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Biomedical subjects

G Stepińska

Publications and source records attributed to G Stepińska.

12 recordsLinked to original sources
PubMed1995

Transcranial Doppler sonography in experimental Cushing response.

Searching for the early warning symptoms of brain ischaemia, transcranial Doppler sonography (TCD) was used in cats during the Cushing response. The study was performed on seven cats. The intracranial pressure was increased by means of different rate lumbar infusions. The TCD changes of middle cerebral artery (MCA) and basilar artery (BA) flows were analyzed at the stage of the slightest but significant systemic blood pressure increase. The first symptoms of Cushing phenomenon were accompanied by BA flow pattern alternations while the MCA flow remained unchanged. The study suggests the necessity of BA TCD monitoring in cases at risk from brain stem ischaemia. It was shown also that in such cases the MCA TCD study can be misleading.

Adrenergic Fibers↗
PubMed1995

Evaluation of craniospinal system condition using standardized volume-pressure loadings.

Standardized volume-pressure craniospinal system loadings based on physiological loadings were developed in order to study the CSF outflow route efficiency and to evaluate the intracranial volume-pressure relations. The study was carried out on 10 cats. Standardized abdominal compression was applied in order to produce a central venous pressure increased and subsequently ICP increase to the level of 20 and 30 mmHg for 2 minutes. The abdominal compression test seems to be useful in the CSF outflow route evaluation. The orthostatic changes were studied in control animals and in cats with an epidural balloon. The animal body was evaluated to an angle of 50 degrees and 80 degrees with the head directed upwards and downwards. This test was found suitable for the intracranial volume reserve estimation. Similar application, especially in experimental conditions can be found in the hypercapnia test. PaCO2 concentration was increased by means of respiration with a gas mixture containing 5% CO2. A steady increase of ICP of 9 +/- 1 mmHg was obtained. Vascular dilatation resulted in an intracranial volume loading. The ICP response in subjects with normal CO2 response can be related to the intracranial volume reserve. The studies performed show the usefulness of the standardized volume-pressure loadings. The loadings applied are more physiological than lumbar infusion tests used so far.

Animals↗
PubMed1992

ICP dependent changes of CSF outflow resistance.

CSF outflow resistance was studied in cats using the lumbar infusion tests. Different infusion rates were applied from 0.012 to 1.8 ml/min. ICP level obtained during infusions varied from 8.9 +/- 3.0 to 144.0 +/- 25.7 mmHg. The calculated resistance (R) values were within 75.2 +/- 14.4 to 255.6 +/- 71.2. mm Hg/ml/min. The relation between ICP and R are characterized by a curve which can be divided into three parts. First R rises until an ICP level of about 20 mmHg is reached, then R decreases fast until the ICP value is about 50 mmHg, a further drop is much slower and the ICP/R curve becomes almost parallel to the ICP axis. The possible reasons for the ICP dependent changes of R as well as the clinical importance of the results obtained are discussed.

Animals↗
PubMed1992

[Evaluation of the usefulness of cerebral perfusion pressure in threatened cerebral ischemia].

The Cushing response was produced using the lumbar infusions in cats. The following parameters were recorded and computed: arterial blood pressure (ABP), central venous pressure (CVP), intracranial pressure (ICP), heart rate and ECG. The lactate concentration was studied in brain stem and brain cortex. The analysis of ABP and ICP recordings showed in some cases that the Cushing response was obtained at CPP over 60 mmHg. The role of adrenergic reaction in Cushing phenomenon was confirmed by the increase in blood catecholamine concentration and typical adrenergic changes in ECG pattern.

Animals↗
PubMedDate not supplied

[Application of physiological data in evaluation of the intracranial volume-pressure interaction. I. An experimental study].

In experimental studies on cats the pressure and volume loadings corresponding to the physiological situations were used. The following tests were applied: central venous pressure increase, postural changes and increase of CO2 percentage in inspired gas mixture. It was found that the central venous pressure increase test is useful in the evaluation of CSF outflow routes, the postural change test examines the intracranial compensation and the elevation of CO2 level in inspired air tests the intracranial volume reserve.

Animals↗
PubMedDate not supplied

[Relation between resorption resistance of cerebrospinal fluid and the degree of intracranial pressure].

