Most of the principles of prehospital airway management are similar to those in the emergency department (ED), with the obvious exception that the prehospital environment is necessarily austere. Patient care must often be provided in awkward circumstances such as in private homes, in stairwells, in the seat of a damaged automobile, or on the street, where lighting and position are often not ideal. Local protocols, regional and topographic differences in transport time, the availability or unavailability of neuromuscular blocking agents, limited and varied equipment, limited backup, and mandatory transport of the patient all introduce issues that are not only different from those in the ED, but also different from one prehospital system to another.

The environment of care is “error prone.” Strategies designed to minimize error must do so reproducibly in a time-sensitive fashion. Clear definitions and simple evaluation and management memory tools, including mnemonics and algorithms, represent such strategies. Identifying the difficult airway, managing the failed airway, and performing a cricothyrotomy are no different prehospital than they are in-hospital. Thus, the “thinking” and “doing” in the prehospital environment is identical to that which occurs in an ED or operating room (OR).

In most North American systems, prehospital care providers perform delegated medical acts based on preestablished, standardized medical protocols. Although protocols ought to reflect best clinical evidence, they are limited from a practical perspective by cost, training, competency maintenance, space constraints, and medical director knowledge of the prehospital setting or individual comfort level.

The equipment available to providers in the field is driven by the protocols approved by the emergency medical services (EMS) system, EMS unit medical director, or medical advisory committee. The type and range of equipment available for managing the difficult airway in the prehospital setting is limited compared with most EDs and ORs. Even basic equipment such as the Eschmann introducer (bougie), laryngoscope blades, and endotracheal tubes in an array of types and sizes may be limited in availability. Similarly, the choice of alternate intubating devices, such as the intubating laryngeal mask airway (ILMA or LMA Fastrach) and rescue devices will vary from system to system.

Regardless of the array of devices available, consummate bag-mask ventilation (BMV) technique (including two-handed mask hold requiring two providers if available or necessary) is essential to the prehospital care provider, particularly where the airway is predicted to be difficult and the transport time is relatively brief.

Inadequate ventilation and oxygenation have been identified as primary contributors to preventable mortality, both in hospital and out of hospital. It would seem intuitive that successful endotracheal intubation (ETI) ought to mitigate these deaths, and because of this thinking, ETI became the gold standard in prehospital airway management. However, there is considerable controversy as to whether patients requiring ETI should have tracheal intubation performed in the field or deferred until hospital arrival. There is ample evidence that ETI is not a benign intervention in the hands of inexperienced personnel, who use the technique infrequently. Studies have identified that intubation in the field may delay transport to higher echelons of care, injure airways, and lead to worse outcomes.

The Recommended Guidelines for Uniform Reporting of Data from Out-of-Hospital Airway Management identifies four methods constituting “advanced airway management”: direct oral
laryngoscopy and intubation, nasotracheal intubation (NTI), oral rescue techniques (e.g., BMV, LMA, and Combitube), and surgical rescue techniques (transtracheal jet ventilation and cricothyrotomy). These four methods may each be modified by five variables:

1. Oral approach: no facilitating sedative drugs or paralytics

2. Nasal approach: no facilitating sedative drugs or paralytics

3. Sedation-facilitated intubation (including “nonparalytic rapid sequence intubation (RSI)”)

4. RSI (i.e., the use of neuromuscular blockade ± induction agents)

5. Other intubation technique (e.g., digital and lighted stylet)

The actual number of alternatives available in an EMS system is limited by protocols, training, equipment, and medical direction.

Various LMAs, the King LT airway, and the Combitube (see Chapters 10 and 11) have been introduced successfully in the prehospital care setting as alternatives to ETI for the cardiac arrest (or deeply comatose) patient by basic life support (BLS) providers. These devices also are used for rescue in the setting of failed intubation by advanced life support (ALS) or critical care providers. In some EMS systems, noninvasive ventilation is used as an alternative to ETI for patients in respiratory failure, particularly from chronic obstructive pulmonary disease or acute heart failure.

