Comparison of Pressure Volume Indices Obtained with Constant Rate and Bolus Infusions

Both CSF outflow resistance (Rcsf) and pressure-volume index (PVI) can be calculated from either constant rate or bolus infusions. It has been demonstrated that Rcsf is determined more accurately by constant rate infusion (Tans, Poortvliet, 1984). For determination of the PVI most investigators use bolus infusions, but constant rate infusions were reported to yield more stable results (Avezaat, Van Eijndhoven 1984). The purpose of the present study was to investigate which infusion technique provides the most reliable PVI, using mathematical models with and without a constant term.