Extended subcutaneous tunnelling technique for external ventricular drainage

Infection is a serious complication of external ventricular drain (EVD) and various strategies have been adopted to minimize its occurrence. The use of an extended subcutaneous tunnel (50-60 cm) was previously described, but has since received little attention in the literature. The authors reviewed their experience with this technique, with emphasis on the rate of infection and predisposing risk factors. This is a retrospective review of 114 patients who received EVD with extended subcutaneous tunnel ('long EVD'). Fourteen of the 114 patients underwent more than one insertion, and a total of 133 cases of 'long EVD' were included. The mean duration of drainage was 20 days. One-hundred-and-three cases started without pre-existent infection and seven became infected, yielding an overall infection rate of 6.8%. The majority of infections were found within the first 5 days and in the third week of drainage. There was, however, no statistically significant difference in daily infection risks between the first, second and third weeks. Only intraventricular instillation of urokinase was identified as a statistically significant risk factor. Non-infective complications occurred in 17 cases (12.8%). In the present study, the overall infection rate of the 'long EVD' was comparable with that of conventional EVD, as reported by other authorities in the literature. The extended subcutaneous tunnel technique did not affect the daily infection risk on a week-to-week basis. The 'long EVD' does not appear to offer any distinct advantage over the standard tunnelling technique in our unit. However, this is essentially an audit within a single centre, and the findings should be interpreted with caution and with the understanding that individual institutions may have their unique patterns and risks of EVD infection.