key: cord-0798383-xeyfkjm5 authors: Ha, Jennifer F title: The covid‐19 pandemic, personal protective equipment, and respirator: a narrative review date: 2020-06-08 journal: Int J Clin Pract DOI: 10.1111/ijcp.13578 sha: d85576532850fe1b164d4f1f98cdf84605490583 doc_id: 798383 cord_uid: xeyfkjm5 The coronavirus disease 2019 (COVID‐19) pandemic has touched almost every continent. Personal protective equipment (PPE) is the final line of protection of healthcare workers (HCW). There is variation as well as controversy of infection control recommendation with regards to the use of PPE for HCW between institutions. The aim of this narrative review is to of examine and summarise the available evidence to guide recommendation for the safety of HCW. A literature search was conducted on the PubMed, MedLine, and Embase databases with the keywords “personal protective equipment”, “COVID 19”, “n95”, “health care worker”, and “mortality”. SARS‐nCoV‐2 is highly contagious. 3.5‐20% of HCW has been reported to be infected. The mortality ranges from 0.53‐1.94%. PPE is part of the measure within a package of prevention and control of pandemic, rather than a replacement of. Respirators are more effective than masks in preventing aerosol transmission to HCWs. Extended use may be considered if guidelines are adhered. PAPRs if available should be used in high risk procedures. Transmission of viruses is multimodal, and in the setting of a novel pathogen with high case fatality with no proven effective interventions, PPE that affords the best protection should be available to HCWs. Certain events (eg coughing or sneezing, cardiopulmonary resuscitation) and aerosol generating procedures (AGP) (eg intubation, tracheostomy) can generate aerosols composed of smaller virus containing particles suspended in air. (17) SARS-nCoV-2 has been reported to remain infectious on inanimate surfaces at room temperature for up to 9 days. (22) SARS-CoV-2 is more stable on plastic and stainless steel than copper and cardboard.(21) It is detected up to 72 hours after application onto plastic, though the viral titre decayed exponentially.(21) The viral half-life was 6.8 hours on plastic, 5.6 hours on stainless steel. (21) SARS-nCoV-2 is contagious during the latency period. (14, 15, 20, (23) (24) (25) (26) (27) ) Viral loads are highest in the first week (peaks at 3 to 5 days) after symptoms began and decline over the second week, especially in the nose than throat. (12, 15, (28) (29) (30) (31) The viral loads in asymptomatic patients has been found to be similar to symptomatic patients. (14, 28) As such, when the COVID-19 status of patients is unknown, they are treated as if they are COVID-19 positive.(32) Prolonged viral shedding after recovery has also been reported. (26) The transmission is reported to be between 2.1 and 4 cases per exposure. (1, 12, 20, (33) (34) (35) Systematic effort is required to reduce the transmission, which is influenced by various factors like: Pathogens, ventilation, air filtration, sterilization and PPE. (36) Respiratory protection is one of the key strategy for pandemic control, and to sustaining the HCW. 3.5-20% of HCW has been reported to be infected. (1, (37) (38) (39) (40) Initially, during the index outbreak in Wuhan, 13 HCWs were infected. ( There was a report of a patient who was not identified as infected early in the Wuhan outbreak and proceeded to infected 14 HCW during a stay for transnasal pituitary surgery.(44) However, the patient was transferred to 4 different wards and infected 10 neurosurgical nurses and 4 medical staff who had no Accepted Article PPE, rather than the operating room team and neurosurgeon.(29) Certain specialty like otolaryngology are disproportionately affected in most countries affected by the COVID-19 pandemic. (44) Wang X et al found none of the 278 staff in the quarantined area with high exposure to the 28 patients with 2019-nCoV infection were infected.(45) They wore N95 respirators, disinfected and performed hand hygiene. Those in the Hepatobiliary Pancreatic Surgery, Trauma and Microsurgery, and Urology departments wore no masks, but disinfected and performed hand hygiene occasionally as there were not considered high risk in the early days of the outbreak in January (45) . 