Personal Protective Equipment (PPE): Contamination common despite better protection
M3 India newsdesk May 16, 2020
On April 15, 2020, Cochrane, widely respected for its authentic unbiased reviews published a 144 page fast-tracked update to a 2019 review giving valuable insights on personal protective equipment for preventing highly infectious diseases due to exposure to contaminated body fluids in healthcare staff in response to the COVID-19 pandemic.
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“We know that basic science research and innovation will be vital in containing and mitigating the effects of the rapidly evolving COVID-19 pandemic. Cochrane is responding promptly to this unprecedented global health crisis by answering the time-sensitive needs of health decision makers, as fast as possible while simultaneously ensuring that the scientific imperative of methodological rigor is satisfied.” Cochrane stated in its summary note.
While appreciating the observations of Cochrane Work, all stake holders including Health Care Workers (HCW) and members of the public must scrupulously follow the orders and recommendations of authorised State and Central agencies to face the pandemic.
Healthcare workers (HCW) treating patients with infections such as coronavirus (COVID‐19) are at greater risk of infection to themselves than patients. They use personal protective equipment (PPE) to shield themselves from droplets from coughs, sneezes or other body fluids from infected patients and contaminated surfaces that might infect them.
PPE may include aprons, gowns or coveralls (a one‐piece suit), gloves, masks and breathing equipment (respirators), and goggles. HCWs must put on PPE correctly; it may be uncomfortable to wear, and healthcare workers may contaminate themselves when they remove it. Some PPE has been adapted, for example, by adding tabs to grab to make it easier to remove. Guidance on the correct procedure for putting on and removing PPE is available from organisations such as the Centers for Disease Control and Prevention (CDC) in the USA.
This is the 2020 update of a review first published in 2016 and previously updated in 2019.
What did they find?
The reviewers found 24 relevant studies with 2278 participants that evaluated types of PPE, modified PPE, procedures for putting on and removing PPE, and types of training. Eighteen of the studies did not assess healthcare workers who were treating infected patients but simulated the effect of exposure to infection using fluorescent markers or harmless viruses or bacteria. One of the frailties of these studies was that most of the studies were small, and only one or two studies addressed each of our questions.
The reviewers realised that covering more of the body leads to better protection. “However, as this is usually associated with increased difficulty in putting on and removing PPE, and the PPE is less comfortable, it may lead to more contamination’, they cautioned.
Coveralls are the most difficult PPE to remove but may offer the best protection, followed by long gowns and aprons. Respirators worn with coveralls may protect better than a mask worn with a gown, but are more difficult to put on. More breathable types of PPE may lead to similar levels of contamination but be more comfortable. Contamination was common in half the studies despite improved PPE.
The reviewers made many useful observations on PPE. Face‐to‐face training, computer simulation and video training led to fewer errors in PPE removal than training delivered as written material only or a traditional lecture.
The Cochrane report conceded that “our certainty (confidence) in the evidence is limited because the studies simulated infection (i.e. it was not real), and they had a small number of participants.”
Gaps in information
Cochrane listed the crucial gaps in information. For instance, there were no studies that investigated goggles or face shields. We are unclear about the best way to remove PPE after use and the best type of training in the long term.
Cochrane recommended that hospitals need to organise more studies, and researchers need to agree on the best way to simulate exposure to a virus. Future simulation studies need to have at least 60 participants each, and use exposure to a harmless virus to assess which type and combination of PPE is most protective. The reviewers suggested that it would be helpful if hospitals could register and record the type of PPE used by their workers to provide urgently needed, real‐life information.
Implications for practice
The reviewers concluded that in addition to other infection control measures, consistent use of full‐body personal protective equipment (PPE) can diminish the risk of infection for healthcare workers.
“EN (European) and ISO (international) standards for protective clothing and fabric permeability for viruses are helpful to determine which PPE should technically protect sufficiently against highly infectious diseases. However, the risk of contamination depends on more than just these technical factors. In simulation studies, contamination happened in almost all intervention and control arms.” they clarified.
“For choosing between PPE types, there is very low‐certainty evidence, based on single‐exposure simulation studies. Covering more parts of the body leads to better protection but usually comes at the cost of more difficult donning (putting on) or doffing (taking off) and user comfort, and may therefore even lead to more contamination”, they cautioned.
“A powered, air‐purifying respirator (PAPR) with a hood may protect better than an N95 mask with a gown but is more difficult to don. A long gown may be the best compromise between protection and ease of doffing. Coveralls may be more difficult to doff. A more breathable fabric may still lead to similar levels of contamination protection to less breathable fabric, and may be preferred by users.” they added.
The reviewers added many points covering the use of PPE and the limitations in training procedures.
The reviewers highlighted the fact that “the certainty of the evidence is low to very low for all comparisons because conclusions are based on one or two small studies and a high or unclear risk of bias in studies, indirectness of evidence, and small numbers of participants.”
“This means that we are uncertain about the estimates of effects and it is therefore possible that the true effects may be substantially different from the ones reported in this review.” they cautioned.
Implications for research
The reviewers concurred with the World Health Organization (WHO) that there is a need to carry out a re‐evaluation of how PPE is standardised, designed, and tested (WHO 2018).
“What is missing is a harmonised set of PPE standards and a unified design for PPE to be used when taking care of patients with highly infectious diseases. This holds for PPE as used for preventing contact transmission as well as other ways of transmission. There is, for example, no unified technical standard for isolation gowns. There is also a need for a more transparent and uniform labelling of infection control measures, such as droplet precautions, and the protection level of PPE for HCW. We believe that this is an important prerequisite for the universal implementation of infection control measures for HCW,” the reviewers asserted.
The report recommended the use of suitable viral markers in simulation studies and acceptable statistical design of such studies and adherence to appropriate reporting guidelines.
The reviewers also suggested prospective follow up studies of Health Care Workers (in statistically respectable numbers) involved in the treatment of patients with highly infectious diseases, to find out how PPE behaves under real exposure with careful registration of PPE, donning and doffing and risk of infection.
They recommended statistically well-designed case‐control studies comparing PPE use among infected HCW and matched healthy controls, using rigorous collection of exposure data. It can provide information about the effects of PPE on the risk of infection.
“There is a need for collaboration between organisations serving epidemic areas to carry out this important research in circumstances with limited resources, and during the throes of an outbreak.” they added.
The reviewers recommended more randomised controlled studies of the effects of one type of training versus another, to find out which training works best, especially at long‐term follow‐up of one year or more.
The Cochrane review gives a bird’s eye view of the status of the field highlighting several areas which need careful strengthening and enhancement.
Disclaimer- The views and opinions expressed in this article are those of the author's and do not necessarily reflect the official policy or position of M3 India.
Dr K S Parthasarathy is a freelance science journalist and a former Secretary of the Atomic Energy Regulatory Board. He is available at email@example.com
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