Does a small-diameter rod-type tunneler reduce postoperative swelling? An evaluation using a canine arteriovenous graft model.

PURPOSE: Sheath-type tunnelers are frequently used to create vascular access using vascular grafts. However, during vascular access creation, tunnelers damage the surrounding tissues, consequently causing problems, such as swelling, failure to heal, and infection. This study evaluated a novel rod-type tunneler that was designed to prevent tunneler-related tissue damage and its sequelae. METHODS: We developed a small-diameter rod-type tunneler that reduces injuries during subcutaneous tunnel creation. The rod diameter of this tunneler is smaller than the vascular graft diameter being implanted. It has a structure in which a vascular graft is implanted at a target site by grasping and pulling the vascular graft. Three dogs were used in the experiment, and arteriovenous grafts were created using a rod-type and a sheath-type tunneler on the left and right thighs, respectively, with a different type of commercially available graft used in each dog. The edema of the tissues surrounding the vascular graft was measured at 11 sites by ultrasonography at prespecified intervals. RESULTS: Compared with implantation using a sheath-type tunneler, when the self-sealing Rapidax II was implanted using the small-diameter rod-type tunneler, the postimplantation edema (degree of change) decreased by 28-53% and 80-247% in the peri-vascular-graft area and within the loop, respectively. The MAXIFLO and SEALPTFE did not significantly reduce postoperative edema but exhibited a tendency for improved postimplantation tissue healing. CONCLUSIONS: The reduced-diameter rod-type tunneler may be a useful device for vascular graft implantation.

Effect of contrast media formulation on computed tomography angiographic contrast enhancement.

The characteristics of contrast media formulation (mgI/ml, osmolarity, and viscosity) are generally not considered important in computed tomography (CT) angiography in animals. The purpose of this study was to assess the contrast effect in CT angiography as a function of contrast media formulation, with a constant iodine dose. The contrast effects of three contrast media with different iodine concentrations were compared by administering identical iodine dosages (mgI/kg). The contrast effects of the three contrast media differed, and the area under the time-attenuation curve of iohexol 350 mgI/ml, which had the highest iodine concentration, was the lowest. It was hypothesized that the contrast effect of a contrast medium decreases with higher iodine concentration because of the high amount of residual iodine present in the circulatory system from the injection site to the portion immediately before the great vessels. In addition, the influence of osmotic dilution on contrast media with high osmolarity was also considered. In conclusion, the contrast effect varies with different contrast media formulations, even when the same iodine dosage is administered.