Search PubMed⌕ Search

Biomedical subjects

E Ryding

Publications and source records attributed to E Ryding.

66 records · Page 4Linked to original sources
PubMed1987

Prediction and prevention of delayed ischemic dysfunction after aneurysmal subarachnoid hemorrhage and early operation.

Mean hemispheric cerebral blood flow (CBF) was studied after the intravenous administration of xenon-133 in 20 anesthetized patients with aneurysmal subarachnoid hemorrhage. Before early aneurysm operation, repeated CBF measurements were made to evaluate the cerebral vascular reactivity to controlled hyperventilation. Thirteen individuals received intravenous treatment with the calcium channel blocker nimodipine, whereas the other seven patients did not receive such specific antiischemic treatment. Five of the latter patients had an impaired CO2 response, and three showed delayed ischemic deterioration (DID), whereas none of the seven nimodipine-treated patients with impaired CO2 response showed DID. One nimodipine-treated patient with a preserved CO2 response, in whom operation was complicated, developed DID. The observed findings indicate that DID after uncomplicated early aneurysm operation may be associated with an early disturbance of cerebral vasoreactivity. Treatment with nimodipine may counteract the development of DID in patients with an impaired CBF CO2 response.

Adult↗
PubMed1986

Cerebral hemodynamics in patients with acute severe head trauma.

Mean hemispheric cerebral blood flow (CBF) was studied in 11 comatose brain-injured patients following intravenous administration of xenon-133. Repeated measurements were performed in order to evaluate cerebral vasoreactivity following a decrease in PaCO2. In addition, the effect of induced barbiturate coma was evaluated in patients with intracranial hypertension. The cerebral vasoreactivity and the CBF response following induction of barbiturate coma varied. In patients with normal CO2 reactivity, barbiturate treatment was accompanied by a considerable decrease in CBF as compared to patients with decreased or abolished CO2 response. During barbiturate treatment the intracranial pressure (ICP) became normal in three of four patients with preserved CO2 response, but reached normal levels in only one of five patients with impaired CO2 reactivity. Patients whose ICP became normal recovered. The data suggest a positive correlation between CO2 reactivity and the effect of barbiturate treatment. Furthermore, preserved cerebral vasoreactivity after severe head injury may be of prognostic value.

Adolescent↗
PubMed1985

A neurophysiologic investigation of thoracic outlet syndrome.

Earlier reports have been conflicting as regards the value of neurophysiologic measurements in the diagnosis of thoracic outlet syndrome (TOS), presumably due to differences in selection of patients and in selection and standardization of neurophysiologic tests. The object of the present study was to assess the value of extensive conventional neurophysiologic measurements for the diagnosis of brachial plexus compression in patients with clinical TOS as determined from standardized criteria. The results are discussed in the light of expected neurophysiologic findings at different degrees of brachial plexus compression.

Adolescent↗
PubMed1984

Monoexponential analysis of 133Xe clearance curves for regional cerebral blood flow measurements.

The theoretical properties of a monoexponential flow index, analogous to the one used earlier by other investigators for regional CBF (rCBF) measured after intraarterial injection, were investigated after the administration of 133Xe intraarterially, intravenously, and by inhalation under high and low flow conditions. The sensitivity of the flow index to changes in fast flow components or changes in the weight ratio between the fast and the slow flow compartments was found to be dependent on whichever part of the 133Xe clearance curve was used for the flow calculation and on the shape of the input function for 133Xe. Since biexponential analysis of the clearance curves includes a monoexponential approximation for each of the two components of the clearance curve corresponding to the high and the low flow "families" in the brain, the limitations of the monoexponential flow index observed are in principle also valid for the results of biexponential analysis of the clearance curves.

Cerebrovascular Circulation↗
PubMed1984

The Angelman or "happy puppet" syndrome. Clinical and electroencephalographic features and cerebral blood flow.

Two cases of happy puppet or Angelman syndrome are presented. They have the typical clinical features and represent the first Swedish cases. One of the patients is a man of 75 years of age, which shows that this form of severe mental retardation is well compatible with long life. Extended EEG monitoring may identify the typical EEG abnormality when this is difficult to demonstrate in routine EEG records. The typical laughter has no specific correlate in the EEG and thus is probably not an epileptic manifestation. Regional cerebral blood flow studies were normal in the young patient (11 years of age) but in the older patient showed a reduced cerebral circulation, compatible with organic dementia.

