Page 586 - Hall et al (2015) Principles of Critical Care-McGraw-Hill

406 PART 4: Pulmonary Disorders

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If time permits, initial evaluation should include a history of the OROPHARYNGEAL CAUSES
present illness, focusing on the duration of symptoms and any associ- Infectious Causes: Infectious etiologies represent relatively common
ated oropharyngeal, gastrointestinal, or constitutional symptoms, along causes of upper airway obstructing lesions. Ludwig angina is a deep neck
with a history of prior upper aerodigestive tract disorders, recent dental infection of the submandibular space of frequently odontogenic origin
problems or procedures, and smoking. Physical examination is directed that commonly begins as a cellulitis but may progress to a fasciitis and
toward localizing the site of the lesion. Inspiratory stridor generally indi- subsequently to a true abscess. The source of infection is usually a second
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cates a lesion at or above the level of the glottis, while biphasic stridor or third mandibular molar tooth, with causative organisms representing
(stridor present during both inspiration and expiration), which is usu- typical oral flora: viridans group streptococci, staphylococci, and anaer-
ally higher in pitch, suggests a lesion at the subglottic or tracheal level. obes. Mixed aerobic and anaerobic infections are typical, mandating
The presence of stridor indicates a severe degree of narrowing, typically broad spectrum coverage. Methicillin-resistant Staphylococcus auerus
to ≤6 mm. Supraglottic lesions may cause a muffling of the voice, while (MRSA) infection should be considered as a potential pathogen in
oral abscesses may cause a “hot potato voice” (ie, the speech of someone communities with a high prevalence of MRSA colonization, or when
who has a hot potato in his mouth). Hoarseness accompanies unilateral the patient is immunocompromised or has other risk factors for this
vocal cord paralysis. An oral examination should be performed, unless infection. Gram-negative and multi-drug resistant organisms including
epiglottitis is suspected and skilled airway personnel are not present. Pseudomonas aeruginosa and the extended-spectrum β-lactamase-
The submental and submandibular regions should be palpated, along producing Enterobacteriaceae should be considered as potential
with the neck and cervical and supraclavicular lymph nodes. etiologies in patients with risk factors for altered oral flora: neutropenia,
The first priority in encountering a patient with suspected UAO is to
determine the severity of obstruction. When the obstruction is severe diabetes mellitus, or other immunocompromised state, recent antibiotic
use or hospitalization, residence in a nursing home or chronic care
and loss of the airway is feared, the airway should be secured by an facility, or postoperative infection. Airway obstruction may result from
experienced operator. Arterial desaturation is an extremely late sign of elevation and posterior displacement of the tongue and supraglottic
UAO in the patient with normal lungs, and often heralds a catastrophe. edema. The infection may extend to the lateral and retropharyngeal
This is illustrated by the difficulty normal, untrained individuals have in spaces, and subsequently along the carotid sheath and to the mediastinum.
achieving arterial desaturation during breath holding. Similarly, arterial Affected patients present with dysphagia, neck swelling (“bull neck”)
blood gases provide little information beyond that obtained through and stiffness, trismus, drooling, and brawny induration of the floor of the
the bedside assessment of an experienced clinician. Better indicators of mouth. Occasionally, crepitus of the submandibular area is present. Tooth
severe airway obstruction include stridor, poor air movement, accessory pain or a history of recent tooth extraction is usual, but not invariable.
muscle use, abnormal mentation or agitation, tachycardia, hypertension, While not all patients with Ludwig angina need to undergo endotracheal
and pulsus paradoxus. All patients with newly diagnosed UAO of more intubation or tracheostomy, the decision to observe the airway rather
than trivial severity should be monitored in an ICU until treatment can than secure it should not be made lightly, and should be made after
be initiated or clinical stability can be determined. consultation with an otolaryngologist. If intubation is deemed necessary,
If UAO is suspected but there is no immediate risk of losing the air-
