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The COVID-19 pandemic has underlined the significance of patient and provider safety to Emergency Medical Service agencies and departments. Proper ambulance disinfection has become a high priority in these conversations, but many Emergency Medical Service leaders require a clear direction on effective strategies for reducing or eliminating the bioburden effectively. Department strategies for proper ambulance cleaning and disinfecting range from general wipe-downs of surfaces in-between patients to various deep clean methods occurring at poorly defined intervals. Many types of disinfectants are available on the market to reduce or kill pathogenic microorganisms that are present inside the patient compartment and cab of the ambulance. Although Emergency Medical Service providers have always tried to be diligent about helping to prevent the spread of infectious diseases, the COVID-19 pandemic revealed that confusion remains in many aspects of this critical mission.
According to the Association for Professionals in Infection Control & Epidemiology-Guide to Infection in Emergency Medical Service, any of 30 different infectious disease causing pathogens can be in your ambulance at any one time. (1) The most prevalent microorganism personnel can encounter daily include Clostridioides difficile, HIV, Hepatitis-A B or C, Conjunctivitis, Tuberculosis, Herpes Simplex, and most recently, SARS-CoV-2. Emergency Medical Service professionals are at greater risk than the general population as patients with these diseases are more likely to be transported by ambulance.
Both EMS professionals and patients are at risk of infection. Unsurprisingly, the CDC recognizes that the risk for occupationally acquired infections is unavoidable to caretakers and can lead to substantial illness or even death as result. (2) And a retrospective analysis conducted from 2016 to 2019 at Duke University Hospital revealed startling findings after tracking patient infections by transportation source. After evaluating patients who arrived at an ER by ambulance versus patients who arrived by non-Emergency Medical Service means, patients who were transported by ambulance were four times more likely to acquire a MRSA or VRE infection within 30 days of hospital admission. (3) This study is the first to indicate an association between ambulance transport and the infection risk for patients.
Furthermore, paramedics ranked outbreaks of new and highly infectious diseases highest in relation to the fear and unfamiliarity of their job as providers. (4) Other studies have demonstrated that blood pressure cuffs, stethoscopes, and respirator masks in ambulances frequently carried enterococci and S. aureus. (5) In addition, 32% of stethoscopes used by paramedics tested positive for MRSA and 57% of patient-ready trauma equipment swabbed tested positive for blood contamination. (6)
While there are effective sprays and wipes, well-defined processes for cleaning are often lacking. Improper cleaning techniques can stem from an inability to repeat cleaning methods exactly, a poor mindset due to the mundane nature of the task, and the simple fact that these pathogens are invisible to the naked eye. In fact, poor techniques are proven to potentially spread the contamination in areas inside the ambulance. It’s important to clearly define what is most critical to clean between each patient, focusing on high touch objects. This will make it more likely that the right objects can be cleaned quickly and efficiently. A recent study recommended the stretcher, backboard, ECG monitor and cables, and stethoscope as important high touch objects to clean between each patient. (7)
Now more than ever, proper cleaning and effective disinfection strategies for the ambulance environment are critical. The greatest enemy of this mission is time. Increased Emergency Room wait times, response area demands, ambulance utilization metrics, and increased staffing demands often sacrifice proper ambulance disinfection for faster turnaround times. Emergency Medical Service crews often feel fortunate if they have a few minutes to quickly wipe down the back of the ambulance before heading to the next call.
Crews should, at the very least, have a small number of clearly identified high touch objects to clean, and effective disinfectant wipes readily available to effectively clean between patients as much as possible. Due to the demanding and urgent nature of the work, even experienced team members find themselves performing a fast pass-through using various wipes on high-touch surfaces. This can mean only one side of the mattress gets cleaned, along with railings and perhaps the stretcher handles.
Are there general guidelines for ambulance decontamination and if so, who governs it? Most Emergency Medical Services rely on the CDC for methods to clean and disinfect such as an EPA-registered pre-saturated wipe. CDC guidelines are enforced by OSHA General Duty Clause of 1970. The Clause is broad protection and covers employees of any business. This requires that in addition to compliance with hazard-specific standards, all employers provide a work environment “free from recognized hazards that are causing or likely to cause death or serious physical harm.”
