OBJECTIVETo study the factors affecting extracellular glycerol (Gly) in patients with severe traumatic brain injury (STBI).

METHODSPerilesional extracellular Gly and cerebral blood flow (CBF) in 53 patients with STBI were consecutively monitored. Simultaneously, the intracranial pressure (ICP) and cerebral perfusion pressure (CCP) were monitored. The hourly minimum of CCP and CBF and the hourly maximum of ICP levels were matched with the hourly Gly. Gly values were divided into several groups according to regional ICP (less than 15 mm Hg or larger than 15 mm Hg), CCP (less than 70 mm Hg or larger than 70 mm Hg), CBF (less than 50 AU or 50-150 AU) and the outcomes (death or persistent vegetative state group, severe or moderate disability group, and good recovery group).

RESULTSIn comparison with the severe or moderate disability group, the Gly concentration of the death or persistent vegetative state group increased significantly, but CBF and CCP decreased significantly. In comparison with the good recovery group, the Gly concentration of the severe or moderate disability group increased significantly, but CBF and CCP decreased significantly. The Gly concentrations in patients with ICP larger than 15 mm Hg, CCP less than 70 mm Hg and CBF less than 50 AU were respectively higher than those of patients with ICP less than 15 mm Hg, CCP larger than 70 mm Hg and 50 AU less than CBF less than 150 AU. In patients with diffuse axial injury, the mean Gly concentration was (201.17+/-55.00) micromol/L, which was significantly higher than that of the patients with epidural hematoma (n equal to 7, 73.26+/-8.37, P less than 0.05) or subdural hematoma (n equal to 9, 114.67+/-62.88, P less than 0.05), but it did not increase significantly when compared with those in patients with contusion(n equal to 24, 167.48+/-52.63).

CONCLUSIONGly can be taken as a marker for degradation of membrane phospholipids and ischemia, which reflects the severity of primary or secondary insult.