ASSESSING THE ROLE OF THE BIOMATERIAL AQUAVENE IN PATIENT REACTIONS TO LANDMARK MIDLINE CATHETERS

Landmark midline catheters (Menlo Care, Inc., Palo Alto, CA) provide p eripheral venous access for the infusion of medications or fluids. The y are constructed of an inner layer of polyurethane and an outer layer of the biomaterial Aquavene, a blend of polyurethane and polyethylene oxide to which butylated hydroxyanisole (BHA), butylated hydroxytolue ne (BHT), and triallyl-s-triazine trione (TTT) are added. Once inside the vein, the Aquavene material becomes hydrated and the catheter swel ls resulting in minimal trauma to the vein. It is well recognized that some patients experience reactions to catheterization. Recent reports of hypersensitivity-like reactions in some patients catheterized with Landmark catheters have prompted the manufacturer to reexamine biocom patibility data and clinical data to assess whether Aquavene was the s ource of the patient responses. None of the biocompatibility studies p rovided by Menlo Care in support of U.S. registration and marketing of Aquavene-based catheters demonstrated any tendency for Aquavene or ma terial extracted from Aquavene to invoke an immunological or toxicolog ical response. Examination of potential catheter residuals revealed th at significant amounts of BHA and BHT were unlikely to be released fro m the catheters during expected use. The amounts of polyethylene oxide and TTT expected to be released during the first few minutes after ca theter insertion (when most of the patient reactions were reported) ar e almost 92,500 and 270,000 times lower, respectively, than non-toxic animal exposures. These analyses do not support chemically mediated to xicity as an explanation for the adverse events experienced by some pa tients. A review of the postmarket surveillance data on Aquavene-based catheters revealed that the reported events were not consistent with a hypersensitivity (immunogenic) response to the biomaterial. The rare reported adverse events tend to occur quickly, most often after hushi ng of the catheter, and resolve quickly, even when the catheter remain s in place. Determining the frequency and severity of adverse events r eported in association with the use of Landmark catheters will ultimat ely require a controlled prospective study, preferably one with a conc urrent control group using alternative products. (C) 1997 Academic Pre ss.