Diagnosis of ventriculostomy-related infection: Is cerebrospinal fluid lactate measurement a useful tool?

Objective: To evaluate the value of CSF lactate (L) for the diagnosis of ventriculostomy related infections (VRI), and compare it with other CSF markers.

Methods: Prospective study of neurocritical patients admitted to Maciel Hospital and Clinicas Hospital ICUs in which an external ventricular drain (EVD) was inserted. In patients with clinical suspicion of VRI, a CSF sample was obtained through the EVD for CSF culture and markers analysis (glucose, protein, lactate and leukocytes). We defined proven VRI according to preset criteria as: fever, plus CSF alterations (glucose <50mg/dl or leukocytes >500/μl), plus positive CSF culture. CSF markers were plotted in a receiver operating curve (ROC) to evaluate their diagnostic accuracy.

Results: 36 CSF samples were obtained: 14 corresponded to proven VRI and 22 to excluded VRI. Median L was 9.90mmol/L (IQR: 4.7-12) for proven VRI versus 2.95mmol/L (IQR: 2.4-3.6) for excluded VRI (p<0.001). Both L and CSF glucose showed a good diagnostic accuracy for VRI, with an AUC of 0.900 and 0.951 respectively. We found the following diagnostic values for L: sensitivity of 86%, specificity of 86%, PPV of 80%, NPV of 91%, cut-off value of 4mM, positive likehood ratio of 6.1, negative likehood ratio of 0.16, Youden Index of 0.72 and Diagnostic Odds Ratio of 34.

Conclusions: For the studied population, L represents a good marker for VRI. It could be used as a quick and specific test to identify the need for antimicrobial therapy in patients with clinical suspicion of VRI.