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.