External Ventricular Drain Column Height Fails to Explain Cerebrospinal Fluid Drainage Volumes

An external ventricular drain (EVD) facilitates cerebrospinal fluid (CSF) diversion and intracranial pressure (ICP) monitoring. CSF drainage can be regulated by controlling the fluid drain height. There is limited evidence guiding nursing practice for adjusting drain height when caring for patients with an EVD.

This purpose of this study is to explore the relationship between EVD drain height setting and CSF drainage volumes.

This was a retrospective observational study. The initial 14 days from EVD placement for patients admitted to a university hospital between 2022 and 2024 who received an EVD and had CSF diversion were considered. Associations between time-stamped data for five drain height categories (< 0 cmH₂O, equal to 0 cmH₂O, 5 cmH₂O, 10 cmH₂O and 15 cmH₂O) and mean daily CSF drainage were analysed using a linear mixed model with Turkey adjustment.

The 115 patients provided 27 552 time-stamped observations over a median of 6.3 (IQR = 2.7-11.8) EVD days. The mean age was 51 (15.5) years; 53.0% were female, 64.9% were White and 74.8% were Non-Hispanic. Across the first 14 EVD days, the mean daily CSF volume was 179.2 (121 mL) with a range from 0 to 539 mL. Mean daily CSF output by height were: < 0 cmH₂O (180.0 [138.8]), 0 cmH₂O (164.1 [133.7]), 5 cmH₂O (162.0 [105.5]), 10 cmH₂O (194.7 [116.2]) and 15 cmH₂O (174.9 [123.4]). The mixed model showed no association between mean daily CSF output and drain height category (p = 0.443).

This study found a limited role of low-altitude settings in facilitating CSF drainage in EVD management.

Future efforts should be made to establish if there is a relationship between ICP management based on CSF drainage volume or drain height setting and to examine the impact of CSF drainage on patient outcomes. This information may also guide clinicians in making decisions about CSF drainage.