Fig. 2.1
The patient was shot with a high-caliber rifle. The entry wound and exit wound demonstrate relatively little damage externally. When the patient was paralyzed, he proved very difficult to bag mask ventilate. CT scan revealed severe, comminuted mandibular fractures and soft tissue edema. This example reveals how, with penetrating facial and neck trauma, relatively benign-appearing external wounds may mask significant airway damage
Auscultate both the chest and neck and focus on asymmetry and signs of airway edema. Stridor, a high-pitched, turbulent sound heard with respiration, indicates the development of airway compromise and impending obstruction. Finally, palpation can offer insight into potential airway compromise. Palpate the face, neck, and chest closely for signs of subcutaneous emphysema, and closely feel along the cricoid and tracheal cartilages for signs of crepitus.
If the patient is already intubated, do not be lulled into complacency: confirm tube position with capnography and auscultation of breath sounds. If these findings are equivocal, you should use a laryngoscope to confirm that the endotracheal tube (ETT) is going through the vocal cords. If it is not, replace the tube. If you are unsure and other clinical signs suggest an esophageal intubation (hypoxia, absent breath sounds, no end-tidal CO2), you should reintubate. If ventilation problems persist, the tube placement should be confirmed with a fiber-optic scope by placing the scope through the endotracheal tube and identifying tactual rings. If no tracheal rings can be identified, the tube could be in the esophagus or in a false passage caused by a tracheal injury. In this case a surgical airway should be established as soon as possible. While many prehospital systems demonstrate remarkable success with intubation, there is obvious variability, and no ETT placed in the field should be considered secure until placement is confirmed.
2.2 Deciding Who Needs a Definitive Airway
A definitive airway is defined as a tube secured in the trachea with the cuff inflated. This can occur via three primary modes of tracheal intubation: nasal, oral, and surgical. The indications for intubation cannot be boiled down to a simple list of criteria, yet it is useful to consider a few broad categories. It should be stressed that determining who needs a definitive airway is a clinical decision and the use of objective criteria such as pulse oximetry, arterial blood gases (ABG), Glasgow Coma Scale (GCS), and vital signs, while useful, should not be relied upon alone. Patients with impending airway disasters may display no vital sign or laboratory abnormalities. Emergent intubation is common in patients with penetrating trauma and is influenced by the location and severity of injuries. Patients with penetrating neck injuries require emergency airway management in 46 % of cases, and 60 % require intubation at some point during their hospitalization.
Indications for a definitive airway generally fall into one of the following broad categories:
- 1.
Obvious airway compromise or inability to protect the airway: Airway obstruction can result from a variety of causes ranging from functional (i.e., in the obtunded patient) to mechanical (from edema, hematoma, or foreign body). Patients who are obtunded often lose the muscle tone of their posterior and oral pharynx, causing their tongue to drop back, leading to functional obstruction. While the obstruction may easily be relieved with simple maneuvers such as the jaw thrust, chin lift, or the placement of an oropharyngeal airway (OPA), the patient remains at a high risk for aspiration. If a patient can tolerate an OPA, he cannot protect his airway and you should intubate him. If a patient displays signs of frank mechanical obstruction, simple basic life support (BLS) maneuvers are unlikely to help, and therefore you should establish a definitive airway.
Even if the primary survey does not reveal obvious signs of airway obstruction, the patient may have lost their protective airway reflexes and be at risk for aspiration. This is particularly true in the patient with a depressed level of consciousness, which can result from a variety of causes: shock, intoxication, head injury, etc. The Advanced Trauma Life Support (ATLS) program recommends that a patient with a GCS <8 be intubated. While a reasonable cutoff, this should not be a rigid one, and you should consider intubation if mental status appears to be declining rapidly even if the GCS is still above 8. The absence of the gag reflex is often cited as evidence of an inability to protect the airway, though there is scant literature to support this. Studies have noted the presence of the gag reflex across a broad spectrum of GCS scores, and the absence of a gag reflex has been documented in individuals who are fully conscious.
- 2.
Predicted airway compromise: Patients with penetrating injuries, particularly of the neck, are at high risk for developing airway compromise, and an “intact” airway is not reassuring if early signs of obstruction are present. Early, mild signs of obstruction include subtle change in voice, cough, and mild neck hematoma. These signs do not mandate immediate intubation but should be monitored closely. Stridor, expanding neck hematoma (especially in conjunction with other signs of obstruction), and obvious tracheal injury mandate early establishment of a definitive airway. The presence of stridor is a later stage of obstruction and indicates a 50 % reduction in airway caliber. Expanding neck hematomas, even when initially small, can lead to precipitous airway obstruction. The swelling of airway structures often requires an endotracheal tube size smaller than usual. In cases with severe swelling of the airway structures, a tube exchanger catheter (gum elastic bougie) can be placed into the trachea via direct laryngoscopy, and the tube then advanced over the tube exchanger.
