View clinical trials related to Vasoconstriction.
Filter by:This study aims to investigate sex differences in blood pressure control associated with exposure to acute hypoxia (low oxygen), and short term acclimatization to hypoxia at high altitude.
The purpose of this project is to determine if hyperinsulinemia attenuates sympathetic nervous system-mediated vasoconstriction in the human leg.
The overall goal of this project is to better understand the effect of intermittent hypoxia (IH) on sympathetic neuronal discharge patterns in humans, as well as mechanisms that mediate persistent sympathoexcitation with IH.
This study aims to investigate sex differences in blood pressure control associated with exposure to acute hypoxia (low oxygen), and short term acclimatization to hypoxia at high altitude.
The CarMA (Carbon Monoxide and Altitude) Study aims to observe the vascular effects of carbon monoxide exposure at low and high altitudes.
This will be a randomized study aiming at investigating the combination of a norepinephrine infusion and colloid preloading versus the combination of a norepinephrine infusion and crystalloid co-loading for the prevention of maternal hypotension during elective cesarean section
This will be a double-blind randomized study, aiming at investigating a fixed rate phenylephrine infusion versus a fixed rate norepinephrine infusion versus placebo in combination with co-hydration with colloids for the prevention of maternal hypotension in elective cesarean section
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.
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.