26.3.1 Why Might Airway Management Be Difficult in Patients with Ludwig's Angina?
Patients with Ludwig's angina or a retropharyngeal abscess frequently have features that create difficulty with all aspects of airway management: bag-mask-ventilation (BMV), ventilation using extraglottic devices (LMA), laryngoscopy and tracheal intubation, and even performing a surgical airway.
Bag-mask-ventilation may be challenging in these patients for a number of reasons. Patients with stridor will have significantly decreased airway caliber, necessitating high airway pressures to produce adequate gas flow. It may not be possible to generate these pressures with BMV. Because of pain and anxiety, both the awake or obtunded patients may not tolerate application of the facemask and airway opening maneuvers due to pain and anxiety. It may prove difficult or impossible to open the airway of the sedated or unconscious patient due to loss of muscle tone and the resultant further narrowing of the airway. Copious secretions may increase the risk of laryngospasm, and tongue swelling may preclude use of an oral airway. A nasal airway is an option but bleeding could possibly trigger laryngospasm.
Upward displacement of the tongue by the infection can make insertion of any of the extraglottic rescue devices difficult or impossible. Although Brimacombe et al reported the successful use of a small Laryngeal Mask Airway (#2) as a rescue device for a hypoxic adult patient with quinsy,7 extraglottic rescue devices for failed BMV, even if they can be inserted, may be ineffective due to glottic edema.
Secretions and edema, particularly tongue swelling, will make direct laryngoscopy more difficult regardless of the type of blade chosen. Nuchal rigidity, trismus, or both may be improved with sedation or muscle relaxants but there is no guarantee that these agents will be effective. Blind intubation techniques, such as the intubating Laryngeal Mask Airway (LMA-Fastrach™, LMA North America Inc., San Diego, California) and light-guided intubation (Trachlight™, Laerdal Medical Corp., Wappingers Falls, New York) would not generally be considered for first-line use in these patients as these techniques run the risk of disrupting infected tissue and potentially soiling the airway. Furthermore, these nonvisual intubating techniques could result in laryngospasm during the intubation attempt. Typically these patients have heavy secretions and occasionally some bleeding, limiting the use of indirect visual techniques such as the flexible and rigid fiberscopes and video laryngoscopes. In true cases of Ludwig's angina, oral intubation with any instrument is frequently not an option due to limited oral access. Most experts would advocate either a nasal intubation or a surgical airway.
Unfortunately, performing a surgical airway in this patient population is difficult. The anatomy is often distorted due to swelling, and hyperemic tissues may increase the likelihood of bleeding. In some patients, the abscess may involve the area surrounding the trachea. Supine positioning of the patient to perform a surgical airway may worsen dyspnea and reduce the patient's cooperation.
To add to the difficulty of airway management in these patients, all possible options of ventilation and oxygenation involve some danger. The ultimate decision will be made based on the urgency of the clinical circumstance, the available resources, the careful setting of priorities, and the skill and experience of the airway team (anesthesia practitioner and surgeon).
26.3.2 Discuss the Role of CT Scan in Assessing These Patients
The advent of the CT scan has revolutionized the ability to accurately assess the swollen, inflamed neck. In addition to determining the severity of the infection involving different tissue planes and neck spaces, the resolution of the CT scan can help to differentiate between a cellulitis and an abscess. The CT scan can also determine the presence or absence of jugular vein thrombosis. Unfortunately, in the presence of a rapidly deteriorating airway, it is necessary to proceed with emergency airway management before a CT examination of the neck becomes available. Even in patients with stable airways, a CT scan may not be possible prior to definitive airway management because the patient may be unable to lie flat. In these cases, the CT scan is done to better determine the extent of the infection only after securing an airway.
26.3.3 Discuss the Technique of Nasopharyngoscopy and Its Role in the Management of Patients with Deep-Neck Infections
Nasopharyngoscopy is a safe and simple technique which should become familiar to anesthesia practitioners, otolaryngologists, and emergency specialists. Following the application of topical vasoconstrictor and topical anesthetic (10% Xylocaine), the flexible nasopharyngoscope is passed into the nasopharynx. The glottis should not be anesthetized as this could trigger laryngospasm. With the flexible nasopharyngoscope, the glottis can be viewed from above without the risk of provoking laryngospasm. The technique is usually first done in the emergency department as part of the initial evaluation, and repeated at the bedside or in the operating room as required to provide an ongoing evaluation of the airway.
26.3.4 How Was This Patient Assessed?
On examination, he appeared anxious and in severe discomfort. He was febrile with a temperature of 38.7°C (101.66°F). His respiratory rate was 26 breaths per minute. His heart rate was 104 beats per minute (bpm) and his blood pressure was 132/76 mm Hg. His oxygen saturation was 91% on 40% oxygen delivered through the facemask. He had a marked decrease in the range of motion of his neck. Significant swelling and erythema was observed extending from the right submandibular region, crossing the midline and down the neck to include his left upper chest.
In a lateral x-ray of the neck, marked submandibular and retropharyngeal swelling was seen, as well as a diminished airway caliber (Figure 26-2). Although potentially helpful, a CT scan was not done as it was felt that the patient could not tolerate lying flat, even for a short period of time.
Although this lateral x-ray view of the head and neck did not show any obvious sign of airway obstruction, it showed an increase prevertebral soft tissue (swelling of the posterior pharyngeal wall) (arrow), an important diagnostic sign of retropharyngeal abscess.18 There was also a loss of normal lordotic curvature of the spine.
Nasopharyngoscopy was performed in the emergency department (ED) by the ENT resident and revealed right lateral pharyngeal swelling and posterior displacement of the epiglottis obscuring the vocal cords.
26.3.5 How Do You Assess the Severity of Airway Obstruction?
Airway obstruction is assessed clinically by history and physical examination, noting symptoms and looking specifically at signs, such as oxygen saturation, respiratory rate, stridor, tracheal tug, intercostal indrawing, and accessory muscle use. Lateral x-ray (Figure 26-2) and CT scan of the head and neck can quantify the degree of obstruction. It is also possible to examine the dynamic aspect of the obstruction through nasopharyngoscopy.