CDC disinfecting guidelines (8) have been adopted for healthcare facilities but do not always translate well to ambulance bio-decontamination due in part to their highly technical nature. In the absence of uniform established guidelines specific for ambulance decontamination, Emergency Medical Service managers are forced to review information from many sources such as the CDC and APIC to make their own determination. Some of these guidelines offer little help in evaluating actual ambulance disinfection technologies and chemistries, and Emergency Medical Service managers often do not have the highly technical infection control background to evaluate them appropriately.
High touch objects must be manually disinfected between each patient. While they do not replace manual cleaning, there are several ways to apply adjunct disinfection solutions, each with its own pros and cons. These technologies include foggers, misters, electrostatic sprayers, UV light devices, and vaporized 35% hydrogen peroxide. Liquid aerosol decontamination methods, such as misters, foggers, and electrostatic sprayers can vary greatly in their use. There are different solutions on the market that are used with these distribution methods, and each has a different efficacy profile and ideal method of application. These methods are also some of the cheapest for Emergency Medical Services to implement. There can be limitations to these methods, however. First, because these are usually applied manually, personnel safety and exposure limits are significant concerns.
Also, having a manual application introduces variability in effectiveness due to personnel training and the potential inability to follow technical guidelines consistently. In addition, these methods project liquid onto the surfaces, which could introduce damage to electrical equipment, disposable medical supplies, and plastic or cloth materials present in the back of the ambulance.
Finally, most of these methods require additional aeration time which is not usually listed in the marketing materials. If you see a product claiming a 5-minute disinfection time, be sure to ask about any additional steps. Does it require additional time for passive aeration to dry or become safe to enter the vehicle? Talk to other departments that have implemented the same technology. Be sure to ask the actual users if they have noticed an unpleasant or unsafe odor in the environment. Find out if they have noticed any residues that may discourage repeated use. Discover if they have confirmed the occupational limits for the chemistries used and have means to confirm that the environment is safe to enter post-disinfection.
In addition to cleaning and disinfection between each patient, it is a good practice to perform a deep clean of the ambulance on a regular basis. A no-touch technology such as ultraviolet light (UVL) or hydrogen peroxide (H2O2) may be a good adjunct to ensure a high level of disinfection. Ultraviolet Light (UVL) has been demonstrated to be an effective adjunct to manual disinfection. However, there are limitations to this technology. The UV-C light coming from the unit will generally only disinfect areas that are in sight of the device. Any surfaces that are blocked from the light by other objects will not be decontaminated. Some reflection of the light occurs but this greatly reduces its effectiveness. Due to the complex layout of most ambulances, the light will likely need to be moved to several different locations to eliminate shadowing as much as possible and disinfect the entire patient compartment. For example, in a study it was found that the best overall disinfection time for Ultraviolet Germicidal Irradiation (UVGI) was 216 minutes. This could be reduced to 79 minutes with reflective aluminum and 59 minutes with UV-reflective paint. (9) UV options can be beneficial as fast to enact methods that can also be stopped instantly to reclaim the vehicle. They can provide an additional level of antimicrobial action over and above manual cleaning (depending upon the device selected), but will not offer the same level of efficacy and ability to reach exposed surfaces within the enclosed area when compared to other systems, such as one utilizing hydrogen peroxide vapor.
Hydrogen Peroxide (H2O2) is a well-studied option with significant evidence for its efficacy against pathogens. H2O2 comes in several forms, and products that use Hydrogen Peroxide are not alike. The concentration of H2O2 can correlate to the strength of disinfection. Ionized Hydrogen Peroxide (iHP) is usually dispensed at a strength of 7.8% and in the form of a wet fog or mist. It is effective against some pathogens with a reduction or kill of at least 99.999% when used according to the directions for use. However, the mist or fog can be wet and may not be evenly dispersed to all areas. Because it is a weaker concentration of H2O2, repeated applications and increased dwell time are required to approximate a similar pathogen kill rate of higher concentrations of H2O2.
