Prognostic significance of the difference between mixed and jugular venous oxygen saturation after severe traumatic brain injury: A post-hoc analysis of the Brain Hypothermia study

Background In patients postcardiac arrest, it has been reported that the small value of the difference between mixed venous oxygen saturation (Sv o 2) and jugular venous oxygen saturation (Sjv o 2) is associated with poor neurologic outcome. However, the importance of the difference between mixed venous oxygen saturation and jugular venous oxygen saturation (ΔS o 2 [v − jv]) remains unknown in severe traumatic brain injury (TBI). The aim of this study was to examine whether ΔS o 2 (v − jv) is associated with neurologic outcome and mortality in patients with severe TBI. Methods We conducted post hoc analyses of the Brain Hypothermia Study, a multicenter randomized controlled trial of mild therapeutic hypothermia for the treatment of severe TBI. The value of ΔS o 2(v − jv) on day 1 and day 3 was compared between survivors (n = 65) and nonsurvivors (n = 25) or between patients with favorable (n = 47) and unfavorable (n = 43) neurologic outcomes. Results The reduction in ΔS o 2 (v − jv) on day 3 was −2.0% (range, −6.9% to 6.5%) in the nonsurvivor group and 6.3% (range, −2.5% to 16.7%) in the survivor group. The difference was statistically significant (P = 0.03). The same tendencies were observed in the nonsurvivor group on day 1 and in the unfavorable neurologic outcome group on day 1 and day 3, but the difference was not significant. Conclusions The reduction in ΔS o 2(v − jv) on day 3 was associated with high mortality in patients with severe TBI.