Reusable Elastomeric Respirators as An Alternative During the Covid-19 Pandemic: Hospital-Based Health Technology Assessment the Covid-19 Pandemic:

Introduction: The pandemic caused by the novel coronavirus SARS-CoV-2 has increased the demand for health services and thereby created a shortage of personal protective equipment for health workers. In a real scenario of a shortage of N95 filtering facepiece respirators, organizations such as the Centers for Disease Control and Prevention recommend the alternative use of reusable elastomeric respirators. Objective: To perform a hospital-based health technology assessment of reusable half-face and full-face elastomeric respirators for use in intensive care units focused on patients with a confirmed or suspected diagnosis of COVID-19. Method: The process was carried out with a multicriterion decision approach to assess six domains according to the recommendations of the European Network for Health Technology Assessment. Results: The available evidence on reusable elastomeric respirators in healthcare settings is scarce. The studies found allow us to recommend the use of elastomeric respirators in a conditional context of a shortage of N95 respirators in specific areas, and our analysis shows that they are less expensive. These respirators are the first-line alternative to scarce N95 respirators and have cost advantages in the simulation scenario. A training, monitoring, and assessment strategy must be in place for the implementation of reusable elastomeric respirators. At the organizational level, the use of these respirators is perceived as safe and comfortable. Conclusions: This hospital-based health technology assessment shows that reusable elastomeric respirators can be used in intensive care units as a rational alternative to disposable N95 respirators whose shortage is caused by a pandemic.


Introduction
The severe acute respiratory syndrome coronavirus (SARS- This PPE is mostly single use. Given the uncertainty regarding the duration of the pandemic and the global increase in the demand for this and other PPE, a scenario of scarcity and potential shortage in the supply chain is a real and immediate concern. Specifically regarding N95R, the CDC has recommended alternatives for their optimization, such as prolonged use, reuse, and decontamination between uses. It has also recommended the alternative use of halffacepiece or full-facepiece reusable elastomeric respirators (RERs) [3][4][5] since they can protect against pathogens and other airborne hazards in healthcare settings.
RERs are frequently used at the industrial level as masks made of synthetic or natural rubber, which can be used, cleaned, disinfected, stored, and reused repeatedly. They are equipped with replaceable filter cartridges or flexible, disc-shaped, or pancakestyle filters or adequate air purification canisters, but this PPE requires maintenance and a supply of replaceable components that include straps, inhalation and exhalation valves, valve covers and filters, cartridges, and canisters [3]. Despite providing full protection of the eyes, nose, and mouth, RERs are not frequently used in the health field, which could hinder their acceptance and handling by health workers and require exhaustive training to achieve proper use at critical safety points such as donning, doffing, cleaning, and disinfecting these devices. However, the durability and reuse of these respirators make them desirable for health emergencies, in which the need for large quantities of respirators can be expected, as happened in previous health crises caused by Middle East respiratory syndrome, H1N1 influenza in 2009, and Ebola in 2014 [6,7]. The WHO defines health technology assessment (HTA) as the systematic evaluation of various aspects of "the application of organized knowledge and skills in the form of medicines, medical devices, vaccines, procedures and systems developed to solve a health problem and improve quality of life" in order to inform decision-making [8].
In the hospital context, studies of HTA are called hospital based HTAs, and they allow a local analysis of the implementation or not of a technology [9]. As in a regular HTA, aspects of clinical effectiveness and safety are evaluated. In some cases, the assessment is accompanied by an economic evaluation and other evaluations of interest to the hospital. On this background, the objective of this study was to evaluate the hospital-based health technology of half-facepiece and full-facepiece RERs as an alternative to the undersupplied N95R for use in the intensive care unit (ICU) for the care of patients with confirmed or suspected COVID-19.
through an electronic survey with the objective of determining the perception of health workers about the safety, comfort, benefits, and limitations related to the use of RERs. A descriptive statistical analysis and narrative synthesis of the qualitative data were performed. Data collection was stopped when saturation in the qualitative responses was achieved. The focus group was conducted with hospital decision-makers, including managers, purchasing agents, and clinical experts in infectious diseases, intensive care, and dentistry. These positions were chosen for their potential role in incorporating the new technology in their work. The participants were informed in advance the results of the assessments of effectiveness and safety and the economic and regulatory aspects in the local context.

Technical Characteristics of the Technology
The high-efficiency respirator types evaluated, and their technical characteristics are described in (Table 1).

Technology
Technical characteristics N95R + goggles + face shield N95 respirators are disposable medical devices with or without a valve that filter 95% of particles smaller than 0.3 µm. Eye protection components such as goggles and a face shield are usually made of polymeric materials (11).

Full-facepiece RER
Provides total protection of eyes, nose, and mouth. The large lens provides a wide field of view for excellent visibility. The lightweight, well-balanced design and silicone face seal provide good comfort, durability, and ease of cleaning (12). Have a higher assigned protection factor (APF) (APF: 50) than N95 (APF: 10) (3).

