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Biomedical subjects

E Schindler

Publications and source records attributed to E Schindler.

At least 55 records · Page 3Linked to original sources

[Presurgical diagnosis of epilepsy and surgical epilepsy treatment].

20% of patients with focal epilepsy suffer from medically refractory seizures. Many of these patients can be cured by a surgical intervention removing the brain area where the seizures are originating (epileptogenic zone). 6000 patients in Austria would benefit from epilepsy surgery with an additional 150-200 new patients appearing each year. Potential candidates have to undergo an extensive presurgical work-up. During the non-invasive Phase I each patient is evaluated with an intensive video-EEG monitoring with scalp-EEG, a high resolution MRI, a SPECT and/or PET, a neuropsychological evaluation and a Wada-test. If the epileptogenic zone cannot be localized adequately with these methods, invasive electrophysiological techniques (epidural Peg-electrodes, Foramen-ovale electrodes, depth electrodes, subdural strip and grid electrodes) have to be applied. Operative strategies for temporal lobe epilepsies include antero-mesial temporal lobe resections and selective amygdala-hippocampectomies. Extratemporal epilepsies are treated by cortical resections guided by structural and electrophysiological parameters. The new technique of multiple subpial transections facilitates treatment of seizures originating in essential brain regions. Catastrophic epilepsies of early childhood often are caused by extensive pathologies affecting one hemisphere and can be treated successfully by large multilobar resections or hemispherectomies. Epilepsy surgery renders 70-80% of patients seizure free and thus can be regarded as an effective and safe treatment option for patients with medically refractory focal epilepsies.

Brain Diseases↗

[Transcranial doppler sonography. Effect of sevoflurane in comparison to isoflurane].

METHODS: Using transcranial Doppler sonography (TCD), we studied the effects of sevoflurane compared to equipotent doses of isoflurane on blood-flow velocity in the middle cerebral artery (MCA) before, during, and after general anaesthesia. In random order, 30 patients received sevoflurane (n = 15) or isoflurane (n = 15) given in stepwise-increasing doses of 0.5, 1.0, and 1.5 MAC in oxygen/air (FiO2 = 0.5). Oxygen/air was then replaced by oxygen/nitrous oxide 33%/65% with decreasing doses (1.5, 1.0, 0.5 MAC) of sevoflurane or isoflurane. During each step, ventilation was controlled to provide first normocapnia (end-tidal pCO2 = 38 mmHg) and then hypocapnia (end-tidal pCO2 = 27 mmHg). MCA blood-flow velocity and pulsatility, arterial blood pressure, heart rate, and body temperature were recorded simultaneously at the end of each period. For statistical analysis, within-group comparison was made by one-way ANOVA. Differences between groups were determined by two-way analysis of variance. Age, weight, and height of the patients were compared using Student's t-test; P < 0.05 was considered significant. RESULTS: Groups were comparable regarding age, weight, and height. TCD parameters were not significantly changed by increasing doses of sevoflurane or isoflurane given in oxygen/air when compared to the awake data. However, increasing MCA blood-flow velocity was found with decreasing doses of sevoflurane or isoflurane given in oxygen/nitrous oxide (P < 0.05 for 0.5 MAC, normoventilation) without intergroup, differences. In both groups, hyperventilation always decreased MCA blood-flow velocity. CONCLUSIONS: We conclude from our TCD data that equipotent doses of sevoflurane and isoflurane comparably affect cerebral perfusion, especially when nitrous oxide is given simultaneously.

Adolescent↗

[The effects of dopexamine. Transpulmonary shunt volume in thoracic surgical procedures with one-lung respiration].

