Intrathecal and systemic concentration of NT-proBNP in patients with severe traumatic brain injury

Outcome of patients suffering from traumatic brain injury (TBI) depends on the development of secondary brain damage. In this context, recent studies underlined the role of the natriuretic peptides-atrial natriuretic peptide and brain natriuretic peptide (BNP)-in aneurysmatic subarachnoidal hemorrhage (SAH). Especially BNP correlates with intracranial pressure and clinical outcome after SAH. Since its role in TBI remains unclear, the intracranial and systemic concentrations of N-terminal (NT)-proBNP were analyzed in patients suffering from severe TBI. We measured NT-proBNP levels in cerebrospinal fluid (CSF) and serum of 14 patients suffering from severe TBI (GCS ≤8 points) and 10 healthy control patients, using proBNP® assay (Roche® Diagnostics). Samples were collected after placement of a ventricular catheter, and at 12, 24, 48, and 72 h after TBI. CSF/serum albumin ratio (Q < a) was daily calculated. At 90 days after TBI, outcome was evaluated using the Glasgow Outcome Scale (GOS). In patients exhibiting a mean ICP of >15 mm Hg (n = 6), the serum (800 ± 150 pg/mL) and CSF levels (55 ± 9 pg/mL) of NT-proBNP were significantly increased after 24 h, as compared to patients with ICP ≤15 mm of Hg (n = 8) as well as to control group. However, Q_a as well as GOS did not significantly differ among both groups. For the first time, we evaluated intrathecal and systemic NT-proBNP concentrations in patients suffering from severe TBI. Interestingly, NT-proBNP in CSF and serum was significantly elevated in patients exhibiting an ICP of >15 mm Hg. Further studies are currently performed to elucidate the physiologic role of NT-proBNP in TBI.