Permissive_hypercapnia
Permissive hypercapnia
Hypercapnia in respiratory insufficiency
Permissive hypercapnia is hypercapnia (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.
This article includes a list of references, related reading, or external links, but its sources remain unclear because it lacks inline citations. (April 2019) |
In acute respiratory distress syndrome (ARDS), decreasing the tidal volume on the ventilator (usually 6-8 mL/kg) to 4-6 mL/kg may decrease barotrauma by decreasing ventilatory peak airway pressures and leads to improved respiratory recovery. Hypercapnia (increased pCO2) sometimes needs to be tolerated in order to achieve these lower tidal volumes. The permissive hypercapnia leads to respiratory acidosis which might have 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 hypercapnia is not, one might choose to accept the latter. Hence the term, "permissive hypercapnia."