Risk factors for infections related to external ventricular drainage

External ventricular drainage (EVD) is frequently used in neurosurgery for cerebrospinal fluid (CSF) drainage in patients with raised intracranial pressure. The major complication of this procedure is an EVD-related infection, i.e., meningitis or ventriculitis. The purpose of the present retrospective single centre study is to assess the possible causes of these infections.

Two hundred and twenty-eight patients were included in the period from January 1993 until April 2005. Patient and disease demographics, as well as EVD data, and the occurrence of infection were reviewed, compared, and included in a risk-analysis study.

The population's mean age was 56 +/- 15 years and the sexes were equally distributed. Most frequently, the indication for EVD was hydrocephalus due to intraventricular haemorrhage (48.2%). An infection was documented in 23.2% of all patients. Duration of EVD drainage appeared to be a risk factor for infection (>11 days: OR 4.1; 95% CI 1.8-9.2, p = 0.001). CSF sampling frequency was also a significant risk-factor (no sampling: OR 0.2, 95% CI 0.2-0.5, p = 0.003).

We found a relatively high percentage of EVD-related infections. After multivariate analysis there appears to be a relation with duration of drainage and frequent CSF sampling. As a result, a new EVD protocol is proposed in our institution that we believe will decrease the number of EVD-related infections to a minimum.