Inhalation injury to the upper respiratory tract
An upper respiratory tract inhalation injury has specific physical signs and symptoms, such as burns to the face and difficulty breathing. Here you can find information on the etiology, signs and symptoms of an inhalation injury to the upper respiratory tract, as well as treatment approaches.
Etiology and pathophysiology
Inhalation injury to the upper respiratory tract is often caused by the inhalation of hot gases, causing a true thermal burn of the airway proximal to the larynx. This type of injury occurs mostly in an enclosed space, with heat exposure for a considerable time. Other, rare, causes are injury due to pressurized steam inhalation or inhalation from explosions with high concentrations of oxygen/flammable gases under pressure; these occur mostly in industry.
Burn injuries > 20% TBSA result in a significant systemic inflammatory response. This may lead to edema of the airway mucosa proximal to the larynx, resulting in obstruction of the airway.
The pathophysiological changes of these burns are the same as those resulting from thermal burns. The edema initially causes respiratory obstruction and later, loss of the protective function of the mucosa. Note that these effects may persist beyond the time of maximal wound edema (between 12 and 36 hours).
Assessment of inhalation injury
During the clinical assessment, an inhalation injury to the upper respiratory tract should be suspected if the findings are consistent with the following history, physical findings and further diagnostics.
The patient would have a history of exposure to flames, smoke, an explosion or chemicals. Ascertain the duration of exposure and find out if the exposure was in an enclosed space, as exposure in an enclosed space would indicate this type of injury. The patient may also have a history of a loss of consciousness.
Signs of this type of injury can include burns to the face (specifically the mouth, nose and pharynx); singed nasal hairs; soot in the oropharynx, nasal passages or proximal airways; carbonaceous sputum; and edema formation in the head and neck.
The patient may also have difficulty breathing, indicated by tachypnoea (>30 breaths per minute) or signs of increased respiratory effort, including flared nostrils, tracheal tug, chest indrawing and use of the accessory muscles of ventilation.
Nasal cavity. A nasal speculum and a light are necessary to inspect the nasal cavity and the turbinates sufficiently.
Oral cavity. Inspection of palates, tongue and pharynx.
Larynx. A headlight and laryngeal mirror are necessary to examine the epiglottis and vocal cords, a flexible scope is an acceptable method.
When examining the patient, listen for hoarseness, stridor, a productive cough and croup-like breathing.
In all patients with a suspected inhalation injury, measure their carboxyhemoglobin (COHb) levels. An initial chest X-ray is recommended. Other diagnostic tests may be requested if indicated.
Treatment of inhalation injury
To treat injuries when the airway is compromised, administer 100% oxygen at 15L/min through a non-rebreathing mask. Secure the airway via one of the following methods:
- Jaw-thrust maneuver or chin lift
- Oral airway device
- Endotracheal intubation
- Tracheostomy (surgical)
It is important to be prepared for emergency intubation at any time, therefore always have the appropriate equipment ready. If there is any concern about the security of a patient’s airway, the patient should be intubated and the airway should be secured by the clinician most experienced in this area. Any decision regarding intubation should be made in a timely manner.
Airway obstruction risk in children
Pay particular attention to children, as the small diameter of their airways means even minor edema can lead to airway obstruction.
The indications for intubation include:
- Respiratory distress
- A reduced level of consciousness (Glasgow Coma Scale < 8)
- Impending airway obstruction (indicating by increasing signs and symptoms of airway obstruction)
- A need to facilitate safe transport of a patient
Patients should be nursed in a semi-upright position with a moderate elevation of the head and trunk. The ability to provide optimal care for patients with inhalation injuries depends on the availability of intensive care facilities and clinical expertise.