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Biomedical subjects

D Menon

Publications and source records attributed to D Menon.

64 records · Page 4Linked to original sources
PubMed1980

Effects of venesection on cerebral function in chronic lung disease.

Regional cerebral blood flow measurements and neuropsychological testing were conducted before and after venesection on 6 patients with polycythemia secondary to chronic obstructive pulmonary disease. Venesection resulted in lowered viscosity and hematocrit, and an accompanying improvement in cerebral perfusion and mental function. Blood flow was significantly increased in the left cerebral hemisphere following phlebotomy, and there was significant improvement in sensory/mental function. Cerebral function would appear to be related to blood flow alterations influenced by the viscosity of the blood.

Adult↗
PubMed1980

The relationship between cerebral blood flow and the EEG in normals.

Using the Xe133 inhalation technique, measurements of the blood flow to the left and right parietal and temporal regions of the cerebrum were obtained in 5 healthy individuals while simultaneously recording their EEGs. Up to 3 measurements were obtained from each of the subjects the first while they were mentally at rest and the others while they were engaged in prescribed forms of mental activity. Relationships between the measured blood flow through grey matter, initial slope index, relative grey weight, percent grey flow and power in the delta, delta-theta, alpha, beta and gamma rhythms of the EEG were examined. The results showed that for the subject group as a whole there was a strong correlation between the power present in the low frequency components of EEG and the grey flow and relative grey weight parameters of blood flow. On an individual basis, the observed relationships were highly variable particularly at high flow rates and at low relative grey weights, but became much more definitive at low flows and high weights. The results as they relate to previous work of this kind are discussed.

Adult↗
PubMed1980

Effects of secondary polycythemia on cerebral blood flow in chronic obstructive pulmonary disease.

Cerebral blood flow was measured before and after venesection in 6 patients with chronic obstructive pulmonary disease and secondary polycythemia. The hematocrit was decreased from a mean of 59.6 to 43.9%, and whole blood viscosity was decreased by 35%. The supratentorial blood flow increased 78.2% (p < 0.005) after venesection; subtentorial flow also increased, but not significantly. The improvement in cerebral blood flow appeared to be related to a decrease in blood viscosity, because pulmonary function and arterial blood gases did not change significantly. There was subjective improvement in all patients, and this improvement might have been due to the increased supratentorial blood flow.

Aged↗
PubMed1979

Evaluation of cerebral blood flow in arteriovenous malformations by the xenon 133 inhalation method.

Fifteen regional cerebral blood flow studies (rCBF) were conducted on 14 patients with arteriovenous malformations (AVM). Only one patient was studied at the time of a hemorrhage. None of the patients were operated upon. All patients had angiographically demonstrated lesions. All the CT scans performed demonstrated the lesions. rCBF was increased in the involved hemisphere compared to the non-involved hemisphere and the difference was greater when the malformations were superficial. There was a higher incidence of high flow regions in the involved hemisphere of patients with AVMs compared to our normal control group and patients with subarachnoid hemorrhage (SAH) from aneurysms. Flow rates within the involved hemisphere demonstrated abnormal distributions and greater variability than normals. Some peaks previously demonstrated in the intra-arterial flow studies are not apparent using the inhalation method. This non-invasive technique has a potential to provide additional useful information on the natural history of this disorder.

Adult↗
PubMed1978

Regional cerebral blood flow in patients with aneurysms: estimation by Xenon 133 inhalation.

Seventy six regional cerebral blood flow (rCBF) studies were conducted on 32 patients who had a total of 39 aneurysms. Twenty three of these patients were studied pre- and post-operatively. Normal values were obtained from a control group of 33 subjects, each of whom underwent one rCBF study. Flow was reduced following subarachnoid hemorrhage (SAH); it increased significantly post-operatively. Lower flows were associated with poorer clinical grades. There was a greater variation in regional distribution of flow immediately following SAH than in normals or in patients who had recovered from the acute phase. rCBF studies correlated with CT scans demonstrated that a progressive increase in ventricular size was accompanied by a progressive reduction in flow. In addition, intraventricular hemorrhage (IVH) was associated with a significant reduction in cerebral blood flow (CBF). No significant correlation between CBF and spasm was demonstrable.

Adult↗
PubMedDate not supplied

Pharmaceutical cost control in Canada: does it work?

Governments in Canada have instituted mechanisms intended to control drug prices. These include the establishment of a semi-judicial body by the federal government to control factory-gate prices and of various measures at the provincial level, such as formulary management, use of generics, reference-based pricing, price freezes, and limits on markups. To a large extent, these measures have been effective in price control. Total drug spending in the country continues to rise, however; clearly, mechanisms other than price controls will need to be developed if drug spending is to be better managed.

Canada↗
PubMedDate not supplied

Inter-provincial variation in government drug formularies.

In Canada, coverage for ambulatory prescription drug expenditures is provided to some groups by provincial drug plans through a provincial formulary. Little is known about the drugs provincial formularies give access to. We report the variation in availability of new drug molecules (NDM) across provincial formularies. We identified 108 NDM approved in Canada between 1991 and 1998. From each drug plan bulletin or formulary, we abstracted names of NDM listed as per 15 January 1999. We compared the level of listing across provinces using kappa coefficients. In the Quebec, BC, Manitoba and Saskatchewan formularies, more than 70% of the NDM were listed. In four provinces, this proportion was lower than 50%. In general, the agreement between formularies was poor. There is a wide variation across provinces in terms of NDM listed in the formularies. This variation reflects inter-provincial differences in the way drugs are selected for coverage.

Canada↗