Permissive hypercapnia in trauma patients

The use of a normal tidal volume in patients with progressive loss of alveolar airspace may increase inspiratory pressure and overdistend remaining functional alveoli. Permissive hypercapnia (PH) is a ventilator management technique that emphasizes control of alveolar pressure, rather than PCO₂. The purpose of this study was to determine if the use of PH is associated with an improved outcome from adult respiratory distress syndrome (ARDS). Over a 2-year period, 39 trauma patients were treated for ARDS. Permissive hypercapnia was used in 11, and the remaining patients were treated conventionally. Demographics and risk factors were well matched in PH patients and controls. The duration of mechanical ventilation was greater in PH patients [49.2 ± 15.2 vs. 20.8 ± 10 days (p < 0.01)]. Survival was also greater in the PH group [91% vs. 48% (p < 0.01)]. A reduction in intensity of mechanical ventilation is associated with a prolongation of ventilatory support and an improved outcome from ARDS.