10 of the 213 staff were confirmed to be infected, despite their lower risk of exposure. (45) The adjusted odds ration (OR) was 464.82. (45) The found no infections in two other hospitals in the N95 respirators groups. (45) The increasing evidence of aerosol transmission during routine care in absence of AGPs, and concerns regarding efficient human transmission has resulted in recommendation for airborne precautions with a fit-tested N95 respirator and other PPE. (46, 47) When the Chinese hospitals instituted full body PPE with goggles, head coverings, N95 respirators, hazmat suits, and they were housed away from their families, there was no new infections. (41) Since then, nosocomial transmission has not been a major amplifier of transmission in China, due to prevention and control. (31) It is believed that with the absence of major nosocomial outbreaks, these are acquired in their families where 85% of human-to-human transmission occurred. (12, 14, 15, 24, 31, 48) This article is protected by copyright. All rights reserved The mortality rate ranges from 1.4-3.83%. (20, 23, 25, 27, 35, 37, 38, 46, (53) (54) (55) (56) (57) (58) (59) China reported 3387 infected HCWs in Hubei alone, with at least 18 deaths (0.53%) in late February. (60) Philippine Medial Association president reported ten doctors have died at the end of May, including the president of the Philippine Paediatric Society, due to the lack of PPE. (61) In Italy, on 28 th March 2020, 2629 (20%) were infected, with 51 deaths (1.94%).(39, 62) The numbers may be higher as those who died suddenly were not tested for the disease. Once community spread of virus is confirmed, the hospital should institute guidelines for airborne and contact precautions during all AGPs.(1, 29) High degree of personal caution, and diligence in infection control procedure (hand and respiratory hygiene etc) are necessary. PPE is part of the measure within a package of prevention and control of pandemic, rather than a replacement of. The education or re-training of proper selection and fit testing of PPE, training on donning, doffing and disposal of PPE training is vital, as up to 90% of staff do not use the correct doffing sequence or technique. (18, (63) (64) (65) Guidance to the level of PPE depends on prevalence of COVID-19 in the community, the degree of community spread, availability, timeliness and accuracy of COVID-19 testing, and availability of PPE. (29) A recent Cochrane review has found gown to be more protective than aprons against contamination (MD This article is protected by copyright. All rights reserved Bischoff et al first reported direct evidence of transocular delivery of influenza virus in airborne form. (66) This trend was found in the current COVID-19 pandemic. One of the expert taskforce who visited Wuhan was infected despite fully gowned with protective suit and the N95 respirator. (12) His first symptom was unilateral conjunctivitis.(12) Safety glasses and or face shield has been recommended. (16) Masks and Respirators Surgical masks are fluid resistant. They filter particulate, droplets and bacteria. They are not designed for a tight seal, thus will allow unfiltered air to flow around the sides. The materials are not regulated for their ability to filter small particles and vary between models. They are not considered respiratory protection. They are worn to protect HCWs from large droplets or sprays of infectious body fluids from patients that may be directly transmitted to the mucus membrane in the wearer's nose or mouth. When worn by patients, they reduce the concentration and amount of large infectious particles released when coughing, talking or sneezing, and thus infection risk to others. (67) They have a reported failure rate of 10-90%, which is inadequate for droplet nuclei protection. (68) Birschoff et al conducted a pilot study testing surgical masks against N95 respirators using a human exposure model, and they only protected 1 in 4 participants with influenza.(66) Respirators either filter the airborne particles and respiratory aerosol; or supply clean air to the respirator wearer; air-purifying, or atmosphere-supplying respirators. The most common respirators are filtering facepiece respirators and powered air-purifying respirators (PAPR). The National Institute for Occupational Safety and Health (NIOSH) tests filters for the effects of loading (particle burden), temperature, and relative humidity and requires minimum filtration efficiency of 95%, 99%, or 99.97% using neutralized 0.075µm count median diameter solid aerosols at 85L/min.(68) NIOSH evaluates the fit performance of some respiratory protective devices using human panels with specified facial dimensions. This article is protected by copyright. All rights reserved These require certification by the NIOSH based on filter efficiencies with an assigned protection factor (APF) of 10.(69) They must have less than 5% penetration for aerosol with a mass median aerodynoamic diameter of 0.3 microns.