CARDIORESPIRATORY AND VASCULAR DYSFUNCTION RELATED TO MAJOR RECONSTRUCTIVE ORTHOPEDIC-SURGERY

Major orthopedic reconstructive surgery is highly traumatic and may be associated with serious perioperative cardiorespiratory and vascular complications which occasionally may be fatal. These complications are commonest in patients receiving cemented hip prostheses following fem oral neck fractures. The etiology is multifactorial. Bone traumatizati on induces activation of the hemostatic system, i.e., thrombin generat ion, in venous blood draining the operation area. When this activated blood passes the lung, more thrombin is generated and the blood become s hypercoagulable and causes fibrin-formation in the lung vessels, wit h trapping of cellular debris. Thrombin has many hormone-like effects beyond its function in the coagulation cascade sys- tem. It may increa se vein wall permeability and cause constriction of vessels, which inc reases blood pressure in the lung. In addition, impaction of bone ceme nt to fill bone cavities or to fix prostheses causes additional mechan ical trauma and further release of procoagulant substances into venous blood. Further, release of the cytotoxic chemical methylmethacrylate monomer into venous blood is super-imposed on the thrombin-primed hemo static disturbances in the lung microvasculature. All these effects ma y finally induce hemodynamic insufficiency, which occasionally may be fatal. To prevent these adverse reactions, thrombin activity should be reduced and impaction of bone cement minimized.