Tourniquet-applied upper limb orthopaedic surgery results in increased inflammation and changes to leukocyte, coagulation and endothelial markers

Abstract

Purpose: During 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).

Methods: Three 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).

Results: Following 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.

Conclusions: Conventionally, 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.

Figure 1. Effect of tourniquet-applied upper limb orthopaedic surgery on CD62L cell surface expression of neutrophils and monocytes.

The results are expressed as mean fluorescent intensity (MFI). The points represent mean ± SD, p = 0.001 (neutrophils) and p = 0.061 (monocytes), as determined by ANOVA.

Figure 2. Effect of tourniquet-applied upper limb orthopaedic surgery on CD11b cell surface expression of neutrophils and monocytes.

The results are expressed as mean fluorescent intensity (MFI). The points represent mean ± SD, p<0.05 for both neutrophils and monocytes as determined by ANOVA.

Figure 3. Effect of tourniquet-applied upper limb orthopaedic surgery on intracellular H₂O₂ production of neutrophils and monocytes.

The results are expressed as mean fluorescent intensity (MFI). The points represent mean ± SD, p<0.001 for both neutrophils and monocytes, as determined by ANOVA and the Friedman test respectively.

Figure 4. Effect of tourniquet-applied upper limb orthopaedic surgery on C-reactive protein (CRP) concentration.

The results are expressed as CRP concentration (ng/ml). The points represent mean ± SD, p<0.001, as determined by the Friedman test.

Figure 5. Effect of tourniquet-applied upper limb orthopaedic surgery on protein C concentration.

The results are expressed as protein C concentration (IU/ml). The points represent mean ± SD, p = 0.004, as determined by ANOVA.

Figure 6. Effect of tourniquet-applied upper limb orthopaedic surgery on vWF concentration.

The results are expressed as vWF concentration (IU/ml). The points represent mean ± SD, p = 0.232, as determined by the Friedman test.