Silicone venous access devices positioned with their tips high in the superior vena cava are more likely to malfunction

BACKGROUND: Silicone venous access devices (VADs) are commonly used for mul tiple intravenous infusions and blood sampling in chronically ill patients, particularly cancer patients. These devices are susceptible to malfunction s most commonly characterized by difficulty infusing fluids or withdrawing blood. We hypothesized that the incidence of such malfunctions is primarily related to the position of the catheter tip relative to the superior vena cava/right atrial junction. METHODS: We reviewed medical records for 141 patients in whom silicone veno us access devices were used. Chest radiographs obtained following catheter insertion were reviewed by a single radiologist to rule out pneumothorax an d determine the position of the catheter tip. Other potential factors inclu ded in the analysis were catheter brand, the vein into which the catheter w as inserted, and the side (right or left). A malfunction was defined as res istance to flushing or infusion of a substance, complete inability to infus e a substance, resistance to blood aspiration attempts, or absence of blood return with aspiration, occurring any time during which the catheter was i n place. Multiple logistic regression was used to determine which factor(s) most strongly predicted catheter malfunction. RESULTS: Catheter tip location was the only factor that was statistically p redictive of malfunctions (coefficient 0.842, P < 0.001), A significant inc rease in malfunctions was observed in cases where the catheter tip was loca ted greater than 4 cm superior to the junction of the right atrium and the superior vena cava (z-test of proportions, P = 0.003). Malfunctions were mi nimized in those cases where the catheter tip was located in the right atri um, CONCLUSIONS: These results indicate that malfunctions can be minimized in s ilicone venous access catheters by locating the catheter tip as close to th e superior vena cava/right atrial junction as possible, or slightly inside the right atrium. To ensure proper location of the catheter tip, placement should be performed under fluoroscopy, and a radiograph should be obtained immediately following placement, with the patient in the upright position. Am J Surg, 1999;178:38-41. (C) 1999 by Excerpta Medica, Inc.