The use of lower extremity tourniquets for procedures of the lower leg is considered routine in orthopedic surgery, but lower extremity tourniquets do harm occasionally. While the tourniquet is inflated, metabolic changes such as increased PaCO2
lactic
acid, and serum potassium and decreased level of PaO2 and pH occur in the ischemic limb. Deflation of tourniquet results in release of anaerobic metabolic products during ischemia into systemic circulation. In this ischemia/reperfusion situation,
oxygen
free radicals could potentially be produced during the reperfusion period by several mechanisms. One of these mechanisms is release of intracellular superoxide or hydrogen peroxide by activated neutrophils in the area. These reactive oxygen
species(ROS)
could be a causative factor for the postreperfusion no-flow, lung injury, induction of tourniquet shock, etc. The purpose of this clinical study was to investigate the effect of tourniquet deflation on the hemodynamic changes, changes of blood
gas
analysis, and hydrogen peroxide production using flow cytometric analysis of fluorescent DCF(Dichlorofluorescein). Quantitative analysis of fluorescent DCF was performed in resting and fMLP(N-formyl-methyonyl-leucyl-pheylalanine) or PMA(phorbol
myristate acetate) stimulated neutrophils. Also differences of these factors between two groups of tourniquet time, one is less than one hour and the other more than one to two hours, were analysed. The hemodynamics(blood pressure, pulse rate),
arterial
PO2, bicarbonate, base excess, and hydrogen peroxide production showed to significant change before and after tourniquet release(p>0.05). Arterial pH and PaCO2 decreased significantly until 10 and 5 minutes after tourniquet release,
respectively(p<0.05)
Tourniquet time didn't reveal any significance differences. These results indicate that tourniquet application with 400mmHg pressure and less than 2 hours does not release significant hydrogen peroxide into systemic circulation during reperfusion
period
after tourniquet release.
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