Laryngology Seminar
Inhalation Injury
R3 許惇彥 2003/12/24
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Demography
(1) 2%~3% thermal injury have inhalation injury, and about half
of these have burns > 50% total body surface area
(2) Given severity of skin burns, inhalation injury doubles the
mortality
(3) Around 50% mortality rate
Clinical Presentation
(1) Sensation of choking, a metallic taste in the mouth, dizziness,
wheezing, hoarseness, odynophagia, dysphagia, coughing,
increasing respiratory difficulty
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(2) Onset usually delayed after exposure
Cause of inhalation injury
(1) Hot, dry gas
 Nasal cavity, nasopharynx, oropharynx, and supraglottis
absorb most of the heat
 Little damage to glottis, subglottis, trachea, or lung
parenchyma
 Further protected by reflex closure of the cords to heat
stimulus
(2) Steam (superheated water vapor)
 4000 times the heat-bearing capacity of air
 Thermal down to the level of subglottis, trachea, and even
bronchioles
(3) Smoke (< 0.5 μm) inhalation
 Affect entire airway and pulmonary tissue
 Chemical toxicity
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 Mucosa sloughing, cartilage denuding, cilia paralyzing, loss
of surfactant, increased capillary permeability,
accumulation of debris blocking smaller bronchi
 Susceptible to infection
 Progress to adult respiratory distress syndrome
Diagnosis
(1) Clinical hint
 Facial burns from flame injury involving mouth and nose
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 Singed nasal vibrissae
 Burns in a closed environment
 Carbonaceous sputum (pathognomonic!!)
(2) Bronchoscope (sensitivity 86%)
 Erythema, ulceration, hemorrhage, edema, necrosis of
mucosa, soot-stained sputum, mucus plugs
 Absence of cough reflex is a diagnostic sign
(3) CXR
Initial CXR usually unremarkable until 2+ days after burn
(up to 92% negative radiograph taken early!!)
(4) 133Xenon scintiphotography (sensitivity 87%)
 Radioisotope trapping > 90 seconds
 False positive: COPD, pulmonary blebs, asthma
(5) Pulmonary function test (sensitivity 91%)
 FEV1↓,peak flow↓,maximum mid-expiratory flow rates↓
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 Precedes radiological abnormality
(3)+ (4): sensitivity 93%
(3)+(4)+(5): sensitivity 96%
Staging (Stone and Martin, 1969)
TABLE 1
Stage
I Ventilation
insufficiency
II Pulmonary
Clinical stages of inhalation injury according to Stone
Onset
0-24 hours
Etiology
Mortality (%)
Bronchospasm
64.5
Pulmonary burn,
40.5
(alveolar damage)
8-36 hours
Edema
underlying heart
disease, over
hydration
III Bacterial
pneumonias
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3-11 days
Airbone bacteria,
20
compromised lung
Management
(1) Oxygen & secure airway
(2) Steroid: effective in bronchospasm. Prophylactic usage is not
recommended.
(3) Antibiotics
(4) Bronchodialtor
Tracheostomy
Indicated while:
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(1) Upper airway obstruction
(2) Difficulty handling secretion
(3) Prolonged intubation (7 to 21 days)
(4) Children (– endotracheal tube is easily dislodged)
(5) Laryngeal burn (– as laryngeal trauma)
(6) Facial burn (– hard to fixed endotracheal tubes)
(7) Need safety airway access for multiple reconstruction surgery
Avoided while:
(1) Significant coincident neck burn wound
However, is tracheostomy associated with further pulmonary
sepsis or further tracheal sequelae ?
(1) Eckhauser, 1974: increased mortality from sepsis in those
who under tracheostomy, possibly due to seeding of the
trachea with bacteria
(2) Lund, 1985: Tracheal stenosis and granulation were generally
more frequent and more severe after tracheostomy
(3) Barret, 2000: No higher incidence of pneumonia in those
receiving tracheosotmy
(4) Saffle, 2002: early tracheosomy does not improve outcome in
burn patients
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Treatment of laryngotraheal stenosis
(1) Laser therapy of granulation tissue
(2) T tube or T-Y tube placement
(3) Laryngotracheal reconstruction
TABLE 2
TOXIC COMPOUNDS PRESENT IN SMOKE
Gas
Carbon monoxide
Source
Organic material
Comments
Inhibits oxygen delivery and
utilization
Carbon dioxide
Organic material
Decreased mental status
Nitrogen oxide
Paper, wood
Respiratory irritation
bronchospasm, pulmonary
edema
Hydrogen chloride
Plastics
Severe respiratory irritation,
bronchospasm, bronchorrhea
Hydrogen cyanide
Wool, plastics
Respiratory failure, inhibits
oxygen utilization
Benzene
Plastics
Respiratory irritation,
bronchospasm, bronchorrhea,
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coma
Aldehydes
Wood, cotton, paper
Severe respiratory mucosal
damage
Ammonia
Nylon
Respiratory irritation,
bronchospasm, bronchorrhea
Acrolein
Textiles, carpeting
Respiratory irritation,
bronchospasm, bronchorrhea
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Reference
1. Otolaryngology Head & Neck Surgery Third Edition Cummings
pp1404-pp1405
2. Tracheostomy and Inhalation Injury Head Neck Surg 1984; 6:1024-1031
3. Effects of Tracheostomies on Infection and Airway Complications in Pediatric
Burn Patients Burns 2000; 26: 190-193
4. Early Tracheostomy Does Not Improve Outcome in Burn Patients J Burn Care
Rehabil 2002; 23: 431-438
5. Using Bronchoscopy and Biopsy to Diagnose Early Inhalation Injury
Macroscopic and Histologic Findings Chest 1995; 107:1365-1369
6. Fiberoptic Bronchoscopy for the Early Diagnosis of Subglottal Inhalation
Injury: Comparative Value in the Assessment of Prognosis J Trauma 1994;
36: 59-67
7. Symptomatic Tracheal Stenosis in Burns Burns 1999; 25: 72-80
8. Tracheostomy Complicating Massive Burn Injury Am J Surg 1974; 127:
418-423
9. Bronchoscopy and Laryngoscopy Findings as Indications for Tracheostomy in
the Burned Child Arch Otolaryngol Head Neck Surg 1998; 124 : 1115-1117
10. Upper Airway Compromise After Inhalation Injury Complex Strictures of the
Larynx and Trachea and Their Management Ann Surg 1993; 218: 672-678
11. Current Status of Burn Resuscitation Clinics in Plastic Surgery 2000; 27:
1-10
12. Smoke Inhalation Injury Pediatrics Clinics of North America 1994; 41:
317-336
13. Fiberoptic Bronchoscopic in Acute Inhalation Injury J Trauma 1975; 15:
641-649
14. Upper Airway Sequelae in Burn Patients Requiring Endotracheal intubation
or Tracheostomy Ann Surg 1985; 201: 374-382
15. Airway Reconstruction Following Laryngotracheal Thermal Trauma
Laryngoscope 1998; 98: 826-829
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