PICCs and DVT

 Q:  What is the maximum limit of the catheter-to-vein ratio advised during insertion of Peripherally Inserted Central Venous Catheters (PICCs)? 

Answer: 45 percent

PICCs are commonly used in ICUs. Clinicians need to be aware of it's increased propensity to cause Deep Venous Thrombosis (DVT). One of the precautions to avoid this complication is to look for catheter-to-vein ratio. Studies have shown that the risk of DVT goes high when the catheter-to-vein ratio goes above 45 percent. If the high-diameter French size catheter placed in a relatively smaller vein, blood will not flow around the catheter leading to coagulation. 

As a rule of thumb, PICCs with size 4 French are safer. Also, single-lumen PICCs are safer than multi-lumen PICCs.

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References:

1. Evans RS, Sharp JH, Linford LH, et al. Risk of symptomatic DVT associated with peripherally inserted central catheters. Chest 2010; 138:803. 

2. Nifong TP, McDevitt TJ. The effect of catheter to vein ratio on blood flow rates in a simulated model of peripherally inserted central venous catheters. Chest 2011; 140:48. 

3. Sharp R, Cummings M, Fielder A, et al. The catheter to vein ratio and rates of symptomatic venous thromboembolism in patients with a peripherally inserted central catheter (PICC): a prospective cohort study. Int J Nurs Stud 2015; 52:677. 

4. O'Brien J, Paquet F, Lindsay R, Valenti D. Insertion of PICCs with minimum number of lumens reduces complications and costs. J Am Coll Radiol 2013; 10:864.