Effect of inline filtration on postinfusion phlebitis

The effect of inline i.v. filters on postinfusion phlebitis (PIP) and bacterial colonization of i.v. catheters was evaluated. The subjects of the prospective double-blind study were 195 men undergoing elective surgery. Polyethylene i.v. catheters of varying sizes were inserted the morning of surgery. Before catheterization, each site was shaved and cleansed with 1% povidone-iodine solution. In the experimental group, all i.v. fluids, additives, and medications were administered through a 0.22-micron micropore inline final filter. In the control group, no membrane filter was present in the filter housing. Drug and fluid therapy were determined by the physician, and flow rates were maintained at 40 ml/hr if not specified. Every 12 hours, sites were inspected and observations were graded according to criteria adapted from an earlier study. The incidence of phlebitis in the two groups was compared. At the termination of i.v. therapy, catheters were removed and cultured. The incidence of PIP in the experimental group (38/95) and the control group (39/100) was not significantly different. There were no differences between groups in variables possibly related to the occurrence of PIP, such as patient age, i.v. flow rate, catheter size, and use of potassium chloride i.v. additive. Of 141 i.v. catheters that were cultured, 25 yielded 10 or more colonies per plate; 21 were coagulase-negative staphylococci. Positive cultures occurred as frequently in patients without filters as in those with filters. No patient had clinical evidence of bacteremia. In these general surgical patients, inline filters did not affect the incidence of PIP or bacterial colonization of i.v. catheters. While the use of inline filters to prevent infusion of microorganisms deserves consideration, their routine use as a means of reducing PIP is unwarranted.