Active clinical trials for "Unconsciousness"

Loss and recovery of consciousness during propofol anesthesia seem to be mediated by different mechanisms beyond the actual effect-site concentration of anesthetic drug. This eventual difference between dose response curves for loss of consciousness (LOC) and for recovery of consciousness (ROC) beyond hysteresis has received the name of neuronal inertia. We performed a volunteer-study comparing LOC and ROC curves during a slow, steady-sate, stepped target controlled infusion of Propofol. Our hypothesis is that, at steady-state conditions between plasma an effect-site concentration, there is still going to exist a difference between LOC and ROC, demonstrating the existence of neuronal inertia.

Iatrogenic hypoglycemia is the most frequent acute complication of insulin therapy in people with type 1 diabetes (T1DM). Recurrent hypoglycemic events initiate a process of habituation, characterized by suppression of hypoglycemic symptoms, eventually leading to hypoglycemia unawareness, which creates a particularly high risk of severe hypoglycemia. Recent evidence suggest a pivotal role for (brain) lactate in the pathogenesis of hypoglycemia unawareness. Indeed, exogenous lactate administration may preserve brain function and attenuate counterregulatory responses to and symptomatic awareness of hypoglycemia. It is unknown whether endogenous elevation of plasma lactate produces the same effects and whether such effects differ between patients with T1DM with and without hypoglycemia unawareness and healthy controls. Objective: To investigate the effect of elevated levels of endogenous lactate on brain lactate accumulation and on counterregulatory responses to, symptomatic awareness of and cognitive function during hypoglycemia in patients with T1DM with and without hypoglycemia unawareness and normal controls. Hypothesis: The investigators hypothesize first that endogenous lactate, when raised through high intensity exercise, preserves neuronal metabolism during subsequent hypoglycemia, which in turn will attenuate counterregulatory hormone responses, appearance of symptoms and deterioration of cognitive function. Second, the investigators posit that these effects will be augmented in patients with hypoglycemia unawareness compared to healthy subjects and T1DM patients with normal awareness as a consequence of greater transport capacity of lactate into the brain.

Purpose of this study is to investigate the mechanisms of action of hyperbaric oxygen therapy for persistent post-concussive symptoms after mild tramatic brain injury

This study will be a single-site, controlled, unblinded study at the University of Wisconsin to examine changes in the electroencephalogram during anesthesia and waking.

Iatrogenic hypoglycemia is the most frequent acute complication of insulin therapy in people with type 1 diabetes (T1DM). Recurrent hypoglycemic events initiate a process of habituation, characterized by suppression of hypoglycemic symptoms and lead to hypoglycemia unawareness, which in itself defines a particularly high risk of severe hypoglycemia. Recent evidence suggest a pivotal role for increased brain lactate transport capacity in the pathogenesis of hypoglycemia unawareness. However, there is uncertainty about the magnitude of this effect and whether such excess brain lactate is oxidizes as a glucose-sparing alternative energy source or acts as a metabolic regulator controlling brain glucose metabolism, oxygen consumption and cerebral blood flow. Objective: The primary objective of this study is to investigate the effect of hypoglycemia on brain lactate accumulation and regional cerebral blood perfusion in humans. The secondary objective is to assess whether this effect is a related to hypoglycemia unawareness or a consequence of T1DM per se. Hypothesis: The investigators hypothesize that hypoglycemia stimulates lactate transport over the blood-brain barrier leading to cerebral lactate accumulation and that this lactate accumulation is a function of prior hypoglycemic exposure frequency contributing to clinical hypoglycemia unawareness. Furthermore, the investigators expect that this effect of hypoglycemia on brain lactate accumulation is related to changes in cerebral blood flow (CBF).

Positron Emission Tomography (PET), Magnetic Resonance Imaging (MRI) and electroencephalography (EEG) studies will be carried out to reveal the neural correlates of consciousness. Consciousness of the subjects will be manipulated with anesthetic agents dexmedetomidine, propofol, S-ketamine and sevoflurane. One-hundred-and-sixty (160) healthy male subjects will be recruited to receive EC50 concentration of the anesthetic (40 dexmedetomidine, 40 propofol, 20 S-ketamine, 40 sevoflurane) or placebo (20) while being imaged for cerebral metabolic rate of glucose (CMRglu). Also genetic, immunological and metabolomics samples will be taken and analysed to find possible genetic factors explaining the variability in drug response and to find chemical fingerprints of acute drug effect.

The aim of this study is to validate that an effect compartment concentration for loss of consciousness (LOC) was varied according to different Keo value.

Memory priming under general anesthesia is a phenomenon of incredible interest in the study of consciousness and unconscious cognitive processing, and for clinical practice. However results from anesthesiological literature are divergent and methodologies vary. To overcome these limits, the present study aims at better defining the phenomenon of memory priming under general anesthesia, manipulating as experimental variables both the anesthetic drug used and the stimuli primed.

One-handed E-C clamp mask holding technique, two-handed mask ventilation with jaw thrust, and two-handed mask ventilation with triple airway maneuver are three common airway management maneuvers. Sniffing position may improve ventilation between these three maneuvers. The investigators hypothesize that ventilation efficiency may be different between these three maneuvers whether the patient is in sniffing position or neutral position. The investigators would like to quantify this effect by measuring the expired tidal volume, airway pressure, EtCO2 slope and hemodynamic change between these three maneuvers during anesthesia induction.

The electroencephalography (EEG) is a noninvasive medical technique for monitoring and recording the electrical activity of brain. The Hilbert-Huang Transformation (HHT) was proposed to decompose EEG signal into intrinsic mode functions (IMF). HHT can obtain instantaneous frequency data and work well for nonstationary and nonlinear data. We applied this method in perioperative EEG signal analysis in order to find the energy shift and quantify the energy change during general anesthesia. Ketamine was a depolarized sedative which was wildly used in anesthesia. We are trying to find the energy change after ketamine injection, and the interaction between different oscillations in EEG. The whole brain mapping for ketamine and other sedatives interaction is the next step.