Lecture on External Ventricular Drainage (EVD) Systems

Overview

EVD systems are used to drain cerebrospinal fluid (CSF) and monitor intracranial pressure (ICP).
Different brands and models exist, but all systems share the same principle and components.

Connection: Tube connecting the EVD to ventricles for CSF drainage.
Labels: Yellow label indicates CSF access to avoid confusion with central line ports.
Stopcocks: Three-way stopcocks regulate fluid flow, with one port typically closed.
- Allows fluid to drain when open.
- Main stopcock is connected to the zero level.
Chamber: Transparent collector graded up to 75 ml, connected to a drainage bag.
- Contains a hydrophilic vent and one-way valve.
- Positioned at the foramen of Monroe level.

Perform hand hygiene and wear sterile gloves, gown, cap, and mask.
Use a two-person method to prime the system.
Connect primary stopcock based on type of drain (e.g., lumbar or ventricular).
Transducer Use:
- Prime and flush with normal saline.
- Avoid pressurized bags to prevent fluid backflow.
- Connect transducer to main stopcock.

Ensure transducer and foramen of Monroe are at the same level (use laser or scale).
Zero system to prescribed pressure levels.
Open system between patient and transducer for accurate pressure reading.
System allows either CSF drainage or ICP monitoring, not both simultaneously.

Dressings should remain dry and clean; change every 72 hours if necessary.
To collect a CSF sample:
- Close from patient side, clean with antiseptic, and collect using a syringe.
Drain bag or change when three-quarters full or as per institutional guidelines.
Maintain sterility to prevent infection.

EVD systems are crucial for managing and monitoring patients with conditions affecting ICP.
Strict adherence to sterile techniques and proper handling is vital to prevent infections.