[Monitor system for local cerebral blood flow. Experimental study of CBF measurement by thermal diffusion using a flow probe with a Peltier stack]

Development of noninvasive measurement of peripheral circulation and its medical application

Surveys were carried out on tissue blood flow measurement based on the thermal diffusion method and on the assessment of peripheral circulatory function using photosensors.Regarding the thermal diffusion method, first noninvasive measurement using a Peltier stack was carried out. Then, measurements using a thermal clearance curve at various temperatures were performed.For noninvasive measurement of the mechanical properties of peripheral arteries using photosensors, the author determined the vascular volume ratio and/or the relative vascular volume.For clinical application in field studies, it is necessary to develop an apparatus with which absolute evaluation of the intravascular volume can be carried out using the blood volume around the unit volume as an indicator. Therefore, an apparatus that removes a signal constituent from tissue other than the blood using two-wavelength photosensors is required.If a noninvasive method to accurately measure the intravascular volume is established, changes in the mechanical properties of the peripheral arteries that correspond to functional and organic changes in the normal response can be observed more directly. Moreover, quantitative assessment of peripheral circulatory function will become possible, and diagnosis of the severity of peripheral circulatory disorders will be facilitated.

Variations in regional cerebral blood flow investigated by single photon emission computed tomography with technetium-99m-d, l-hexamethylpropyleneamineoxime = l-h during temporary clipping in intracranial aneurysm surgery: preliminary results

Single photon emission computed tomography with technetium-99m-d, l-hexamethylpropyleneamineoxime was used to assess variations in regional cerebral blood flow during temporary clipping in the course of intracranial aneurysm surgery and during the postoperative period in 20 patients, 14 of whom underwent temporary clipping. Of these 14 patients (Group A), 9 had aneurysms of the anterior communicating artery, 2 had aneurysms of the middle cerebral artery, and 3 had aneurysms of the carotid siphon. Temporary clips were applied, according to the site of the lesion, on A1, on the trunk of the middle cerebral artery, or on the trunk of the internal carotid artery. The occlusion time ranged from 2 to 31 minutes. The six patients who did not undergo temporary clipping served as controls (Group B), as follows: three had aneurysms of the posterior communicating artery, one of the anterior communicating artery, one of the middle cerebral artery, and one of the internal carotid artery. All patients were investigated with cerebral single photon emission computed tomography preoperatively, perioperatively, and postoperatively. In all the patients of Group A, the preliminary results of the study show a sharp fall in the perfusion of the territories of the temporarily clipped parent vessel and practically a complete recovery within 2 to 7 days of surgery, with no significant neurological symptoms. No similar disturbance of perfusion was found in the patients of Group B.