Central venous catheters (CVCs) are temporary devices implanted into patients when easy or frequent intravenous access is needed. Doctors often use them. A Hickman line is an example of a CVC. A CVC is used, for instance, for monitoring patients in intensive care, or for giving chemotherapy or intravenous nutrition. However, such catheters can cause blood clots, which can block the line, increase the risk of infection and travel elsewhere in the body such as to the lung (this is called thromboembolism). Heparin is a drug that helps to prevent blood clots and may help prevent these unwanted consequences. But heparin can also cause serious adverse effects (bleeding, allergic reactions, fall in platelet count, etc.). Normal saline solution, a sterile solution of salt in water at a concentration suitable for the blood, is typically used for intravenous infusions. We wanted to know whether heparin helps prevent the unwanted effects of blood clots in CVCs, and if this benefit outweighs its risk of harms.
Six studies with a combined total of 1433 participants were included. The quality of the evidence ranged from very low to moderate for the main outcomes.
Our review found no compelling evidence of a decrease in the rate of blocking of CVCs flushed with heparin compared with CVCs flushed with sterile saline solution, nor of differences in the number of days the catheter lasted, the rate of thrombosis, rate of infection, mortality, bleeding rates or heparin-induced fall in platelet count.
We conclude there is no good evidence that heparin flushing of CVCs is better than flushing with sterile saline solution. As heparin is more expensive, the findings of this review do not support its use except in future clinical trials.