Daily drained CSF volume is a predictor for shunt dependence – A retrospective study

• Given constant EVD pressure level of 15 cm H2O, the CSF output volume is a predictor for a weaning clamp trial.
• No other predictive factors could be identified in our study group.
• We found a simple factor usable to predict the result of the EVD clamp trial.
• Daily drained volume over 130 ml identified patients needing shunts with 65% sensitivity and 84% specificity.

ObjectivesAcute hydrocephalus ensues from various intracranial processes and is usually treated using external ventricular drainage (EVD). After the acute phase, a clamp trial is usually performed to identify patients requiring permanent CSF shunting. The aim of our study was to identify simple and clinically accessible factors that can help predict the result of the EVD clamp trial.Methods86 patients were selected for this retrospective analysis. Average CSF drained volume over 3 days given a constant EVD pressure level of 15 cm H2O and other clinical and laboratory parameters were statistically compared with the result of an EVD clamp trial.ResultsThe univariate analysis identified significant differences between the groups of patients who failed or passed the EVD clamp trial for the mean daily drained volume over 3 days (Mann–Whitney U-test, p < 0.01). In the multivariate logistic regression, the average daily CSF output over 3 days was also significant (p = 0.02), no other significant factors could be identified. Using hierarchical clustering, the best threshold daily value for EVD clamp trial failure was found at 130 ml (mean daily drained CSF volume) with the sensitivity of 64.5% and specificity of 83.6% (chi-square 20.6, p < 0.01).ConclusionWe have identified a simple, clinically available factor for identifying patients who are likely to fail the EVD clamp trial.