Blood perfusion studies in cerebrovascular accidents,hypertensives,diabetics and healthy controls

Abstract

The objective of this study was to compare peripheral microvasculature status non-invasively in heal thy controls and recent stroke cases having history of hypertension. The high risk group of patients viz. hypertensives and diabetics were also included in the study. We used a combination of Laser Doppler flowmetry and reactive hyperemia test along with parallel estimation of blood viscosity factors such as, hematocrit, red cell rigidity, plasma viscosity and biochemical parameters. Reacti ve hyperemia was induced by arterial occlusion for 3.5 min. duration in the forearm of all four groups. Basal skin perfusion before inducing reactive hyperemia (Per_bas), did not vary significantly in any group. However, the increased maximum skin perfusion after inducing reactive hyperemia (Per_max) in the case of stroke and hypertension were found significantly different (p<0.05) as compared to healthy controls. The recovery time (Trh) i.e., time taken for induced maximum perfusion to return to basal value, were significantly less in stroke (p<0.05) and hypertensive groups (p<0.001) whereas it was significantly high in diabetic group (<0.02) as compared to healthy controls. A reduced Trh may be considered as an indicative of myogenic dysfunction while a delayed Trh may be regarded as an indicative of metabolic dysfunction. Further the calculation of two dimensionless microcirculatory parameters reactive hyperemia perfusion index (RHPI) and reactive hyperemia time index (RHTI) were proposed for use in preliminary screening of the degree of myogenic or metabolic dysfunction in various disease conditions. The correlation of above mentioned parameters with blood viscosity factors were discussed.