View clinical trials related to Cerebrovascular Circulation.
Filter by:Sedentary behaviour of healthy subjects may have a detrimental impact on cerebral blood flow as well as cognitive measures related to mood and alertness. In this study we focus on the impact of leaving the desk to consume a cup of tea at regular intervals during a sedentary working day.
Cerebral autoregulation (CA) is the mechanism by which the brain vasculature maintains constancy of cerebral blood flow (CBF). Reliable direct measurements of CBF at different blood pressure levels are difficult because they are invasive and time-consuming. This type of measurement to quantify CA is generally referred to as static cerebral autoregulation (sCA). Alternatively, it is possible to measure CA indirectly from blood pressure oscillations. Dynamic cerebral autoregulation (dCA) measures how quickly the cerebral vessels react to a change in blood pressure to normalize CBF. Since the introduction of transcranial Doppler ultrasound (TCD), it has become possible to estimate CBF velocity relatively easy, which in turn correlates well with CBF changes. This method is widely used to quantify dCA. However, it is not clear how sCA correlates with dCA over a range of physiologic mean blood pressure (MBP). It is important to compare different methods of assessing CA, because impaired CA may result in increased risk of perioperative complications such as stroke. In this study, the investigators were interested in establishing the relationship between sCA and dCA during surgery under general anesthesia. The investigators aim to compare these methods during propofol and sevoflurane anesthesia.
The investigators hypothezised that CO2-reactivity of cerebral vessels is affected by systemic non-pulsatile blood flow. Patients undergoing elective cardiac surgery with CPB were enrolled in this prospective case control study. Blood flow velocity in the middle cerebral artery as well as regional cerebral oxygenation was determined during step changes of PaCO2 between 30, 40, and 50 mmHg. Measurements were conducted intraoperatively during non-pulsatile as well as postoperatively after admission to the ICU under pulsatile blood flow.
The current study would investigate the effects of a single dose of darolutamide and enzalutamide compared with placebo and compared to each other on human brain blood flow using arterial spin labeling magnetic resonance imaging (ASL-MRI), a non-invasive MRI technique. The change in cerebral blood flow was an indirect measure of brain penetration. The risk of drug-associated CNS-related adverse events was likely to be correlated with the concentration of the drug in the brain. In contrast to enzalutamide, preclinical studies of darolutamide indicate that its brain penetration was much lower. The aim of this study was to determine whether there was a difference between darolutamide and enzalutamide compared to placebo in cerebral blood flow and thus in brain penetration.
Selective antegrade cerebral perfusion (sACP) during aortic arch surgery in hypothermic circulatory arrest (HCA) is an established method for intraoperative neuroprotection. Although sACP is established as a beneficial method to reduce secondary neurological side effects due to brain-malperfusion, there are several parameters like sACP flow rate, perfusion pressure or temperature of the perfusate, where the optimal values remain unclear. The flow rate of the sACP-perfusate is increased according to center-specific standard-procedures. The optimal sACP flow rate, monitored by near infrared spectroscopy (NIRS), is to be investigated in this single center clinical prospective observational study. 40 Patients are enrolled over an estimated period of 14 months.
The present study is an explorative analysis of the relationship between cerebral blood perfusion and oxygenation and lung mechanical variables at different ventilator settings. It is a safety study excluding patients with severe lung injury or brain edema.
Despite improvements in management, mortality in severe traumatic brain injury (TBI) remains 25% and only 40% of patients survive without major handicap. Medical/surgical interventions aim to maintain adequate brain perfusion, which is critically dependent on cerebral perfusion pressure (CPP); calculated as the difference between mean arterial pressure (MAP) and intracranial pressure (ICP). Current guidelines aim for a CPP above 50 mmHg, based on population means. However, this 'one size fits all' approach is flawed, because the relation between CPP and brain perfusion varies between individuals. Further, this approach takes no account of autoregulation, a key protective mechanism that maintains cerebral perfusion despite CPP fluctuations. Autoregulation is variably preserved following TBI, and there are large between patient variances in the 'optimal' CPP (CPPopt) at which autoregulation operates best. Individual CPPopt can be retrieved automatically by plotting autoregulation data against the CPP over a certain time window. The investigators have shown that maintenance of CPP close to CPPopt is associated with improved outcomes. These data pose the hypothesis that optimisation of management in individuals may be achieved by using the zone of optimal autoregulation as a basis for defining individualised CPP targets. The investigators propose, together with collaborators in the CPPopt study group (Maastricht, Cambridge, Leuven and Aachen) to set up a pilot (multicenter) feasibility study to develop a protocol for a definitive outcome randomized controlled trial (RCT). This study aims to develop protocols for CPPopt guided critical care, and show that they maintain patients closer to their optimum perfusion levels than standard protocols which keep above a population CPP threshold of 60 mmHg. Hence, the main objective is to offer clinicians monitoring and therapy algorithms that achieve individualized optimal CPPopt targets and potentially improve TBI outcome.
The overall goal of observational study is to examine the age-related and habitual exercise training status-related differences in structural and functional changes in the human brain, detected by magnetic resonance (MR) imaging.
Cerebral vasodilator responses to CO2 will be measured in young healthy adults, healthy sedentary older adults, and healthy exercise trained older adults. This variable will be examined before and after administering the cyclooxygenase inhibitor indomethacin, which has been shown to blunt cerebral vasodilator responses. In addition, the investigators will examine these counter-regulatory hemodynamic mechanisms to hypoperfusion caused by indomethacin.
Nitrate provides the body with an alternative source of Nitric Oxide which plays a large role in promoting blood flow and reducing blood pressure. Nitrate supplementation with vegetable/fruit juice has recently been shown to reduce blood pressure and reduce energy expenditure during low intensity exercise. Such findings combined with the previously known biological effects of nitric oxide would suggest that nitrate supplementation would also impact on blood flow. The aim of this study is to examine the effects of dietary nitrate supplementation via vegetable/fruit juice drink on cerebral (brain) blood flow (using Near Infrared Spectroscopy).