OBJECTIVE: To study the influence of dopexamine on pulmonary shunt and hypoxic pulmonary vasoconstriction during major thoracic surgery with one-lung ventilation (OLV). DESIGN: Prospective, randomised, placebo-controlled study. SETTING: University hospital. PATIENTS: Twenty adult patients undergoing elective pulmonary resection. ANAESTHESIA: General anaesthesia was performed using propofol, fentanyl, N2O and vecuronium. Volume-controlled ventilation was performed to maintain normocapnia over the whole investigation period. During OLV, the tidal volume was reduced and the respiratory rate was increased to avoid a peak airway pressure exceeding 40 cm H2O. Furthermore the FiO2 was increased to 1.0 and the external PEEP was removed during OLV. INTERVENTIONS: The patients received either dopexamine at 2 micrograms/kg/min (group A, n = 10) or 0.9% saline as control (group B, n = 10) after assessing the baseline values. MEASUREMENT AND RESULTS: The following cardiorespiratory variables were recorded: Heart rate, mean arterial pressure and mean pulmonary arterial pressure. Cardiac output was measured by thermodilution using a continuous cardiac output thermodilution catheter. Arterial and mixed venous blood gas analysis were measured from simultaneously drawn samples. Cardiac index (CI), systemic vascular resistance index, pulmonary vascular resistance index, oxygen delivery index (DO2I), oxygen consumption index and the venous admixture were calculated using standard formula. Furthermore, pressure-flow-curves were constructed to analyse flow independent changes in the pulmonary vascular resistance. Data were recorded at the following times: After induction of anaesthesia in stable haemodynamics during two-lung ventilation (baseline values, T0), intraoperatively during one-lung ventilation (T1) and postoperatively after re-establishing two-lung ventilation (T2). Patients characteristics, data from the preoperative lung function testing and surgical procedures did not differ significantly between the groups. CI increased in the dopexamine group from 2.5 +/- 1.2 1.min-1.m-2 (T0) to 3.6 +/- 0.9 l.min-1.m-2 (T1) and 4.0 +/- 1.3 l.min-1.m-2 (T2). The course of the intrapulmonary right-to-left shunting did not differ between the groups. In the dopexamine-treated group the DO2I increased from 430 +/- 143 ml.min.m-2 (T0) to 652 +/- 255 ml.min.m-2 (T1) and 653 +/- 207 ml.min.m-2 (T2). Regarding the pressure-flow-curves there was no difference during OLV between the two groups indicating no major blocking effect of dopexamine on hypoxic pulmonary vasoconstriction. CONCLUSION: It is concluded that dopexamine can be used to improve haemodynamics and oxygen delivery during thoracic surgery without increasing venous admixture during one-lung ventilation.

Aged↗

Progressive multifocal leukoencephalopathy in AIDS: initial and follow-up CT and MRI.

We sought to determine the value of follow-up CT and MRI in patients with acquired immuno-deficiency syndrome (AIDS) and progressive multifocal leukoencephalopathy (PML). We reviewed 50 CT and 19 MRI examinations performed in 21 biopsy- or autopsy-proven cases of PML; 17 patients had follow-up examinations (mean time 5.9 weeks). The radiological examinations were correlated with pathological findings at autopsy. On initial imaging studies, 73 lesions were found. On follow-up, the most striking feature was rapid progression in both size and number of the lesions (from a mean of 3.2 to 6.9 per patient). One third of the patients showed increasing mass effect. A central area suggesting necrosis, of variable size, was found in 12/16 patients. Autopsy revealed macroscopic necrotic changes in the lesions in 11/16 patients.

AIDS Dementia Complex↗

Tumour blood flow and partition coefficients: correlation with grade of cerebral gliomas using xenon-enhanced computed tomography.

It is possible to underestimate the grade of nonenhancing cerebral tumours on conventional contrast-enhanced MRI or CT. Differentiation of high- and low-grade gliomas by measurement of the brain-blood partition coefficient lambda (T lambda) with Xe-enhanced CT (XeCT) has been reported. We assessed the practical applications of XeCT in suspected low-grade astrocytomas. We examined 15 patients with tumours which showed no contrast enhancement on conventional MRI and CT, using XeCT. Tumour blood flow (TBF) and T lambda were calculated. Fourteen patients underwent surgery, one patient had a biopsy. We recognized three histological groups. While T lambda differed significantly between them, TBF did not. Group 1 contained grade II-III astrocytomas and T lambda was 0.77; group 2 contained grade I-II astrocytomas with T lambda 1.14, and group 3 four oligodendrogliomas in which a T lambda of 1.50 was found.

