Matt Harmon

156 Chapter eight Abstract Background Dyscarbia is common in out-of-hospital cardiac arrest (OHCA) patients and its association to neurological outcome is undetermined. Methods Exploratory post-hoc sub-study of the Target Temperature Management (TTM) trial, including resuscitated OHCA patients, investigating the association between serial measurements of arterial partial carbon dioxide pressure (PaCO 2 ) and neurological outcome at 6 months, defined by the cerebral performance category (CPC) scale, dichotomized to good outcome (CPC 1,2) and poor outcome (CPC 3 - 5). The effects of hypercapnia and hypocapnia, time weighted mean PaCO 2 and absolute PaCO 2 difference were analyzed. Additionally, the association between mild hypercapnia (6.0 - 7.30 kPa) and neurological outcome, its interaction with target temperature (33°C and 36°C), and the association between PaCO 2 and peak serum-Tau were evaluated. Results Of the 939 patients in the TTM-trial 869 were eligible for analysis. 96% of patients were exposed to hypo- or hypercapnia. None of the analyses indicated a statistically significant association between PaCO 2 and neurological outcome (P = 0.13-0.96). Mild hypercapnia was not associated with neurological outcome (P = 0.78) and there was no statistically significant interaction with target temperature (Pinteraction = 0.95). There was no association between PaCO 2 and peak serum-Tau levels 48 or 72 hours after ROSC. Conclusions Dyscarbia is common after ROSC. No statistically significant association between PaCO 2 in the post cardiac arrest phase and neurological outcome at six months after cardiac arrest was detected. There was no significant interaction between mild hypercapnia and temperature in relation to neurological outcome.