Reactions Associated with Midline Catheters for Intravenous Access

Things are not always what they seem.

Phaedrus

Fables (c. 8 A.D.)

The prospective study of midline catheters by Mermel and colleagues in this issue [1] reaffirms this ancient truism.

Reliable vascular access is one of the most basic and yet essential therapeutic modalities of modern-day health care. More than 175 million intravascular devices of various types are sold in the United States each year [2]. Most are 1.24-inch (3.2-cm) peripheral venous catheters made of Teflon or polyurethane, but the usefulness of these catheters for periods longer than 3 days is limited by a high incidence of infusion phlebitis (in the range of 40%) [3]. Central venous catheters reduce the risk for phlebitis but are 20 to 300 times more expensive [4] and are associated with as much as 20-fold higher rates of catheter-related bloodstream infection [2]. Three-inch to 8-inch (7.6-cm to 20.3-cm) catheters (termed midline catheters), inserted in the antecubital fossa or upper arm and terminating in the proximal cephalic or basilic vein or the distal subclavian vein, have been promulgated as an attractive and cost-efficient option for intermediate periods of venous access. The period of access averages 2 weeks in published reports but can be as long as 4 weeks [4-8]. Inserted in a larger peripheral vein, midline catheters appear to cause less phlebitis than peripheral venous catheters and are less expensive than central venous devices of all types [4].

The midline catheters available are made of silicone, polyurethane, or a novel composite polymer in which polyurethane is cross-linked chemically with polyethylene oxide, resulting in an elastomeric hydrogel (Aquavene, Menlo Care, Menlo Park, California). The elastomeric hydrogel catheter has the attractive feature of softening and expanding in length and diameter after insertion. The elastomeric hydrogel midline catheter (Landmark, Menlo Care) has been promoted …