MONITORING OF CYCLOSPORINE BLOOD-LEVELS FROM CENTRAL VENOUS LINES - AMISLEADING ASSAY

In order to assess the suspected influence of indwelling lines on the measurement of cyclosporine (CSA) blood levels, we evaluated CSA conce ntrations in samples drawn simultaneously from both silicone catheter lumens and peripheral veins of eight bone marrow transplant recipients . Blood samples were obtained at 30 min or 6-12 h after discontinuatio n of intravenous CSA. CSA concentrations were determined in whole bloo d by specific monoclonal antibody assay. Mean CSA levels from the lume n used for CSA administration were significantly higher than those fro m samples drawn from the second lumen (i.e., not used for CSA infusion ) or peripheral vein. This difference, obtained when the infusion had been interrupted for 30 min, was still the case 6-12 h after discontin uation of CSA infusion. No difference was found between samples obtain ed from the second lumen and peripheral vein. These observations sugge st that CSA might be adsorbed or bound by the silicon catheter and, th us, CSA blood level measurements may be misleading. The second lumen o f the catheter or a peripheral vein should be used for accurate monito ring of CSA concentrations.