What is it?
An external ventricular drain (EVD) is a medical device that is used to drain excess cerebrospinal fluid (CSF) from around the brain. It is commonly placed during neurosurgery to relieve elevated intracranial pressure. An EVD consists of a catheter that is inserted through a small hole in the skull and placed into one of the ventricles inside the brain. The other end of the catheter leads to a drainage system outside of the body. This allows for continuous drainage and monitoring of CSF to ensure normal pressure levels are maintained.
EVDs are most often used on a temporary basis for conditions that cause increased intracranial pressure such as traumatic brain injury, hemorrhage, tumors, and hydrocephalus. Once the underlying condition has improved and pressure has stabilized, the drain is typically removed. External Ventricular Drains some patients require long-term drainage with an EVD if their hydrocephalus cannot be treated another way. Proper placement and care of an EVD is crucial for effectively managing increased intracranial pressure and optimizing patient outcomes.
Indications and Benefits of EVD Placement
As mentioned, EVDs are commonly placed to treat elevated intracranial pressure from various neurological conditions and injuries. Some specific indications for EVD placement include:
- Traumatic brain injury - Head injuries that cause bleeding, swelling, and increased pressure inside the skull. Draining excess CSF helps reduce pressure and decrease risk of further injury.
- Intracerebral hemorrhage - Bleeding within the brain tissue such as from a ruptured aneurysm or arteriovenous malformation. Drainage controls swelling to prevent additional damage.
- Subarachnoid hemorrhage - Bleeding occurring between the brain and the tissues covering it, often from an aneurysm. EVDs are used pre- and post-operatively to manage pressure levels.
- Hydrocephalus - A neurological condition where excess CSF builds up in the ventricles, putting pressure on the brain. This is either treated short-term with an EVD until a permanent shunt can be placed or long-term with a ventriculoperitoneal shunt.
- Brain tumors - Both cancerous and non-cancerous growths can cause swelling and increased pressure inside the skull. An EVD provides decompression prior to surgery or radiation/chemotherapy treatments.
The main benefit of EVD placement is that it allows for continuous and precise monitoring and drainage of CSF to maintain normal intracranial pressure levels. This protects the brain from further injury and optimizes recovery from the underlying problem causing increased pressure.
Proper Placement and Ongoing Care
Accurate external ventricular drains placement involves careful image-guided insertion of the catheter into one of the ventricles deep within the brain. An entry point is made just above the hairline using sterile technique. Advanced monitoring modalities like ultrasound or computer tomography ensure the distal tip reaches the targeted ventricle location.
Once placed, the external portion of the catheter is connected to a closed drainage and monitoring system. Adjustable clamping of the drain tube regulates outflow of CSF and maintains desired pressure. The amount and characteristics of drained fluid are logged. Any changes could indicate complications warranting medical review.
To prevent infection, utmost care is given to keep the catheter exit site clean and dressed. Strict hand hygiene is followed during dressing changes which are typically performed every 1-3 days depending on the condition of the insertion tract. Antibiotic ointments are often applied. The whole drainage assembly is also changed regularly depending on the healthcare facility's protocols to reduce infection risks.
Additionally, bedside monitoring devices linked to the EVD tubing allow for continuous measurement of intracranial pressure levels which are also logged. Abnormal pressures may prompt medical intervention like adjusting the CSF drainage rate to bring pressure back within a safe target range. Overall management involves a team approach between neurosurgeons, nurses and other specialists.
Complications and Their Management
While external ventricular drains placement provides lifesaving drainage, there are also certain risks involved:
- Infection is a leading complication occurring in 5-25% of cases. Strict sterility precautions must be followed during insertion, care and all contact with the drainage system. Antimicrobial therapies manage suspected or confirmed infections.
- Hemorrhage can result from damage to brain blood vessels during catheter insertion, occurring in 1-10% of EVD placements. Bleeding is carefully controlled in the operating room and patients are closely monitored post-procedure.
- Malposition happens when the catheter tip is misplaced outside the ventricles rather than inside, seen in 5-15% of procedures. Adjustment or replacement of the drain may be needed under imaging guidance.
- Blockage can occur from fibrin or blood clots forming on or within the catheter, requiring catheter irrigation or replacement in 10-35% of cases.
- There is a small risk of over-drainage causing issues like edema or subdural hematomas in 1-2% of cases. Pressure monitor-guided drainage oversight aims to prevent this.
With experienced placement, diligent ongoing care, and prompt response to any warning signs, risks are minimized and EVDs effectively accomplish their purpose of controlling intracranial pressure in eligible patients. Overall, external ventricular drain remains a vital neurocritical care intervention globally.
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Falls and car accidents are two of the top reasons for traumatic brain injuries.
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Individuals associated with specific callings or exercises have a higher danger of TBIs, including:Athletes (both recreational and professional).Construction workers.Police and law enforcement.Military personnel’s.What are the major types of head injuries?HematomaHemorrhageConcussionEdemaSkull fractureDiffuse axonal injuryHow is a head injury diagnosed?One of the principal ways your PCP will evaluate your head injury is with the Glasgow Coma Scale (GCS).
