P REPORTS have accounted for autoregulation of renal blood flow on the basis of increases in extravascular pressure" which act as compressing forces on the renal vascular bed. Renal tissue pressures ranging between 2 and 120 mm. Hg have been found to approximate closely the pressures in deep renal veins of a caliber exceeding 0.73 mm. diameter. As a result of these investigations, the concept h...

Although many organs maintain constant blood flow despite changes in perfusion pressure, autoregulation in the total systemic circulation has only been reported in animals after destruction of the central nervous system. The present study examined the role of the baroreceptors in this autoregulatory response in open-chest dogs anesthetized with chloralose-urethane. Cardiac output was varied ove...

Cerebral autoregulation adjusts cerebrovascular resistance in the face of changing perfusion pressures to maintain relatively constant flow. Results from several studies suggest that cardiac output may also play a role. We tested the hypothesis that cerebral blood flow would autoregulate independent of changes in cardiac output. Transient systemic hypotension was induced by thigh-cuff deflation...

BACKGROUND Although inhalation anesthetic agents are thought to impair cerebral autoregulation more than intravenous agents, there are few controlled studies in humans. METHODS In the first group (n = 24), dynamic autoregulation was assessed from the response of middle cerebral artery blood flow velocity (Vmca) to a transient step decrease in mean arterial blood pressure (MABP). The transient...

Principles of Cerebral Autoregulation Testing Cerebral Autoregulation (CA) is the intrinsic ability of the brain to maintain stable cerebral blood flow (CBF) while mean arterial blood pressure (MAP) and cerebral perfusion pressure (CPP) are changing. It constitutes a regulatory mechanism to provide metabolic substrates under physiological and pathological conditions, for instance after neuro-tr...

The goal of this study was to elucidate the association between the development of periventricular white matter lucency and autoregulation of cerebral blood flow in hypertensive patients through the arteriovenous oxygen saturation difference method. We studied 51 hypertensive patients who had previously suffered from minor strokes (lacunar infarction, 43; deep basal minor hemorrhage, 8). Patien...

We examined whether nitric oxide (NO) generated from neuronal NO synthase (nNOS) contributes to the reduced ability of the newborn to autoregulate retinal blood flow (RBF) and choroidal blood flow (ChBF) during acute rises in perfusion pressure. In newborn pigs (1-2 days old), RBF (measured by microsphere) is autoregulated over a narrow range of perfusion pressure, whereas ChBF is not autoregul...

Autoregulation of cerebral (CBF) and cerebellar blood flow (CeBF) was studied before, during and after acutely induced cerebral ischemia in spontaneously hypertensive rats. Cerebral ischemia of the supratentorial portion was induced for one hour by bilateral carotid artery ligation (BCL). The animals were artificially ventilated and the blood flow was measured with a hydrogen clearance techniqu...

BACKGROUND AND PURPOSE We compared relative changes in middle cerebral artery velocity and internal carotid artery flow during autoregulation testing to test the validity of using transcranial Doppler recordings of middle cerebral artery velocity to evaluate cerebral autoregulation in humans. METHODS Seven human volunteers had dynamic autoregulation tested during surgical procedures that incl...

OBJECT The object of this study was to investigate whether a failure of cerebrovascular autoregulation contributes to the relationship between age and outcome in patients following head injury. METHODS Data obtained from continuous bedside monitoring of intracranial pressure (ICP), arterial blood pressure (ABP), and cerebral perfusion pressure (CPP = ABP - ICP) in 358 patients with head injur...