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Biomedical subjects

D Menon

Publications and source records attributed to D Menon.

At least 55 records · Page 3Linked to original sources
PubMed1995

The development of a health technology assessment program. The case of Alberta.

Canada comprises 10 provinces and 2 territories. The Constitution assigns responsibility for the provision of health services in the provinces to provincial governments. Over the past 5 years, provincial governments have identified technology assessment as a priority. This paper describes an initiative taken by the government of the province of Alberta to develop a health technology assessment program for that province.

Alberta↗
PubMed1995

An observational study of near-infrared spectroscopy during carotid endarterectomy.

Near-infrared spectroscopy was used to monitor changes in the cerebral oxygenation state in 13 patients during carotid endarterectomy. Variations in the levels of the chromophores (oxygenated hemoglobin (HbO2), deoxygenated hemoglobin (Hb), and oxidized cytochrome (CytO2)), and the total hemoglobin content (tHb) were compared with changes in middle cerebral artery flow velocity measured using transcranial Doppler ultrasonography. Of eight patients who showed a fall in flow velocity on application of the internal carotid artery cross-clamp, seven demonstrated a rapid and closely correlated fall in HbO2 signal, and an increase in Hb. Levels of CytO2 and tHb remained unchanged. During endarterectomy, recovery of the HbO2 and Hb levels toward preclamp baseline values occurred in three of these patients. Intraoperative shunts accelerated recovery of HbO2 and Hb signals in two of three individuals. Release of the internal carotid cross-clamp resulted in a rapid increase in HbO2 and decrease in Hb signal in those patients in whom spontaneous recovery had not occurred; in five instances, a hyperemia evolved with raised flow velocity and HbO2 to above baseline values. Cross-clamping and subsequent reperfusion of the external carotid artery had no effect on any parameter measured. The authors conclude that near-infrared spectroscopy can register changes in cerebral oxygenation during carotid endarterectomy without significant contamination from extracranial tissues.

Adult↗
PubMed1994

Medical device regulation in Canada: direction for change.

The medical device regulatory programme in Canada was first instituted in 1975. Recently this programme underwent a review. This paper first describes the system of regulations as it has been administered by the Health Protection Branch of the government of Canada. The rationale for the establishment of the Medical Devices Review Committee, its deliberations and report are then discussed. Finally, the paper examines measures currently being taken to implement recommendations that will take the regulatory programme for medical devices in Canada into the twenty-first century.

Canada↗
PubMed1994

Diffusion of laparoscopic cholecystectomy in Canada.

Patterns of the diffusion of laparoscopic cholecystectomy in Canadian hospitals were determined by a telephone survey of 153 randomly selected hospitals over two years. Results were analyzed by region, hospital size, and type of hospital. Laparoscopic cholecystectomy has diffused very quickly compared with other technologies, before any comprehensive evaluation to consider its potential impact could take place.

Canada↗
PubMed1994

Magnetic field strength issues in magnetic resonance imaging.

The authors review the current status of magnetic resonance imaging (MRI) with respect to magnetic field strength. The discussion covers the practical aspects of MRI--safety, throughput and costs--as well as the clinical aspects as they are influenced by field strength. Data on the world distribution of MRI units of various field strengths are presented. Canada had the highest proportion of high-field units among the 11 countries or regions included in this comparison, probably because most Canadian MRI units are located in teaching hospitals, where they are used for both research and clinical work.

Costs and Cost Analysis↗
PubMed1993

Technology assessment and biomedical engineering education.

Technology assessment is research that is intended to help decisionmakers deal with the development, acquisition and utilisation of healthcare technologies. Healthcare professionals now recognise the need for assessment information in decisionmaking. Among these professionals are biomedical and clinical engineers who need to manage technology assessment activities and use assessment information appropriately. It is imperative therefore that proper educational programmes be developed to prepare engineers for a broader role in healthcare. The paper elaborates on aspects of technology assessment and the need for training of engineers in specific concepts and principles.

Biomedical Engineering↗
PubMed1984

A method for measurement of arterial concentration of cerebral blood flow tracer for autoradiographic experiments.

A new method for continuous monitoring of the concentration of 131I-labelled iodoantipyrine during an autoradiographic local cerebral blood flow (LCBF) experiment is described. During infusion of iodoantipyrine, radioactivity in an external femoral arteriovenous loop is monitored by a scintillation detector. Data is collected with a variable time base, and the arterial activity curve displayed visually in its entirety. The main advantage of this method is that there is no blood loss. It will therefore be of particular importance in dual-label autoradiography. This method can also be used for other gamma-emitting blood flow tracers, e.g. 123I-iodoantipyrine.

Animals↗
PubMed1984

Influence of the input function on the calculation of the local cerebral metabolic rate for glucose in the deoxyglucose method.

We describe here a modification of Sokoloff's deoxyglucose method which requires fewer blood samples but does not diminish accuracy. To calculate the local cerebral metabolism for glucose (LCMRglu), the input function containing the initial peak must be known. This requires many blood samples for accurate definition. To estimate the influence of the peak on the LCMRglu, a dummy input function was generated by extrapolating the data points after 2 min back to 0 min. Next, a biexponential curve, fitted to a reduced number of samples, was applied for the input function. The error introduced into the LCMRglu by using these different approximations was analyzed with an error function derived from an operational equation. The results indicate that the error of LCMRglu caused by neglecting the peak is less than 3%. Furthermore, the error of LCMRglu resulting from use of the biexponential approximation is a function of LCMRglu: the error decreases as the LCMRglu increases and remains at less than 3% even when only seven data points are used (half the usual number of the standard method). Finally, the LCMRglu was calculated by the biexponential curve-fitting, using the experimental data, and compared with that calculated by Sokoloff's computer program. Both methods were in good agreement. This modified method offers great advantage for simultaneous measurement of CMRglu, CBF, and other physiological parameters by means of the multiple tracer autoradiographic technique in the small laboratory animal.

Animals↗
PubMed1981

Effect of therapy on cerebral blood flow following aneurysm surgery.

The authors report on a patient with a ruptured anterior communicating aneurysm treated surgically on the day following her subarachnoid hemorrhage (SAH). Repeated measurements of cerebral blood flow (rCBF) were carried out using the inhalational Xenon 133 method. Dramatic acute increases in rCBF occurred, coincident with clinical improvement, following mannitol, CSF drainage and dopamine. Later, further elevation to normal levels occurred following ventriculoperitoneal shunting.

Adult↗
PubMed1981

Ventricular size and cerebral blood flow following subarachnoid hemorrhage.

The relationship among ventricular size on computed tomography (CT), the clinical status of the patient, and cerebral blood flow alterations in subarachnoid hemorrhage is examined. Fifty patients with subarachnoid hemorrhage underwent a total of 71 cerebral blood flow measurements and 115 CT scans. Flow was measured noninvasively using 133Xe inhalation. It is demonstrated that increasing ventricular size is accompanied by clinical deterioration and also by a reduced flow. The effects of the various lesions (as demonstrated by CT) on cerebral perfusion are examined. Of the 23 patients scanned 5 days or less after hemorrhage, 12 had subarachnoid blood visible on the scan. These 12 had flows that averaged 20% lower than the other 11 when examined 6 to 17 days after the hemorrhage. Ventricular enlargement is more prevalent in the first week after the hemorrhage than in the second. Also, blood flow is maximally reduced at the end of the first week following hemorrhage.

Adult↗