Clearance of aerosolized 99mTc-diethylenetriaminepentacetate before and after smoke inhalation

Current concepts in the pathophysiology and treatment of inhalation injury

The opinions or assertions contained herein are the private views of the author, and are not to be construed as official or as reflecting the official views of the Department of the Army or Department of Defense. Smoke inhalation injury occurs in about 10% of patients admitted to burn centres, and increases the mortality of burn patients by up to 20% over predictions based on age and burn size alone. The primary lesion in smoke inhalation injury is localized to the small airways, with alveolar injury and pulmonary oedema exercising a less prominent role during the initial phases. Injury incites a cascade of events that include ventilation-perfusion mismatch, secondary lung injury, systemic inflammation, impaired immune function, and pneumonia. The most important recent developments in the treatment of inhalation injury have included improved methods of pulmonary care targeted at the pathophysiology of the injury, such as high-frequency percussive ventilation and gentle mechanical ventilation.

Airway management and smoke inhalation injury in the burn patient

Smoke inhalation injury, a unique form of acute lung injury, greatly increases the occurrence of postburn morbidity and mortality. In addition to early intubation for upper-airway protection, subsequent critical care of patients who have this injury should be directed at maintaining distal airway patency. High-frequency ventilation, inhaled heparin, and aggressive pulmonary toilet are among the therapies available. Even so, immunosuppression, intubation, and airway damage predispose these patients to pneumonia and other complications.

Effect of particle emissions from biofuel combustion on surface activity of model and therapeutic pulmonary surfactants

This study was designed to determine the effects of particle emissions from biofuel combustion in household cooking devices, commonly used in rural India, on surface activity of model lung surfactants using Langmuir monolayers. The effect of wood and dried particles from combustion of cowdung on the surface activity of model lung surfactant dipalmitoylphosphatidylcholine (DPPC), DPPC:PG (phosphatidyl glycerol) 7:3 and the therapeutic surfactant, Exosurf, were evaluated. Dried particles from combustion of cowdung in 50wt.% mixture with DPPC elevated the γ(min) to 15.08±1.28mN/m and 50wt.% particles from combustion of wood increased minimum surface tension γ(min) to 13.46±1.70mN/m from a zero value for DPPC alone. A graded response of inhibitory potential for all three surfactants with increasing doses was found for each type of particles. An increase in the minimum surface tension achieved by surfactants in the presence of biofuel particles implies surfactant dysfunction, a greater tendency of alveolar collapse in vivo on exposure to biofuel emissions and can lead to respiratory distress.

Effects of wood and cotton smoke on the surface properties of pulmonary surfactant

The effects of wood and cotton smoke and several known smoke components on the dynamic surface activity of pulmonary surfactant were characterized with a modified Wilhelmy balance. Surfactant was harvested by saline lavage from dog lungs, placed in the balance and a control surface tension/area isotherm (y-A) and surface tension at minimum area (control y/min = 6.6 +/- 1.6 dynes/cm) measured. Hysteresis area (HA), recruitment index (RI), and stability index (SI) were calculated. Following control measurements, smoke (wood or cotton) was gently blown over the surfactant in the balance. Similarly, each of the individual smoke components or Liquid smoke (prepared by bubbling wood smoke through saline) were injected onto the balance. Wood smoke significantly (P < 0.05) altered all surface properties measured, increasing ymin (22.0 +/- 1.6 dynes/cm) and decreasing HA, RI, and SI as compared to control; cotton smoke exposure had almost no effect on surfactant function. A supplementary dose of surfactant was added to the balance, following wood smoke exposure, which decreased ymin (9.4 +/- 2.6 dynes/cm, P = NS vs control) but not the other parameters to control. Acrolein, formaldehyde, and HCl had little effect on any of the surface properties measured whereas isobutyraldehyde and liquid smoke altered the y-A curve but did not increase ymin. These data demonstrate that wood but not cotton smoke inhibit surfactant function, however, surfactant function can be restored, following deactivation by smoke, suggesting that surfactant replacement therapy for victims of severe smoke inhalation may be of benefit.

Exosurf treatment following wood smoke inhalation

Pulmonary surfactant deactivation is an important factor in the pathophysiology caused by wood smoke inhalation. Surfactant replacement is beneficial in treatment of surfactant-deficient neonates and possibly the adult respiratory distress syndrome (ARDS). In this study, the effect of exogenous Exosurf treatment for acute wood smoke injury was examined in four groups of rabbits. All groups were anaesthetized, placed on a ventilator, and surgically prepared for haemodynamic, peak airway pressure (P(aw)), and blood gas measurements. Rabbits were monitored for 2 h following smoke or sham smoke inhalation. At the conclusion of the experiment pulmonary oedema and surfactant function were measured. A Control group (n = 5) was followed without intervention. A Smoke group (n = 4) was ventilated with wood smoke for 3 min. A third group (Smoke+Exo, n = 4) was subjected to smoke followed by pulmonary instillation of Exosurf (5 ml/kg). Saline (5 ml/kg) was instilled into the lungs of the fourth group (n = 3) as a control for Exosurf instillation. Saline, Smoke and Smoke+Exo all significantly lowered PO2 and elevated P(aw) compared to baseline and the Control group. Exosurf treatment did not reduce the pulmonary oedema or restore surfactant function caused by smoke exposure. This study indicates that wood smoke inhalation acutely damages the lung and that administration of Exosurf by instillation is not an effective treatment.

Smoke inhalation

An attempt has been made to review the characteristics of fire and smoke and the epidemiology of smoke inhalation to identify some of the many variables which interact to control the severity of the injury. An experimental model appropriate to study the pulmonary injury of smoke victims who survive to enter the health care system is described. Experiments which define how smoke damages the lung are reviewed in an effort to explain why the smoke-damaged lung is vulnerable to additional stress and why those with an injured lung and a burn have such a high mortality rate.