[The complementation test with feedback. Preliminary assessment of the test and comparison with a test using a continuous infusion rate]. / Test dopelnieniowy ze sprzezeniem zwrotnym. Wstepna ocena testu i porównanie z testem o stalym natezeniu wlewu.

The complementation test with feedback is described as a method for the assessment of disturbances of volume-pressure compensation. The method is characterized by changing infusion rate and the value of this rate depends on the value of cerebrospinal fluid pressure rise in the test. The infusion is stopped when the relative pressure rise reaches 10 mm Hg. Computer-assisted control of infusion and pressure measurement makes possible achieving of greater accuracy of determination of parameters. The test with feedback was compared with the test with stable infusion rate with regard to the indices characterizing the invasiveness of the method. A statistically significant reduction of this invasiveness was noted.

[The sinusoidal infusion test--an additional filling test for evaluating the mechanisms of the volume-pressure compensation in the intracranial cerebrospinal fluid space]. / Sinusoidalny test infuzyjny--test dopelnieniowy dla oceny mechanizmów kompensacji objetosciowo-cisnieniowej wewnatrzczaszkowych przestrzeni plynowych.

A diagnostic additional filling test is described which is used for the assessment of the mechanisms of volume-pressure compensation. In the test infusion is used of "physiological" sinusoidal relationship between the infused volume and time. The duration of the test is 10 minutes and it does not require pressure stabilization. On the basis of 23 clinical tests the values were determined of four indices of method "invasiveness" which were compared with analogous indices obtained in the group of tests with stable infusion rate. The obtained results indicate that the sinusoidal test is less invasive and is better tolerated by the patients.

Analysis of CSF dynamics by computerized pressure-elastance resorption test in hydrocephalic children. Indications for surgery.

Since 1982, 23 hydrocephalic children have been studied for compensatory mechanisms of the cerebrospinal fluid system. The authors describe the method and results of a computerized pressure-elastance resorption test (CPERT), a spinal steady-state infusion test, in hydrocephalic children. Computerized analysis of the P/V and AMP/P curve provides valuable data that precisely describe the degree of disturbances of CSF dynamics. The following parameters were quantitatively determined: out-flow resistance, opening pressure, elastance, elasticity, reference pressure and optimum (break-point) pressure. It is concluded that the described test allows the differential diagnosis of chronic hydrocephalus in children. The value of optimum pressure (analysis of AMP-P relation) gives precise indications for surgery and the selection of a valve system with adequate opening pressure. In some cases, the CPERT test can be used instead of continuous ICP monitoring.

[Computerized infusion test. II. Clinical use]. / Skomputeryzowany test infuzyjny. II. Zastosowanie kliniczne.

In 39 patients with intracranial lesions the resorption resistance was measured using an own computerized infusion test. A high usefulness of this test was demonstrated in the diagnosis of hydrocephalus and for establishing indications to ventriculocardiac valve implantation. In patients after craniocerebral injuries a rise was observed of the resorption resistance immediately after trauma in cases with subarachnoid haemorrhage. Later on, this resistance decreased gradually reaching a stable value after 1-2 years. Data obtained in the infusion test make possible establishing of optimal intracranial pressure and choice of an appropriate valve. The determination can be performed intraoperatively.

[Computerized infusion test. I. The method]. / Skomputeryzowany test infuzyjny. I. Metoda.

Biophysical aspects and the method of the Computerized Infusion Test (CIT) developed in the Neurosurgical Clinic of the Medical Research Center, Polish Academy of Sciences, are presented. The CIT is a development of classical methods of estimating the cerebrospinal fluid outflow resistance. It is based on a clinically tested mathematical model of the intracranial pressure-volume compensating mechanisms. The CIT enables the etrapolation of the infusion curve in cases when it is impossible to reach the upper steady during the constant infusion test because of the ICP exceeding values estimated as being critical.

CSF absorptive capacity in patients without intracranial pathology.

The role of changes in CSF inflow in patients without intracranial pathology has been studied. The CSF outflow resistance has been calculated, by dividing the CSF pressure rise by the speed of intrathecal saline infusion. The average CSF pressure rise produced during infusion test (infusion 2 ml/min) amounted to 11.15 mmHg. The calculated CSF outflow resistance equaled to 5.58 +/- 1.1 mm Hg/ml/min. On-line computer assisted analysis during infusion test helps to shorten the procedure and makes it more precise.

A fast method of estimating the elastance of the intracranial system.

