However, despite advances in ventilator management, the mortality rate of acute lung injury and the acute respiratory distress syndrome remains very high (approximately 40 to 50 percent). In 2000, ARDS Network trial compared the effects of 6 versus 12 mL/kg of tidal volume per predicted body weight (PBW) among 861 patients and noted an overall 22% reduction in mortality rate, more ventilator-free days, and more organ-failure-free days in the low-tidal-volume group. Therefore, the current approach to mechanical ventilation of a patient with ARDS emphasizes the use of lower tidal volumes with lower pressures to avoid causing lung overdistension and ventilator associated lung injury.