key: cord-0890386-nc0jf77g
authors: Westafer, Lauren M.; Soares, William E.; Salvador, Doug; Medarametla, Venkatrao; Schoenfeld, Elizabeth M.
title: No evidence of increasing COVID-19 in health care workers after implementation of high flow nasal cannula: A safety evaluation
date: 2020-10-07
journal: Am J Emerg Med
DOI: 10.1016/j.ajem.2020.09.086
sha: ec7d971b2052c12423f34e58a2d8461854b8d138
doc_id: 890386
cord_uid: nc0jf77g

BACKGROUND: Initial recommendations discouraged high flow nasal cannula (HFNC) in COVID-19 patients, driven by concern for healthcare worker (HCW) exposure. Noting high morbidity and mortality from early invasive mechanical ventilation, we implemented a COVID-19 respiratory protocol employing HFNC in severe COVID-19 and HCW exposed to COVID-19 patients on HFNC wore N95/KN95 masks. Utilization of HFNC increased significantly but questions remained regarding HCW infection rate. METHODS: We performed a retrospective evaluation of employee infections in our healthcare system using the Employee Health Services database and unit records of employees tested between March 15, 2020 and May 23, 2020. We assessed the incidence of infections before and after the implementation of the protocol, stratifying by clinical or non-clinical role as well as inpatient COVID-19 unit. RESULTS: During the study period, 13.9% (228/1635) of employees tested for COVID-19 were positive. Forty-six percent of infections were in non-clinical staff. After implementation of the respiratory protocol, the proportion of positive tests in clinical staff (41.5%) was not higher than that in non-clinical staff (43.8%). Of the clinicians working in the high-risk COVID-19 unit, there was no increase in infections after protocol implementation compared with clinicians working in COVID-19 units that did not use HFNC. CONCLUSION: We found no evidence of increased COVID-19 infections in HCW after the implementation of a respiratory protocol that increased use of HFNC in patients with COVID-19; however, these results are hypothesis generating.

Early treatment recommendations for patients with COVID-19 discouraged noninvasive oxygenation methods for respiratory support, including non-invasive ventilation (NIV) and high flow nasal cannula (HFNC), instead favoring early endotracheal intubation. 1,2 This was largely driven by concerns regarding health care workers' (HCW) exposure to aerosolized SARS-CoV-2. In response, many hospitals restrict HFNC and NIV use despite emerging evidence that noninvasive modalities effectively prevented intubation in many patients and that aerosolization of SARS-CoV-2 from HFNC may be minimal. [3] [4] [5] [6] Between April 3, 2020, and April 7, 2020 we implemented a multidisciplinary respiratory protocol for patients with suspected or confirmed COVID-19) across the healthcare system. The protocol (Supplementary Materials) increased use of HFNC for patients admitted to the hospital with COVID-19, utilizing non-negative pressure rooms in a dedicated COVID-19 intermediate care (COVID Intercare) unit. 7 Staff safety and infection rates are critical metrics in the evaluation of COVID-19 interventions. 8 The objective of this study was to explore whether the increased the use of HFNC and NIV also resulted in an increased rate of COVID-19 infections in HCWs.

We performed a retrospective evaluation of an existing Employee Health Services (EHS) database at XXX, an 800-bed tertiary care center with over 12,000 clinical and non-clinical employees. We obtained data for all employees tested for COVID-19 between March 15, 2020 and May 23, 2020. Beginning March 14, 2020, all symptomatic employees were referred to EHS for reverse transcriptase-polymerase chain reaction (RT-PCR) nasopharyngeal swab for SARS-J o u r n a l P r e -p r o o f CoV-2 (Roche COBAS 6800). The database also included employees tested during any hospital visit. Available data included the date of the test result, department of employment, and job title but did not include demographic information. To triangulate our data, we obtained numbers of positive tests and dates for clinical staff who worked in the COVID-19 Intercare unit and were exposed to COVID-19 patients using HFNC/NIV and numbers of positive tests for staff working in a similar sized COVID-19 unit where HFNC/NIV were not used. The medical director of Hospital Medicine and unit leadership independently kept records of hospitalists and staff on the COVID-19 units who were diagnosed with COVID-19. The XXX Institutional Review Board determined our evaluation was not human subjects research. We adhered to the SQUIRE reporting standards. 9

Cases were listed on the day the result was reported. In mid-March the time to result for outpatient testing was 3-5 days, which shortened to 1-2 days in early April. To account for batching of tests, we used 3-day averages of positive tests. We stratified employees as "clinical,"

involving direct patient interactions, or "non-clinical." Nursing, physicians, advanced practitioners, respiratory therapists, and "clinical support staff" were categorized as clinical, while administrative support, information technology, "trades/engineering," behavioral health, finance, and contractors were categorized as non-clinical. Not all staff classified as "clinical" treated COVID-19 patients; however, some were redeployed to COVID-19 units, thus it's likely some clinical staff did not have in-hospital exposures. We classified cases as pre-implementation or post-implementation of the respiratory protocol. Tests that resulted after April 7 were considered post-implementation.

