobin concentrations, and decreases in albumin concentrations were observed following tourniquet release and before discharge.


CONCLUSIONS
Post-operative myoglobin elevations indicated that skeletal muscle ischemia was sufficient to produce detectable myocyte necrosis. Post-operative IMA increases are consistent with ischemic modification of albumin during exposure to ischemic conditions in skeletal muscle during and /or immediately after tourniquet application. However, the negative correlations between IMA and albumin results suggest that increases in IMA were in part due to lower post-operative albumin concentrations resulting in decreased cobalt binding.
Refaai
Majed A
MA
Division of Laboratory Medicine, Department of Pathology and Immunology, Washington University School of Medicine, 660 South Euclid Avenue, Box 8118, Saint Louis, MO 63110, United States.
Wright
Rick W
RW
Parvin
Curtis A
CA
Gronowski
Ann M
AM
Scott
Mitchell G
MG
Eby
Charles S
CS
D000328:Adult; D000368:Aged; D001182:Arthroscopy / Q000379:methods*; D005260:Female; D006801:Humans; D007511:Ischemia / Q000503:physiopathology*; D007717:Knee / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000098:blood supply*; D009211:Myoglobin / Q000097:blood; D012709:Serum Albumin / Q000378:metabolism*; D013997:Time Factors
D009211:Myoglobin; D012709:Serum Albumin