Evaluation of micro tip pressure tranducers for the measurement of intracerebral pressure transients induced by fluid percussion

We describe the application of MIKRO TIP(R) miniature pressure transducers (MPT) for the in vivo measurement of intracerebral stresses induced by trau matic brain injury (TBI). In order to test the linearity of these transduce rs pressure pulses of different amplitudes (duration approximate to 10ms) w ere generated in a closed calibration chamber. A piezoelectric pressure tra nsducer (PPT) served as the reference measure. A linear correlation was fou nd within the pressure range between 0.57 and 5.09 bar (R-2 = 0.998). The f requency transmission characteristics of the MPTs are comparable to the PPT . In three juvenile swines (6 weeks of age) pressures within the brain tiss ue were induced by fluid percussion (FP) and were measured in the anterior, middle, and posterior cranial cavity as well as in the extracranial part o f the medulla oblongata. The data obtained in our experiments agree with th e basic biomechanics of FP known from studies in cats and rabbits. Due to t heir small size, MPTs can be applied in living animals. Stereotaxic positio ning of these catheters at any site of the brain and spinal cord requires o nly minimal surgery. Therefore, MPTs are useful in evaluating animal models of brain injury and in generating input data for computational models of h ead injury as well as to validate the mathematical results of such models w ith experimental data.