The catheter-to-vein ratio at the tip level, not the catheter type, as a risk factor for a catheter failure. A retrospective comparative study of polyurethane midline and long peripheral catheters

Background: In patients requiring a peripheral venous access for more than seven days, long peripheral catheters (LPCs) or midline catheters (MCs) are recommended. Since MCs and LPCs share many characteristics, studies comparing devices made of the same biomaterial are needed. Moreover, a catheter-to-vein ratio >45% at the insertion point has been recognized as a risk factor for catheter related complications, but no study investigated the effect of the catheter-to-vein ratio at the catheter tip level in peripheral venous devices. Objectives: To compare the catheter failure risk between polyurethane MCs and LPCs, considering the effect of the catheter-to-vein ratio at the tip location. Methods: Retrospective cohort study. Adult patients having an expected need for a vascular access of more than 7 days and receiving either a polyurethane LPC or MC were included. The catheter uncomplicated indwelling time within 30 days was considered in survival analysis. Results: In a sample of 240 patients, the relative incidences of catheter failure were 5.13 and 3.40 cases for 1,000 catheter days for LPCs and MCs, respectively. In univariate Cox regression, MCs were associated to a statistically significant lower risk of catheter failure (HR 0.330; p = 0.048). After adjusting for other relevant conditions, a catheter-to-vein ratio >45% at the catheter tip location not the catheter itself was an independent predictor of a catheter failure (HR 6.762; p = 0.023). Conclusions: The risk of catheter failure was strongly associated with a catheter-to-vein ratio > 45% at the catheter tip level, irrespective for having used a polyurethane LPC or MC.