Endoscopic laser flowmetry: A valid method for detection and quantitative analysis of inhalation injury

Hyperemia of the tracheobronchial area is a major sign of inhalation injury. However, this is usually a qualitative symptom, without quantitative measurement. We have developed a technique to diagnose inhalation injury and to analyze damaged areas quantitatively with laser-doppler flowmetry. In chronically instrumented sheep (N = 10), the tissue blood flow in the wall of second generation bronchi was determined with an endoscopic flowmeter probe. After baseline data had been obtained, the right lung was exposed to smoke in seven animals. Three sham-smoked animals underwent the same procedure, but without actual smoke. The bronchial blood flow was measured again 30 minutes after insufflation in both groups. Inhalation injury caused a significant increase in flow, from 35.1 ± 2.6 to 51.7 ± 2.1 ml/min · 100 gm tissue in the airway of the smoked lungs but not in the control lungs. This increase correlated with an increase in the carboxyhemoglobin level (r = 0.87). The sham-smoked animals showed no change in bronchial blood flow. A valid technique for diagnosing inhalation injury in the early phase and a quantitative analysis of injured areas has been demonstrated.