From the Guidelines
External ventricular drain (EVD) placement is indicated after aneurysmal subarachnoid hemorrhage (aSAH) primarily for managing acute hydrocephalus, controlling intracranial pressure (ICP), and facilitating cerebrospinal fluid (CSF) drainage. The most recent and highest quality study, 1, published in 2023, highlights the importance of EVD placement in patients with aSAH, particularly those with hydrocephalus, high-grade aSAH, or elevated ICP. Specific indications for EVD placement include:
- Presence of hydrocephalus on imaging (enlarged ventricles)
- Clinical deterioration with decreased level of consciousness
- High Hunt-Hess grade (grades 3-5) or World Federation of Neurological Surgeons (WFNS) grade (grades 3-5)
- Intraventricular hemorrhage
- Elevated ICP (>20-25 mmHg)
EVD placement is also indicated when there is a need for continuous ICP monitoring in high-grade aSAH patients or when CSF diversion is required to manage communicating hydrocephalus caused by blood products obstructing CSF flow. Although the study 2 from 2022 provides some insights into EVD placement in patients with intracerebral hemorrhage, it is not directly applicable to aSAH patients. Therefore, the recommendation is based on the most recent and relevant study, 1. The procedure should be performed urgently when hydrocephalus is causing neurological deterioration, as prompt CSF drainage can lead to significant clinical improvement. The EVD is typically kept in place until the patient's ICP stabilizes, usually for 7-10 days, with gradual weaning before removal. This intervention is crucial because hydrocephalus occurs in approximately 20-30% of aSAH patients and can significantly worsen outcomes if not promptly addressed.
From the Research
Indications for External Ventricular Drain (EVD) Placement
The indications for EVD placement after an aneurysmal subarachnoid hemorrhage include:
- Impaired cerebrospinal fluid (CSF) circulation 3
- Intracranial hypertension (ICHyp) 3
- Intraventricular hemorrhage (IVH) 3
- Hydrocephalus 3, 4, 5, 6
- Patients in the acute stage of subarachnoid hemorrhage with Hunt-Hess severity of III-V should receive EVD immediately before surgery 3
Patient Selection
Patient selection for EVD placement is crucial, and the following factors should be considered:
- Severity of hemorrhage according to the Fisher scale 3
- Condition of patients on the Hunt-Hess (H-H) scale during surgery 3
- Time of placement of EVD (before, during, and after surgery) 3
- Duration of EVD 3
EVD Management
The management of EVDs is critical, and the following approaches have been suggested:
- Early clamp trials and intermittent CSF drainage may be safe and result in fewer EVD complications and shorter length of stay 6
- A gradual EVD weaning strategy is commonly used, but its effectiveness is debated 5
- The optimal timing and manner of EVD removal have yet to be defined 4
- Prophylactic systemic antibiotics and antibiotic-coated EVDs may be considered to reduce the risk of EVD-associated infection 4