Overview
Definition:
Inhalational injury refers to damage to the respiratory tract caused by the inhalation of heat, smoke, or toxic chemicals during fires or explosions
It is a significant cause of morbidity and mortality in burn patients, often complicating their management and prognosis.
Epidemiology:
Occurs in approximately 10-20% of burn patients
It is more common in those with burns involving the face, neck, or chest, or those found unconscious in a fire environment
Associated with higher mortality rates and longer hospital stays compared to isolated cutaneous burns.
Clinical Significance:
Inhalational injury can lead to airway obstruction, respiratory failure, and acute respiratory distress syndrome (ARDS)
Early recognition and prompt management are crucial for preventing life-threatening complications and improving patient outcomes
Surgical intervention is often required for definitive airway control.
Clinical Presentation
Symptoms:
Facial burns
Singed nasal or facial hair
Oral or nasal soot
Hoarseness or stridor
Dyspnea or tachypnea
Cough
Chest pain
Carbonaceous sputum
Altered mental status.
Signs:
Edematous airway
Pharyngeal or laryngeal erythema and ulceration
Wheezing or crackles on auscultation
Paradoxical chest wall movement
Hypoxemia or hypercarbia
Evidence of facial burns with circumferential involvement.
Diagnostic Criteria:
No single definitive diagnostic criterion
Diagnosis is primarily clinical, based on a high index of suspicion derived from the circumstances of the injury and characteristic clinical findings
The Abbreviated Burn Severity Index (ABSI) and the presence of specific risk factors are used to stratify risk.
Diagnostic Approach
History Taking:
Mechanism of injury: enclosed space, duration of exposure, type of material burned, loss of consciousness
Associated injuries: blunt or penetrating trauma
Pre-existing respiratory conditions.
Physical Examination:
Thorough head and neck examination: facial burns, soot in airways, vocal cord integrity
Chest examination: auscultation for adventitious sounds, paradoxical movements
Neurological assessment
Full burn survey.
Investigations:
Arterial blood gases (ABGs) to assess oxygenation and ventilation
Carboxyhemoglobin levels, especially in suspected carbon monoxide poisoning
Chest X-ray to rule out pneumonia or atelectasis, though initial X-rays may be normal
Bronchoscopy for direct visualization of airway damage
this is the gold standard
Ventilation-perfusion (V/Q) scan or CT pulmonary angiography if pulmonary embolism is suspected.
Differential Diagnosis:
Asthma exacerbation
Pneumonia
Pulmonary embolism
Pneumothorax
Upper airway obstruction from other causes (e.g., angioedema, foreign body aspiration).
Management
Initial Management:
Secure the airway: immediate endotracheal intubation if signs of airway compromise are present or highly suspected (e.g., stridor, facial burns, soot)
100% oxygen administration
Fluid resuscitation based on burn size and depth
Intravenous analgesia.
Medical Management:
Mechanical ventilation with appropriate settings for lung protection
Bronchodilators and mucolytics to manage bronchospasm and secretions
Steroids are controversial and not routinely recommended
Antibiotics for suspected or confirmed infection
Sedation and analgesia
Chest physiotherapy.
Surgical Management:
Endotracheal intubation for definitive airway control
Tracheostomy may be considered for prolonged ventilation requirement or to facilitate tracheobronchial toilet
Escharotomy if circumferential chest wall burns impair ventilation
Surgical débridement of necrotic tissue if indicated.
Supportive Care:
Continuous monitoring of vital signs, oxygen saturation, and ventilation parameters
Nutritional support via enteral or parenteral routes
Psychological support
Early mobilization as tolerated
Strict infection control.
Complications
Early Complications:
Acute airway obstruction due to edema
Pneumonia
Acute respiratory distress syndrome (ARDS)
Barotrauma
Ventilator-associated pneumonia (VAP)
Atelectasis
Hypoxemia and hypercarbia.
Late Complications:
Bronchiolitis obliterans
Tracheal stenosis
Chronic cough and dyspnea
Pulmonary fibrosis
Vocal cord damage and dysphonia
Post-intubation tracheal stenosis
Bronchiectasis.
Prevention Strategies:
Early and proactive airway management
Judicious fluid resuscitation
Aggressive pulmonary toilet
Early mobilization
Prompt treatment of infections
Close monitoring for signs of airway compromise or respiratory failure.
Prognosis
Factors Affecting Prognosis:
Severity of inhalational injury (extent of airway damage)
Presence and severity of associated cutaneous burns
Age and comorbidities of the patient
Development of complications such as ARDS or sepsis
Timeliness and effectiveness of airway management and supportive care.
Outcomes:
Patients with mild inhalational injury may recover fully with appropriate supportive care
Severe inhalational injury carries a high mortality rate and can lead to long-term respiratory disability
Survival is significantly impacted by the synergistic effect of burn injury and inhalational damage.
Follow Up:
Regular pulmonary function tests
Chest physiotherapy
Speech therapy if vocal cord damage occurs
Long-term follow-up with a pulmonologist to monitor for chronic respiratory sequelae
Surveillance for airway stenosis.
Key Points
Exam Focus:
Always maintain a high index of suspicion for inhalational injury in burn patients, especially with facial burns, soot in airways, or altered mental status
Immediate airway assessment and securement are paramount
Bronchoscopy is the definitive diagnostic tool for airway injury.
Clinical Pearls:
Stridor is a late sign of upper airway obstruction
intubate before stridor develops
Circumferential chest burns can restrict ventilation
escharotomy may be necessary
Early aggressive pulmonary toilet is vital to prevent pneumonia and atelectasis
Monitor carboxyhemoglobin levels in all patients exposed to smoke.
Common Mistakes:
Delaying intubation until airway obstruction is severe
Underestimating the severity of airway edema
Inadequate fluid resuscitation leading to hypoperfusion of respiratory tissues
Failing to consider inhalational injury in the absence of significant cutaneous burns
Reliance solely on chest X-ray for diagnosis.