- 3.
Failed ventilation/oxygenation: Consider the patient who cannot maintain adequate ventilation or oxygenation despite noninvasive measures such as supplemental oxygen as likely, but not necessarily, requiring intubation. The primary survey and adjuncts to the primary survey (respiratory rate, breath sounds, the presence of cyanosis, pulse oximetry, arterial blood gases) will often make it clear whether or not a patient is in frank respiratory failure.
- 4.
Predicted clinical deterioration: Even when a patient does not show hard signs of airway obstruction, inability to protect the airway, or respiratory failure, one should consider whether the likely clinical course will lead to one of these conditions. If this is the case, it is more prudent for you to intubate the patient early rather than waiting for clinical deterioration (which may occur in a less-controlled environment such as the CT scanner). Is the patient extremely agitated, belligerent, and uncooperative? Will they be unlikely to tolerate diagnostic tests such as computed tomography (CT) without high doses of sedation? Is the patient in hemorrhagic shock and likely to require large-volume fluid resuscitation?
2.3 Approaches to Establishing a Definitive Airway
There are numerous approaches to gaining a definitive airway, and the approach used will depend on the location of injuries, the presence or suspicion of laryngotracheal injury, equipment available, and the experience of the clinician. In patients without obvious airway trauma, direct laryngoscopy generally is appropriate. In the past, it was common teaching that patients with penetrating neck injuries should proceed directly to a surgical airway. However, several retrospective studies suggest that direct laryngoscopy has a high success rate in such patients. That said, if there are obvious injuries to the larynx or trachea, placement of an ETT through the cords might worsen a tracheal injury or lead to intubation of a false passage. In patients with suspected tracheal injury, you should proceed to cricothyrotomy if the patient is unstable or, in the non-“crash” situation, go directly to the operating room (OR). In the OR, you can attempt fiber-optic intubation (when available) and be in a more controlled environment if a surgical airway is necessary. Fiber-optic intubation allows visualization of injuries below the vocal cords and can help you to place the cuff of the ETT below the injury. The different modes of obtaining a definitive airway are discussed briefly below.
Direct Laryngoscopy
It is an appropriate initial approach for most emergent airways. It can be performed in patients with penetrating neck injuries but should be avoided if there are signs of laryngotracheal injury. It may worsen injury below vocal cords or lead to intubation of false passage.
Video-Assisted Laryngoscopy
This technique allows a better view for the less-experienced airway manager and also allows other members of the team to watch the intubation on the screen. It does not allow visualization below the vocal cords and also results in injury below the vocal cords or intubation of false passage. Video laryngoscopy often requires longer time to intuition than direct laryngoscopy.
Fiber-Optic Intubation
If available and there is a clinician experienced in the technique, this is a good option when laryngotracheal injury is suspected but not obvious. It allows for identification of injuries below the cords and placement of cuff distal to the injury site. It can be done awake in non-crash situation if the patient is cooperative. The use of the fiber optic is very limited in patients with blood in the airway as the blood will easily cover the small lens of the fiber optic.
Cricothyrotomy
It is indicated in patients with obvious laryngotracheal injury above the cricothyroid membrane that demonstrate signs of significant airway compromise. It is also an option when distortion of upper airway anatomy makes any form of laryngoscopy impossible or unlikely. This approach should be avoided if there is obvious tracheal injury below the cricothyroid membrane or if underlying pathology (i.e., tumor or abscess) makes the approach impossible.
Direct Intubation Through Neck Wound
This should be considered in patients with obvious large defects of the trachea below the cricothyroid membrane or in cases of complete tracheal transection.
Blind Nasal Intubation
There is no role for this technique if there is potential for injury anywhere in the airway. Blind passage may worsen underlying injuries and lead to complete obstruction.
Tracheotomy
This is generally avoided in the emergent setting as it is slower and carries a higher complication rate than cricothyrotomy. In cases where cricothyrotomy is impossible or there is obstruction or injury below the cricothyroid membrane, it may be indicated.
