Introduction: It is widely known that external ventricular drains(EVD) are associated with ventricultis and multiple risk factors have been identified, specifically, greater days of implantation has been associated with greater infection risk. The specifics of this relationship remains obscure, especially in EVDs in place for an extended duration of time. Furthermore, it is unclear if the advent of antibiotic-impregnated catheters has any impact on these temporal measures.
Methods: Data from a single center neurosurgical department was reviewed retrospectively. Patients undergoing EVD placement between 2008 and 2011 were included. Type of catheter, days of implantation and signs of infection were recorded. Chi square tests were used to evaluate relationships between variables. A Life-Table analysis was used to estimate hazard functions, with infection as the end point.
Results: A total of 291 patients and 3033 EVD days were included. EVDs were in place for an average of 10.42(SD=7.26) days with 51(17.5%) in place >15 days. Confirmed infections were seen in 50(17.18%) patients and on average infections occurred 7.06(SD=4.60) days after implantation. The use of antibiotic impregnated catheters did not produce a significant change in rate of infection (15.6% vs 19.1%, p=.4364) or time to infection (6.48 vs 7.64 days, p=.8762).
Hazard rate of infection remained between 0 and 4% between days 1 and 17 with peaks on day 7(3.3%), 10(3.4%) and 16(3.9%). The greatest hazard ratio was seen on day 17 at 11.8%. Hazard rate dropped precipitously to 0% after day 17 (Figure 1).
Conclusions: Our results show that all EVD associated infections occurred within 17 days of implantation. Therefore, when managing patients with prolonged implantation, further risk of infection may not be necessary to consider. Additionally, the use of antibiotic-impregnated catheters does not impact infection rate nor does it improve time to infection.
Patient Care: This research improves patient care by assisting the provider in predicting and avoiding external ventricular drain associated infections.
Learning Objectives: By the conclusion of this session participants should be able to 1) Describe the association between external ventricular drain related infections and days of implantation 2) Be aware of the hazard rate associated with long term catheter placement and 3) Utilize this information in the clinical decision making of discontinuing such catheters.