1. A supportive therapy that does not treat the underlying disease. 2. Two important physiological goals: (1) Normalize blood gas and acid-base balance by providing adequate ventilation and oxygenation; (2) Reduce the patient’s respiratory effort. 3. Pathological states: (1) When heart failure or ARDS – improve oxygenation – increase FiO2, PEEP, mean airway pressure. (2) When the patient is in hypercapnic respiratory failure (COPD, drug overdose, neuromuscular disease), more attention must be paid to providing adequate ventilation. (3) As in epilepsy may require only airway protection or simple maintenance of normal respiratory function. (4) Four basic ventilation modes are commonly used: assist/control (A/C), volume-assisted control (VAC), pressure support (PSV), and synchronous gap command (SIMV).