Comparing test methods for moisture-vapor transmission rate (MVTR) for vascular access transparent semipermeable dressings

BACKGROUND: Catheter insertion sites are commonly covered by transparent film dressings, offering protection of the insertion site from external contaminants and securement of the catheter while allowing site observation through a clear window. Currently, there is considerable focus on creating IV film dressings with ever-increasing moisture vapor transmission rates (MVTR) to prevent the accumulation of moisture under the film and reduce the risk of infection. These increasingly high MVTR IV dressings are often promoted as superior to IV dressings with lesser MVTR values. METHODS: Since there are different methods to determine MVTR, we chose to test a series of commercially available dressings with two standard methods to compare the results and better understand the information provided by this measurement. We used European Standard EN 13726 to test the MVTR of seven different IV dressings with two different methods (upright and inverted). RESULTS: We measured a range of MVTR values from 773 to 2838 g/m(2)/day for the upright method and from 845 to 30,530 g/m(2)/day for the inverted method for the seven IV dressings tested. Three dressings showed statistically different MVTR values with the two test methods. CONCLUSIONS: The MVTR test method (upright or inverted) used and considered for IV dressing product selection matters because the results obtained can be very different. We suggest that the upright method is better suited for IV dressings because they are not in constant contact with fluid. We conclude that the inverted method alone is not adequate to compare IV dressings.