Use of ventricular cerebrospinal fluid lactate measurement to diagnose cerebrospinal fluid infection in patients with intraventricular haemorrhage.

Early diagnosis of ventriculostomy-associated cerebrospinal fluid (CSF) infection in acute neurosurgical patients can be difficult. The use of prophylactic antibiotics in intraventricular or subarachnoid haemorrhage decreases the sensitivity of cell counts, Gram staining and bacterial culture as diagnostic tools. We prospectively collected clinical and cerebrospinal data for 16 patients with intraventricular haemorrhage, with an external ventricular drain inserted, with or without spontaneous subarachnoid haemorrhage. Three (18.8%) patients had cerebrospinal fluid infection, with appropriate changes in antibiotic regimens needed. All three patients had CSF lactate levels of >4 mmol/L (6.4 mmol/L, 7.8 mmol/L, 7.9 mmol/L). Eleven out of 13 patients without CSF infection had CSF lactate levels of below 4 mmol/L. The two patients with CSF lactate levels of 4-6 mmol/L were grade 5 subarachnoid haemorrhage patients, one with renal impairment. Using a cut-off lactate level of 4 mmol/L, the positive predictive value was 60% and negative predictive value was 100% for CSF infection. A CSF lactate level of above 4 mmol/L should prompt suspicion of CSF infection in intraventricular haemorrhage patients with an external ventricular drain.