Smoke inhalation injuries

Laryngeal Trauma Following an Inhalation Injury: A Review and Case Report

The primary concern when managing a patient with inhalation injury is security of the airway. Airflow may be impeded by both edema of the upper airway and reduction of oxygen delivery to the lower respiratory tract. Although there has been much discussion regarding management of the latter, the focus of this article is the management of the former. This review aimed to determine the optimum management in burn victims with upper airway inhalation injury as an attempt to prevent laryngeal trauma leading to long-term voice disorders and upper airway dyspnea. We describe the case of a 57-year-old woman with significant inhalation injury and discuss the natural progression of her injuries and the laryngeal controversies surrounding her care. We conclude with advice on the optimal management of this condition based on our experience, combined with current best evidence.

Toxic inhalational exposures

Respirable toxicants are a spectrum of irritant and nonirritant gases, vapors, fumes, and airborne particles that can be entrained into the body through the respiratory tract, resulting in exposures that cause pulmonary injury and/or systemic disease. Sources of respirable toxicants include structural fires, industrial accidents, domestic mishaps, and intentional releases of injurious agents on the battleground (warfare) or in civilian settings (acts of terrorism). Acute toxic inhalational exposures may result in respiratory failure, multisystem organ dysfunction, and death. Management of victims includes assessment and protection of the airway, monitoring and treatment of systemic toxicity, and delivery of exposure-specific and nonspecific therapies that improve outcomes. Treatments may include antidotes, hyperbaric oxygen, and other nonspecific life-supporting interventions.

Effect of ablated airway blood flow on systemic and pulmonary microvascular permeability after smoke inhalation in sheep

The bronchial circulation plays a significant role in the pathogenesis of smoke inhalation. We investigated the physiological manifestations in both the systemic and the pulmonary circulation after smoke inhalation injury, and determined whether ablation of the bronchial circulation had any effect on these changes. We used a chronically instrumented ovine model with lung and prefemoral lymph fistulae to determine the changes in pulmonary and systemic microvascular permeability. Fourteen animals were divided into two groups. The injection group had bronchial circulation ablation with an ethanol injection into the bronchial artery, whereas it was left intact in the sham group. The sham group showed a four-fold increase in lung lymph flow (l-Q(L)) and a two-fold increase in prefemoral lymph flow (s-Q(L)) 24 h after injury. The increase in s-Q(L) was associated with a decrease in lymph oncotic pressure. Therefore, systemic colloid clearance (s-CC), an indicator of systemic microvascular permeability to protein, was unchanged. The ablated bronchial circulation reversed the pulmonary but not the systemic manifestations after smoke inhalation. In conclusion, the pathophysiological events occurring after smoke inhalation were confined to the lung with increased bronchial blood flow delivering inflammatory mediators directly to the lung parenchyma.

[Acute respiratory insufficiency in burn patients from smoke inhalation]

Respiratory injuries by smoke inhalation are one of the most frequent reasons for acute respiratory failure in burn victims. They are most often of chemical origin and are responsible of a 20 to 70% increase of the mortality compared to the mortality of patients with similar burn injuries, but without inhalation lesions. They are often associated to a certain degree to other factors of acute respiratory failure: superior air way obstruction by oedema in face and neck burns, thoracic expansion hindrance due to thoracic burns, lung trauma lesions by blast injury. The generalized inflammatory reaction due to the extent of burns and an initial inadequate resuscitation are worsening factors. The inflammatory process may be responsible of lung injuries similar to those induced by smoke inhalation, even when there is no inhalation. The treatment remains symptomatic and based on the oxygen therapy, mechanical ventilation, prevention of infections and maintain of homeostasis by hydroelectrolytic adequate resuscitation. The nitric oxyde associated to the almitrin allows in a certain number of cases to minimize intra pulmonary shunting and to normalize the VA/O ratio. The development of treatments allowing to modulate inflammatory mediators may lead to news therapies in the future.

Hospital treatment of victims exposed to combustion products

Combustion toxicology is complex so, although victims exposed to combustion products are mainly treated symptomatically, it is important to identify those situations when specific therapeutic measures might be of importance. Victims presenting respiratory symptoms including severe cough, bronchoconstriction, hypoxia and respiratory distress should be given oxygen and ventilatory assistance or support. Furthermore, bronchoconstriction should be treated with bronchodilators (beta-2-adrenoreceptor agonists, theophylline). Corticosteroids should be considered both for inhalation and systemically due to the risk of developing toxic pulmonary oedema that may appear after a symptom-free interval that might last up to 48-72 h. Victims with impaired consciousness should be regarded as being exposed to carbon monoxide and cyanides. Apart from oxygen and optimal symptomatic treatment hyperbaric oxygen therapy should be considered in carbon monoxide poisoning. Certain cyanide antidotes, namely those with low intrinsic toxicity (as sodium thiosulphate, hydroxocobalamin) should be given liberally in these situations. Other specific therapeutic measures that might be considered when appropriate are administration of organophosphate antidotes (atropine, oximes), heavy metal chelators (e.g. dimercaptopropane sulfonate, dimercaptosuccinic acid) and methemoglobinemia antidotes (methylthionine, toluidine blue). Inhalation of hot fumes may cause upper respiratory tract oedema (e.g. laryngeal oedema) necessitating orotracheal intubation and ventilatory support.