In neurosurgery, a vacuum refers to a controlled negative pressure environment applied to drainage systems. It enables passive, continuous evacuation of fluid—such as blood from a chronic subdural hematoma—through a catheter connected to a sealed collection device.

Vacuum-based systems (e.g., SEPS) use low-level suction to promote safe decompression of the subdural space, minimize reaccumulation, and avoid the risks associated with manual aspiration or high-pressure systems.