Prediction of Hydrostatic Pressure and Blood Penetration of Medical Protective Clothing

Disposable materials enjoy annually steady growth in volume in the field of medical applications as surgical gowns, isolation gowns, and medical drapes which impede cross contamination from reusable protective apparel in a hospital. There are four levels of liquid barrier performance according to the American National Standard/Association for the Advancement of Medical Instrumentation (ANSI/AAMI) PB70:2012 in terms of liquid impact penetration, hydrostatic pressure or hydrohead, and blood penetration. Different areas in a surgical gown require different levels of liquid barrier performance. Laminates of spunbond (SB), meltblown (MB), and spunbond (SB), called SMS fabric, and laminates of a porous membrane with a nonwoven fabric, usually with the SB layer for strength and ease of handling, are widely used as medical protective clothing. SMS materials are usually made to achieve up to Level 3, which requires a hydrostatic pressure of greater than 50 cm tested according to ANSI/AAMI PB70:2012. Above that level, Level 4 requires the liquid barrier to resist penetration by blood, in which case a laminate with a porous membrane is necessary. In this paper, the pore size, calculated from the fluid flow through a fibrous media, was used to estimate the hydrostatic pressure. The hydrostatic pressure was then used to correlate with the resistance of the media to blood penetration. The agreement of experimental and calculated data indicated that these theories were successful not only in predicting the pore size and the hydrostatic pressure of a fibrous material but also in correlating the hydrostatic pressure and blood penetration. The fiber fineness required to resist the penetration of blood was also calculated.