This practice guideline contains changes related to COVID-19.
Airway management sits at the core of effective patient management in out-of-hospital care. In the vast majority of cases, it is the first clinical decision to be made. All patients require a structured airway assessment during their initial evaluation, even those who are not obviously in distress.
The decision to intervene is predicated on a combination of factors. Although the patient’s clinical status is the most obvious of these, consideration must be given to crew resource management, training, scopes of practice, and conveyance times. The interplay between these factors can be complex and daunting regardless of the experience of individual paramedics and EMRs/FRs.
Airway intervention decisions can be broken down into three major categories, each of which carries with it a particular level of urgency. The first question revolves around whether there is a need to obtain or maintain an airway – this suggests there is an immediate problem that requires correction, whether that takes the form of a jaw thrust or a pharyngeal airway. The second question considers whether or not there is a problem with oxygenation or ventilation. These types of problems often require rapid intervention, either with supplemental oxygen, a bag-valve mask, or through the use of medications. The third question asks paramedics and EMRs/FRs to consider what the anticipated clinical course is; if patient deterioration is expected, it may be advantageous to intervene earlier, when treatments are more likely to be effective and easier to implement, as opposed to later.
The goal of all airway management is effective and safe oxygenation and ventilation, regardless of modality or intervention strategy. Effective ventilation depends on sufficient tidal volume and respiratory rate. Effective oxygenation depends on the fraction of inspired oxygen, the capacity for gas to diffuse across the alveolar membrane, the ability (and availability) of haemoglobin to transport oxygen throughout the body, and the propensity of oxygen to diffuse into tissues.
Because end-organ and tissue perfusion depends on the ability of the body to transport oxygen in the blood, paramedics and EMRs must ensure that patients have a blood pressure sufficient to support life. Volume replacement may be required before airway interventions can take place effectively.
A thorough and comprehensive respiratory assessment must be performed on all patients. Assessments of airway patency and adequacy of respiration should be performed concurrently with other elements of the primary survey.
Intervention strategies should progress from simple strategies to more complex approaches and must be based on an understanding of the patient’s needs rather than a technical imperative.
If unable to ventilate despite basic airway maneuvers, consider the presence of an obstructed airway and begin chest compressions.
The elastomeric half-face respirator (EHFR) is the primary device to be used for respiratory protection during COVID-19. If an N95 is worn, it can be used for the full duration of a shift. The N95 mask and/or face shield should be replaced or discarded if it becomes grossly contaminated with blood, secretions, or body fluids. The N95 respirator and/or face shield must be discarded if it becomes obviously soiled or damaged (e.g., creased, torn, or saturated) or if visibility is impaired. Paramedics and EMRs are required to wear a procedure mask over the exhalation port as the exhalation port on EHFRs are not filtered.
Additional Treatment Information
The jaw thrust is the most effective manual maneuver to open an airway when the patient’s own muscle tone is lost. In using a jaw thrust, the tongue and epiglottis are lifted away from the posterior oropharynx, maximizing the available space. Pharyngeal airways provide additional assistance at resolving these functional airway obstructions, though a jaw thrust will still need to be maintained even with the adjunct in place to ensure the best possible airway opening. There is no evidence to suggest that a nasopharyngeal airway is better or worse than an oropharyngeal airway; device selection should be based on the presence or absence of gag and airway reflexes.
Effective bag-valve mask ventilation is a difficult skill to learn and maintain. Optimal bag-valve mask ventilation, in most cases, requires two operators: one to maintain a mask seal and provide a jaw thrust, the other to operate the bag. Lift the patient’s face into the mask while providing ventilations. Exposure of the patient's thorax to visualize chest rise and fall is essential; deliver only enough volume to see chest rise and avoid high tidal volumes.
Critically ill patients can be supported by use of a nasal cannula with a maximum flow rate of 5 L/min in addition to a bag-valve mask (NODESAT or high-flow nasal cannula technique). The inclusion of a PEEP valve in this scenario provides for maximal oxygen delivery in the out-of-hospital environment and allows paramedics to assist ventilations if it becomes necessary.
When applying CPAP, watch oxygen saturations carefully. Be prepared for a transient fall in oxygen saturation: this is the result of a change in the FiO2 from a face mask to the CPAP device. Give the device time to work properly before making adjustments. Additional oxygen may become necessary if saturations remain low.
A functional airway obstruction occurs when muscle tone in the upper airway is lost and structures collapse under their own weight. The culprits are generally the tongue against the soft palate and the posterior oropharynx, as well as the epiglottis. Functional airway obstructions should be suspected in all patients with an altered level of consciousness and may present as snoring or stertorous respirations, asynchronous chest and abdominal movements, or irregular breathing patterns.
Be aware of the development of pathological airway obstructions, from infectious diseases, trauma, medication reactions, or anaphylaxis. Options for managing pathological airway obstructions in the out-of-hospital environment are limited - epinephrine (and cricothyrotomy by advanced providers) is generally the only effective choice.
Carefully consider the interplay between ventilation and oxygenation. Ventilation is the mass movement of gas between the lungs and the atmosphere. Oxygenation is the diffusion of oxygen across the alveolar membrane, the binding of oxygen with hemoglobin for transport to other body tissues, and the subsequent release of that oxygen once it reaches its destination. Both are required to support life, and problems with one can affect the other. Paramedics and EMRs/FRs should remember that they are distinct processes.
Patients with ventilation deficits do not respond solely to supplemental oxygen. They may require bronchodilation (either with salbutamol or epinephrine, depending on the clinical scenario) or positive pressure ventilation by bag-valve mask. An inadequate respiratory rate, with or without a concurrent fall in tidal volume, requires immediate intervention.
Hypoxia is the sign of an oxygenation problem. These patients may have adequate ventilation, but are unable to diffuse oxygen across their alveolar membranes (or transport oxygen in the blood). Supplemental oxygen is required in these cases.
Continuous positive airway pressure (CPAP) masks are not ventilation devices. They are designed to improve the diffusion of oxygen across the alveolar membrane: they will not help patients who do not have an adequate respiratory rate or tidal volume. The specific FiO2 produced by a CPAP mask is unknown due to the entrainment of ambient air required to generate the positive pressure – when using CPAP, carefully monitor oxygen saturations and adjust flow rates as required. It may be necessary to add oxygen via nasal cannula in critically ill patients.
First Responder (FR) Interventions
Assess patient and position for optimal access based on clinical need
Functional airway obstruction present:
Perform jaw thrust to open airway
Attempt placement of oropharyngeal airway
Provide optimized bag-valve mask ventilation as necessary
Consider higher level of care intercept where available
Primary Care Paramedic (PCP) Interventions
Supraglottic airway devices may be used to support oxygenation and ventilation in a staged approach, following confirmation of the ability to ventilate the patient with a bag-valve mask and pharyngeal airway