Aged↗
PubMed1984

Transcutaneous CO2 monitoring and disordered breathing during sleep.

A new device for non-invasive monitoring of PCO2, the Hewlett Packard cutaneous capnometer, was studied. Seven patients with disordered breathing, three with sleep apnoea syndrome, and four with chronic respiratory insufficiency, underwent polygraphic sleep recording including non-invasive measurement of oxygen saturation and transcutaneous CO2 pressure (PtcCO2). Two of the apnoea patients showed a modest increase in PtcCO2 with sleep. The patients with respiratory insufficiency showed larger increase in PtcCO2 and more profound hypoxemia during sleep. When the patients with respiratory insufficiency received oxygen (0.3-0.5 l/min) via nasal prongs, the sleep induced hypoxemia almost vanished but their PtcoCO2 increased. Nocturnal hypoventilation probably increased the effectiveness of the low oxygen supply, thus counteracting hypoxemia during periods of hypoventilation. The capnometer was easy to apply and the patients felt no discomfort. It promises to be a useful method for detection of hypercapnia indicating hypoventilation in patients with disordered breathing.

Aged↗
PubMed1983

Persistent vegetative state with high cerebral blood flow following profound hypoglycemia.

A persistent vegetative state (severe dementia) developed in a 30-year-old man following hypoglycemic coma. Despite the poor clinical outcome, sensory evoked response recovered between 6 and 34 months after the insult. The cerebral blood flow level at rest after 34 months was slightly above the normal range. This finding contrasts with the low cerebral blood flow regularly reported in patients who are comatose or stuporous following severe brain hypoxia-ischemia.

Adult↗
PubMedDate not supplied

Cerebral hemodynamic changes and electroencephalography during carotid endarterectomy.

Some patients undergoing endarterectomy for occlusive carotid artery disease run a risk of brain ischemia during cross-clamping of the artery. The present study of 15 patients was undertaken to evaluate changes in cerebral blood flow (CBF), as measured with an intravenous (IV) tracer (133Xenon) technique, and to relate CBF changes to changes in the electroencephalogram (EEG). CBF was measured before and after induction of anesthesia, during cross-clamping of the carotid artery, after release of the clamps, and at 24 hours after the operation. All the patients were anesthetized with methohexitone, fentanyl, and nitrous oxide and oxygen. EEG was continuously recorded during the operation. Carotid artery shunts were not used. In 8 patients, cross-clamping of the carotid artery did not influence the EEG. In this group of patients, induction of anesthesia caused a 38% decrease in CBF, which presumably reflects the normal reaction to the anesthetic agent given. There were no further changes in CBF during cross-clamping. In 7 patients, the EEG showed signs of deterioration during the intraoperative vascular occlusion. In these patients, anesthesia did not cause any CBF change, whereas cross-clamping the artery induced a 33% decrease in CBF. In individual patients, the severity of EEG changes correlated with the decrease in CBF. The absence of a change in CBF by anesthesia and a decrease due to cross-clamping of the carotid artery may be explained by the presence of a more advanced cerebrovascular disease and an insufficiency to maintain CBF during cross-clamping.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMedDate not supplied

Regional cerebral blood flow distributions in normal volunteers: dynamic susceptibility contrast MRI compared with 99mTc-HMPAO SPECT.

PURPOSE: Relative regional cerebral blood flow (rCBF) at rest was measured in 44 volunteers using both dynamic susceptibility contrast (DSC) MRI and (99m)Tc-HMPAO SPECT on the same day. METHOD: In MRI, a Gd-DTPA-BMA contrast agent bolus (0.3 mmol/kg body wt) was monitored with a simultaneous dual FLASH pulse sequence (time resolution 1.5 s). MRI-based rCBF images were calculated by singular value decomposition-based deconvolution of the measured tissue concentration-time curve with an arterial input function from a small artery within the imaging slice. In the SPECT investigation, 900 MBq of (99m)Tc-HMPAO was injected intravenously. Relative rCBF in gray matter in the thalamus and in frontal white matter was determined. RESULTS: The ratio of relative rCBF in gray matter to relative rCBF in white matter was 2.21 +/- 0.57 using MRI and 2.24 +/- 0.54 using SPECT (mean +/- SD). CONCLUSION: Relative rCBF maps from DSC MRI and (99m)Tc-HMPAO SPECT showed good agreement, and the MRI-based rCBF ratio correlated with the corresponding SPECT-based ratio (r = 0.79, p < 0.0000006).

Adult↗