Clinical practice and effect of carbon dioxide on outcomes in mechanically ventilated acute brain-injured patients: a secondary analysis of the ENIO study

Purpose The use of arterial partial pressure of carbon dioxide (PaCO 2 ) as a target intervention to manage elevated intracranial pressure (ICP) and its effect on clinical outcomes remain unclear. We aimed to describe targets for PaCO 2 in acute brain injured (ABI) patients and assess the occurrence of abnormal PaCO 2 values during the first week in the intensive care unit (ICU). The secondary aim was to assess the association of PaCO 2 with in-hospital mortality. Methods We carried out a secondary analysis of a multicenter prospective observational study involving adult invasively ventilated patients with traumatic brain injury (TBI), subarachnoid hemorrhage (SAH), intracranial hemorrhage (ICH), or ischemic stroke (IS). PaCO 2 was collected on day 1, 3, and 7 from ICU admission. Normocapnia was defined as PaCO 2 > 35 and to 45 mmHg; mild hypocapnia as 32–35 mmHg; severe hypocapnia as 26–31 mmHg, forced hypocapnia as < 26 mmHg, and hypercapnia as > 45 mmHg. Results 1476 patients (65.9