way, further evaluation may employ a range of techniques, depending on placement via a flexible fiberoptic approach may be useful in decreas-
ing the risk of laryngospasm during the procedure. Treatment consists
the suspected diagnosis. Spirometry is useful in the elective evaluation of antibiotic therapy, and in some patients, surgical decompression
of subacute to chronic UAO; however, because the airway must be nar- and drainage. Obviously, any infected teeth should be extracted. The
rowed to ≤8 mm in order to affect the flow volume loop, spirometry is mainstays of management of Ludwig angina—airway protection, broad-
relatively insensitive. Inspection of the flow volume loop for flattening of spectrum antibiotic use, and surgical decompression—have reduced the
the inspiratory or expiratory limb is the most reliable spirometric indi- mortality from this disease to below 10%.
cation of UAO, particularly when done by an experienced reader. Poor Lymphatic drainage from the oropharynx, teeth, maxillary sinuses,
effort may mimic UAO but is suggested by poor reproducibility of the and ears passes through the retropharyngeal space, predisposing it to
loops and by the technician’s subjective assessment of inadequate patient infections from the ear, nose, and throat. While the retropharyngeal
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effort. In such cases it is necessary to either repeat the tests or consider an space itself contains no vital structures, infection may extend from this
alternative diagnostic approach if the patient appears unable to provide space into the mediastinum or epidural space, or provoke atlantoaxial
high quality loops. Spirometry may fail to detect even significant degrees dislocation. Whereas this condition usually follows an upper respiratory
of UAO in patients with severe chronic obstructive pulmonary disease. tract infection, pharyngitis, or otitis media in children, in adults the
Plain chest radiographs may demonstrate tracheal deviation from
masses arising in the mediastinum or neck. Lateral neck films may more common antecedent problems are odontogenic infection or pro-
cedures, or oral trauma. Patients present with throat and neck pain, and
suggest the diagnosis of croup or epiglottitis. Computed tomography may have drooling or symptoms of upper airway obstruction. On occa-
(CT) is extremely useful in evaluating suspected tumors of the upper sion, infection may spread to the retropharyngeal space from the prever-
airway, and in characterizing the extent of upper airway soft tissue tebral space, such as with tuberculosis of the spine (Pott disease). The
infections. Three-dimensional reconstruction is useful in identifying diagnosis may be made through a lateral neck radiograph; however, CT
fixed anatomic abnormalities of the upper airway, such as tracheal ste- is advisable for helping define the boundaries of infection. Importantly,
nosis, and in following the response to therapy. However, dynamically physical examination may fail to reveal any posterior pharyngeal swell-
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determined disorders such as tracheomalacia generally require direct ing, highlighting the need for a high index of suspicion for this condition
visualization. and further investigation via endoscopy or imaging. Treatment consists
Endoscopic evaluation may be flexible or rigid. Rigid endoscopy is useful
in the management of suspected foreign body aspiration. Flexible endos- of antibiotics directed at oral flora (streptococci, staphylococci, anaer-
obes, and in some patients, gram-negative organisms), airway stabiliza-
copy may be performed via the oropharyngeal or nasopharyngeal route.
tion, and surgical exploration.
Because the lateral pharyngeal space is bounded by the retropha-
CAUSES OF UPPER AIRWAY OBSTRUCTION ryngeal and submandibular spaces, it serves as a means of transmit-
■ NASAL AND PHARYNGEAL CAUSES ting infections from diverse sources, as suggested previously. Potential
complications include involvement of the carotid sheath with potential
Benign and malignant masses of the nose and nasopharynx constitute carotid artery rupture, suppurative jugular thrombophlebitis, and the
important sources of morbidity, and occasionally, mortality. However, development of Horner syndrome or palsies of cranial nerves IX-XII.
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because ventilation can usually be maintained via the oropharyngeal Again, infections in this space are typically treated with a combination
route in these cases, they will not be discussed here. of antibiotics and surgical drainage.

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