Plasma Potassium Concentration on Admission Correlates with Neurologic Outcome in Traumatic Brain Injury Patients Treated with Targeted Temperature Management: A Post Hoc Analysis of a Multicenter Randomized Controlled Trial

Abstract

Recent studies have focused on the association between plasma electrolytes, particularly potassium level and neurologic outcomes in patients with traumatic brain injury (TBI). We hypothesized that potassium level on admission is an indicator for initiation of targeted temperature management in patients with severe TBI. We re-evaluated the Brain Hypothermia Study data based on the potassium levels on admission (i.e.,hypokalemia [<3.5 mEq/L] or normokalemia [3.5-5 mEq/L]) and compared these values and Glasgow Outcome Scale scores at 6 months by per protocol analysis. Consequently, 135 patients were enrolled. Finally, groups 50 and 23 patients with hypokalemia and 34 and 23 patients with normokalemia were allocated to mild therapeutic hypothermia (MTH) and fever control groups, respectively. Baseline characteristics, complication rates, and favorable neurologic outcome rates were compared between the two groups. In the normokalemia patients, fever control management was associated with a significant increase in favorable neurologic outcome compared with those in the MTH group (68.2% vs. 35.3%; P= 0.03). The complication rate was significantly higher in the MTH group than in the fever control group for patients with normokalemia (23.4% vs. 0%; P= 0.03). Conversely, hypokalemia patients in the MTH group revealed relatively better favorable neurologic outcomes compared with those in the fever control group (52.0% vs. 39.1%; P= 0.33). The initial potassium level may be an indicator in determining appropriate targeted temperature management for patients with TBI. Fever control may be considered instead of MTH for normokalemia patients with TBI on admission.