4.1 Significance-Dried blood represents a significant challenge to cleaning surgical instruments. The water-soluble components of blood are easily rendered insoluble when exposed to heat, chemical solutions, or time at room temperature. The water insoluble component of blood is fibrin built up during coagulation. These proteins bind quite readily to the surfaces of surgical instruments making them difficult to remove even with the aid of chemical cleaning agents. Instruments contaminated with blood residue after reprocessing represent a significant threat for infection to healthcare workers and patients. Healthcare facilities typically employ the use of automated instrument washers. These devices combine mechanical action along with chemical cleaning agents in a staged cleaning cycle designed to thoroughly clean surgical instruments. To function properly, these machines must be performing at targeted mechanical efficiency and deliver the correct chemical cleaning agents at the correct temperature, at the correct dosage for the correct period of time. Manufacturers of automated washers and manufacturers of cleaning detergent need to evaluate the performance of their products utilizing a surrogate for surgical instruments soiled with blood. The results of the performance testing will be used to improve product design and for validation of the performance of their product for various regulatory requirements.

4.2 Use-The regular, periodic use of the blood soil test is a systemic challenge to the functioning of an automated washer. To properly challenge the cleaning device, the test must be analogous to the dried blood soil, to the stainless steel substrate, and to the physical barriers presented by surgical instruments. These physical barriers include the box lock, or pivot joint of a hinged instrument, the serrated tips, and crevices of surgical instruments. On the test coupon, the components of blood are similar to the state of dried blood on instruments. By utilizing a grooved stainless steel coupon, the substrate is similar to that of stainless steel instruments. By mounting the soiled coupon in a plastic holder the physical barriers represented by cracks and crevices of instruments (for example, box locks) are represented. Users are provided with an interpretation guide that aids them in interpreting results that are less than optimal. For instance, failure to remove the fibrin layer of blood soil (which is water insoluble) indicates a problem with the chemical cleaning agent(s). Failure to evenly remove a hemoglobin soil indicates a mechanical failure. Failure to remove any soil indicates either a catastrophic mechanical failure, or inappropriate settings for the initial rinse stage. As a standardized challenge, the test provides a reproducible means for the washer manufacturer and the detergent manufacturer to compare new designs and formulations to those existing within their own product line as well as those of others in the market. For the purpose of submitting their instructions for use, the test provides a means to validate the performance of their product with a device that is a surrogate for the devices their products will be used to clean in the practical setting. This validation testing can be used as part of any necessary documentation for regulatory filings and records.