PREHOSPITAL AIRWAY MANAGEMENT: INTUBATION, DEVICES, AND CONTROVERSIES

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CHAPTER 10 PREHOSPITAL AIRWAY MANAGEMENT: INTUBATION, DEVICES, AND CONTROVERSIES

Raul Coimbra, Daniel P. Davis, David Hoyt

Prehospital trauma airway management is probably the biggest challenge faced by prehospital providers. These professionals must not only acquire but also maintain essential skills to adequately manage airway problems at the scene and during transport of trauma victims to trauma centers.

Endotracheal intubation is the definitive method of airway management. However, to acquire such skill requires significant training and practice. Although the emergency medical technician-basic (EMT-B) cur riculum contains an advanced airway module, the low frequency of these procedures makes it difficult for these professionals to maintain proficiency. In most systems, paramedics and flight nurses are the only professionals allowed to perform rapid sequence intubation (RSI). Therefore, there is a need for simpler ways to maintain a patent airway by emergency medical technicians, until the patient is delivered to a hospital. Several devices are now available and have been used by prehospital personnel when endotracheal intubation is not practical or possible. These alternate methods include bag-valve-mask with oral or nasopharyngeal airway, the laryngeal mask, and the esophageal-tracheal double lumen tube, popularized as the Combitube.

In this chapter, the indications for airway management in the prehospital arena, the different modalities, devices and techniques, the recognition of a difficult airway, and associated pitfalls will be discussed.

WHO NEEDS AN AIRWAY?

Before we define who needs an airway in the prehospital arena, it is important to clarify that few studies to date have shown efficacy of advanced airway management in trauma prior to arrival at a trauma center.

The goal of airway management is to provide adequate oxygenation and ventilation as part of the overall resuscitation effort. Candidates include those with decreased or absent respiratory movements, signs of airway obstruction, and cardiopulmonary resuscitation (CPR) in progress. Severe traumatic brain injury (TBI) as an indication for prehospital intubation will be discussed later.

In trauma, it has been shown that moribund patients would benefit from an airway, particularly those who are candidates for a resuscitative thoracotomy upon arrival at the hospital.¹

DIFFICULT AIRWAY

The Mallampati classification has been used for many years by anesthesiologists during preoperative evaluations for the identification of a difficult airway and to predict difficult intubation ² (Figure 1). It compares tongue size with the oropharyngeal space, and its reliability has been questioned because it does not take into account other factors that may make intubation difficult or impossible in the prehospital setting. However, if the patient is still able to follow simple commands, direct visualization of the oropharynx by asking the patient to open the mouth will give additional and important information to the astute prehospital provider. Rich³ described the 6-D methods of airway assessment: disproportion; distortion; decreased thyromental distance; decreased interincisor gap; decreased range of motion in any or all of the joints—atlanto-occipital, temporomandibular, and cervical spine, always present in trauma; and dental overbite.

Figure 1 Difficult airway—the Mallampati score modified by Samsoon and Young.

(From Mallampati SR, et al: A clinical sign to predict difficult tracheal intubation: a prospective study. Can Anaesth Soc J 32:429–435, 1985.)

Identifying a difficult airway prevents patient deterioration or death. Alternative devices and strategies should be used when the diagnosis of a difficult airway is made. These include the laryngeal mask airway (LMA), Combitube, or bag-valve-mask.

WHICH STRATEGY SHOULD BE USED?

The strategies described as follows are alternatives to conventional bag-valve-mask with either a nasopharyngeal or an oropharyngeal airway.

Laryngeal Mask Airway

The LMA is one alternative to endotracheal intubation (Figure 2). Its use is particularly important in patients with difficult airways (defined later) and in patients treated in “unfriendly” environments (rain, dark, prolonged extrication, etc.). It also can be used as a rescue strategy following a failed RSI. Additionally, it can be used to facilitate intubation, which is obtained by passing the endotracheal tube through the LMA.