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 include ETI, SGA, and surgical airways. These procedures are generally reserved for paramedics and EMS physicians. However, SGAs are included at the AEMT level in the 2019 National EMS Scope of Practice model, and in some areas EMTs may use SGAs as well [18, 19].
Tracheal intubation
ETI is the most widely recognized method of advanced airway management. Paramedics have performed endotracheal intubation in the United States for over 30 years [20–23]. ETI has many theoretical advantages, including isolation of the airway from secretions or gastric contents and the provision of a direct conduit to the trachea without separate airway opening maneuvers.
Orotracheal intubation
Direct orotracheal intubation is the most common method of ETI (Figure 3.2). The most common laryngoscope blades used for orotracheal intubation include Macintosh (curved) and Miller (straight) blades, which require slight variations in laryngoscopy technique [24]. The rescuer places the curved Macintosh blade into the vallecula (the space immediately anterior to the epiglottis) to facilitate indirect lifting of the epiglottis and exposure of the vocal cord structures. In contrast, the rescuer uses the broad side of the straight Miller blade to displace the oropharyngeal structures, using the tip of the blade to lift the epiglottis directly. Blade selection is a matter of personal preference; there are no data indicating the superiority of either blade during prehospital ETI.
Orotracheal intubation optimally requires the absence or near‐absence of protective airway reflexes. It is extremely difficult in patients who are awake or have intact airway reflexes. In these situations, drug‐facilitated intubation techniques are often necessary.
In scenarios with potential cervical spine fracture or injury, EMS personnel must perform orotracheal intubation with “manual in‐line stabilization” of the cervical spine, without hyperextension of the head or neck during laryngoscopy (Figure 3.3). This approach requires a second rescuer to hold the cervical spine “in‐line” during laryngoscopy attempts. However, a critical review questions the value of manual in‐line stabilization, suggesting that it significantly impairs laryngoscopy while not affording adequate spinal cord protection [25]. Video laryngoscopy may improve visualization of the glottis while minimizing cervical spine movement during ETI [26].
Figure 3.2 Orotracheal intubation
Figure 3.3 Manual in‐line stabilization for intubation of the patient with suspect cervical spine injury
Video laryngoscopy
Video laryngoscopy uses a camera with a view from the end of the laryngoscope blade, providing video images of the airway that are displayed on a screen. Newer generation video laryngoscopes include portable and disposable configurations that are suited to the prehospital setting. While video laryngoscopy has demonstrated equal or improved ETI success rates when compared to traditional laryngoscopy in nearly all clinical settings, its cost is higher than conventional laryngoscopy [27–29]. Some studies suggest that proficiency with video laryngoscopy may be obtained in as few as five intubations [30]. Some video laryngoscopes also allow clinicians to record their efforts for offline review for quality improvement or educational initiatives