Diagnosis

Clinical examination should occur concurrently with emergency management of the airway-obstructed patient, with resuscitation facilities immediately available. Evaluation includes the following.

1. Direct inspection of the oral cavity and oropharynx with clearance of any foreign material.

2. Auscultation over the larynx, trachea, and lung fields to exclude concurrent or alternate diagnoses (e.g. tension pneumothorax, lower airway obstruction). Inspiratory stridor suggests upper airway obstruction.

3. Palpation of the neck to identify possible tumor or hematoma.

4. Consideration of traumatized adjacent structures (e.g. major vessels, axial skeleton, facial bones).

Repeated clinical examinations are required to detect progressive or recurrent upper airway obstruction and its sequelae. Patients with partial obstruction requiring additional diagnostic tests must be escorted by personnel skilled and equipped for management of an acute decompensation.

A wide variety of indirect clinical signs may be detected during the initial examination or following relief of the upper airway obstruction ( Table 2).

Table 2 Indirect effects of upper airway obstruction

Special investigations

Special investigations are only possible when the obstruction is stable and non-life-threatening and will not delay or interfere with timely definitive management. Useful investigations defining the site and extent of obstruction include the following ( Cameron 19.9.0; i.§.n,U.,m..Of...1..9.91.; Eagle 1992).

1. Visualization of the airway directly (laryngoscopy or tracheobronchsocopy via a rigid endoscope under local or general anesthesia) or via a fiber-optic endoscope.

2. Radiological evaluation of the airway: lateral cervical radiography or tomography; CT; magnetic resonance imaging with axial, coronal, and sagittal views; fluoroscopy may determine the dynamic component of obstruction.

3. Flow-volume loops may differentiate extra- from intrathoracic obstructions and fixed from dynamic/variable obstructions.

4. Assessment of adequacy of gas exchange by arterial blood gas analysis and pulse oximetry.

5. Polysomnography for suspected obstructive sleep apnea.

6. Primary pathology investigations for the various types of cervical tumors, tumor markers, angiography, etc. Management

Management must include the following.

1. Vigilance and early recognition of the obstructed airway and its sequelae.

2. Supplemental oxygen.

3. Rapid clearance of the obstructed airway. Debris is removed manually, by suction, or by Magill forceps. Optimal positioning of the jaw, tongue, and neck is essential. The Heimlich maneuver (abdominal thrust) may prove lifesaving in the acute setting.

4. Establishment of intravenous access and a patent secure airway to permit adequate gas exchange and avoidance of aspiration of gastric and other debris.

5. Pursuit of an 'awake' technique (ienumof .1.994) with avoidance of injudicious use of sedation.

These principles are applied at a rate and sequence consistent with the acuteness and severity of the obstruction. The patient with severe facial bone fractures and depressed level of consciousness requires rapid recognition of airway compromise, suctioning under direct vision, and intubation with a cuffed endotracheal tube within seconds to minutes. Less acute laryngeal edema patients with stridor require frequent assessment to detect deterioration and temporizing measures include parenteral corticosteroids and nebulized epinephrine (adrenaline) (2 ml 1:1000 epinephrine in 2 ml normal saline).

Morbidity and mortality occur under the following conditions.

1. There is failure to recognize obstruction, mostly in the acute setting (e.g. upper airway debris in a trauma patient) or when obstruction is insidious (e.g. slowly deteriorating level of consciousness and loss of compensatory mechanisms) or progressive (e.g. chemically or thermally injured upper airway or epiglottitis). The need for frequent evaluation of the patency and security of the airway cannot be overemphasized.

2. Management is inappropriate; for example, a laryngeal mask airway may be suitable for a fasted patient, pending recovery from muscle relaxants and narcosis, but not for an obtunded patient with copious blood in the pharynx secondary to a fractured larynx.

3. The chosen course of management fails; for example, endotracheal intubation fails owing to anatomical or technical difficulties. Failed intubation protocol is discussed elsewhere (.Be.n.um.o.f...1991, i..e..n,u.,m..of 199.4).

Alternatives to endotracheal intubation include the following.

1. Oro- or nasopharyngeal airway placement and protective posturing against pharyngeal secretion pooling.

2. Face mask and self-inflating resuscitation bag (for assisted ventilation).

3. Fiber-optic-guided intubation of the trachea.

4. Intubation over a guidewire or stylet introduced retrograde into the oropharynx via a cricothyroid puncture.

5. A laryngeal mask can be used as a temporizing measure.

6. Surgical access to the upper airway. Examples include the following.

a. Cricothyrotomy (open or percutaneous), which permits rapid placement of a small-bore tube or cannula into the trachea via the cricothyroid membrane to allow oxygen insufflation or jet ventilation (expiration must be unobstructed). Skill in this technique may be readily acquired by non-surgeons.

b. Percutaneous tracheostomy, which is an elective technique useful in avoiding expected postextubation stridor after a prolonged course of oral endotracheal intubation (van H§e.rd§0...aLa/- 1996).

c. Surgical tracheostomy under local anesthesia when a difficult or impossible endotracheal intubation is predicted.

7. Extracorporeal membrane oxygenation may be planned when control of the upper airway is lost consequent upon a major elective surgical intervention.

Pharmacological adjunctive therapy includes the following.

1. Intravenous antihistamine, epinephrine, and corticosteroid therapy for anaphylactic or anaphylactoid swelling of upper airway mucosa.

2. Intravenous corticosteroids and nebulized epinephrine for postextubation laryngeal edema.

3. Antibiotics for epiglottitis or other local infections.

4. Fresh frozen plasma for swelling due to angio-edema or hematoma following coagulopathy.

5. Parasympathomimetic agents to counter excessive secretions.

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