Half-facepiece RER
Made of a softer silicone material, which provides greater comfort when used, especially over long periods.
Have the same filtration capacity as the full-facepiece RERs. Also require the use of goggles and face masks (13). Have the same APF as N95R (APF: 10) (3).

Effectiveness and Safety of RERs
Experimental and simulation studies provide the main evidence on the use of RERs in the health context. A clinical, randomized, pragmatic, and multicenter study funded by the CDC evaluated the acceptance of and feasibility of rapidly training and fit testing RERs and 26 routine performance indicators in 153 participants. The RERs showed an advantage over N95R [12]. An observational study with eight subjects that evaluated the fit and tolerance of an RER with modifications to the original design approved by NIOSH found good tolerance to this device for 1 hour, which was the estimated time to perform an aerosol-generating procedure in the ICU [13]. Lastly, a descriptive study compared the technical characteristics of different respirators and concluded that RERs should be accompanied by 99-to 100-level filters in aerosol-generating procedures [14]. The studies agree on the recommendation that RERs are the first-line alternative to N95R in shortage scenarios given that they have the same safety and effectiveness advantages, Regarding filtration capacity, the CDC recommends the use of NIOSH-certified RERs with a capacity equal to or greater than that of N95R for protection against inhalation of aerosolized contaminants in the hospital environment [4]. There are several filter types or series available for these respirators, classified according to their resistance to degradation by oil-based aerosols into the N, R, and P series, and according to their ability to filter particles into the 95, 99, and 100 levels [4]. Depending on the conditions of use, the manufacturers propose filter replacement 40 hours to 30 days after the first use if there are no oil mists. However, in crisis situations, OSHA indicates that filters may be replaced "when necessary," for example, when they are damaged, dirty, contaminated, or obstructed [3,19], given that in a hospital environment, the concentration of

Economic Evaluation
Based on the projection of the minimum number of health workers and conditions of use of the PPE, it was established that for an ICU with 15 beds at full capacity, a care team consisting of 78 people per 24 hours will be required (Annex 1). For these workers, the provision of reusable PPE, such as goggles, face shields, and respirators, and disposable PPE, including N95R and RER filters, was considered, the latter according to three replacement scenarios: at one, three, and six months. The N95R were assumed to be discarded after each shift.

Comparative Cost Per Month Between the Alternatives with Sensitivity Analysis
The estimated costs per month for the N95R (gold standard) and the RER are described in (Table 2). The unit value of each equipment is found in (Annex 1) [20]. The estimation of the base case was performed with the average costs (Annex 1). The highestcost strategy at six estimated months was the strategy with N95R, goggles, and face shield because it was the strategy in which the PPE were discarded after each use. Additionally, due to scarcity and high demand, the market price of N95R has fluctuated and at times even tripled. If the filter is changed every month, the full-facepiece RER strategy would cost $USD 57,800. The lowest-cost strategy was the half-facepiece RER. According to the proposed scenarios, if filters are replaced every three or six months, the costs of the RER strategy in the ICU would be approximately 30% lower than those given in (Table 3). Given the fluctuation of local prices observed during the pandemic, a sensitivity analysis was performed on the prices of the alternatives.
Annex Table 2: Unit cost of the evaluated personal protective equipment (PPE).  If the price of N95R returned to that before the pandemic (USD$ 2.76) and the price of RERs doubled, the pattern of cost of the compared strategies would be maintained in the model: N95R were the highest-cost strategy, followed by full-facepiece and then halffacepiece RERs (Table 4). This analysis showed that the difference between the analyzed strategies was less than that estimated in the base case. Lastly, we estimated that for the N95R strategy to have the same cost as the full-facepiece RER alternative, the latter at the highest observed price, the price of N95R would have to be approximately USD 2.02, close to 30% less than its cost before the pandemic.

3.
Regarding the comfort of elastomeric respirators, you consider them: More comfortable than N95 respirators/Less comfortable than N95 respirators/As comfortable as N95 respirators.

4.
Regarding the perception of the safety of elastomeric respirators for health workers, you consider them: Safer than N95 respirators/Less safe than N95 respirators/As safe as N95 respirators.

5.
What  of the use of this PPE and involves a standardized and centralized process for RER cleaning, disinfection, storage, and maintenance by qualified personnel [7]. Additional aspects should be evaluated in other services, such as in operating rooms, for which the American College of Surgeons recommends the use of RERs only in repeated-exposure circumstances during an N95R shortage due to a pandemic, accompanied by a surgical mask, because there is concern that unfiltered air leaving the exhalation valve can potentially contaminate the sterile field [22]. Our cost analysis in the ICU showed that the difference between the half-or fullfacepiece RER option versus N95R is high, that is, RERs are a less expensive alternative even if the price of N95R is lowered to the pre-pandemic price. This conclusion is similar to that drawn by others [24]. Although the data are shown in US dollars, they may vary in different countries; thus, it is advisable to introduce RERs early in institutions by combining the use of the N95R and RER PPE.

Conclusions
This hospital-based HTA shows that despite the lack of evidence in hospital settings, RERs are a viable, lower-cost alternative and