Inhalation Injury as a Prognostic Factor for Mortality in Burn Patients

Inhalation injury is an acute respiratory tract insult caused by steam or toxic inhalants such as fumes, gases, and mists. Inhalation injury may occur without cutaneous burn injury, though the two injuries usually occur together. Despite increasing clinical interest in the problem of inhalation injury over the last few decades, the pathophysiology of inhalation injury remains poorly understood and there have been few improvements in treatment. Inhalation injury continues to be one of the most serious associated injuries complicating the care of thermally injured patients. Prevention or early diagnosis and treatment of associated life-threatening complications are necessary to decrease its associated morbidity and mortality: airway injury is present in up to one-third of patients with major burns, and the risk of concurrent pulmonary damage is directly related to the extent of the body surface area burned. Inhalation injury greatly increases the incidence of respiratory failure and acute respiratory distress syndrome. It is also the cause of most early deaths in burn victims. The mortality rate following smoke inhalation ranges from 45 to 78%. Shirani et al. estimated that the burn-related death rate is 20% higher in patients with combined inhalation injury and cutaneous burns than in those with cutaneous burns alone. Smoke inhalation remains a serious and life-threatening problem. The heat generated during combustion can cause significant thermal injury to the upper airways. Particulate matter produced during combustion (soot) can mechanically clog and irritate the airways, causing reflex bronchoconstriction. The noxious asphyxiant gases released during thermal decomposition include carbon monoxide and hydrogen cyanide. Other by-products produced by the combustion of furniture and cotton (aldehydes) or rubber and plastics (chlorine gas, ammonia, hydrocarbons, various acids, ketones) also cause injury.