Most discussions of strategies for ventilation in ARDS focus on the acute stage that lasts for roughly a week following the inciting event. Acute ARDS is characterized by progressive hypoxemia, decreased lung compliance, intrapulmonary shunting, and non-cardiogenic pulmonary edema in an appropriate clinical setting. This, however, is well beyond the scope of this discussion. Mortality rates for ARDS in children are at best uncertain. The best estimates are based on very few patients.
Resistance is normal or near normal as is anatomic dead space.
The defect is usually one of oxygenation rather than ventilation. The total compliance of the lung is reduced however, given the inhomogeneity of involvement the lung is best conceptualized as having a small volume of normally functioning lung. Those areas that remain are normally compliant and therefore are subject to overdistension when subjected to excessive inflating pressures. When discussing approaches to mechanical ventilation in any setting some basic assumptions must be accepted. The higher the pressures used the greater the injury.