key: cord-0942387-j5hpouz0
authors: Roca, Oriol; Pacheco, Andrés; Rodon, Jordi; Antón, Andrés; Vergara-Alert, Júlia; Armadans, Lluís; Segalés, Joaquim; Pumarola, Tomás; Campins, Magda; Ferrer, Ricard; Rodríguez-Garrido, Virginia
title: Nasal high flow oxygen therapy in COVID-19 patients does not cause environmental surface contamination
date: 2021-05-31
journal: J Hosp Infect
DOI: 10.1016/j.jhin.2021.04.034
sha: 45674e4b5e3ee82ee1aa23652c8bd50f773f8122
doc_id: 942387
cord_uid: j5hpouz0

nan

To the Editor: Nasal high flow oxygen therapy (NHF) may spread the severe acute respiratory syndrome coronavirus (SARS-CoV-2) virus through respiratory droplets and contact with fomites. This concern leads to significant controversies regarding recommendations of its use in different evidence-based guidelines of therapy of coronavirus infectious disease 2019 (COVID-19) patients 1 . We, therefore, aimed to determine if NHF use for COVID-19 patients was associated with higher environmental surface SARS-CoV-2 contamination compared with those who were intubated and mechanically ventilated (MV).

We performed an observational, single-centre study initially including 10 consecutive critically ill COVID-19 patients who required ICU admission (5 NHF and 5 MV). All patients were admitted to ICU negative pressure single rooms with 12 air changes per hour. Closed-aspiration systems were used in mechanically ventilated patients. Patients with NHF only wore surgical masks above the NHF cannula when healthcare personnel were inside the room. The Ethics Committee of Vall d'Hebron University Hospital approved this study (PR(AG)225/2020), and the need for informed consent was waived due to the observational nature of the study.

Confirmation of SARS-CoV-2 persistence on environmental surfaces was based on the detection of viral genome by reverse-transcription quantitative polymerase chain reaction (RT-qPCR). Sample collection was performed within the first 24 hours of admission and after 3 days, before the daily room cleaning, from the following sites: bedside monitor, mechanical ventilator screen, computer keyboard, nurse medication trolley, infusion pumps, patient sheet, bed handle, personnel protective equipment (gloves, coat, protection glasses, hat), stethoscope, room floor at 1.5 metres distance from the patient, and a filter paper placed immediately before the room high efficiency particulate air (HEPA) filter. Environmental and equipment surfaces (approximately 5x5 cm) were sampled using moistened sterile swabs. The main characteristics of the patients included in this study are summarized in Table 1 . Two of the patients were initially included as MV patients (only have samples at day 1 of MV) and J o u r n a l P r e -p r o o f subsequent samples were collected when they were supported with NHF after extubation (cases 1 and 2 among MV patients that correspond to cases 6 and 8 among NHF patients, respectively). A total of 252 environmental samples were collected from the first 10 patients.

No differences between the time of positive nasopharyngeal swab collection and time of environmental sample collection were observed (median of 3 days [1] [2] [3] [4] [5] in NHF and 4 [3] [4] [5] [6] [7] [8] [9] An additional 29 samples were obtained from two more patients. Only the sample collected from the NHF cannula was positive for SARS-CoV-2 RNA. This NHF cannula positive sample was inoculated to susceptible Vero E6 cells, but no CPE was observed after a 6-day observation period. Therefore, no infectious SARS-CoV-2 was found in any of the environmental samples collected in this study. However, the degree of surface and air contamination from SARS-CoV-2 in a previous study was highly heterogeneous 4 . The singularity of the present study is that it includes the largest data on the environmental persistence of SARS-CoV-2 in the rooms of COVID-19 patients being treated with NHF. Moreover, we compared the environmental contamination associated with NHF use to MV. Lack of environmental contamination in an ICU environment with negative pressure rooms was observed in both groups. Indeed, it has recently been shown that NHF by itself may not increase aerosol generation in healthy volunteers in a negative-pressure room 5 . Interestingly, despite it being impossible to place living SARS-CoV-2 on a surface to obtain a positive control for obvious safety reasons, we could obtain one positive RT-qPCR from the nasal cannula of one of the non-intubated patients suggesting that the sample collection and PCR technique was correctly performed. These J o u r n a l P r e -p r o o f

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Severe acute respiratory syndrome coronavirus 2 RNA contamination of inanimate surfaces and virus viability in a health care emergency unit. Clinical microbiology and infection : the official publication of the European Society of

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