Indications for Treatment
- Clinical and/or laboratory evidence of CSF infection: After the diagnosis of shunt infection has been established on clinical and laboratory grounds, the shunt system is usually removed as soon as possible to lessen the risk for formation of a parenchymal or ventricular abscess, cellulitis along the shunt tract, and diffuse peritonitis or bacteremia and endocarditis (when a shunt drains into the bloodstream). An infected shunt can present in various clinical scenarios such as a shunt failure associated with CSF parameters suggestive of infection, wound breakdown with exposure of shunt components and purulent discharge, presence of an abdominal pseudocyst with laboratory parameters suggestive of infection, a hollow viscus perforation by the distal catheter (e.g., rectal prolapse), or any clinical evidence of CNS sepsis in a patient with a shunt.
- Persistently positive CSF cultures require new EVD: Patients with CSF shunt infections who have EVD systems often require extended antibiotic management to sterilize the CSF. In most centers, whenever a ventricular catheter has been in place for more than 14 days and the infection persists with positive cultures, or if CSF cultures indicate the presence of a new microorganism (suggesting colonization of the catheter), a complete EVD system change is warranted.
- Steroids: No current guidelines suggest that steroids are of use in treating CSF shunt infections.
- Antibiotics: Antibiotic management is usually set according to the infectious diseases guidelines for CSF shunt infection. If there is clear-cut evidence of infection (open wound draining, purulent discharge, CSF with microorganisms on stain), antibiotics can be started preoperatively and then changed according to culture patterns of antibiotic resistance.
Clamp time for CSF drain
- Clamp time varies with CSF output: The CSF output chart for an EVD can be used to determine how long the system must be closed preoperatively to create a CSF ventricular volume that will facilitate the new EVD catheter insertion.
Surgical site preparation
- Hair removal optional: Hair removal is optional. If done, it should probably be delayed until the time of surgery and clippers used instead of a razor.
- Protection from skin contamination: The skin of the patient should be cleaned prior to being covered with a sterile, adhesive plastic film. Some have advocated the use of an iodophor solution to lessen skin flora proliferation along with an adhesive plastic layer impregnated with an iodine solution (63, 95).
- Adequate analgesia for creation of EVD: Patients should be managed so that the wound opening, shunt extraction, and insertion of a new EVD system causes no discomfort and the patient cooperates with the procedure. This usually means general anesthesia. Occasionally, if a shunt device has been inserted in the past, has subsequently been found not to be working on repeated examinations, and becomes infected, it can be removed with local anesthesia and conscious sedation.
Devices to Be Implanted
Several EVD systems are available. Most of them are constituted of the following parts:
- Catheter: The catheter for the EVD is typically 30 cm in length with a stylet that assists in directing the insertion into the ventricular cavity to be drained. Its distal end is connected to a Luer-lock adaptor on the tubing of the drainage bag.
- Tubing with collection chamber: The catheter is connected to a silastic tubing that usually has a three-way stopcock valve that enables CSF sampling and/or attachment to a pressure-monitoring device. It ends in a collection chamber with a volumetric scale that allows the determination of CSF output during the day. The container’s height in relationship to the patient can be altered to set the drainage pressure at which the EVD system will work. In some systems the chamber slides on a rigid scale, and the zero-line is placed at the level of the patient’s external auditory meatus, allowing the resistance setting to drainage to be easily determined and managed. Not uncommonly there is a millipore filter at the inlet to the chamber whose purpose is to resist colonization of the tubing proximal to it by bacteria that have entered the system during changing of the drainage bag.
- Drainage bag: The bag is attached to the collection chamber and can be changed or drained as needed.
Ancillary/Specialized Equipment Required for Surgery
- EVD setup: An EVD catheter and collection system are required.