Which of the following statement(s) is/are true concerning inhalation injury?

a. The physiology of these injuries include upper airway obstruction secondary to progressive edema, reactive bronchospasm from aerosolized irritants, and microatelectasis from loss of surfactant and alveolar edema

The pathophysiology of inhalation injury is complex and varies with the aerosolized toxins particular to the circumstances of individual injuries. However, these injuries routinely demonstrate the following: 1) upper airway obstruction secondary to progressive edema; 2) reactive bronchospasm from aerosolized irritants; 3) small airway occlusion initially from edema and subsequently from sloughed endotracheal debris and loss of ciliary clearance mechanisms; 4) microatelectasis from the loss of surfactant and alveolar edema; and 5) interstitial and alveolar edema secondary to loss of capillary integrity. The physiologic consequences of these aberrations are upper and lower airway obstruction, increased airway resistance, decreased compliance, and an increase in the dead space to tidal volume ratio and intrapulmonary shunting.

Upper airway obstruction is best managed with prompt endotracheal intubation which is maintained for 48 to 72 hours and elevation the head. In equivocal cases, bronchoscopy is performed and patients with significant airway edema are intubated using the bronchoscope as a stylet. Although severe steam inhalation can result in direct heat injury to the distal tracheobronchial tree, more distal airway injuries are usually caused by aerosolized toxins rather than thermal injury, as the upper airway is a highly effective heat sink. Although moderate inflating pressures will help expand recruitable segments, peak inspiratory pressures in excess of 40 cm H2O should be avoided because they are associated with both overt barotrauma as well as more subtle overpressure injuries to the pulmonary microvasculature and alveoli which themselves exacerbate respiratory failure. High inflating pressures are also ineffective in recruiting additional lung, because the compliance decrements are not homogeneous and high pressures simply over distended more compliant segments.