In neonatal critical care medicine, the loss of functioning alveoli in acute lung injury or the acute respiratory distress syndrome. In both of these diseases large sections of the lungs lose their compliance, collapse, or fill with fluids, leaving only a remnant of the lung available for ventilation. Ventilatory strategies designed for fully operational, adult-sized lungs may provide too much air at too high a volume and pressure to the limited lung tissue that can be potentially recruited. This hypothesis suggests that overtaxing an infant-sized lung with adult ventilation can result in further injury to an already damaged lung.