Reperfusion injury is greater with delayed restoration of venous outflow in concurrent arterial and venous limb injury

Background: Complex limb trauma often involves combined arterial and venous injury, and the resultant ischaemia-reperfusion injury (IRI) causes both l ocal and remote organ injury. This study assessed the influence of the timi ng of restoration of venous drainage on IRI. Methods: Male New Zealand white rabbits (n=36) were randomized into six gro ups: sham operation (group 1) and unilateral hind limb arterial and venous occlusion for 1 h followed by no reflow for 2 h (group 2), arterial and ven ous reflow for 2 h (group 3), arterial reflow alone for 2 h (group 4), arte rial reflow alone for 1 h followed by arterial and venous (delayed) reflow for a further 1 h (group 5), and pretreatment with an enteral combination a ntioxidant before occlusion of both artery and vein and delayed venous refl ow (group 6), Plasma hydroperoxide (HPO) and glutathione peroxidase concent ration, hind limb skeletal muscle and lung tissue wet:dry weight ratios and myeloperoxidase (MPO) concentration were measured, Results: The plasma HPO level in the femoral vein effluent was significantl y greater after delayed venous reflow (mean(s.e.m.) 2.02(0.54) mu mol/l) th an. in control animals (0.98(0.10) mu mol/l) (P<0.05). There was also a sig nificantly greater tissue wet:dry weight ratio after delayed venous reflow than in controls, in skeletal muscle (mean(s.e.m.) 6.89(0.14) versus 5.34(0 .54); P<0.05) and lung (9.20(1.14) versus 7.23(0.38); P<0.05) tissue. Lung tissue MPO activity was significantly greater after delayed venous reflow c ompared with controls (3.20(0.28) versus 1.86(0.14) units/g; P<0.005), and also in comparison to simultaneous arterial and venous reflow (2.40(0.24) u nits/g; P<0.05). In the antioxidant pretreatment group there was no signifi cant increase in plasma HPO concentration, tissue MPO level or tissue wet:d ry weight ratio compared with the control group. Conclusion: In combined major arterial and venous injury of the limb, delay ed restoration of venous drainage leads to significantly greater local skel etal muscle injury and remote neutrophil-mediated lung injury. These result s support the clinical rationale for early restoration not only of arterial inflow but also venous drainage by means of intraluminal shunts.