Changes in the CSF resorption resistance in relation to the value of the intracranial pressure have been assessed in 44 cats. Changes in the intracranial pressure have been produced with fluid infusions. Between 1 to 5 infusion tests with the rate 0.012-1.8 ml/min have been performed in each animal. A relationship between CSF resorption resistance and intracranial pressure has been found. With an increase in the intracranial pressure CSF resorption resistance increased to maximum value of 34 kPa/ml per minute (255.6 mm Hg/ml per minute) at pressure 2.96 +/- 0.69 kPa (22.2 +/- 5.2 mm Hg). At the intracranial pressure about 6.7 kPa (50 mm Hg) CSF resorption resistance rapidly decreased to the value of 13.9 kPa/ml per minute (104 mm Hg/ml per minute). Later, changes have been rather slight. It is possible, that the breaking point at 6.7 kPa corresponds to the mobilisation of all ways of CSF evacuation.

Absorption↗
PubMedDate not supplied

[Circulatory and respiratory disorders caused by increased intracranial pressure].

In an experimental model the effect of increased intracranial pressure on respiration and circulation was studied. Infusions of varying volumes of fluid into the subarachnoid space over the convexity of the brain in the right parietal area were carried out, recording then changes in respiration and arterial blood pressure, heart rate and ECG, paying attention to arrhythmias and ischaemic myocardial changes. Intracranial pressure rise caused a sympathetic system response with increased arterial blood pressure, increased heart rate and various arrhythmias, even ventricular fibrillation. The observed ischaemic changes, even those suggesting electric gap presence, were reversible indicating absence of fixed structural changes.

Animals↗
PubMedDate not supplied

[Concentration of lactates, sodium and potassium in brain tissue obtained during neurosurgery].

In samples of brain tissue obtained during operations from 40 neurosurgical patients the concentrations of lactate, sodium and potassium were determined. A statistically significant fall of potassium concentration and increased sodium concentration was found in patients with lactate concentration exceeding 0.9 mg/g of fresh tissue. All patients with raised lactate level in the cerebrospinal fluid before the operation tolerated poorly the neurosurgical intervention. Examination of brain tissue in these cases showed changes compatible with advanced brain oedema.

Adolescent↗
PubMedDate not supplied

[Diagnosis of brain stem ischemia by transcranial Doppler ultrasonography].

Intracranial pressure (ICP) was elevated in cats by intrathecal infusions. Middle cerebral artery and basilar artery were studied using Transcranial Doppler (TCD) during the infusion followed by systemic arterial pressure increase (Cushing response). Cushing response was symptomatic for brain stem ischaemia. The earliest TCD changes concerned the basilar artery. The most informative data for the diagnosis were pulsatility index increase and diastolic velocity decrease.

Animals↗
PubMedDate not supplied

[Application of transcranial Doppler ultrasonography in the assessment of cerebrovascular reactivity studies and cerebral vascular reserve estimation in patients with focal brain injury].

Cerebrovascular reactivity and cerebrovascular reserve were studied using transcranial Doppler sonography (TCD). Investigations were carried out in acute cases--8 patients with severe head injury within 5 days after trauma and in chronic cases with brain tissue defect (12 patients), and in cases with cerebral circulation insufficiency (15 patients). In acute cases the pCO2 cerebrovascular response was studied and in chronic cases cerebrovascular reserve was estimated using acetazolamide. TCD was found suitable for local vascular reactivity disturbances determination independently in three intracranial compartments--both hemispheres and infratentorial space. In patients with local brain tissue defect cerebrovascular reserve remained within normal range. In cerebral circulation insufficiency vascular reserve disturbances were limited to one compartment in cases with local vascular lesion they were found in all three compartments in cases with generalized atheromatosis.

Acetazolamide↗
PubMedDate not supplied

[Application of physiological loadings in evaluation of intracranial volume-pressure relations. II. Clinical studies].

The effects of physiological loadings (venous pressure increase, postural changes, pCO2 increase) on intracranial volume-pressure relations were studied. The standardized increase of venous outflow pressure was found to be a good test for the evaluation of CSF outflow routes. Standardized venous outflow pressure increase in Queckenstedt test seems to be especially useful.

Adult↗