Adolescent↗

CNS involvement in AIDS: spectrum of CT and MR findings.

The brain may be affected by a variety of abnormalities in association with human immunodeficiency virus (HIV) infection. Knowledge of their existence and characteristic imaging features are important to radiologists for detection, diagnosis, and initiation of an appropriate treatment. Although there is a considerable overlap in the imaging characteristics of different entities, some findings are found to be very suggestive of a particular disease. The CT and MR imaging techniques are commonly used in the diagnosis of neurological disorders in acquired immunodeficiency syndrome (AIDS) patients, to verify treatment response and to guide brain biopsy. This review attempts to describe CT and MR features of infectious and malignant brain disorders in HIV-seropositive patients.

AIDS-Related Opportunistic Infections↗

Potential problems with simplified selective cerebral perfusion--experimental investigations and clinical improvements.

Currently the most used perfusion techniques during aortic arch surgery to prevent cerebral damage include hypothermic circulatory arrest, retrograde cerebral perfusion and selective cerebral perfusion (SCP). The application of simplified SCP, which does not require deep hypothermia, has become an alternative procedure for brain protection. Including the physiological principle of autoregulated cerebral blood flow, cerebral perfusion flow is not predetermined, but differentiated from the different cannula sizes for the lower and upper body perfusion. In a mock circulation loop, we could show that resistance changes in the two compartments led to flow shifts between the systemic and brachiocephalic regions. In addition to mechanical factors cerebral perfusion is determined from physiological changes. In practice, these shifts can be initiated with disrupted autoregulation due to ph-stat management or dramatic pressure changes. To prevent mismatched cerebral perfusion extended perioperative monitoring was included in our clinical setting. With bilateral somatosensory evoked potentials, a computer aided topographical electroencephalometry system, transcranial doppler-sonography and jugular venous bulb saturation, we could provide a sufficient bihemispheric perfusion. Between 1990 and 1995 we operated on 21 patients using SCP. Intraoperatively no signs of cerebral ischaemia due to inadequate perfusion could be observed. Only temporary neurological changes were found postoperatively. In summary, the simplified SCP, despite its physiological basis, is intricately involved in control and influence. We think that the application of SCP is safe if extended neurophysiological monitoring is included in the clinical setting.

Cerebrovascular Circulation↗

Comparison of T2-weighted and fluid-attenuated inversion-recovery fast spin-echo MR sequences in intracerebral AIDS-associated disease.

PURPOSE: To compare the value of fast fluid-attenuated inversion-recovery (FLAIR) with T2-weighted fast spin-echo MR imaging in the detection of acquired immunodeficiency virus (AIDS)-related lesions of the brain. METHODS: Forty-four human immunodeficiency virus (HIV)-positive patients were examined with both sequences on either a 1.0-T or a 1.5-T MR system. The number, size, location, and conspicuity of the lesions were evaluated by two independent observers. Contrast ratios between lesions and normal brain/cerebrospinal fluid were determined, and contrast-to-noise ratios were calculated. RESULTS: FLAIR was found to be superior to T2-weighted fast spin-echo in detection of small lesions and of lesions located in cortical/subcortical regions and deep white matter. The two techniques were equal in delineation of lesions larger than 2 cm and for lesions located in the basal ganglia and posterior fossa. In 24 patients, more lesions were detected with the FLAIR fast spin-echo technique. Lesion/cerebrospinal fluid contrast ratios and contrast-to-noise ratios were significantly higher for the FLAIR fast spin-echo sequences than for the T2-weighted fast spin-echo sequences. CONCLUSION: FLAIR allows early detection of small lesions in subcortical and cortical locations, especially in HIV encephalitis. Because of its improved lesion detection rate and greater overall lesion conspicuity, we believe FLAIR is useful in the evaluation of subtle changes in the brains of AIDS patients with central nervous system disease, and could even replace the T2-weighted fast spin-echo technique.

