Respiratory Protection for VHFs: Turning Evidence Into Practice
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When a patient presents with symptoms and epidemiologic risk factors that could indicate a viral hemorrhagic fever (VHF), healthcare workers may need to make decisions about respiratory protection before the diagnosis is known.
That uncertainty is an important part of preparedness. The goal is not to determine immediately whether a patient has a VHF, but to have systems in place that protect healthcare workers, patients, and visitors while the risk is recognized, assessed, and, when appropriate, ruled out.
During the NETEC webinar From Evidence to Action: Respiratory Protection for VHFs, experts in aerosol science, special pathogen preparedness, nursing, and personal protective equipment (PPE) explored the science behind respiratory protection and what it means for healthcare facilities preparing to identify and care for patients with suspected or confirmed VHFs.
The webinar was moderated by Jill Morgan, RN, of Emory University Hospital, one of the Region 4 Regional Emerging Special Pathogen Treatment Centers (RESPTCs). Panelists included:
- William Bennett, PhD, adjunct retired professor of medicine at the University of North Carolina at Chapel Hill, whose research has focused on aerosol physics, particle deposition and clearance in the lungs, and pulmonary physiology;
- Sarah Haroth, MSN, RN, PHN, Patient Care Supervisor and Unit Educator for the Special Pathogens Unit at M Health Fairview University of Minnesota Medical Center, one of the RESPTCs in Region 5;
- Bethany Little, BSN, RN, Nursing Operations Director and Training and Education Coordinator at MedStar Washington Hospital Center, one of the RESPTCs in Region 3; and
- Morgan Shradar, MPH, BSN, RN, Nurse Manager and Special Pathogens Program Lead Educator Coordinator for the Region 7 RESPTC and National Quarantine Unit at Nebraska Medicine.
Understanding the Science Behind Respiratory Protection
Aerosols are solid or liquid particles suspended in air. They can be generated through normal respiratory activities—including breathing, speaking, coughing, and sneezing—and vary in size. Particle size, in turn, influences how long particles may remain suspended and where inhaled particles may deposit in the respiratory tract.
But particle size is only part of the respiratory protection equation. The effectiveness of a mask or respirator also depends on its filtration material and, critically, how well it fits the wearer.
Research conducted during the COVID-19 pandemic helped demonstrate the importance of both. Mask and respirator materials can capture particles through several mechanisms, but gaps between the face and the device create opportunities for particles to bypass that material altogether.
For healthcare preparedness, the science points to several interconnected principles: particle behavior, filtration, and fit all matter.
Why Aerosolization of Body Fluids Matters for VHF Care
Aerosol-generating procedures such as intubation and bronchoscopy are familiar considerations in respiratory protection programs. But they are not the only activities capable of generating aerosols.
The webinar examined evidence that potentially infectious body fluids can become aerosolized during activities not traditionally categorized as aerosol-generating procedures. Studies involving other infectious diseases have detected aerosolization associated with vomiting, diarrhea, defecation, and toilet flushing, and have demonstrated that aerosolized particles can be inhaled.
These studies do not establish a new mode of transmission for VHFs. Instead, they help illuminate a practical occupational-exposure question: What happens when healthcare workers are in close proximity to large quantities of potentially infectious body fluids?
That question is especially relevant when caring for patients experiencing significant vomiting, diarrhea, bleeding, or other fluid losses. Healthcare workers may need to assist with toileting, repositioning, hygiene, bedding changes, or other tasks that bring them into close contact with body fluids.
As Morgan explained during the webinar, evidence that virus-containing body fluids can potentially become aerosolized and inhaled provides an important rationale for including respiratory protection when caring for a wet or confirmed VHF patient.
Current guidance reflects somewhat different approaches. WHO guidance for Ebola and Marburg emphasizes PPE that protects health care workers from contact with blood and body fluids and includes a fluid-resistant medical or surgical mask as part of routine PPE. In the United States, CDC recommends an N95 respirator or powered air-purifying respirator (PAPR) when caring for patients with confirmed VHF and for suspected VHF patients who are clinically unstable or experiencing bleeding, vomiting, or diarrhea.
For U.S. health care facilities preparing for VHFs, that evidence and guidance support a proactive approach to respiratory protection when the patient’s condition creates greater potential for exposure.
Protect People at Every Point of Entry
A patient with an unrecognized special pathogen could encounter the healthcare system at several points of entry: during an EMS assessment, at a hospital entrance, during registration or triage, or in a treatment area. A patient’s condition may also change after arrival, requiring staff to rapidly adjust the level of protection being used.
As Haroth emphasized, the goal isn’t to predict who has VHF at the door. The goal is to have a system that protects staff while the risk is recognized.
That system begins with Identify, Isolate, Inform:
Identify: Recognize signs, symptoms, and epidemiologic risk factors that could indicate a high-consequence infectious disease.
Isolate: Promptly separate the patient from the general patient population and healthcare personnel and implement appropriate infection prevention measures.
Inform: Use the facility’s high-consequence pathogen protocols and engage infection prevention and other appropriate partners to determine next steps.
Source control can begin early in that process. When appropriate and tolerated, providing a patient with a medical mask can reduce the particles released into the surrounding environment. Making masks readily available at points of entry, along with appropriate signage and screening processes, can therefore be one practical component of preparedness.
Healthcare workers also need rapid access to the protection they may require. As Haroth put it, respiratory protection needs to be available where the patient is—not where staff expect the patient to go.
