This chapter discusses the management of mechanical ventilation. The different modes of ventilation are controlled mandatory ventilation (CMV), assist volume control, synchronized intermittent mandatory ventilation (SIMV), pressure control (PC), and pressure support (PS). The two ventilation strategies that can be used in critically ill patients in the emergency department are lung protective strategy and obstructive strategy. Both of these strategies utilize the assist control (AC) volume cycled mode of ventilation. The lung protective strategy is designed for patients with acute lung injury (ALI) or acute respiratory distress syndrome (ARDS), or who are at risk for lung injury. Obstructive strategy is designed for patients with obstructive lung disease (i.e., asthma or COPD) whose airways are constricted and therefore require a longer time to fully exhale. There are two basic pressures that should be monitored in mechanically ventilated patients: peak inspiratory pressure and plateau pressure.