Input the measured opening pressure and patient mobility status to calibrate the optimal programmable shunt valve setting.
Guidelines & Evidence
Clinical Details
Section 1
When to Use
When to Use
Programming a new programmable Ventriculoperitoneal (VP) or Lumboperitoneal (LP) shunt in the operating room.
Adjusting shunt settings in clinic based on under-drainage (persistent gait apraxia) or over-drainage (subdural hematoma, orthostatic headaches).
Section 2
Literature
Physics vs Biology
Programmable valves revolutionized hydrocephalus management by avoiding revision surgeries. The physics governing proper selection relies on understanding the "Siphon Effect." A column of water (CSF) extending from the ventricles down to the abdomen creates immense negative vacuum pressure when a patient stands up. If the valve restriction (measured in mmH2O) is too low, standing will suck the ventricles dry instantly, causing the brain to collapse and the bridging veins to tear.
Section 3
Pearls/Pitfalls
The Bedbound Trap
If a patient is bedbound (e.g. severe subarachnoid hemorrhage vasospasm), the siphon effect evaporates. If you set the valve to a "normal" upright setting (e.g. 120 mmH2O), the shunt will never drain, and the hydrocephalus will persist. Horizontal patients require much lower settings.
Section 4
Evidence Appraisal
Primary Reference
Seven years of clinical experience with the programmable Codman Hakim valve: a retrospective study of 583 patients
