I recently had the opportunity to interview Cliff Yahnke, PhD, Kenall Manufacturing’s Director of Clinical Affairs for Indigo-Clean. The topic? Using LED luminaires to disinfect spaces using a germ-sensitive portion of the visible light spectrum. The interview informed an article I wrote for the February issue of tED Magazine, the official publication of the NAED.

DiLouie: What is visible light disinfection, and how does it differ from other germicidal light technologies and disinfectant strategies?

Yahnke: Visible light disinfection (VLD) uses non-UV light to reduce bacteria and other organisms in an environment. It does this by using a low-level, blue-violet (visible) light to create a continuous, low-level of disinfection while in use. It is not intended for use in sterilizing devices (such as endoscopes) or purifying water. Compared to UV light, visible light disinfection works on a more select set of organisms (primarily bacteria) at a lower germicidal rate. While this may seem to make visible light disinfection inferior to UV light, it actually highlights some of the key differences. By its nature, UV light is unsafe for humans and therefore requires the room to be evacuated when in use. This limits its application and typically requires manual operation, which adds cost, complexity, and potential compliance issues with its use. Furthermore, the transmission of organisms is greatest while the room is occupied and, therefore, any form of disinfection that can be applied during that time is clearly of benefit.

Another key difference between UV and VLD is that the latter can be applied continuously throughout the day, whereas UV can only be applied episodically at the end of the day or between room turnover (delaying room turn time). This suggests that the best strategy for disinfection is to combine both technologies to provide continuous 24/7 coverage.

DiLouie: What pathogens does visible light disinfection eliminate, and what benefits does this produce? What is the business case?

Yahnke: Laboratory research from the University of Strathclyde and other manufacturers has shown that visible light disinfection can reduce a wide range of organisms including MRSA and C.diff. However, it is important to note that, to date, only one manufacturer’s products have been shown through published, peer-reviewed data to reduce harmful bacteria and surgical site infections in a clinical setting (“Continuous Environmental Disinfection in the OR- A Case Study, Murrell L., AORN 2018). The business case for VLD is quite simple. It represents a one-time capital purchase by the institution that is easily offset by preventing a single infection. In the study previously cited, a payback of 2.2 months was achieved using this manufacturer’s product.

DiLouie: What are the pros and cons of visible light disinfection compared to other disinfection strategies?

Yahnke: While there are some obvious differences between UV and visible light, there are also some subtle implications related to how each is implemented in a clinical setting. By its nature, UV light is highly germicidal and harmful to humans. It is, therefore, best used in “episodic” disinfection applications, such as terminal cleaning. Visible light is safe for humans, however, it is less germicidal and, as such, is best used for “continuous” disinfection applications. It can also disinfect both hard and soft surfaces, and the surrounding air, which is of interest in orthopedic procedures that can be lengthy, and often involve large open incisions.

Both types of disinfection work together to improve environmental hygiene, however, each is optimized for a range of applications. In general, UV light is good for applications in which a high amount of disinfection is needed in a short period of time (typically a few minutes up to 1 hour). Visible light works slowly, but more continuously, and can achieve similar levels of disinfection for certain organisms over an entire day. The key to using each is to understand the types of organisms that need to be eliminated in the desired space, the time available (or needed) for this enhanced disinfection, the tolerance for operational disruption, and the ongoing costs (labor, training, maintenance, consumables, etc.) beyond the initial capital purchase.

DiLouie: What research validates the utility of this technology?

Yahnke: VLD was discovered in 2002 by researchers at Scotland’s University of Strathclyde and has been clinically proven to reduce harmful bacteria up to 70 percent beyond routine disinfection efforts. It was first used in 2008 to reduce bacteria linked to hospital-acquired infections at the Glasgow Royal Infirmary, a major teaching hospital in the U.K., and has been the subject of more than 40 peer-reviewed journals and conference presentations. The University was granted the U.S. patent on the technology in 2013 and granted a single US manufacturer the exclusive rights for this healthcare technology. That manufacturer launched its first commercial product in 2015 and is the only manufacturer whose product has 3rd party, peer-reviewed data showing a reduction in bacteria and Surgical Site Infections (SSIs) in a clinical setting (“Influence of a Visible Light Continuous Environmental Disinfection System on Microbial Contamination and Surgical Site Infections in an Orthopedic Operating Room” Murrell L., et. al. Am J Infect Cont, accepted for publication, 2019).

DiLouie: What are typical applications for visible light disinfection? What is the most common application? What are poor applications?

Yahnke: While visible light disinfection can be used in any healthcare setting where the spread of bacteria and risk of infections are an issue, currently installations include Operating Rooms, Emergency Departments, Pharmacies, Procedure/Exam Rooms, and Patient Bathrooms. The system is ideal for use in hospital operating rooms and ASCs performing high acuity cases due to the increased risk of surgical site infections in these locations.

Because visible light disinfection is safe for people and equipment, it can be applied across a broad range of applications where infection prevention is valued.

DiLouie: In what luminaire types is visible light disinfection typically implemented? What is the most common luminaire type?

Yahnke: The business case for VLD is best made in those areas where the risk of infection is highest. In these areas, the use of a sealed enclosure light fixture is critical to reduce the ingress of pathogens into the environment regardless of the presence of VLD. Therefore, VLD is best suited for use in sealed enclosure, specification-grade light fixtures. In a healthcare setting, these are lay-in, recessed fixtures (1’x4’, 2’x2’, 2’x4’, and 6” downlights).

DiLouie: How should electrical distributors sell visible light disinfection luminaires?

Yahnke: VLD is a paradigm shift for electrical distributors as the fixtures cost substantially more (25%-100%) than a standard fixture. This cost however, is easily addressed through the prevention of a single infection. Therefore, distributors should work with their contractors and customers to reach the facility owner where the benefits of the technology can be fully realized. They should stress that the avoidance of just a single infection over the 10-year life span of the visible light disinfection system represents a 2.2 month payback on the cost of the entire system.

These distributors should also focus on the safe, automatic nature of visible light disinfection. The VLD system’s operation requires no special staff or training, and requires no room downtime or on-going maintenance.

DiLouie: What do electrical contractors need to know? Are there any special requirements related to installation and functional testing?

Yahnke: Some critical areas of the hospital benefit from the use of a dual-mode fixture, which uses a disinfecting only mode to increase the amount of disinfection in the space when the room is unoccupied. As such, this requires a control solution with multiple occupancy sensors to effectively determine when the room is vacant. Such wiring is clearly addressed in the comprehensive installation instructions, however, it is recommended that electrical contractors use staff trained in the installation of automated lighting controls and sensors (such as ultrasonic, passive infra-red, etc.).

DiLouie: What standards apply to this type of lighting, and what do they certify?

Yahnke: The standards for this type of lighting can be broken down into those that apply to the light being emitted and those that apply to the fixture (or enclosure) itself.

VLD is an emerging application and, not surprisingly, there are no approved standards for its correct application. Therefore, it is critical for all distributors and contractors to require third-party, peer-reviewed data showing reductions in infections for the actual product being used in the same application. This is the best way to ensure that the institution realizes the proposed benefits of VLD. Fortunately, there are multiple, international standards for its safety. IEC 62778 (2014) is the most commonly used standard to assess the health effects of acute and prolonged exposure to visible light. All distributors and contractors should ask for this data on any products being considered.

Visible Light Disinfection fixtures need to meet the same demanding performance requirements, listings and standards of sealed enclosure fixtures, including UL & ETL for environmental performance, IP64/65 (or Ingress Protection) rating, and NSF2 listing for fixture cleanability.

DiLouie: Is visible light disinfection supplemented by other disinfection technologies, or is it sufficient standalone for its intended applications?

Yahnke: Visible light disinfection is not intended to replace the institution’s current cleaning protocols. It is a complement to their existing efforts.

DiLouie: If you could tell the entire electrical industry just one thing about visible light disinfection, what would it be?

Yahnke: Deploying VLD is not the same as lighting a room. To achieve the promised benefits, the room must have a sufficient amount of disinfecting light (i.e. be properly dosed) based on the number of fixtures, their output, and their layout within the room. Distributors and contractors should require the manufacturer to provide 3rd party, peer-reviewed data demonstrating reductions in infections using their VLD product in the intended application.

DiLouie: Is there anything else you’d like to add about this topic?

Yahnke: Not all products that claim to have VLD are the same. Just as there are differences between different types of UV products related to spectrum, output, and duration, there are similar differences that apply to VLD. These differences manifest themselves as differences in price per fixture and price per room, and, most importantly, the clinical benefit provided. Understanding these differences is critical to the successful deployment of VLD in any capacity. Most distributors and contractors don’t have the time or expertise to work though these differences and, therefore, it is imperative that they demand 3rd party, peer-reviewed data demonstrating reductions in infections using the VLD product being considered in their intended application.

Craig DiLouie

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