A 35% hydrogen peroxide vapor when used according to direction, can provide a 6-log sporicidal kill, meaning when validated against a sporicidal indicator with 1 million spores, it will kill all of them. It is dispensed in a vapor form, micro-condensing onto surfaces to provide a microscopic layer of H2O2. This makes it invisible to the naked eye and is proven compatible with sensitive electronics. A solution such as Bioquell Hydrogen Peroxide Sterilant is an EPA-registered sterilant (EPA Registration Number: 72372-1-86703).
However, 35% hydrogen peroxide vapor solution is not typically used in between every transport, unless a patient with a known or suspected highly infectious disease was present. Emergency Medical Services typically use hydrogen peroxide vapor to proactively help eliminate the ambulance bioburden, deploying it as part of a routine maintenance schedule. Since 35% hydrogen peroxide vapor is compatible with electronics, the ambulance does not need to be unloaded prior to the disinfection cycle beyond linens that may absorb the vapor. The process takes at least 45 minutes to complete in most ambulances.
Your due diligence and vetting of any product are critical, as the chosen technology and corresponding disinfectant can affect the health and safety of your crew, patients, and hospital personnel involved in the patient’s treatment. Is the application of your current technology providing the same level of protection on exposed surfaces or is it only on select spaces/surfaces with limited results?
Before you invest in a bio-decontamination system for your ambulance(s), investigate its efficacy, and verify that the information is evidence-based and from an independent source. Look at the product in person by requesting a demo and talk to others who are currently using it to determine satisfaction with the product and support from the vendor. In addition, ask if your department has conducted an environmental risk assessment and determine if new or revised policies and procedures are needed to help guard your personnel, equipment, and vehicles and prevent them from transmitting infectious diseases throughout the community.
References:
1. Guide-to-Infection-Prevention-in-EMERGENCY MEDICAL SERVICE-APIC.pdf (nasEmergency Medical Serviceo.org), 2013; 13-16
2. Sepkowitz KA. Occupationally acquired infections in health care workers. Part I. Ann Intern Med 1996; 125:826-34
3. Schaps, D., Godfrey, A., & Anderson, D. (2021). Risk of methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus (VRE) acquisition during ambulance transport: A retrospective propensity-score–matched cohort analysis. Infection Control & Hospital Epidemiology, 1-6. doi:10.1017/ice.2021.272
4. Smith EC, Burkle FM, Archer FL. Fear, familiarity, and the perception of risk: A quantitative analysis of disaster-specific concerns of paramedics. Disaster Medicine and Public Health Preparedness. 2011;5(1):46-53
5. Kober P, Labes H, Möller H, Hülsse C, Kramer A. Hygienestatus von Fahrzeugen und Ausrüstung im Rettungsdienst [Hygiene status of ambulances and equipment in rescue services]. Anasthesiol Intensivmed Notfallmed Schmerzther. 2001 Jan;36(1):25-30. German. doi: 10.1055/s-2001-10237. PMID: 11227305.
6. Merlin MA, Wong ML, Pryor PW, Rynn K, Marques-Baptista A, et al. Prevalence of methicillin-resistant Staphylococcus aureus on the stethoscopes of Emergency Medical Services providers. Prehospital Emergency Care. 2009;13(1):71-74
7. Bryan E. Bledsoe, Richard J. Sweeney, Ross P. Berkeley, Korey T. Cole, Wesley J. Forred & Larry D. Johnson (2014) EMS Provider Compliance with Infection Control Recommendations Is Suboptimal, Prehospital Emergency Care, 18:2, 290-294
8. Guideline for Disinfection and Sterilization in Healthcare Facilities (2008),
https://www.cdc.gov/infectioncontrol/guidelines/disinfection/index.html
9. Lindsley WG, McClelland TL, Neu DT, Martin SB Jr, Mead KR, Thewlis RE, Noti JD. Ambulance disinfection using Ultraviolet Germicidal Irradiation (UVGI): Effects of fixture location and surface reflectivity. J Occup Environ Hyg. 2018 Jan;15(1):1-12. doi: 10.1080/15459624.2017.1376067. PMID: 29059039; PMCID: PMC6379899.