AIDS Dementia Complex↗

MRI in patients with general paresis.

Few cases of MRI in neurosyphilis have been reported. We examined the value of MRI in patients with general paresis; MRI was performed on four HIV-negative patients with parenchymatous neurosyphilis. It demonstrated frontal and temporal atrophy, subcortical gliosis and, in one patient, increased ferritin in the basal ganglia. The progression of the lesions on MRI correlated well with the neuropsychiatric disturbances. The MRI findings correlated with the well-known neuropathological findings. This combination of pathological findings in neurosyphilis has not been described before and we suggest that MRI is of prognostic value in patients with general paresis.

Adult↗

Stable xenon CT in patients with chronic cerebrovascular disease.

Xenon-enhanced CT (XeCT) is a method of measuring regional cerebral blood flow (rCBF). Although it is used for acute and perioperative assessment the ability of XeCT to show hypoperfused areas in vivo, as compared with morphological imaging modalities other than noncontrast CT, is not defined. Correlation with MRI helps to define the smallest detectable hypoperfused area. We examined 17 patients 6 weeks after acute cerebral infarcts with CT, XeCT and MRI and the findings were compared. All examinations were performed with the same slice angulation and thickness and the sizes of the abnormal areas were measured. XeCT showed a high correlation with MRI, but less so with conventional CT. Lesions appeared significantly smaller on CT than on XeCT or MRI. No significant difference between MRI and XeCT changes was found. The minimal lesion on MRI correlating with a hypoperfused area on XeCT was 0.8 cm2, whereas lesions measuring less than 0.5 cm2 on MRI could not be detected on XeCT. The good correlation between XeCT and MRI underlines the reliability of rCBF examinations with XeCT. A significant difference between CT and XeCT findings shows the difficulty of interpreting hypoperfused regions only by correlation with CT. Combined XeCT and MRI gives a better estimate of the vascular state of the brain.

Aged↗

[Is the elimination of osteosarcoma cells with intraoperative "mesh autotransfusion" and leukocyte depletion filters possible?].

UNLABELLED: Intraoperative autotransfusion is contraindicated in cancer surgery because of the possible risk of systemic tumor spread. The aim of the present study was to investigate whether a cell saver in combination with a white blood cell depletion filter can remove osteosarcoma cells. METHODS: A defined number of osteosarcoma cells from an established cell line were added to red cell concentrates and Ringer solution. The tumor cell concentration was 1000/ ml in the first five experiments, 7111/ml in test no. 6, 1667/ml in test no. 7 and 167/ml in test no. 8. Following thorough mixing, each unit was processed separately by a cell saver (DIDECO BT 795/P) in its normal operation mode to produce a red cell concentrate. This red cell concentrate was filtered using a leukocyte depletion filter (PALL BPF 4). Samples were taken before and after processing with the autotransfuser and after filtration with the white cell depletion filter. Cytospin specimens from all samples were examined for osteosarcoma cells by three different methods (Papanicolaou stain, Vimentin antibodies, DNA analysis). RESULTS: After processing with the autotransfuser, tumor cells were identified in the red cell concentrate. No osteosarcoma cells were evident after the combined use of cell saver and leukocyte depletion filter. CONCLUSION: The sole use of the autotransfuser DIDECO BT 795/P during osteosarcoma surgery is not recommended because of the potential danger of retransfusion of malignant cells. In combination with the leukocyte depletion filter PALL BPF 4, no osteosarcoma cells were identified in the red cell concentrate. Since the adhesiveness of tumor cells from established cell lines may be different from that of tumor cells in the intraoperative salvaged blood, further studies with blood from the surgical field are necessary to determine the efficacy of white cell depletion filters to eliminate osteosarcoma cells.

Blood Transfusion, Autologous↗

[Examination of the unconscious patient].

