why clamp an evd
The rationale for clamping a ventriculostomy device (EVD) is to evoid overdraining of CSF, which may lead to brain herniation. If you place the EVD below the patient, you will normally see an increase of CSF drainage, due to gravity. For this reason, most EVD protocols recommend clamping it with any changes in patient's position that may place the EVD below the patient. I also clamp when draining the cylinder, which is how I was taught.