Vol. 2.9 Early Release Special Edition
Respiratory Support for Adult Patients with COVID”19. Whittle JS, Pavlov I, Sacchetti AD, Atwood C, Rosenbert MS. J Amer Coll Emerg Phys Open. Published on-line April 2020, https://doi.org/10.1002/emp2.12071.
Previous: International Prehospital Medicine Institute Literature Review, April 2020
Care of patients with COVID-19 presents many challenges. As with any disease disseminated by airborne droplets, a focused treatment plan, particularly as it relates to the airway and patient ventilation, needs to be in place. A crucial component of this treatment plan involves the safety of the Health Care Providers (HCP) caring for the coronavirus-infected patient.
The authors of this clinical review paper discuss strategies for the delivery of respiratory support for patients with COVID-19 infection and focus on commonly used airway and oxygenation treatments and the disbursement of infected droplet particles associated with those procedures using a high-fidelity mannequin.
Oxygen delivery is a primary treatment modality for the care of those in respiratory distress. The goal is to maintain an oxygen saturation greater than 90% and greater than 92% in the pregnant COVID-19 patient. The authors looked at available oxygen delivery devices and the relative disbursement distance of aerosolized particles generated by each.
They conclude that the device that produces the least amount of spread at less than 10cm is the Non-rebreathing mask (NRBM) using an oxygen flow rate of 10L/minute. This is followed by high flow nasal oxygen (HFNO) at 17cm at the highest flow rate of 60L/minute, however it was noted that if the canula became dislodged the distance would increase. Nasal cannulas provide up to 45% FiO2 to patients in mild to moderate distress however particle dispersal with a nasal cannula can reach as far as 40cm at 5 lpm flow rate. Venturi masks can deliver precise oxygen concentrations but can produce a particle reach of 40cm at 10 lpm.
A simple oxygen mask produces particle distances of 40 cm at 10 lpm. Nebulized medication treatments are a cornerstone of treating patients with bronchospasm; however, they are a high-risk procedure in the face of COVID-19 or any viral condition. Modeling shows a dispersion of particles up to 80 cm at flow rates needed for optimal medication delivery.
Closed systems or the use of a facemask may decrease the distance. Finally, the use of non-invasive positive pressure ventilation (NIPPV), to include CPAP or BiPAP, demonstrates the highest dispersion of particles at up to 95 cm, depending on device settings and patient condition.
EMS services currently respond to many patients with COVID-19 that require supplemental oxygen or airway management and may also be required to provide interfacility transport of patients receiving any of the treatment modalities discussed in this paper. There are several of these modalities that EMS providers commonly employ.
The use of each of these for a particular patient should be evaluated using a risk vs. benefit decision, taking into consideration the patient’s need and the availability of a comparable treatment with a lower risk profile for aerosolization and dispersal of infected particles. The management of a hypoxic patient with known or suspected coronavirus infection should follow a standard progression of steps, beginning with a non-rebreather mask and progressing to more advanced interventions as necessary to maintain oxygen saturation above 90%.
Traditionally, EMS providers administer aerosolized bronchodilator medications for wheezing, usually by oxygen powered jet nebulizer. An alternative therapy that should be considered in coronavirus patients is the use of metered dose inhalers (MDI). CPAP, often utilized by EMS providers, has the greatest distribution of particles; this, combined with the limited patient care space in the patient compartment of an ambulance, makes CPAP intervention a high-risk treatment modality. Some newer CPAP and NIPPV devices have an exhalation port that will accept a viral filter, thus decreasing particle dispersion and reducing any potential exposure.
Conflict of Interest Statement: Two of the authors disclosed working relationships with companies that produce HFNO delivery systems.
