Smoke inhalation: initial physical examination and preliminary investigations are insensitive for diagnosing inhalation injury.

Clinical bottom line (level 4)

  1. Inhalation injury occurs in half of patients exposed to smoke.
  2. The commonest clinical features are facial burns, carbonaceous sputum, nasal or oral soot or wheeze.
  3. clinical features and investigations may be initially normal.
Clark et al: Journal of Burn Care Rehabilitation 1989; 10: 52-62
Expires July 2003

The study

Setting: regional burns unit, USA

805 patients (aged ?, 67% male) diagnosis of burn, smoke exposure or smoke inhalation

Non-independent unblinded reference standard, applied in some patients from a consecutive appropriate spectrum.
Reference standard:
  • combination of history, laboratory findings, pulmonary imaging and laryngoscopy or bronchoscopy
Diagnostic test:
  • physical examination at presentation
  • non-invasive preliminary investigations at presentation

The evidence

pre-test probability of inhalation injury: 55%, (95% CI: 48% to 62%)

differential diagnosis number of patients prevalence
(95% CI)
unconscious 31 29%
(20% to 37%)
exposure >10 minutes 21 19%
(12% to 27%)
facial burn 70 65%
(56% to 74%)
carbonaceous sputum 52 48%
(39% to 58%)
nasal or oral soot 47 44%
(34% to 53%)
wheeze 34 32%
(23% to 40%)
voice change 21 19%
(12% to 27%)
corneal burn 20 19%
(11% to 26%)
singed nasal hair 12 11%
(5.2% to 17%)
cough 10 9.3%
(3.8% to 15%)
stridor 5 4.6%
(0.7% to 8.6%)
dyspnoea 3 2.8%
(0.0% to 5.9%)
abnormal chest x-ray 8 7.5%
(2.5% to 13%)
HbCO level >20% 33 31%
(22% to 39%)
A-a gradient >100 mmHg 42 39%
(30% to 48%)

Citation

  1. Clark WR, Bonaventura M, Myers W, et al: Smoke inhalation and airway management at a regional burn unit: 1974-1983. Part I: diagnosis and consequences of smoke inhalation. Journal of Burn Care Rehabilitation 1989; 10: 52-62
Contributor: Joel Ray and Chris Ball, July 2000
Reviewer:

Clinical Question.
Patient exposed to smoke
Intervention or Exposure prevalence
Outcome inhalation injury and clinical causes