ACEP ID:
COVID-19 is thought to spread mainly through close contact from person to person, including between people who are physically near each other (<6 ft). Asymptomatic carriers can also spread the virus to others.
COVID-19 spreads very easily from person to person
COVID-19 most commonly spreads during close contact
COVID-19 can sometimes be spread by airborne transmission
COVID-19 spreads less commonly through contact with contaminated surfaces
COVID-19 rarely spreads between people and animals
More information can be found in the CDC Guidance on How Coronavirus Spreads.
Author: Susan R. Wilcox, MD, FACEP, Division Chief, Critical Care, Department of Emergency Medicine, Associate Professor of Emergency Medicine, Harvard Medical School, Associate Chief Medical Officer, Boston MedFlight
Given the risk of aerosolization of the virus, increasing the exposure risk to health care workers or other patients, nebulized medications should be avoided. Respiratory medications should be administered as metered-dose inhalers (MDIs).
Author: Susan R. Wilcox, MD, FACEP, Division Chief, Critical Care, Department of Emergency Medicine, Associate Professor of Emergency Medicine, Harvard Medical School, Associate Chief Medical Officer, Boston MedFlight
Both BiPAP and CPAP are controversial in patients with COVID-19. The concern is that noninvasive positive-pressure ventilation (NIPPV) could theoretically increase aerosolization of the virus, increasing the exposure risk to health care workers or other patients. Additionally, experience with prior viral pneumonias has demonstrated a high failure rate of approximately 60% to 80%. Lastly, there are concerns that patients with acute respiratory distress syndrome (ARDS) may have large, unchecked tidal volumes on NIPPV, resulting in lung-injurious ventilation. The potential benefits of avoiding intubation are obvious for the individual patient. When also considering ventilators as a scarce resource, a prevented intubation can result in better resource allocation. While many institutions are not promoting NIPPV at this time, its use has been supported by the Society of Critical Care Medicine, with caveats. If NIPPV is used, patients must be monitored carefully, and intubation should not be delayed if there are any signs of worsening. However, there is insufficient evidence to recommend CPAP or BiPAP.
Whittle JS, Pavlov I, Sacchetti AD, Atwood C, Rosenberg MS. Respiratory support for adult patients with COVID-19. JACEP Open. Published 2020 Apr 2. doi:10.1002/emp2.12071
Author: Jessica Whittle, MD, PhD, FACEP, Director of Research, Department of Emergency Medicine, University of Tennessee College of Medicine
High-flow nasal oxygen (HFNO) includes high-flow nasal cannula (HFNC) and high-velocity nasal insufflation. The use of HFNO has been associated with lower mortality in hypoxemic respiratory failure.1 Compared to conventional oxygen therapy, HFNO is associated with decreased risk of subsequent intubation (RR 0.85, 95% CI 0.74-0.99)2 and need for ICU admission.3,4 Initial concern existed on the risk of aerosolization with HFNO, leading some to recommend avoiding use of this modality. However, the degree of aerosolization has been shown to be minimal with these devices, and it is now recommended as the oxygenation therapy of choice in patients with respiratory distress (Figure 3.3). Guidelines from the WHO,5 the Italian Thoracic Society,6 the Respiratory Care Committee of the Chinese Thoracic Society,7 and The Australian and New Zealand Intensive Care Society;8 a joint statement from the German intensive care, anesthesia, and emergency medicine societies;9 and the joint guidelines produced by the European Society of Intensive Care Medicine and The Society of Critical Care Medicine10 all recommend HFNO as a therapy for COVID-19 respiratory failure. Recent publications suggest that newer HFNO and NIPPV systems with good interface fitting do not create widespread dispersion of exhaled air and therefore may be associated with low risk of airborne transmissions.5,8
A high-fidelity mannequin study demonstrated that even at the highest setting of 60 L/ min, exhaled air dispersion was 17 cm in a healthy lung scenario and 4.8 cm in a severely diseased lung scenario.11 Some guidelines recommend placement of a surgical mask over patients being treated with high-flow therapies as a secondary safety measure.9 High-fidelity human mannequin simulation studies show surgical masks do, in fact, reduce exhaled air dispersion.12 If HFNO oxygen therapy is used, medical staff should use airborne protection, and the patient should be treated in a negative-pressure room, if available.5,8
Newer data also support the safety of high-flow oxygen therapies. A recent study was published evaluating computational fluid dynamic simulation and a different model of high-flow oxygen therapy.13 It demonstrated that a patient treated with high-flow oxygen therapy at maximal settings with a surgical mask placed over the face generated an aerosol dispersion cloud similar to a patient with tidal breathing.13
There is no currently published evidence that HFNO is a risk factor for nosocomial transmission of respiratory pathogens.14-17 During the 2003 Toronto SARS-CoV outbreak, HFNO was not found to be a risk factor for transmission to health care workers.17 This is in contrast to endotracheal intubation, which was strongly associated with transmission to health care workers during the SARS epidemic.18
There are currently no defined criteria for HFNO failure, but patients who require vasopressor support17 and whose respiratory rate and thoracoabdominal asynchrony are not rapidly relieved with HFNO19 are potentially at high risk of HFNO failure. Recently, the “ROX Index” was developed to aid in the prediction of clinical outcomes of patients treated with HFNO. It is calculated by the ratio of oxygen saturation, as measured by pulse oximetry/FiO2 to respiratory rate. A ROX Index >4.88 is predictive of success, meaning the patient is unlikely to progress to needing mechanical ventilation.20 Patients with established ARDS should move rapidly to mechanical ventilation and treated per published recommendations.21,22
Figure 3.3 Comparison of aerosol dispersion differences, using various treatment modalities.
