Thromboelastographic Evaluation of Cut Down-Induced Accelerated Coagulation

Dear Sir, The role of major operative surgery in the genesis of acceler­ ated coagulation is well appreciated. However, the relationship of a cut down to accelerated coagulation has not been previously described and was therefore the purpose of this study. Mongrel dogs (10 to 15 kg) were randomly assigned to one of two groups A (n=6) and B (n=6). Following procurement of an initial (0 min) blood sample by venipuncture, the animals were anesthetized with pentobarbital sodium (30 mg/kg). In group B, immediately after induction of anesthesia, a teflon catheter (Angiocath, Deseret) was placed in a femoral vein of each animal by cut down. Samples of venous blood were then obtained for thromboelastography (TEG) at periodic intervals of time by serial venipunctures in group A, and via cut down catheter in group B. TEG mean values of R and RK for both groups at 0, 15, 30 and 60 min are shown in Table 1. Group A animals show no change in TEG readings at 15, 30 and 60 min when compared with the initial reading at 0 min. TEG readings in group B at 30 and 60 min are significantly shortened. Marked shortening of R and RK values are indicative of accelerated coagulation. The mechanism by which cut down causes accelerated coagula­ tion is speculative, but one or more of the following considera­ tions may be possible: 1) increased release of thromboplastin, 2) exposure of collagen in the vessel wall to blood and 3) physical interaction of blood with catheter. That the TEG changes are not due to the barbiturate anesthetic is verified by absence of changes in the anesthetized control animals without a cut down. Further­ more, in the animals with the cut down, blood was taken simultaneously via jugular venipuncture and from the catheter and there was no difference in the TEG values of blood obtained.