<unk>  is<unk> , (i.e. high concentration of carbon dioxide in blood), in respiratory insufficient patients in which oxygenation has become so difficult that the optimal mode of mechanical ventilation (with oxygenation in mind) is not capable of exchanging enough carbon dioxide. Carbon dioxide is a gaseous product of the body's metabolism and is normally expelled through the lungs.
In acute respiratory distress syndrome (ARDS),<unk>  (allowing increased CO2 retention) by decreasing the tidal volume on the ventilator (usually 10-15 mL/kg/min) to 8 mL/kg/min may decrease barotrauma by decreasing ventilatory peak airway pressures and leads to improved respiratory recovery.  The<unk>  leads to respiratory acidosis which has negative side effects, but given that the patient is in ARDS, improving ventilatory function is more important.
Since hypoxemia is a major life threatening condition and<unk>  is not, one might choose to accept the latter. Hence the term,<unk> ."
Permissive hypercapnia
Hyperventilation
Hypoventilation
High frequency ventilation
Positive end-expiratory pressure
Positive airway pressure
Bag-Valve-Mask Ventilation
Ischemic preconditioning