We report descriptive data of the incidence of positive tests before and after the implementation of the respiratory protocol, when HFNC use increased, stratified by clinical or non-clinical role. We report cases over time in relation to the COVID-19 daily census. We also compare the number of employees who tested positive from the dedicated COVID-19 Intercare unit with the number of employees who tested positive from the acute care COVID-19 unit which did not use HFNC and NIV.

To estimate community prevalence and account for the risk of an increasing daily census Of the 79 staff members (nurses and patient care technicians (PCTs)) exposed to HFNC/ NIV in the COVID-19 Intercare unit, 2 tested positive, one during the pre-intervention period Our study reports employee COVID-19 testing results in a health system with over 45 days experience using HFNC/NIV in patients admitted with COVID-19. Further, our study J o u r n a l P r e -p r o o f benefits from an integrated employee health record, as well as independent triangulation and verification of infection rates in clinicians with confirmed contact with patients with COVID-19.

It is important to note that our airway protocol was designed with safety measures to prevent potential transmission of SARS-CoV-2. First, clinical staff caring for COVID-19 patients were universally instructed to wear full personal protective equipment and N95/KN95 masks during aerosolizing procedures throughout the study period. N95/KN95s became mandatory for all care of patients with COVID-19 on April 7, 2020. Additionally, admitted patients requiring HFNC/NIV were cohorted into a single unit to limit staff exposure, although HFNC/NIV were also used in the emergency department and critical care units. Finally, the protocol required patients receiving HFNC to wear standard surgical masks to limit droplet spread; however, in practice this often did not happen. It remains unclear which safety measures, if any, may have helped to limit SARS-CoV-2 transmission. However, these safety measures do not require specialized equipment or training to implement.

Our findings should be interpreted in the context of several limitations. As in other regions, our hospital struggled with access to PPE; however, staff caring for COVID-19 patients wore N95s/KN95s during aerosolizing procedures throughout the study period. HFNC may be less safe for HCWs in a facility without appropriate PPE. 10 Second, hospital infection control policies changed during the course of the study. Universal masking was "encouraged" on March 28 but was not mandatory until April 7. Additionally, employee temperature screening began 

We are reassured that, at our institution, a respiratory protocol that included HFNC and NIV, combined with appropriate PPE and cohorting precautions, did not lead to a measurable increase in symptomatic COVID-19 infections in our HCWs; however, our results should be viewed as hypothesis generating and additional research on this topic is needed. 

The COVID-19 respiratory protocol (Supplemental Figure 1 ) encouraged the stepwise use of HFNC and NIV for patients with COVID-19 and hypoxemic respiratory failure, in an effort to avoid early intubation.

The protocol encouraged HFNC preferentially, with no limit on flow rate. The recommendations for consideration of intubation were not hard stops, rather recommendations to be integrated into the clinical decision making on an individual basis. The protocol was implemented between April 3, 2020 and April 7, 2020 across the hospital and was used in the Emergency Department, Intensive Care Unit, and in an intermediate care unit that was created to facilitate the protocol (COVID-19 Intercare). Prior to April 3, 2020, HFNC/NIV use was rare in patients at our institution with COVID-19 and was discouraged by initial protocols for managing respiratory failure in COVID-19.

All non-ICU admitted patients who required HFNC or NIV were cohorted in a dedicated unit, separate from the other general COVID admission units. The COVID-19 Intercare unit has 5 negative pressure rooms, a maximum capacity of 42 patients, and 79 staff (nurses and patient care technicians) while the comparable general COVID inpatient unit has 1 negative pressure room, a capacity of 39 patients, and a staff of 67 nurses and patient care technicians. Patients requiring HFNC and NIV were not managed exclusively in negative pressure rooms, as there were not sufficient numbers of negative pressure rooms for the volume of patients and engineering constraints did not allow for conversion of units or the Emergency Department to negative pressure. Staff caring for patients on HFNC/NIV wore personal protective equipment (PPE), including N95/KN95 masks. Figure 1 

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