Ebola and the Need for New Personal Protective Equipment
Editor’s note: This article was published online October 28th 2014 in the Journal of the American Medical Association and offered free to the public. We repost it here on ThirdAge in the interest of providing reasoned and scientific information in the wake of the Ebola fears that have gripped the country and the world.
By Michael B. Edmond, MD, MPH, MPA; Daniel J. Diekema, MD, MS; and Eli N. Perencevich, MD, MS of the Department of Internal Medicine, University of Iowa Carver College of Medicine, Iowa City. Dr. Perencevich is also affiliated with Iowa City VA Health System.
Preventing transmission of pathogens in the health care setting with the use of personal protective equipment (PPE) has been an area of longstanding debate in the infection prevention community. Recently, reports of nosocomial transmission of Ebola virus to 2 nurses from the same patient in Texas (despite their use of PPE) has generated great concern and presents new challenges, particularly because there is no postexposure prophylaxis or effective antiviral therapy for Ebola, and approximately half of the cases are fatal.
Health care workers are at particular risk for Ebola infection, accounting for one-quarter of cases in prior outbreaks. This appears to be related to low infectivity early in the infection, when patients are in the community. As the severity of illness increases and patients are often hospitalized, infectivity increases, accounting for an elevated risk for infection among health care workers.
Some health care workers should have extensive experience wearing PPE during routine care as currently recommended by the Centers for Disease Control and Prevention (CDC), and most research concerning PPE has focused on its utility for preventing the transmission of multidrug-resistant bacterial organisms (MDROs) from the clothing and hands of health care workers to patients. However, there is evidence that routine use of gowns, gloves, and masks is associated with frequent self-contamination. A study at the University of Maryland showed that when caring for intensive care unit patients infected or colonized with an MDRO, health care workers self-contaminated their hands with the same MDRO after wearing gloves and gowns during 5% of care episodes. It has also been shown that contamination increases with environmental burden, which is particularly important later in the course of Ebola disease given the high viral load, gastrointestinal manifestations, and, in some cases, bleeding. Despite the high rate of self-contamination, health care workers are rarely infected with one of these MDROs but can serve as vectors spreading the MDRO to other critically ill patients if their hand hygiene adherence is not 100%. These silent transmission events have been tacitly allowed to occur because of the inability to link a specific episode of nonadherence with hand hygiene to transmission, and there has been limited funding for MDR-bacterial research, which might target PPE or other infection prevention system improvements.
Key clinical and microbiologic features of Ebola virus disease should guide current recommendations on how best to protect health care workers. The virus is found in body fluids that health care workers are likely to contact. These include blood, urine, vomitus, and stool. Gastrointestinal fluid losses can be massive (5-10 L/day), and simulated vomiting studies have shown droplet dispersion greater than 10 ft. In patients dying of Ebola virus infection, serum viral loads can reach 10 billion copies/mL. Although indirect contact (via fomites) with the virus has been documented to result in transmission, existing data suggest that this is uncommon.
The frequency with which gloves and gowns become contaminated during the care of the Ebola patient is unknown. However, given that virus is found both in bodily fluids and on the surface of the skin, it should be assumed that gowns and gloves become highly contaminated during direct patient care, particularly when the patient is vomiting and has diarrhea. Recent training of health care workers on use of PPE has revealed that removal without touching skin or underclothing with the external surface of the gloves or gown is difficult and that extensive practice is required to achieve proficiency with currently available PPE technology. The important point is that wearing and removing PPE require a high level of precision. There is no information about the risk for infection after skin contamination, but until further research provides additional data, contamination of even intact skin must be completely avoided. Even if skin breaks are necessary for infection, transfer of virus from intact skin to mucous membranes is likely to occur given the frequency with which many persons typically touch their nose, mouth, and eyes.
On October 20, 2014, the CDC announced revised recommendations for the type of PPE to be used for the care of the patient with Ebola virus disease, as well as detailed specific guidance on the processes for donning and removing PPE. The new recommendations require that all skin be covered, provide greater detail on the sequence of donning and removing PPE, and emphasize hand hygiene with alcohol-based hand rub at multiple time points while PPE is being removed. In addition, the donning and removal processes are to be coached and supervised by a trained observer to minimize breaches in protocol. While the changes should diminish the risk of transmission to the health care worker, removal of the PPE is now even more complicated. Thus, the need for improved protective technologies continues to evolve.
The ideal protective gear for Ebola virus disease would meet the following characteristics: (1) be impervious to fluid, (2) cover all skin and all underclothing (ie, surgical scrubs), (3) be easy to don, (4) be easy to remove while minimizing the risk for self-contamination, (5) provide maximal comfort for health care workers, and (6) be easy to dispose of while minimizing contamination of health care workers or environmental services workers and be environmentally friendly. Trade-offs must be made because the first 2 characteristics are absolute requirements and affect the other 4. Some currently available products provide excellent protection but are nearly impossible to remove without self-contamination. For example, some of these products are hoods that cover the head and neck and were designed to protect the patient from the hair or skin squames of the health care worker during surgical procedures. When a worker removes the hood over the head, the external surface of the hood frequently touches the skin of the face. Thus, there is a need to redesign these products to provide protection of the same body areas but make removing them easier via having the products open and fall away from the worker to avoid touching skin. Another potential option may be the use of disposable blunt scissors to cut the PPE in strategic locations to facilitate removal. However, this would require controlled experiments to ensure safety.
Given the ideal characteristics of PPE needed for health care workers and others caring for patients with Ebola virus disease, it is clear that reengineering of PPE is required, both in US hospitals but more critically for the outbreak zones in Africa. The use of cumbersome PPE in the extreme heat and difficult working conditions of Ebola treatment centers in Africa places great stress on health care workers and limits the time they can spend providing patient care. A novel approach to PPE that provides an impermeable fluid barrier that is both more comfortable and easier to don and remove would be a substantial step forward. This will require new materials and designs. Indeed, the US Agency for International Development, White House Office of Science and Technology Policy, CDC, and US Department of Defense have recently announced a campaign to develop and test innovations for PPE in response to the Ebola outbreak. Importantly, improvements in PPE will also assist with better control of MDROs, which is especially needed given the lack of therapeutic options for highly resistant gram-negative bacillary infections. Better PPE will improve safety for both health care workers and patients.
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