Hickman catheter clots: a common occurrence despite daily heparin flushing

Central vein thrombosis is the major Hickman catheter complication in our patient population. After noting clots attached to the disposable infusion plug of these catheters, we prospectively determined whether the presence of clots indicated a high-risk group for thrombosis. Forty-three patients (41 with solid tumor, two with acute leukemia) were studied. Catheters were flushed daily with heparin (10 units/ml), and urokinase (5000-10,000 units) was injected when blood could not be drawn. Clots within the catheter lumen were detected visually after expressing, onto a 4 X 4-inch gauze pad, the first 5-10 ml of admixed blood and flush solution or iv infusion fluid drawn from the catheter prior to blood drawing. Clots were detected in 153 of 508 specimens (30%). Forty of 43 patients had clots, varying in length from fragments to 5 cm, in at least one specimen. Inpatients and outpatients had a similar percentage of clotted specimens. Eight patients developed clinical (six) or autopsy-proven (two) thrombosis. There was no difference between patients with and without thrombosis in percent of discards positive for clots. This study indicates that clots are frequently present in the lumina of Hickman catheters. It is likely that these clots embolize to the lungs when catheters are flushed. Consequences of embolization are unknown.