Pulse pressure and mean pressure relationship of intracranial pressure and lumbar cerebrospinal fluid pressure / 生物医学工程学杂志

Intracranial pressure fluctuates due to heart beat, respiration, neuro-regulation, etc. Traditional intracranial pressure study focuses on the static pressure and related factors, putting emphasis on mean intracranial pressure, while paying little attention to the pulse components. This study was composed of two parts: animal experiment and theoretical analysis. The animal experiment was performed on 14 mongrel dogs, studying the variation of intracranial pressure wave form under different intracranial pressure level. The dogs were installed epidurally with latex sacculus to establish models of increased intracranial pressure. The degree of intracranial pressure and volume could be altered by changing the volume of fluid in the sacculus. During the process, pressure transducers were arranged to monitor and record the variations of the pressure of intracranial ventricle and lumbar subarachnoid cavity. The result demonstrated that, with the continual increase of intracranial pressure, intracranial pulse pressure increased correspondingly, showing a linear relationship with the change of intracranial pressure. After the sacculus was emptied and reinfused, the slope of the linear relationship was determined to be greater than the former slope. The same result was obtained in the lumbar cerebrospinal fluid pressure. Therefore, the lumbar cerebrospinal fluid pressure is consistent with the intracranial pressure. Intracranial pulse pressure is in linear relationship with mean pressure, and the slope of their linear relationship predicts the perform of intracranial autoregulation.

Capillary blood flow with dynamical change of tissue pressure caused by exterior force / 生物医学工程学杂志

A hemodynamic model of capillary and tissue, in which tissue pressure changed with swing manipulation of Traditional Chinese Medical Massage (TCMM), is presented in this paper to explain the hemodynamic mechanism of swing manipulation. Blood flowed in capillary with low Reynolds number. Plasma exuded through capillary according to the Starling's Law. Tissue pressure changed linearly with the massage force measured. Blood apparent viscosity, plasma protein concentration and red cell's hematocrit were taken into account. Capillary flow rate, blood apparent viscosity, filtration rate and filtration fraction with dynamical change of tissue pressure were calculated numerically, and were compared with those in static tissue pressure condition. Results showed that, dynamical change of tissue pressure led to the increase of capillary flow rate and the decrease of blood apparent viscosity, which qualitatively explained the hemodynamic mechanism of "promoting blood circulation and removing blood stasis" in swing manipulation of TCMM.