Fluid Percussion Device
|The DRAGONFLY R&D INC. MODEL
# HPD-1700 FLUID PERCUSSION DEVICE is used to create reproducible, hydraulic pulses
for closed CNS/brain injury research.
The device consists of a closed hydraulic system actuated by a falling pendulum. The pressure with which the pendulum strikes the closed hydraulic system is adjusted by changing the angle through which the pendulum falls or by adding optional weights to the pendulum.
The system pressure is measured directly by a precisely calibrated pressure transducer through a charge amplifier/coupler to a digital or analog oscilloscope (digital dual-trace with RS-232 output is ideal for storing and analyzing the data), or to most PC based data acquisition systems. The time-base of the oscilloscope in combination with the mechanically adjustable remote oscilloscope trigger allows the pressure signal to be seen at the correct time. The time duration of the shock wave or pressurization event occurs in approximately 10 ms with the flat faced striker plate, however, it can be lengthened to 20 ms or more by using shock absorbing closed cell foam pads on the striker plate of the piston. The time duration component is read directly on the oscilloscope (horizontal screen grid), as is the pressure component (vertical screen grid).
The closed hydraulic system is attached to the animal model using a flexible high-pressure hose attached to a chronically implanted Lure lock fitting on the animal model.
Both behavioral and pathological data are used to grade the trauma. Animal models are conditioned by learned time-trial routines. Techniques and devices such as balance beams, Rotor-Rods, grip strength meters. treadmills, inclined planes, maze or water-maze navigation, paw placement trials, etc. Post- percussive trial data is used to evaluate and grade the deficit incurred. Pathological data such as histograms are also be used to document deficit.