View clinical trials related to Vasoconstriction.
Filter by:Obstetric hemorrhage is one of the leading causes of maternal death worldwide. One of the challenges in management of hemorrhage is that young, healthy women compensate for blood loss via peripheral vasoconstriction, so they maintain their blood pressure and heart rate at normal levels even after experiencing significant blood loss. By the time vital sign abnormalities appear, interventions must be performed extremely rapidly to avoid organ damage and maternal death. Clinical methods of estimating blood loss in real time, such as visual estimation, are notoriously unreliable, and changes in laboratory testing such as hemoglobin levels lag hours behind actual blood loss. A tool which can detect and quantify blood loss in real time, before vital sign changes occur, has the potential to allow for earlier mobilization of resources and intervention in these cases, thus saving lives. This device is meant to detect changes in skin blood flow which reflect vasoconstriction. The investigators believe that this device, therefore, has the potential to be able to detect and quantify blood loss in real-time. However, as this novel device has never been used for this purpose, before undertaking a large clinical trial, the investigators feel it is necessary to perform a pilot study to assess the feasibility and tolerability of this device. The investigators plan to test this by asking 50 patients undergoing planned cesarean section to wear the device during their surgery. The device will collect skin perfusion measurements during the surgery, which will not be available to the operating team. The patients will also be asked to complete a survey regarding their experience wearing the device. The investigators will use this information to ensure that the device is transmitting interpretable data, that patients feel the device is tolerable during surgery, and to ensure that the device can be used in the operating room without any unforeseen logistical challenges which would need to be addressed in planning a larger trial. The investigators will perform a preliminary comparison of sensor readings to laboratory findings, to assist in planning a larger trial.
Acutely, during different bouts of passive stretching (PS), blood flow (Q ̇) and shear rate ( ) in the feeding artery of the stretched muscles increases during the first two elongations and then it reduces during the following bouts. This hyperemic response during the first two elongations is mediated by the local release of vasoactive molecules (e.g. nitric oxide, NO). This phenomenon disappears during the following elongations due to the NO and other vasoactive molecule depletion. The relaxation phase between stretching bouts, instead, is always characterized by hyperemia as results of stretch-induced peripheral resistances decrease. Whether chronic PS administration may influence vascular function is still a matter of investigation. The hypothesis is that repetitive PS-induced Q ̇ and changes may be an enough stimulus to provoke increments in NO bioavailability, thus improving vasomotor response.
Chronic kidney disease (CKD) is associated with a pro-oxidative and pro-inflammatory state, and this is thought to contribute to a decrease in vascular function leading to greater cardiovascular disease (CVD) risk. Curcumin supplementation has been shown to reduce oxidative stress and improve endothelial function at rest in healthy older humans, although the magnitude of this effect remains unknown during exercise in CKD. The primary aim of this proposal is to determine whether exercising blood flow and vasoconstrictor responsiveness are improved as a result of acute oral supplementation with curcumin in patients with CKD. We hypothesize that: 1) acute curcumin supplementation will increase steady state exercise blood flow, and 2) reduce vasoconstriction induced by an acute sympathetic stimulus (cold pressor test) CKD.
The aim of this study is to observe the mechanism of spreading vasoconstriction in human healthy gingiva. Epinephrine solution is applied on the attached gingiva in group "A" and on the surface of the tooth next to the ginvial sulcus in group "B". The different placement of the solution causes different effect in the microcirculation.
The overall goal of this study is to address fundamental questions regarding how the molecule acetylcholine interacts with the sympathetic nervous system to regulate blood flow and oxygen delivery to working skeletal muscle in young and older adults. With advancing age, blood vessels supplying active muscle lose their ability to override sympathetic constriction, which limits delivery of oxygen and results in fatigue. Findings from these studies will serve as the foundation for new strategies to improve regional blood flow regulation in older adults and clinical populations, which will increase quality of life and help to preserve functional independence.
Microcirculatory flow is subject to cyclic changes under the influence of heart rate, respiration, myogenic activity, neurogenic factors and endothelial factors. Microcirculatory oscillations (vasomotion) contribute significantly to tissue perfusion. Vasomotion analysis allowed to discriminate normoglycemic subjects, prediabetic subjects and diabetic subjects. Furthermore, changes in vasomotion can precede the emergence of global signs of microangiopathy complications in type 2 diabetes. In fact, few studies reported impaired vasomotion in type 2 diabetes with peripheral neuropathy. Vasomotion analysis after vasodilator (6-min walking test and hyperthermia) and after vasoconstrictor (foot lowering) stimulus could be an effective diagnostic tool to sharpen the diagnostic. Objectives and Methodology: to study vasomotion at baseline and after exercise, hyperthermia and foot lowering within 3 groups of patients: diabetic without peripheral neuropathy, diabetic with subclinical peripheral neuropathy and diabetic with peripheral neuropathy and one group of sex- age- and body mass index-matched healthy control subjects. All the subjects will benefit from a clinical, anthropometric, level of physical activity and biological evaluations. Type 2 diabetes participants will benefit from neuropathy evaluation. In addition, cutaneous microcirculation (perfusion and vasomotion) by means of Laser Doppler Flowmetry and Laser Speckle Imaging will be recorded at rest and after different stimuli (exercise, hyperthermia and foot lowering).
The aim of this double-blind randomized study will be to compare a fixed-rate prophylactic noradrenaline infusion to a fixed-rate prophylactic phenylephrine infusion during elective cesarean section under combined spinal-epidural anesthesia
The objective of this trial is to compare the vasoconstriction potential
Cardiovascular disease (CVD) afflicts nearly one-third of the adult population with all races and ethnicities represented in CVD prevalence. Unfortunately, a disparity exists such that the black population (BL) is disproportionately affected compared to other groups, including the white population (WH). While the underlying cause of this disparity is multifactorial, vascular dysfunction (i.e., impaired vasodilation and/or augmented vasoconstriction) is a key contributor. As has been previously observed, BL exhibit a heightened vasoconstrictor response to both pharmacological (e.g., alpha-adrenergic receptor agonists) and environmental (e.g., cold pressor test) stimuli compared to their WH counterparts. Additionally, reactive oxygen species (ROS) and the subsequent reduction in nitric oxide (NO) bioavailability may partially mediate this response. Our laboratory has recently observed (UTA IRB 2016-0268) that the small blood vessels in the skin (cutaneous microvasculature) in BL, but otherwise healthy individuals, produce an impaired blood flow response to local heating when compared to age-, body mass index (BMI)-, and gender-matched WH. However, pre-treatment of the cutaneous microvasculature with various antioxidants abolishes this skin blood flow difference. These antioxidant drugs inhibit possible sources of ROS, which, as mentioned, maybe mediating the heightened vasoconstrictor response in BL. However, this has not been investigated in this population and thus remains unknown. Therefore, the purpose of this study proposal is to test the following hypotheses: 1) BL will have a greater reduction in cutaneous blood flow in response to local administration of Norepinephrine (alpha1-adrenergic and alpha 2-adrenergic receptor agonist) relative to WH. 2) This greater reduction in the BL population will be related to elevated oxidative stress and subsequent reduction in bioavailability of the potent vasodilator Nitric oxide.
The goal of this study is to examine possible mechanisms of heightened vasoconstriction in Black/African American men and women as possible links to the elevated prevalence of cardiovascular dysfunction and disease. The main targets in this study are sources of oxidative stress