(68) When the air is forced through the filtering material, contaminants are captured, which reduce the exposure to large droplets and small infectious particles in both directions. (67) The two types are filtering facepiece respirator where the entire facepiece is made of filtering material, or elastomeric respirators that have replaceable filters or cartridges. (67) Air-purifying respirators are further classified according to the efficiency at which they remove particles (95%, 99% or 100%), and the resistance to oil. A surgical mask overlay has been recommended to provide barrier protection in order to diminish contamination and attrition.(75, 76) This increases the breathing resistance and discomfort. (76, 77) However, the increased CO2 has not been shown to be clinically relevant after a 12-hour shift. (78) Increasing layers of PPE not only increase risk for confusion and contamination, it also increase the complexity of patient care. (79) Evaluation of the deterioration of the filtration efficacy is difficult. Safety is affected by multiple variables that impact respirator function and contamination over time. Other factors than can potentially influence this include viral aerosol concentration, wearer's breathing rate, time of patient interaction, effect of humidity, diffusion, and particle retention efficiency of the mask. Research on the physiologic impacts of the long term N95 respirator use has been limited, and most are laboratory based. There is inadequate understanding of the number, size and dispersion of droplets containing live, infectious particles or aerosol. (6) This article is protected by copyright. All rights reserved This article is protected by copyright. All rights reserved CDC advocated extended use (wearing the same N95 respirators for repeated close contact encounters with several patients without removing the respirator between patient encounters), over limited re-using to conserve supplies. (1, 82, 88) The decision is made by each institution, taking into account the characteristic of the respiratory pathogen and local conditions. (88) If no manufacturer guidance is available, limiting the number of reuse to no more than 5 uses per device to ensure an adequate safety margin. (82, 88, 94) The filtration efficiency is reduced to below 95% for filters after 9 and 13 weeks of simulated reuse. (82) A Dutch study reported that the polypropylene masks (3M type 8822 masks), which do not contain cellulose can be used three times when sterilised twice with hydrogen peroxide in between use.(95) The mask is reported to be safe to be treated in hot air at 70•C for 30 minutes, or 125•C for 3 minutes but This article is protected by copyright. All rights reserved On average, noncompliance in terms of adjusting the N95 respirator, touching the respirator or under it, face, or eye has been found to be 25.7 times per 12-hour shift. (78) Compliance is worst in those with higher BMIs.(78) Body movement when performing medical procedures by HCW may increase the risk of seal leakage. (99) Having a COVID positive patient wearing the respirator will help filter the exhaled infectious droplets and aerosols. However, in practice, there are the same issues that exist with HCWs in terms of failure of fit limiting its effectiveness, as well as compliance that may result in contamination. In addition, many of these patients have respiratory problems, and it is unknown if the increased CO2 may impact the patient physiologically. Surgical mask use has been reported in the literature, but its effectiveness has not been formally studied. PAPRs have a battery powered motor that draw air through a filter (for particles), catridges or canisters This article is protected by copyright. All rights reserved Concurrent use with the N95 respirator to prevent transmission of infection is controversial. (77, 79) N95 in addition to PAPR during AGP has been recommended to supplement the respiratory protection, prevent passage of unfiltered exhalation gases from wearer to the immediate environment, and serve as a backup in the event of a PAPR mechanical failure, or over breathing which may create negative pressure in the PAPR and entrains unfiltered outside air. (103) This was found to multiplicatively increase the mean protection factor of the functioning PAPR, and even in a non-functioning PAPR.(103) The main concern is the higher cost, challenges in training HCWs to safely remove PAPRs without contamination, the need for re-training if infrequently use, inability to re-use disposable filters between patients, the need for explicit decontamination and recycling of blower units, potential compromise of disposable components through inappropriate attempts to sterilise and reuse to conserve supply leading There is much to learn from this pandemic. We need to enhance the reserve medical supplies program, improve the system for allocation, distribution and utilisation of PPE. They should also be properly implemented to ensure we are ready for the next pandemic. This article is protected by copyright. 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