Abstract
PurposeDuring this pilot clinical study, patients scheduled for elective tourniquet-applied upper limb orthopaedic surgery were recruited to investigate the effects of surgery on various biological markers (n = 10 patients).MethodsThree venous blood samples were collected from the arm at the ante-cubital fossa, at baseline (pre-operatively), 5 and 15 minutes after reperfusion (post-operatively). Neutrophil and monocyte leukocyte sub-populations were isolated by density gradient centrifugation techniques. Leukocyte activation was investigated by measuring the cell surface expression of CD62L (L-selectin), CD11b (Mac-1) and the intracellular production of hydrogen peroxide (H2O2), via flow cytometry. C-reactive protein (CRP) was measured using a clinical chemistry analyser. Plasma concentrations of protein C and von Willebrand factor (vWF) were measured using enzyme-linked fluorescent assays (ELFA).ResultsFollowing tourniquet-applied upper limb orthopaedic surgery, there was a decrease in neutrophil CD62L expression (p = 0.001), an increase in CD11b expression and in the intracellular production of H2O2 by neutrophils and monocytes (p<0.05). An increase in CRP concentration (p<0.001), a decrease in protein C concentration (p = 0.004), with a trend towards elevated vWF levels (p = 0.232) were also observed during this time.ConclusionsConventionally, patients undergoing orthopaedic surgery have been monitored in the peri-operative period by means of CRP, which is a non-specific marker of inflammation. This test cannot differentiate between inflammation due to current or pre-existing disease processes and the development of ischaemia-reperfusion injury surgery. The findings from this study suggest that markers such as CD11b, protein C and H2O2 may provide alternative ways of assessing leukocyte and coagulation activation peri-operatively. It is proposed that by allowing orthopaedic surgeons access to laboratory markers such as CD11b, protein C and H2O2, an accurate assessment of the extent of inflammation due to surgery per se could be made.
Highlights
With respect to tourniquet-applied orthopaedic surgery, comparing a range of biological markers as part of the post-operative period has not yet been extensively researched
Neutrophils and monocytes are components of the nonspecific immune system and are capable of phagocytosis. Both neutrophils and monocytes have been implicated to play a key role in the development of the inflammatory response post surgery, where they are intrinsically involved in leukocyteendothelial cell interactions [1,2,3,4]
Specific adhesion molecules important in mediating adhesive interactions include CD62L (Lselectin) and CD11b (Mac-1) on neutrophils and monocytes, which bind to their corresponding counter-receptors to facilitate leukocyte-endothelial cell interactions [5,6,7,8]
Summary
With respect to tourniquet-applied orthopaedic surgery, comparing a range of biological markers as part of the post-operative period has not yet been extensively researched. CRP was measured as a marker of non-specific inflammation, with Protein C and VWF assessing coagulation and endothelial activation respectively. Neutrophils and monocytes are components of the nonspecific immune system and are capable of phagocytosis. Both neutrophils and monocytes have been implicated to play a key role in the development of the inflammatory response post surgery, where they are intrinsically involved in leukocyteendothelial cell interactions [1,2,3,4]. Specific adhesion molecules important in mediating adhesive interactions include CD62L (Lselectin) and CD11b (Mac-1) on neutrophils and monocytes, which bind to their corresponding counter-receptors to facilitate leukocyte-endothelial cell interactions [5,6,7,8]. The adhesion of leukocytes to the endothelium is associated with neutrophil and monocyte activation, which leads to the respiratory burst and subsequent production and release of reactive oxygen intermediates (ROIs), such as hydrogen peroxide and superoxide [9,10,11]
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