Experimental Research Of Intracranial Dynamics Changes And The Corresponding Frequency Spectrum During Intracranial Hypertension

【Objectives】 By making animal models of intracranial hypertension to probe into the regulations of the variation of intracranial comliance and volume compensation under the circumstances of increased intracranial pressure. Introduing a new method to survey the intracranial compliance and to compare it with the present method used extensively. To analyze the variation and regulation of cerebrospinal fluid pulse pressure during the process of increasing intracranial pressure and to study the relationship with the changing regulation of intracranial compliance. Using the method of frequency spectrum analysis to investigate the frequency, occurring condition, changing regulation, influencing factors, and the relationships with heart rate and respiration of M wave.【Methods】 Health mongrel dogs were used to be made into models of intracranial hypertension by arranging latex sacculus epidurally and injection physiological saline into it. Pressure transducers were arranged with the intubation in the contralateral ventricle and lumbar subarachnoid cavity to monitor and record the variations of intracranial pressure. During the whole process, a multi-conductor recording system of biological signal was used to monitor the systematic blood pressure, heart rate, respiration and the electrocardiagram. All the material processed were totally from the original records by the system.15 dogs were used. 1ml physiological saline was injected instantaneously into epidural sacculus and then VICP and LICP were recorded for 10 minutes; then 1ml physiological saline was also injected instantaneously into epidural sacculus and VICP and LICP were recorded for 10min. According to this way, 1ml physiological saline was injected into the saccululs every 10 minutes until VICP or LICP reached to or above 100mmHg. And then the epidural sacculus was emptied. This process was called the first stage of pressure increasing test. Resting for 1hr, 1ml physiological saline was then injected into epidural sacculus every 10min until VICP or LICP reached to or above 100mmHg and then injection was stopped. This process was called the second stage of pressure increasing test. By using the software of Matlab6.5 to analyze the original material, mSAP, mVICP, mLICP, mICPP and CSFPP were adopted with the heart rate as the collecting point and then the values of PVI before the every injection of physiological saline into the sacculus were calculated. All the numerical values of VICP and LICP collected were transferred with natural logarithm and then processed by linear correlation and regression with the collecting time. All the values of CSFPP collected were processed by the way of linear correlation and regression with the values of mVICP, mLICP, mICPP and PVI. All the data sects showing linear relationship processed by aboveways were chosen to be grouped according to the volume of the epidural sacculus, the different stages of pressure increasing test and the showing or not of M wave. All the linear slopes of different groups were compared and analyzed with t-test.7 dogs were used. 1ml physiological saline was first injected into the epidural sacculus as the basic volume increment and then the changes of VICP and LICP were recorded for 20 minutes. Using the injection pump to infuse 1ml physiological saline into the epidural sacculus in the initialized time of 10s ,20s, 30s and 40s in order and then to withdraw 1ml physiological saline in the same initialized time in order. During infusion and withdrawal, VICP, SAP, HR and electrocardiagram were continually recorded. Every dog was treated in this way and repeated in 3 times. Matlab6.5 was used to collect the value of VICP with 1/100 of infusion or withdrawal time as the collecting point. All the numerical values of VICP collected were transferred with natural logarithm and then processed by linear correlation and regression with the collecting time. The data sects showing linear relationship processed by above ways were chosen to be grouped according to injection or withdrawal, and the diff...