Matos RI, Chung KK, Benjamin J, et al. DoD COVID-19 practice management guide: clinical management of COVID-19. Defense Health Agency. Published 2020 Mar 23.
To consolidate resources and optimize the management of patients requiring clinical care during the global COVID-19 pandemic, selected information from the practice management guide regarding HFNC is listed here. Refer to the full document cited above for a detailed rationale and complete list of references.
Give supplemental oxygen therapy immediately to patients with respiratory distress, hypoxemia, or shock and target SpO2 92% to 96% (No. 1).
For adults, initiate oxygen therapy during resuscitation at 5 to 6 L/min, and titrate flows to reach target SpO2 92% to 96% during resuscitation. If a persistent requirement for 5 to 6 L/min continues and resources are lacking for invasive ventilation, consider use of HFNC or a face mask with a reservoir bag at 10 to 15 L/min if the patient is in critical condition (No. 3).
Recommendations are evolving regarding the risk-benefit ratio but favor HFNC over BiPAP/noninvasive ventilation (NIV) if early intubation and mechanical ventilation is not possible. HFNC is a more effective intervention for noninvasive management of ARDS that requires less staff intervention. HFNC is also potentially safer for staff than BiPAP/NIV. Avoid BiPAP, if HFNC is unsuccessful; early intubation is recommended (No. 4).
All forms of respiratory therapy have a risk of aerosolization of the virus and risk to others. Comparison of noninvasive respiratory modalities continues to evolve, but presently, use of HFNC should be favored over BiPAP. HFNC is more efficacious for noninvasive management of ARDS compared to BiPAP, is generally well tolerated, and requires less staff intervention (coming in and out of room for alarms and trouble-shooting). If this therapy is attempted, it should ideally be confined to negative-pressure isolation rooms, and health care workers should have appropriate personal protective equipment (PPE), including N95 masks and PAPR (No. 2).
Although an area of controversy, early expert opinion favors HFNC over other noninvasive modalities (see The Internet Book of Critical Care: COVID-19) because it appears to be well tolerated, more efficacious than BIPAP and less provider intensive. There is presently no definitive evidence that HFNC augments transmission of the virus (No. 2).
Patients requiring nasal cannula or those who are intubated on mechanical ventilation (closed circuit) require contact/droplet precautions when handling, including a surgical mask, a gown, a hair cover, and gloves (No. 5).
Per WHO guidance for clinical management of COVID-19, “newer high-flow nasal cannula (HFNC) and non-invasive ventilation (NIV) systems with food interface fitting do not create widespread dispersion of exhaled air and therefore should be associated with low risk of airborne transmission.” These patients could be cared for with contact/droplet precautions only (to include a face mask) but could consider N95 (or PAPR) if readily available.
American Association for Respiratory Care. Guidance document: SARS CoV-2. AARC website.
Author: Richard D. Branson, MSc, RRT, FAARC, Editor-in-Chief, Respiratory Care, University of Cincinnati; Dean R. Hess, Editor, Respiratory Care; Rich Kallet, MSc, PhD, RRT, FAARC, Managing Editor, Editor, Respiratory Care, San Francisco General Hospital; Lewis Rubinson, PhD, MD, Chief Medical Officer, Morristown Medical Center, Morristown, NJ
Below is select information from the guidance document regarding HFNC (Table 3.1). Refer to the full document cited above for a detailed rationale and complete list of references.
Table 3.1 Recommendations from the Society for Critical Care Medicine Task Force.
Ensuring adequate ventilation throughout the work environment can help to maintain a safe and healthy workplace. Employers should work with heating, ventilation, and air conditioning (HVAC) professionals to consider steps to optimize building ventilation. The following tips can help reduce the risk of exposure to the coronavirus: