| Emergency response organizations are a vital link to any community’s access to immediate medical response and care. | 
(Fig. 3). Post disinfection (Fig. 4). ATP swab readings taken from the jump seat. Pre disinfection — 957 |
In an environment prone to contamination, even the best efforts can still leave germs behind. For this reason, there is a need for high level disinfection which is not prone to human error and can be validated.
During the COVID-19 pandemic and the resulting shortage of personal protective equipment (PPE), personnel of these agencies had a potential exposure level far beyond that of many other healthcare workers. Due to the high level of asymptomatic patients as well as the wide variety of COVID symptoms, many emergency responses thought to be for other causes, also led to exposure to SARS-CoV-2.
For the sake of first responders, as well as for that of the larger community, it is crucial to create an environment free of biological contaminates as a staging point for this vital work to occur.1 Though cleaning and disinfection for ambulances is a routine part of emergency response,2 these cleaning and disinfection protocols do not commonly have a consistent and reliable way to ensure a full disinfection has occurred.
In an environment prone to contamination, even the best efforts can still leave germs behind. For this reason, there is a need for high level disinfection which is not prone to human error and can be validated. In this study, a portable disinfection device was used to enhance existing cleaning protocol. This automated device injects seven percent hydrogen peroxide to fill the interior space of the ambulance with disinfecting solution. As a measure of an effective treatment, pre and post ATP swabs were collected, and both chemical indicators and spore-based biological indicators were used to test for a 99.9999 percent kill in even the hardest to reach areas of the ambulance.
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| Figure 1. HHP™ device orientation for treatment of cabin and cab of ambulance. | Figure 2. Validation Tools: Biological Indicators with tryptic soy broth medium, H2O2 Chemical Indicators, and ATP swabs with ATP meter. | Figure 5. Chemical indicators showing a color change indicating exposure to H2O2. | Figure 6. Biological Indicators (Geobacillus stearothermophilus 1 x 106) encased in a Tyvek/myler pouch. | Figure 7. Challenged chemical indicators showing the importance of opening cabinets, glove box, and other storage spaces to allow for complete migration. |
This case study examines whether using this system significantly improves disinfection outcomes for emergency response ambulances.
Methods
Patented Pulse™ Technology
The system used in this study is a mobile fogging device combined with a proprietary seven percent Hydrogen Peroxide (H2O2) solution which together are EPA registered for high-level disinfection. To calculate treatment time, the device is programmed for the cubic footage of the space being treated. As the target environment of this study was the interior of ambulances, the device was programed to treat the space of the forward cab and all compartments in the rear cabin at one time.
The device can be programmed manually using an onboard screen or remotely via APP. Once started, the system engulfs the space with Hybrid Hydrogen Peroxide™, a combination of vapor (VHP) and aerosolized hydrogen peroxide fog.
Following the initial delivery, the device then intermittently injects solution via Pulse™ technology to maintain the concentration of H2O2 for a set dwell time. For this study, dwell times of both 20 minutes and 30 minutes were used. As hydrogen peroxide naturally decomposes to oxygen and water, no neutralization.
Disinfection of Ambulances
Ambulances were parked in a large non-climate-controlled garage. The HHP™ device was placed inside the rear cabin and directed towards the window opening to the front cab (Figure 1). ATP pre-swabs were collected, and chemical and biological indicators were placed in challenging locations throughout the ambulance (Figure 2). The device was started, and the ambulance was closed for the duration of the disinfection cycle. Following the disinfection cycle, the ambulance was opened and allowed to air out. ATP post-swabs were collected, chemical indicators checked, and all biological indicators were retrieved and processed.
These three tables show reductions in ATP readings of porous and non-porous material.
ATP Swabs
Adenosine triphosphate (ATP) swabbing was performed pre and post disinfection treatment to measure the presence of microorganisms and residual organic matter. Swabbing was collected from a 4×4 square inch area of both porous and non-porous surfaces. Swabs were taken from frequently touched locations within the rear cabin, the jump seat, and the rear bench seat (Figures 3 and 4).
Chemical Indicators
Hydrogen peroxide chemical indicators were used to validate that disinfecting fog reached all areas of the ambulance, including hard to reach spaces such as a closed glove box and inside closed cabinets (Figure 5).