The following are the most significant changes in the approach to airway management in EMS over the last decade:

Factors contributing to improved RSI success rates for prehospital providers have also been identified:

Improved outcomes for services using RSI are contingent on three factors:

1. Knowing how to correctly perform RSI

2. Being able to identify those patients in whom RSI should not be performed (i.e., identifying the difficult airway [see Chapter 2])

3. Being able to rescue the airway in the event that intubation is unsuccessful and BMV fails

The decision to intubate the patient in the prehospital setting is based on the same principles as those applied in the ED (see Chapter 1). A prehospital algorithm for the decision to intubate is shown in Figure 28-1.

If the patient is not maintaining his or her own airway, the stepwise approach to opening the airway and performing BMV is as described in Chapter 9. In most circumstances, BMV in this setting
should be followed by ETI as soon as adequate preparations have been made, and provided the provider is trained and credentialed to intubate. If BMV is unsuccessful, despite careful attention to proper technique, then immediate intubation or placement of an alternate airway device, such as a Combitube, King LT, or LMA, is indicated (see Chapters 10, 11, and 29). As mentioned previously, in Approach to the Airway, there is a school of thought emerging that the use of an EGD may leapfrog ahead of BMV as the first-line technique. This is based on the relative ease of use and high ventilation success rates seen with EGDs relative to the more difficult technique of BMV.

After a patent airway has been established, the next evaluation should determine whether the patient is protecting the airway from aspiration (see Chapter 1). If a “coma cocktail” is unsuccessful in reversing the patient’s coma sufficient to permit self-protection of the airway, then active airway management is indicated.

If the patient is maintaining and protecting the airway, assessment of ventilation and oxygenation are made as described in Chapter 1. Similarly, the anticipated clinical course, particularly with respect to likelihood of deterioration, is assessed. Decision-making follows the principles outlined in Chapter 1.

Once a decision to intubate is made, the next step is to choose the best method for intubation. The choice will depend on whether the airway is determined to be difficult, whether neuromuscular blockade is permitted, and the particular protocols related to airway adjuncts and rescue devices, including cricothyrotomy. Oral intubation employing direct laryngoscopy is the usual method. In the case of the agonal, unresponsive patient, management proceeds exactly as described in Chapter 3 as a crash airway. The crash airway algorithm is no different in EMS than it is in the ED. In some settings, medication-assisted intubation will include both induction (sedative) agent and neuromuscular blockade. In other settings, where neuromuscular blockade is not permitted, medication-assisted intubation will be done with a sedative hypnotic agent. In either case, medication-assisted intubation may be preferable to blind NTI, even in the clenched jaw patient.

If the patient is conscious and combative and requires intubation, then medication-assisted intubation is indicated. At the outset, though, the benefits and risks of intubation should be weighed against the benefits and risks of rapid transport without intubation. Combative or uncooperative behavior is a relative contraindication to blind NTI because of the increased risk of complications in attempting to insert the tube in a patient who is resisting. If the patient is not frankly comatose and is not uncooperative or combative, then assessment must be made as to whether the patient would tolerate laryngoscopy. If the patient is sufficiently cooperative or sufficiently obtunded to permit oral laryngoscopy without medications, then oral intubation may be attempted. Again, preference is expressed for oral intubation over nasal intubation except in circumstances in which the jaw is clenched, preventing oral access. Even in such cases, oral intubation with medication generally is preferable to blind NTI.

Blind NTI is discussed in detail in Chapter 17. In general, although blind NTI has been widely used in prehospital care, it has declined in popularity because of the superiority of medication-assisted oral intubation. Even though RSI is clearly the method of choice many prehospital care providers do not have this option, and blind NTI may be preferable or may be the procedure of choice for the individual operator. Details regarding contraindications and cautions related to NTI are discussed in Chapter 17.

Although many devices have been developed that may be useful for airway management in the prehospital setting, providers should become facile with one or perhaps two rescue techniques and devices such as EGDs (Chapter 29).