Problems with Broviacs!

Recently (for about the past 6 months), our PICU and general peds floor have seen a huge increase in ruptures/clotting of Broviac lines. Within the past month in the PICU alone, we have had four separate Broviacs on three separate patients placed by two separate surgeons all end up clotted and/or ruptured (all were ruptured, some were clotted as well). We've also had issues with lines becoming clotted or not drawing back, despite being in the correct location.

Now, it's possible the Broviacs are rupturing because they are clotting and the attempts to force-flush the line (which should never be done) are causing breaks. But that raises the question- why are they clotting?

Our central line protocols have not changed at all. Our policy is to run a potency solution (Normal Saline with heparin 1 unit/mL at either 3 or 5 mL/hr) continuously through the line. The only thing we have changed is the pumps on which we run the potency solution when it's ordered for 5 mL/hr. (We changed from Baxter pumps to Sigma pumps for medication delivered via bags. Due to the volume of fluid needed, rates of 5 mL/hr are dispensed from pharmacy in a bag, while rates of 3 mL/hr are dispensed in syringes and run on syringe pumps.) But the change in pumps does not account for all of the patients who ruptured.

The only other thing we could think of is that there has been some sort of manufacturing defect on the part of the Broviac company recently that hasn't yet come to light. Some of these Broviacs didn't even last a week after placement.

So I'm asking other PICU nurses- have you noticed an increase in complications with your newly placed Broviac catheters in recent months? Do you have any ideas about what might be contributing to our unit's problems or suggestions for improvement?