Whole-blood thrombin time: a bedside method for determination of heparin activity.

A bedside method of measurement of the whole-blood thrombin time for the determination of heparin activity was used in 300 dialyses. It was easily performed by the whole staff despite the absence of previous training in laboratory work. This test, using a clot timer with an automatic pipette device, gives a minimum risk of exposure to hepatitis virus. An increase of the thrombin time of 50-100 per cent above the starting value (3.7-6.6 sec) was aimed at during the heparin infusion. Bleeding complications, which were minor, were seen only on 18 and fibrin formation only on 26 occasions out of 1500 observations. Within the 50-100 per cent limits bleeding complications were observed on 2 and fibrin formation on only 13 occasions. No protamine was given.