The authors describe a fast method for estimating the elastance of the intracranial system in man. The method consists in constructing the so-called amplitude-pressure (Amp-P) curve which describes the relationship between the amplitude of pulse-related oscillations in cerebrospinal fluid pressure and the basic level of intracranial pressure. The Amp-P curve consists of two straight lines, and the point of intersection of these lines is thought to indicate the intracranial pressure level at which there occurs a qualitative change in the functioning of compensatory mechanisms of the intracranial system. The authors applied the method to examine the Amp-P curves of 10 patients without intracranial pathology and found that they provide a good description of the state and dynamics of the intracranial system. Preliminary data obtained in patients with intracranial pathology indicate that the method is a valuable tool in the diagnosis and treatment of neurosurgical patients.

[Statistical correlation between lactate concentration and acid-base equilibrium in cases of brain tumors, craniocerebral injuries and meningitis]. / Ocena statystyczna wspólzaleznosci stezenia kwasu mlekowego i równowagi kwasowo-zasadowej w plynie mózgowo-rdzeniowym w przypadkach guzów mózgu, urazów czaszkowo-m57OZGOWYCH I ZAPALENIA OPON

Statistical significance of correlations between lactate concentration and pH value as well as pCO2 in the cerebrospinal fluid was assessed in patients with brain tumours, craniocerebral injury and meningitis. After calculation of correlation indices it was found that with increasing lactate level the correlation between this level and the pH and pCO2 of the cerebrospinal fluid increases. Correlation coefficients were far from their maximal values (+1 or -1) which indicates absence of a direct cause-and-effect relationship between lactate concentration and both remaining values. The analysis of results in the group with lactate level exceeding 30 mg/100 ml demonstrated lowest correlation coefficients between these values in patients with meningoencephalitis.

A method of estimating intracranial decompensation in man.

A new method of estimating intracranial decompensation in man is described. An on-line computer system is connected to an intracranial pressure (ICP) monitoring system to compute regression plots of mean ICP vs standard deviation; standard deviation is used as a measure of ICP instability. Two zones with distinctly different slopes are a characteristic feature of these plots. It is thought that the changes of slope signify intracranial decompensation.

[Statistical analysis of cerebrospinal fluid acid-base equilibrium and cerebrospinal fluid lactate concentration in cases of brain tumors, cerebrocranial injuries and meningoencephalitis]. / Ocena statystyczna równowagi kwasowo-zasadowej i stezenia mleczanów w plynie mózgowo-rdzeniowym w przypadkach guzów mozgu, urazów czaszkowo-mozgowych i zapalenia opon mózgowo-rdzeniowych

A statistical analysis of CSF lactate concentration and CSF pH and PCO2 was performed. The values were obtained from 211 samples taken from 76 neurosurgical patients. The values of pH and pCO2 were classified in three groups corresponding to the following three ranges of lactate concentration: below 15 mg%, 15-30 mg%, over 30 mg%. The mean values and standard deviations were calculated: suitable tests: F, t (Student), C (Cochran and Cox) were used. It was established, that statistically significant changes of CSF acid-base balance were present at lactate levels over 30 mg%. Next, the patients with lactate concentrations over 30 mg% were analysed. They were divided into three groups according to etiology: inflammatory changes, injuries, tumours. It was shown, that the CSF acid-base balance in patients with brain tumours is less disturbed then in patients with inflammatory changes or brain injury.

A computerized neurosurgical intensive care system.

A specialized neurosurgical data acquisition and processing system was developed and applied in practice to monitor some 60 patients after head injury or neurosurgical operations. At first the system allowed off-line operation, and the experiences thus gained made it possible to implement the system in its present form for real-time on-line patient monitoring. The algorithms prepared in our laboratory allow rapid and concise presentation of results and have proved their usefulness in clinical practice. The main parameters of interest in neurosurgery are intracranial pressure (ICP) and the volume of cerebrospinal fluid (CSF) drained from one of the lateral ventricles. Examples of statistical analysis of both these variables, and their presentation in the form of tables, diagrams and histograms are given.

Computer-assisted analysis of intraventricular pressure after mannitol administration.

The effect of prolonged mannitol infusion upon intraventricular pressure was investigated with the aid of a specially-designed automatic digital recording system; the data recorded were processed off-line by a minicomputer. The character of the pressure curves is thought to result from interaction between the mannitol effect and the observed system's shifting equilibrium position, which is caused by other factors. The character of the pressure curves prior to mannitol infusion must be taken into consideration in estimating the actual effect of the drug; the authors suggest that in certain cases it might be possible to decrease further the rate of mannitol administration. The advantages of statistical approach to the evaluation of intracranial pressure variations are discussed.