Studies in which brain metabolism has been monitored using microdialysis have indicated decreases in cerebral glucose concentration and increases in lactate concentration in patients with traumatic brain injury (TBI). However, few data are available on glucose and lactate concentrations in the cerebrospinal fluid (CSF) of TBI patients. This study investigates the relationship between CSF glucose and lactate concentrations and outcomes after TBI.
Consecutive adult (>18 y) TBI patients were admitted to our 35-bed medicosurgical between 2011 and 2014 and were included in the study if they met the following inclusion criteria: presence of an external ventricular drain (EVD) for intracranial pressure monitoring, daily analysis of CSF glucose and lactate concentrations for 4 consecutive days, and concomitant measurements of blood glucose/lactate concentrations. Neurological outcome was assessed at 3 months using the extended Glasgow Outcome Scale (GOS), and unfavorable outcome defined as a GOS 1 to 4.
Of 151 TBI patients who had an EVD, 56 met the inclusion criteria. Most EVDs were placed on the day of intensive care unit admission, and maintained for 10 (interquartile range: 6 to 14) days. On day 1, there was a weak but significant correlation between blood and CSF glucose concentrations (R=0.07, P=0.04), and a greater correlation between blood and CSF lactate (R=0.32, P<0.001). In multivariable analysis, day 1 CSF glucose/lactate ratio was independently associated with mortality (odds ratio: 0.22, 95% confidence interval: 0.08-0.61; P=0.003), and day 1 CSF lactate concentration with unfavorable outcome (odds ratio: 4.86; 95% confidence interval: 1.86-12.67; P=0.001).
Low CSF glucose/lactate ratio is observed in nonsurvivors after severe TBI and may have prognostic value.