Better Performance with Higher Hydrostatic Head

Does Your Medical Fabric Protect You From Infection?

People always assume that more is better, don’t they? Like more the price, better is the product. The more thickness better is the protection. The more the number of beams, the better the Barrier Protection it offers.

[But this is not the case!] The hydrohead of a fabric is what determines its barrier performance against infection.

What Is Hydrohead of a Fabric?

The Hydrohead or the Hydrostatic head of fabric determines its water resistance. It measures how much liquid in a vertical column a fabric can hold before letting it pass through it.

Sterile gowns and drapes are expected to have a sterile field and restrict the transmission of pathogens during the surgery. There is an interdependence between the post-operative infection rate and water repellency of the medical fabric used during surgery. The nonwoven surgical barrier material with superior bacterial penetration resistance reduces post-operative infections. [1]

It is logical to conclude that when a liquid has transversed a barrier, the suspended micro-organisms have also passed or are soon to pass through the barrier. Hence having a high Hydrostatic head leads to better water resistance and better barrier protection from infection.

Factors Influencing the Hydrohead of a Fabric: [2]

1. Fiber Diameter.A decrease in fiber diameter increases the hydrohead. The decline in fiber diameter increases the surface area resulting in a tighter and compact web structure that does not let the water pass through the fabric. This is due to the tortuous path the fabric offers to the water.
2. Solid volume fraction.The higher the solid volume fraction of the fabric, the higher is the hydrohead. Because it creates fewer paths for the air to flow through and more fibers per unit area resist the air passing through the fabric.
3. Pore Diameter.An increase in the pore diameter of fabric decreases the hydrohead. Because an increase in pore size makes it easier for the liquid to pass through the fabric.
4. Percentage of Spunbond- Meltblown Layers.When a spunbond layer is attached on either side of a meltblown fabric during processing, i.e., making SMS and Spuntmelt composition, the hydrostatic head of the fabric is increased. The increase in hydrohead depends on the percentage of meltblown and spunbond layers in the fabric.The reason behind this is that the spunbond layer increases the strength of the fabrics. This provides extra strength to the meltblown fabric that helps it withstand higher water pressure.
5. Process setting Parameters.Various process setting parameters like Raw Material Selection, Air Flow Rate, Die-to-Collector Distance (DCD), Basis Weight, Mean Pore Diameter affect the hydrohead.

Though the number of beams does influence the fabric properties, it does not impact the final mechanical strength and barrier performance.

Medical fabrics hold the stakes of life and death for both the patients and the doctor. If any infectious micro-organism penetrates the barrier of your fabric, it can cause problems post the operation. So, while selecting fabric for your medical textile products, you should consider all these parameters before taking any decision.

Reference:

1. https://journals.sagepub.com/doi/abs/10.1243/EMED_JOUR_1984_013_009_02
2. https://repository.lib.ncsu.edu/bitstream/handle/1840.20/33454/etd.pdf?sequence=1