Stroke; a journal of cerebral circulation
-
The pressure-flow velocity relationship in the cerebral circulation is characterized by the critical closing pressure (CCP), which is the pressure at which flow ceases, and the linear slope of a plot between pressure and flow velocity. It has been suggested, but not validated, that CCP can be determined from arterial blood pressure (ABP) and transcranial Doppler (TCD) recordings during the cardiac cycle. We studied a group of patients in whom ventricular fibrillation (VF) was induced. The time interval before defibrillation enabled calculation of CCP from data in which flow approached zero. These estimates were compared with values calculated before and after fibrillation and during regular heartbeats. ⋯ CCP can be accurately estimated from regular heartbeat data and is an important factor in regulation of the cerebral circulation.
-
Circulating blood cells have been implicated in the pathogenesis of cerebral ischemia/reperfusion (I/R) injury and stroke. The objective of this study was to define the magnitude and molecular determinants of the platelet- and leukocyte-endothelial cell adhesive interactions induced by I/R in the mouse brain. ⋯ These findings indicate that I/R promotes the adhesion of both platelets and leukocytes in cerebral venules, with the accumulation of adherent leukocytes preceding the recruitment of platelets. Both P-selectin and ICAM-1 contribute to the inflammatory and prothrombogenic state induced by cerebral I/R.
-
Clinical Trial Controlled Clinical Trial
Effect of carotid endarterectomy on primary collateral blood flow in patients with severe carotid artery lesions.
In patients with severe obstruction of the internal carotid artery (ICA), it is recognized that the preoperative failure to visualize collaterals of the circle of Willis increases the risk of hemispheric ischemia before, during, and after carotid endarterectomy (CEA). The purpose of the present study was to assess the effect of CEA on the anatomy and function of the circle of Willis. ⋯ CEA reduces the caliber of compensatory collateral channels to normal levels by MR angiography measurements in the presence of severe unilateral stenosis; when the opposite side is occluded and the stenosis is removed ipsilaterally, a greater amount of compensatory collateral circulation can be measured on both the occluded side and the fully opened side.
-
Clinical Trial
Neither arm nor face warming reduces the shivering threshold in unanesthetized humans.
Hand warming and face warming, combined with inhalation of heated air, are reported to suppress shivering. However, hand or face temperature contributes only a few percent to control of shivering. Thus, it seems unlikely that manipulating hand or facial skin temperature alone would be sufficient to permit induction of therapeutic hypothermia. We tested the hypothesis that focal arm (forearm and hand) warming or lower facial warming, combined with inhalation of heated and humidified gas, only minimally reduces the shivering threshold (triggering core temperature). ⋯ Focal arm or face warming did not substantially reduce the shivering threshold in unanesthetized volunteers. It thus seems unlikely that these nonpharmacological modalities will substantially facilitate induction of therapeutic hypothermia.