Complications associated to midline- and long peripheral catheters in adults. Systematic review of literature and proposal for a standardized model for data collection.

INTRODUCTION: Long peripheral catheters (LPCs) and midline catheters (MCs) are indiscriminately labelled with different names, leading to misclassifications both in primary and secondary studies. The available studies used different methods to report the incidence of catheter-related complications, affecting the possibility of properly comparing the catheter outcomes. The aim of this review was to explore the complications related to LPCs and MCs after reclassifying according to their length. METHODS: Systematic literature review based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses, conducted on PubMed, Scopus and CINAHL databases. The study protocol was registered in the International Prospective Register of Systematic Reviews. Data regarding LPCs and MCs were compared. Catheter outcomes were classified into major and minor complications, recomputed and reported as cases/1000 catheter-days. RESULTS: Fourteen studies were included. Over-half of the devices were correctly labelled by the authors, misclassifications affected particularly LPCs improperly labelled MCs. The cumulative incidence of catheter-related bloodstream infections was 0.3 and 0.4/1000 catheter-days, that of symptomatic catheter-related thrombosis was 0.9 and 1.8/1000 catheter-days for MCs and LPCs, respectively. Minor complications and catheter failure were higher for LPCs. CONCLUSIONS: A misclassification exists in the labelling of MCs and LPCs. A widespread heterogeneity of diagnostic criteria adopted to classify the catheters' outcomes was found, exposing the risk of misestimating the incidence of complications and undermining the possibility of effectively comparing results of the published research. We proposed a list of definitions and relevant variables as a first step toward the development of standardized criteria to be adopted for research purposes.

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.