Conversion of external ventricular drains to ventriculoperitoneal shunts after aneurysmal subarachnoid hemorrhage: effects of site and protein/red blood cell counts on shunt infection and malfunction.

OBJECT: The purpose of this study was to determine the incidence of shunt infection in patients with subarachnoid hemorrhage (SAH) after converting an external ventricular drain (EVD) to a ventriculoperitoneal (VP) shunt using the existing EVD site. The second purpose was to assess the risk of shunt malfunction after converting the EVD to a permanent shunt irrespective of the cerebrospinal fluid (CSF) protein and red blood cell (RBC) counts.

METHODS: Data obtained in 80 consecutive adult patients (18 men and 62 women, mean age 60.8 years, range 33-85 years) who underwent direct conversion of an EVD to a VP shunt for post-SAH hydrocephalus between August 2002 and March 2007 were retrospectively reviewed. In each patient, the existing EVD site was used to pass the proximal shunt catheter. In no patient was VP shunt insertion delayed based on preoperative RBC or protein counts.

RESULTS: The mean period of external ventricular drainage before VP shunt placement was 14.1 days (range 3-45 days). No patient suffered ventriculitis. The mean perioperative CSF protein level was 124 mg/dl (range 17-516 mg/dl). The mean and median perioperative RBC values in CSF were 14,203 RBCs/mm(3) and 4600 RBCs/mm(3) (range 119-290,000/mm(3)), respectively. No patient was lost to follow-up. The mean follow-up duration was 24 months (range 2-53 months). Three patients (3.8%) had shunt malfunction related to obstruction of the shunt system after 15 days, 2 months, and 18 months, respectively. There were no shunt-related infections. No patient suffered a clinically significant hemorrhage from ventricular catheter placement after VP shunt insertion.

CONCLUSIONS: In adult patients with aneurysmal SAH, conversion of an EVD to a VP shunt can be safely done using the same EVD site. In this defined patient population, protein and RBC counts in the CSF do not seem to affect shunt survival adversely. Thus, conversion of an EVD to VP shunt should not be delayed because of an elevated protein or RBC count.