For facilities, that means planning beyond the isolation room or biocontainment unit. N95 or higher-level respiratory protection should be immediately accessible to personnel who may encounter and initially care for a patient with suspected VHF.
Use the Hierarchy of Controls
PPE is an important layer of protection, but it is part of a larger strategy for reducing exposure.
Haroth used the hierarchy of controls, an occupational safety framework that prioritizes measures to eliminate or reduce exposure before relying on PPE alone, to illustrate how facilities can approach potential VHF risks.
Depending on the situation, controls may include avoiding unnecessary aerosol-generating procedures; substituting disposable equipment when appropriate; using engineering controls such as appropriate isolation spaces and designated donning and doffing areas; and using administrative controls such as rapid screening processes and limiting the number of personnel entering a patient care space.
Source control adds another important layer by reducing potentially infectious material at its source.
PPE then provides the final barrier between the hazard and the healthcare worker.
Match PPE to the Patient’s Condition
Respiratory protection is one component of the complete PPE ensemble, and the appropriate equipment depends on the patient’s condition and anticipated exposure.
NETEC’s Know Your PPE guide provides ensemble recommendations for both dry and suspect VHF and wet or confirmed VHF scenarios. The webinar also noted that significant sweating or aggressive coughing may be important considerations when assessing the potential for exposure.
Facilities can also use NETEC’s PPE Matrix for High-Consequence Infectious Diseases to compare PPE and precaution recommendations for different high-consequence infectious diseases.
The webinar reviewed three types of air-purifying respirators:
- Filtering facepiece respirators, such as N95s: Single-use, tight-fitting respirators designed for particle filtration. They require fit testing and a user seal check each time they are worn.
- Elastomeric respirators: Reusable respirators available in quarter-, half-, and full-facepiece configurations. Their filtration capabilities depend on the filters or cartridges being used.
- Powered air-purifying respirators (PAPRs): Reusable, battery-powered systems that pull air through a filter. PAPRs may have tight-fitting facepieces, which require fit testing, or loose-fitting hoods or helmets, which do not.
Facilities need to understand not only which respirators they stock but how they are configured, maintained, cleaned, and incorporated into the complete PPE ensemble.
NETEC’s Personal Protective Equipment Featured Resources page brings together these and other tools for PPE selection, training, donning and doffing, and preparedness.
Fit Is Part of the Protection
A respirator’s filtration rating does not by itself guarantee that the wearer is receiving the expected protection.
Shradar outlined four fundamentals for N95 fit testing using the acronym MEFF:
M – Medical clearance: Staff must be medically cleared to wear the respirator.
E – Exact match: The respirator used for fit testing should be the respirator the employee will actually wear in the work environment.
F – Frequency: Fit testing should occur at least annually and may need to be repeated when changes to facial shape or fullness could affect fit.
F – Facial hair: Staff using tight-fitting respirators must meet facial-hair requirements necessary to maintain the respirator’s seal.
Fit testing is not the final step. A user seal check should be performed every time a tight-fitting respirator is donned.
The webinar also reviewed the two primary methods of fit testing. Qualitative fit testing is a pass/fail sensory test that relies on the wearer’s response to a taste, smell, or irritant inside a test hood. Quantitative fit testing uses an instrument to measure leakage into the respirator and produces an objective fit score.
Train for the PPE Staff Will Actually Use
How much training staff need depends in part on how familiar they already are with the PPE they will be expected to use.
Haroth encouraged facilities to begin by looking at day-to-day practice. Emergency department staff, for example, may already be comfortable donning and doffing gowns and N95 respirators but have far less experience with coveralls. Introducing less familiar equipment requires additional practice to build competency and confidence.
Facilities should also determine who needs competency with which PPE ensembles based on their role and potential exposure. Personnel who may be among the first to encounter a patient with an unrecognized special pathogen need to understand what protection is available, when to use it, and how to access it quickly.
For staff learning a dry or suspect VHF ensemble, NETEC’s PPE Donning and Doffing: Non-PAPR Dry and Suspect VHF provides step-by-step guidance that can be incorporated into education and hands-on practice.
Respiratory protection also depends on a culture of safety in which team members are comfortable identifying and correcting improper respirator use. Shradar encouraged facilities to establish language or cues staff can use to respectfully redirect a colleague when respiratory protection is being worn incorrectly.
The webinar’s larger message is that respiratory protection is not a single piece of equipment or a single decision. It is a system.
Understanding how particles behave, making respiratory protection accessible at points of entry, selecting PPE based on patient condition and anticipated exposure, ensuring respirators fit and function as intended, and preparing staff to use the equipment available to them all contribute to safer care.
Special pathogen preparedness cannot eliminate uncertainty. It can ensure healthcare workers have the systems, equipment, and training they need to protect themselves while that uncertainty is being resolved.
Questions & Answers from the Webinar
How do you know when a patient is going to become “wet”?
You don’t, which is why proactive protection is important. Respiratory protection in the form of an N95 or higher and other appropriate PPE should be readily available so healthcare workers can quickly escalate protection as a patient’s condition or exposure risk changes.
Does fluid resistance matter when selecting a mask or respirator?
Yes. Surgical N95 respirators provide respiratory protection and fluid resistance, while the level of fluid resistance provided by medical masks varies by product.
How much PPE training do staff need?
Training needs depend in part on how familiar staff already are with the PPE they will use. Facilities should consider staff members’ roles, day-to-day PPE use, and likely exposure when determining who needs training and how much practice they need.