Study objective: To examine whole blood coagulation in uremic patients presenting for surgery with the thromboelastogram and the Sonoclot analyzer.
Design: Prospective, observational study.
Setting: Operating rooms of a university-affiliated hospital.
Patients: 30 ASA physical status II and III patients with chronic renal failure, and 30 age-matched and gender-matched patients with normal renal function, presenting for elective surgery.
Interventions: Blood sampling for thromboelastograph and Sonoclot analysis immediately after anesthetic induction, prior to surgical incision.
Measurements and main results: Thromboelastographic indices of coagulation, reflecting coagulation factor function (R time), fibrinogen-platelet interaction (K time and alpha angle), and qualitative platelet function (maximum amplitude) were hypercoagulable in the uremic group compared with the control group (p < 0.05). Fibrinolysis (%) was decreased in the uremic group (p < 0.05). Fibrin formation (initial slope) and platelet function (time to peak) of the Sonoclot trace also were hypercoagulable in the uremic group (p < 0.05).
Conclusions: The high incidence of arteriovenous graft and fistulae thromboses in uremic patients belies in vitro laboratory evidence of platelet dysfunction. We have demonstrated perioperative hypercoagulability in uremic patients with viscoelastic measures of whole blood coagulation. These data suggest that traditional concern for coagulopathy and platelet dysfunction in uremic patients may require re-assessment in light of this "pro-thrombotic" state.