Biological Indicators
For validation of a high-level disinfection, biological indicators of Geobacillus stearothermophilus strain 12980 1×106 were used (the same indicators used in EPA testing). The indicators consist of bacterial spores on a stainless-steel carrier encased in Tyvek/mylar pouches. Indicators were placed throughout the ambulance’s back cabin and forward cab (Figure 6).
Following decontamination, indicators were collected, placed in tryptic soy broth, incubated, and monitored for seven days.
Results and Discussion
The disinfection cycle was simple to operate as the HHP™ device automates the process. Initial measurements of the ambulances were taken by measurements or from schematics. These measurements were input into the device which automates the time necessary for treatment. For this study, measurements were manually input into the device through its control panel; however, operators can also input this information through a cloud-based system, storing the measurements for future disinfection cycles and eliminating potential future errors in measurement or input. For emergency response organizations with large fleets, this method would eliminate the need to measure each individual vehicle prior to disinfection.
Table 4. Biological Indicators (Geobacillus stearothermophilus 1×106). Passing results indicate a complete 6 log reduction (99.9999 percent) of present pathogens for an achieved successful disinfection cycle.
ATP swab readings demonstrated a notable reduction in the presence of organic matter (viruses and live particles possibly including dangerous germs) from pre to post disinfection. Both porous and non-porous materials were swabbed. Non porous materials repeatedly demonstrated a complete or near complete reduction in organic matter. Porous materials demonstrated a >50 percent reduction in organic matter, which is consistent with the known greater difficulty in disinfecting porous materials (Tables 1-3).
Chemical Indicators change color when exposed to hydrogen peroxide, indicating the disinfection treatment has reached the locations where indicators are placed. All 15 chemical indicators, located throughout the vehicle, demonstrated exposure to hydrogen peroxide, validating the ability of HHP™ to engulf a space and even migrate to hard-to-reach spaces (Figure 7).
Biological indicators of Geobacillus stearothermophilus are used to demonstrate proof of disinfection. These spore-based indicators ensure a pathogenic presence within the space prior to treatment. By introducing this inactive but difficult to kill pathogen to the environment, it becomes possible to measure the degree of disinfection which has taken place. Indicators are processed in tryptic soy broth and monitored for signs of growth.
Growth of bacteria indicates a less than 6-log (99.9999 percent) reduction in present pathogens, conversely, lack of growth is a sign of a successful high-level disinfection (equal or greater than 6-log) of all treated spaces (Table 4). Notably, testing for this study occurred without environmental conditioning of either vehicles or the enclosing bay. This testing resulted in repeated demonstration of a complete 6-log reduction as indicated by the spore-based biological indicators.
These results indicate successful treatment is possible even when environmental conditions exceed that of the manufacturing specifications. These results indicate a wide range of environmental conditions retain the potential for a successful disinfection cycle.
Conclusion
Hydrogen peroxide systems are increasingly being used in the hospital environment; however, there remains limited use in this application for ambulance disinfection. Given the crucial role of emergency services personnel, and the importance of a pathogen-free environment at every step of the care process, thorough disinfection practices are a critical foundation for emergency response.
By enhancing disinfection with employment of the latest technology, those in the emergency management field protect themselves as well as their patients in the vulnerable time of transport. As the target of disinfection is invisible to the naked eye, validation tools can be employed to verify and create records of successful disinfection cycles.
The results of this study clearly show a significant and measurable improvement in the ambulance environment following treatment with the seven percent Hybrid Hydrogen Peroxide™ System.
REFERENCES
1. Andersen, B. M., Rasch, M., Hochlin, K., Jensen, F. H., Wismar, P., & Fredriksen, J. E. (2006). Decontamination of rooms, medical equipment and ambulances using an aerosol of hydrogen peroxide disinfectant. The Journal of hospital infection, 62(2), 149–155. https://doi.org/10.1016/j.jhin.2005.07.020
2. United States Department of Labor, Occupational Safety and Health Administration (January 2011) Bloodborne Pathogens Standard (29 CFR 1910.1030) https://www.osha.gov/OshDoc/ data_BloodborneFacts/bbfact01.pdf
