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77 77 Spaite DW, Bobrow BJ, Keim SM, et al. Association of statewide implementation of the prehospital traumatic brain injury treatment guidelines with patient survival following traumatic brain injury: the Excellence in Prehospital Injury Care (EPIC) study. JAMA Surg. 2019; 154:e191152.
CHAPTER 3 Airway procedures
Jestin N. Carlson and Henry E. Wang
Introduction
Airway management is one of the most important considerations during prehospital care of critically ill or injured patients. This chapter provides an overview of the procedures and techniques that are integral to prehospital airway management.
Personal protective equipment during airway interventions
Whenever an EMS clinician performs an airway intervention, it is essential to ensure the safety of that individual and that of others in close proximity. The recent SARS‐CoV2 (COVID‐19) pandemic has highlighted the importance of personal protective equipment (PPE) during airway management. At minimum, PPE should include a facemask, face shield, and gloves. In situations where COVID‐19 or other communicable disease is a possible underlying condition, rescuers should consider using a particulate filtering mask (N95 or similar respirator), face shield, gown, and gloves (see Chapter 23) [1]. All rescuers assisting with care of the patients should wear the same level of PPE during the procedure.
Basic airway interventions
Oxygen cannulas and face masks
In spontaneously breathing patients, EMS personnel may deliver supplemental oxygen using nasal cannulas or oxygen masks. The nasal cannula provides low‐flow (2–5 L/min) oxygen in inhaled fractions (FiO2) from 0.2 to 0.4 (for convenience we will use the percentage convention: 20%–40%). Oxygen masks used in the prehospital setting include simple facemasks (6–10 L/min oxygen delivery, 40%–60% FiO2) and nonrebreather masks (10–15 L/min oxygen delivery, close to 100% FiO2).
Nasal cannulas and facemasks are designed for patients with spontaneous respiratory drive and intact protective airway reflexes. Patients with frank respiratory compromise or apnea should receive bag‐valve‐mask (BVM) ventilation support or advanced airway management.
Bag‐valve‐mask ventilation
BVM ventilation is the primary method for providing active ventilatory support (Figure 3.1). The key BVM device components include a self‐inflating bag, oxygen reservoir, and conforming facemask. The primary indications for BVM ventilation include hypoventilation (inadequate respiratory drive or effort) or frank apnea.
The technique of BVM ventilation can be challenging, requiring rescuers to open the airway and maintain a mask seal with one hand while squeezing the ventilation bag with the other hand. Seasoned clinicians often recommend performing BVM using two people, with one rescuer opening the airway and holding the mask with both hands and the other squeezing the bag [2]. Two‐handed BVM techniques provide greater tidal volumes than one‐handed techniques [3]. Several studies have demonstrated the difficulty of performing effective BVM ventilation, particularly in a moving ambulance or during prolonged resuscitation efforts. This is one of the motivations for advanced airway interventions for many prehospital patients [4].
An important potential adverse effect associated with BVM ventilation is gastric insufflation, which may result in regurgitation and aspiration of gastric contents into the airway. While some anesthesiologists use Sellick’s maneuver (cricoid pressure) to minimize gastric insufflation during operating room BVM ventilation, a multicenter, blinded, randomized controlled trial of 3,500 operating room patients found no benefit from the technique [5–9].
Figure 3.1 BVM ventilation
Demand valve ventilation
The demand valve is an oxygen‐powered resuscitator that delivers high‐flow oxygen through a mask via a trigger valve. The valve is actuated by a single finger, allowing the rescuer to use both hands to seal the mask and open the airway. The major limitation of this device is the inability to sense lung compliance, which may be important in the presence of barotrauma or pneumothorax. Formal comparisons to BVM ventilation or other ventilatory devices remain limited [10, 11]. Although once popular, fewer agencies are using these devices.
Oropharyngeal and nasopharyngeal airways
Oropharyngeal and nasopharyngeal airways are important adjuncts for basic airway support. The oropharyngeal airway is a curved plastic device that is inserted into the oropharynx, maintaining airway patency by lifting the tongue forward from the posterior wall of the pharynx. The nasopharyngeal airway is a soft plastic tube that is inserted through the nose, similarly facilitating airway patency. EMS personnel should use one of the adjuncts during BVM ventilation. It is possible to use both airway adjuncts simultaneously. While either may be suitable with a nonrebreather mask for a spontaneously breathing patient, insertion of the oropharyngeal airway should be reserved for the patient without a gag reflex. The patient with an intact gag reflex is not likely to tolerate, and probably doesn’t need, the airway adjunct.
Noninvasive positive‐pressure ventilation
Prehospital clinicians commonly use noninvasive ventilatory support, or noninvasive positive‐pressure ventilation, as an alternative to endotracheal intubation (ETI) or supraglottic airways (SGAs) [12–17]. These systems deliver pressurized oxygen through a specially designed, tight‐sealing facemask. (See Chapter 6.)
Advanced airway management
Advanced airway procedures involve the insertion of an airway tube into the oropharynx and hypopharynx to facilitate oxygen delivery and ventilatory support. Advanced airway management is indicated for hypoventilating or apneic patients or individuals with actual or potential airway compromise. Current options for prehospital airway management