The unconscious patient presents an challenging emergency in the intensive care unit. Patient evaluation and treatment must occur simultaneously. After checking vital signs, deciding about cardiopulmonary resuscitation or intubation, an intravenous line must be established, blood samples collected and glucose and thiamine should be given. The physical and neurological examination should be performed in a efficient way and must consider the following eight points: best reaction to loud commands, best motor reaction to noxious stimuli, respiratory pattern, size and reactions of pupils, eye movements, corneal and blink reflex, meningismus, muscle tone and deep tendon reflexes. With this approach it is possible to formulate a working diagnosis, and the appropriate diagnostic steps can be performed.

Coma↗

Endothelin plasma levels during heart surgery: influence on pulmonary artery pressure?

OBJECTIVE: Some studies found endothelin-1 to be a trigger for pulmonary hypertension. Endothelin-1 is an endothelial derived substance with generally vasoconstrictive properties, but probably vasodilatory effects on pulmonary arteries. The aim of the present study was to look for influences of endothelin-1 plasma values on pulmonary artery pressure. METHODS: Endothelin-1 levels during and after cardiac surgery and correlations to pulmonary artery pressure were tested in 10 control patients and 21 patients with pulmonary hypertension (mean pulmonary arterial pressure > 20 mmHg, systolic pulmonary arterial pressure > 30 mmHg). RESULTS: According to endothelin-1 values before anaesthesia (normal value below 4 pg/ml) patients with pulmonary hypertension could be divided into a "high endothelin-1" (10 patients, mean 8.25 +/- 2.06 pg/ml) and a "normal endothelin-1" (11 patients, mean 2.13 +/- 0.86 pg/ml) subgroup (p < 0.01). Values of the "high endothelin-1" group decreased until end of operation (from 7.58 +/- 2.35 to 2.95 +/- 1.44 pg/ml, n = 6) when pulmonary artery pressure returned to normal. Otherwise they slightly increased (from 9.43 +/- 2.24 to 11.07 +/- 1.96 pg/ml, n = 4). Levels of the "normal endothelin-1" group increased (to 2.55 pg/ml). Endothelin-1 values peaked on the intensive care unit (ICU) in all patients. Baseline endothelin-1 and systolic pulmonary artery pressure values correlated well with each other (r = 0.73, p < 0.001). Endothelin-1 decreased after extracorporeal circulation in all patients in whom pulmonary artery pressure tended to normalise, whereas no rise in pulmonary artery pressure paralleled the marked increase in endothelin-1 on the ICU. Vasodilatory effects of endothelin on pulmonary arteries can attribute to this course. CONCLUSIONS: Endothelin-1 seems not to trigger pulmonary hypertension but rather to vasodilate pulmonary vasculature.

Aged↗

[Blood supply to the liver in the human after 1 MAC desflurane in comparison with isoflurane and halothane].

OBJECTIVE: Objective of this investigation was to compare the effects of the new inhalation agent desflurane with equipotent doses of isoflurane and halothane on hepatic blood flow (tHBF). METHODS: 36 Patients scheduled for elective aortocoronary bypass grafting were enrolled to the study. tHBF was assessed by plasma clearance and hepatic extraction of indocyanine green, and standard haemodynamic parameters were measured by thermodilution technique. The measurements were performed awake and after intubation at equilibration of 1 MAC. All measurements were terminated before skin incision. RESULTS: We found a significant decrease of tHBF in all patients regardless of the inhalation agent used (H 918 ml/min +/- 107 to 625 ml/min +/- 181, I 930 ml/min +/- 195 to 637 ml/min +/- 137, D 940 ml/min +/- 129 to 677 ml/min +/- 122). The tHBF in relation to cardiac output also decreased significantly (H 17% +/- 5 to 14% +/- 3, I 16% +/- 3 to 14% +/- 5, D 20% +/- 5 to 18% +/- 6). No difference was seen between the groups according to tHBF and haemodynamics. CONCLUSION: The results of this study suggest that all inhalation agents included in the study significantly decreased tHBF during anaesthesia with the concentration of 1 MAC.

Aged↗