Smoke Inhalation Injury

• It is one of the major factors contributing to death in burn injury patients. 

• Smoke damage adds another inflammatory focus to the burn and impedes the normal gas exchange vital for critically-injured patients. 

• The response to smoke inhalation is an immediate dramatic increase in blood flow in the bronchial arteries to the bronchi along with edema formation and increases in lung lymph flow. 

Hallmark features of inhalation injury are:

• Separation of ciliated epithelial cells from the basement membrane, followed by the formation of exudates within the airways. 

• Exudates coalesces (merge) to form fibrin plugs. 

• Fibrin plugs are hard and sticky and can be difficult to clear with standard airway suction techniques. 

• Bronchoscope removal could be required. 

• Fibrin plugs add to air pressure injury to localized areas of the lung by producing a ball-valve effect that prevents the inhaled air from escaping. 

• Increasing residual volume leads to localized increases in intra-pulmonary pressure causing complications such as pneumothorax and decreased lung compliance. 

The clinical course of patients with inhalation injury is divided into three stages:

1. The first is acute pulmonary insufficiency. Patients with severe lung injury may begin to show signs of pulmonary failure from the time of injuries, such as asphyxia, carbon monoxide poisoning, bronchospasm, and upper airway obstruction. Clinical signs of parenchymal damage with hypoxia are not common during this phase. 

2. The second stage occurs 72 to 96 hours after injury associated with hypoxia and the development of diffuse lobar infiltrates. Clinically similar to the adult respiratory distress syndrome (ARDS) that occurs in non-burned injured and critically-ill patients. 

3. In the third stage, clinical bronchopneumonia dominates. These infections generally occur 3 to 10 days after inhalation injury and are associated with the expectoration of large mucous casts formed in the tracheobronchial tree. 

Ball-valve effects and ventilator-associated barotrauma are also hallmarks of this period.

Management of Inhalation Injury:

• Management of inhalation injury is directed at maintaining open airways and maximizing gas exchange while the lung heals. 

• A coughing patient with a patent airway can clear secretions effectively, and effort is made to manage patients without mechanical ventilation.

• If respiratory failure is imminent, endotracheal intubation is done, followed by frequent vibration, percussion, and suctioning to remove secretions. 

• Frequent bronchoscopy may be needed to clear mucus-fibrin plugs.