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 multiple intravenous infusions and blood sampling in chronically ill patients, particularly cancer patients. These devices are susceptible to malfunctions 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 venous access devices were used. Chest radiographs obtained following catheter insertion were reviewed by a single radiologist to rule out pneumothorax and determine the position of the catheter tip. Other potential factors included in the analysis were catheter brand, the vein into which the catheter was inserted, and the side (right or left). A malfunction was defined as resistance to flushing or infusion of a substance, complete inability to infuse a substance, resistance to blood aspiration attempts, or absence of blood return with aspiration, occurring any time during which the catheter was in 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 predictive of malfunctions (coefficient 0.842, P < 0.001). A significant increase in malfunctions was observed in cases where the catheter tip was located 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 minimized in those cases where the catheter tip was located in the right atrium. Conclusions: These results indicate that malfunctions can be minimized in silicone venous access catheters by locating the catheter tip as close to the 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.