Abstract:The objective of this pilot study was to determine the minimum operational flow for loose-fitting powered air-purifying respirators (PAPR) used in healthcare cleaning services. An innovative respiratory flow recording device was worn by nine healthcare workers to obtain the minute volume (MV, L/min), mean inhalation flow (MIF, L/min), and peak inhalation flow (PIF, L/min) while performing “isolation unit work” (cleaning and disinfecting) of a patient room within 30 min. The MV and PIF were compared with the th… Show more
“…Figure 2 shows the pressure drop as a function of air velocity for the HEPA filter used. Hence, while choosing a fan, we assumed a total static pressure drop of 1.5 inch-H 2 O across prefilter, HEPA H14 filter and through 3D printed parts and tubing, meaning the fan must deliver a static pressure of at least 1.5 inch-H 2 O while delivering an air flow of 6-8.8 CFM (170-250 LPM) which is typical for loose-fitting PAPR systems [24] , [25] . Figure 2 Pressure drop as a function of air velocity of the HEPA filter used in PROPER.…”
The supply of Personal Protective Equipment (PPE) in hospitals to keep the Health Care Professionals (HCP) safe taking care of patients may be limited, especially during the outbreak of a new disease. In particular, the face and body protective equipment is critical to prevent the wearer from exposure to pathogenic biological airborne particulates. This situation has been now observed worldwide during the onset of the COVID-19 pandemic. As concern over shortages of PPE at hospitals grows, we share with the public and makers’ community the Pressure Optimized PowEred Respirator (PROPER) equipment, made out of COTS components. It is functionally equivalent to a Powered Air Purifying Respirator (PAPR). PROPER, a hood-based system which uses open source and easily accessible components is low-cost, relatively passive in terms of energy consumption and mechanisms, and easy and fast to 3D print, build and assemble. We have adapted our experience on building clean room environments and qualifying the bioburden of space instruments to this solution, which is in essence a miniaturized, personal, wearable cleanroom. PROPER would be able to offer better protection than an N95 respirator mask, mainly because it is insensitive to seal fit and it shields the eyes as well. The PROPER SMS fabric is designed for single-use and not intended for reuse, as they may start to tear and fail but the rest of the parts can be disinfected and reused. We provide a set of guidelines to build a low-cost 3D printed solution for an effective PAPR system and describe the procedures to validate it to comply with the biosafety level 3 requirements. We have validated the prototype of PROPER unit for air flow, ISO class cleanliness level, oxygen and carbon-dioxide gas concentrations during exhalation, and present here these results for illustration. We demonstrate that the area inside the hood is more than 200 times cleaner than the external ambient without the operator and more than 175 times with the operator and in an aerosol exposed environment. We also include the procedure to clean and disinfect the equipment for reuse. PROPER may be a useful addition to provide protection to HCPs against the SARS-CoV-2 virus or other potential future viral diseases that are transmitted aerially.
“…Figure 2 shows the pressure drop as a function of air velocity for the HEPA filter used. Hence, while choosing a fan, we assumed a total static pressure drop of 1.5 inch-H 2 O across prefilter, HEPA H14 filter and through 3D printed parts and tubing, meaning the fan must deliver a static pressure of at least 1.5 inch-H 2 O while delivering an air flow of 6-8.8 CFM (170-250 LPM) which is typical for loose-fitting PAPR systems [24] , [25] . Figure 2 Pressure drop as a function of air velocity of the HEPA filter used in PROPER.…”
The supply of Personal Protective Equipment (PPE) in hospitals to keep the Health Care Professionals (HCP) safe taking care of patients may be limited, especially during the outbreak of a new disease. In particular, the face and body protective equipment is critical to prevent the wearer from exposure to pathogenic biological airborne particulates. This situation has been now observed worldwide during the onset of the COVID-19 pandemic. As concern over shortages of PPE at hospitals grows, we share with the public and makers’ community the Pressure Optimized PowEred Respirator (PROPER) equipment, made out of COTS components. It is functionally equivalent to a Powered Air Purifying Respirator (PAPR). PROPER, a hood-based system which uses open source and easily accessible components is low-cost, relatively passive in terms of energy consumption and mechanisms, and easy and fast to 3D print, build and assemble. We have adapted our experience on building clean room environments and qualifying the bioburden of space instruments to this solution, which is in essence a miniaturized, personal, wearable cleanroom. PROPER would be able to offer better protection than an N95 respirator mask, mainly because it is insensitive to seal fit and it shields the eyes as well. The PROPER SMS fabric is designed for single-use and not intended for reuse, as they may start to tear and fail but the rest of the parts can be disinfected and reused. We provide a set of guidelines to build a low-cost 3D printed solution for an effective PAPR system and describe the procedures to validate it to comply with the biosafety level 3 requirements. We have validated the prototype of PROPER unit for air flow, ISO class cleanliness level, oxygen and carbon-dioxide gas concentrations during exhalation, and present here these results for illustration. We demonstrate that the area inside the hood is more than 200 times cleaner than the external ambient without the operator and more than 175 times with the operator and in an aerosol exposed environment. We also include the procedure to clean and disinfect the equipment for reuse. PROPER may be a useful addition to provide protection to HCPs against the SARS-CoV-2 virus or other potential future viral diseases that are transmitted aerially.
“…CUXS10, Griflex, Birmingham, UK) was used to connect the fan to the flowmeter. Flow rate was kept at 165 L/min [46], increasing the voltage over time to ensure ideal flow rate would reach the hood through the breather tube.…”
Healthcare workers are at high risk of catching SARS-CoV-2 because of their regular interaction with patients with the disease. In low-resource settings, the ratio of healthcare workers to the whole population is lower than in high income countries, and there is often limited access to personal protective equipment (PPE). Illness or death of healthcare workers will, therefore, have a disproportionate impact in these settings, so it is particularly important to find ways to protect them.To protect against airborne infection in healthcare settings, PPE recommendations typically include filtering facemask respirators or powered air purifying respirators (PAPR). The former, passively filter inhaled air. They are small, noiseless and do not require a power supply, but they are single-use, presenting manufacturing and supply issues. Fit testing is crucial, and many users find them difficult to tolerate, due to breathing resistance and elevated humidity. There is also the potential for contamination due to the exposed face. PAPRs are re-usable devices that may last for months and provide airflow through a filter from a battery-powered blower unit to a hood or helmet which covers the face. This creates a positive pressure in the hood or helmet that enables the wearer to breathe filtered air easily, without requiring an air-tight fit needed for standard face masks. This is reported to be more comfortable and provides better protection for the face from droplets and splashes, and infection by self-contact with the hands. PAPRs have typically been expensive, bulky and not readily available or easy to ship to low-resource settings.Although the design presented here has not been through any form of regulatory approval, the aim of this paper is to share ideas and offer possible solutions to other groups around the World who may be thinking of manufacturing a low-cost, reusable PAPR. The design is novel because it uses readily available materials, scalable manufacturing processes, and it may be shipped flat-packed and easily assembled. This offers an option for manufacturing in low-resource settings and for shipping in bulk. This paper provides the CAD designs that can be fabricated using a laser cutter.
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