2.4 Rapid Sequence Intubation
Once the decision has been made that a patient requires a definitive airway and that direct laryngoscopy or video-assisted laryngoscopy is appropriate, the next steps will depend on how emergent the situation is. A “crash” intubation essentially refers to the patient who is in frank cardiopulmonary arrest (or close to it) or in respiratory arrest. In such cases, proceed to laryngoscopy, often without the need for induction agents or paralytics. If the patient needs a definitive airway emergently but is not “crashing,” take time to further assess the airway for potential difficulties, prepare equipment, optimize patient positioning, and formulate a backup plan in case the airway fails.
Rapid sequence intubation (RSI) is the near simultaneous administration of a sedative/hypnotic agent with a neuromuscular blocking agent to rapidly achieve unconsciousness and paralysis. In unconscious or semiconscious patients, the dose of the hypnotic should be reduced. Use this technique in emergent settings in which a patient has likely not been fasting and is at a higher risk of aspiration. If done with adequate preoxygenation, it can often be performed without having to bag mask ventilate the patient at all, thus reducing gaseous distension of the stomach. If mask ventilation is required, use small tidal volumes to avoid extension of the stomach. While RSI generally improves intubation success, you should consider an alternate approach (such as awake fiber-optic intubation) in the spontaneously breathing patient who displays predictors of a difficult airway, especially if you predict they will be difficult to bag mask ventilate.
Predicting the Difficult Airway
Before you attempt intubation (in the non-“crash” situation), you should ask these questions: Will the patient be difficult to bag mask ventilate (BMV)? Will the patient be difficult to intubate? Will it be difficult to perform a surgical airway (Table 2.1)?
Table 2.1
Difficult airway predictors
Difficult BMV | Difficult laryngoscopy | Difficult surgical airway |
|---|---|---|
Beard | Reduced mouth opening | Obesity |
Elderly | Receding chin | Anterior neck hematoma |
Edentulous | Obstruction (neck hematoma, stridor, tongue swelling) | Surgical disruption (radical neck dissection, neck trauma, etc.) |
Perioral trauma that affects mask seal | Large tongue | Neck irradiation |
Mandible – fracture | Obesity | Overlying neck abscess |
Obesity | Reduced neck mobility (C-collar, ankylosing spondylitis) | |
Significant tongue trauma/edema | ||
Obstruction/debris/airway hemorrhage |
2.4.1 Preparing for Intubation
Prior to intubation, it is important to make sure all equipment is laid out and working – laryngoscope with different-sized blades, different-sized ETT’s with stylet, suction, end-tidal CO2 detector, preferable capnography, airway adjuncts, alternative intubation device, and a rescue device (see below). While equipment is being gathered, the patient should be preoxygenated with 100 % FiO2 for at least 3 min. Keep in mind that 100 % non-rebreather masks typically deliver only 65–70 % FiO2. It is preferable to preoxygenate with a well-sealed mask attached to an anesthesia bag or BMV system using 100 % oxygen. During preoxygenation, you should attempt to place the patient in the most optimal position. Position the head of the patient as close to the end of the stretcher as possible, at a level high enough that you can get proper visualization without having to contort your body too much (usually around waist level). Pay attention to the alignment of the “airway axis”: drawing an imaginary line, the patient’s external auditory canal should align with the sternal notch. You can accomplish that with towels underneath the patient’s head (“sniffing position”) or by lifting the patient’s head with your right hand once they are paralyzed. Morbidly obese patients may need to be “ramped” up with blankets underneath their back and head in order to align the airway axis.
An important part of the intubation preparation process is choosing which RSI drugs you should give. A detailed discussion of induction agents and neuromuscular blocking agents is beyond the scope of this text, but one should have a broad understanding of the indications and contraindications of the agents available. There are several reasons for administering an induction agent: amnesia, sedation, and mitigation of the physiologic response to intubation (hypertension, tachycardia, increased intracranial pressure). Ideally, the induction agent chosen should have a rapid onset and a short half-life. In trauma, there is no ideal agent, although etomidate is often used in patients with shock as it is hemodynamically stable and does not raise intracranial pressure (ICP). Unless there are contraindications, succinylcholine (SCh) is generally the preferred paralytic for RSI, as it has a rapid onset and is very short acting. If there are absolute contraindications for SCh, one of the non-depolarizing agents should be used. Rocuronium is perhaps the most attractive alternative as it has a rapid onset and is short acting. Furthermore, a reversal agent for rocuronium, sugammadex, has been approved for use in Europe and has been shown to recover muscle function quite quickly (Tables 2.2 and 2.3).
Table 2.2
Commonly used induction agents for rapid sequence intubation
Related posts:
Stay updated, free articles. Join our Telegram channel
Full access? Get Clinical Tree
