OBJECTIVETo evaluate plasma arginine vasopressin (AVP) level in patients with traumatic brain injury and investigate the role of AVP in the process of brain edema.

METHODSA total of 30 patients with traumatic brain injury were involved in our study. They were divided into two groups by Glasgow Coma Scale: severe traumatic brain injury group (STBI, GCS less than or equal to 8) and moderate traumatic brain injury group (MTBI, GCS larger than 8). Samples of venous blood were collected in the morning at rest from 15 healthy volunteers (control group)and within 24 h after traumatic brain injury from these patients for AVP determinations by radioimmunoassay. The severity and duration of the brain edema were estimated by head CT scan.

RESULTSPlasma AVP levels (ng/L) were (mean+/-SD): control, 3.06+/-1.49; MTBI, 38.12+/-7.25; and STBI, 66.61+/-17.10. The plasma level of AVP was significantly increased within 24 h after traumatic brain injury and followed by the reduction of GCS, suggesting the deterioration of cerebral injury (P less than 0.01). And the AVP level was correlated with the severity (STBI r equal to 0.919, P less than 0.01; MTBI r equal to 0.724, P less than 0.01) and the duration of brain edema (STBI r equal to 0.790, P less than 0.01; MTBI r equal to 0.712, P less than 0.01).

CONCLUSIONSThe plasma AVP level is closely associated with the severity of traumatic brain injury. AVP may play an important role in pathogenesis of brain edema after traumatic brain injury.