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Entropy Monitoring
Entropy monitoring is a method of assessing the effect of certain anaesthetic drugs on the brain's EEG. It was commercially developed by Datex-Ohmeda, which is now part of GE Healthcare. Entropy is a quantitative EEG device which captures a single-lead frontal EEG via a 3-electrode sensor applied to the patient's forehead. The system calculates the " spectral entropy" of the electroencephalogram (EEG) signals, which is a measure of the degree that the power spectrum is uniform. Increasing brain levels of anaesthetic drugs causes the predominant frequencies in the EEG to be lower than when awake, and this is reflected in a decrease in the spectral entropy. Entropy monitors generate two numbers that are derived from different frequency bands used. The ''state entropy'' (SE) is calculated from the 0.8 Hz to 32 Hz range, whereas the ''response entropy'' (RE) uses frequencies up to 47 Hz. Electromyogram activity is more predominant in those higher frequencies, and so th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Inhalational Anaesthetic
An inhalational anesthetic is a chemical compound possessing general anesthetic properties that is delivered via inhalation. They are administered through a face mask, laryngeal mask airway or tracheal tube connected to an anesthetic vaporiser and an anesthetic delivery system. Agents of significant contemporary clinical interest include volatile anesthetic agents such as isoflurane, sevoflurane and desflurane, as well as certain anesthetic gases such as nitrous oxide and xenon. List of inhalational anaesthetic agents Currently-used agents * Desflurane * Isoflurane * Nitrous oxide * Sevoflurane * Xenon Previously-used agents Although some of these are still used in clinical practice and in research, the following anaesthetic agents are primarily of historical interest in developed countries: * Acetylene * Chloroethane (ethyl chloride) * Chloroform * Cryofluorane * Cyclopropane * Diethyl ether * Divinyl ether * Enflurane * Ethylene * Fluroxene * Halothane (still widely use ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anesthesia
Anesthesia (American English) or anaesthesia (British English) is a state of controlled, temporary loss of sensation or awareness that is induced for medical or veterinary purposes. It may include some or all of analgesia (relief from or prevention of pain), paralysis (muscle relaxation), amnesia (loss of memory), and unconsciousness. An individual under the effects of anesthetic drugs is referred to as being anesthetized. Anesthesia enables the painless performance of procedures that would otherwise require physical restraint in a non-anesthetized individual, or would otherwise be technically unfeasible. Three broad categories of anesthesia exist: * ''General anesthesia'' suppresses central nervous system activity and results in unconsciousness and total lack of Sensation (psychology), sensation, using either injected or inhaled drugs. * ''Sedation'' suppresses the central nervous system to a lesser degree, inhibiting both anxiolysis, anxiety and creation of long-term memory, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spectral Flatness
Spectral flatness or tonality coefficient, also known as Wiener entropy, is a measure used in digital signal processing to characterize an audio spectrum. Spectral flatness is typically measured in decibels, and provides a way to quantify how much a sound resembles a pure tone, as opposed to being noise-like. Interpretation The meaning of ''tonal'' in this context is in the sense of the amount of peaks or resonant structure in a power spectrum, as opposed to the flat spectrum of white noise. A high spectral flatness (approaching 1.0 for white noise) indicates that the spectrum has a similar amount of power in all spectral bands — this would sound similar to white noise, and the graph of the spectrum would appear relatively flat and smooth. A low spectral flatness (approaching 0.0 for a pure tone) indicates that the spectral power is concentrated in a relatively small number of bands — this would typically sound like a mixture of sine waves, and the spectrum would appear "spik ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Evoked Potentials
An evoked potential or evoked response is an electrical potential in a specific pattern recorded from a specific part of the nervous system, especially the brain, of a human or other animals following presentation of a stimulus such as a light flash or a pure tone. Different types of potentials result from stimuli of different modalities and types. Evoked potential is distinct from spontaneous potentials as detected by electroencephalography (EEG), electromyography (EMG), or other electrophysiologic recording method. Such potentials are useful for electrodiagnosis and monitoring that include detections of disease and drug-related sensory dysfunction and intraoperative monitoring of sensory pathway integrity. Evoked potential amplitudes tend to be low, ranging from less than a microvolt to several microvolts, compared to tens of microvolts for EEG, millivolts for EMG, and often close to 20 millivolts for ECG. To resolve these low-amplitude potentials against the background of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bispectral Index
Bispectral index (BIS) is one of several technologies used to monitor depth of anesthesia. BIS monitors are used to supplement Guedel's classification system for determining depth of anesthesia. Titrating anesthetic agents to a specific bispectral index during general anesthesia in adults (and children over 1 year old) allows the anesthetist to adjust the amount of anesthetic agent to the needs of the patient, possibly resulting in a more rapid emergence from anesthesia. Use of the BIS monitor could reduce the incidence of intraoperative awareness during anaesthesia. The exact details of the algorithm used to create the BIS index have not been disclosed by the company that developed it. BIS cannot be used as the sole monitor of anaesthesia, as it is affected by several other factors, including the anaesthetic drugs used (BIS is relatively insensitive to agents such as ketamine and nitrous oxide), and muscle movement or artefact from surgical equipment. BIS is used as an adjunc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electroencephalograph
Electroencephalography (EEG) is a method to record an electrogram of the spontaneous electrical activity of the brain. The bio signals detected by EEG have been shown to represent the postsynaptic potentials of pyramidal neurons in the neocortex and allocortex. It is typically non-invasive, with the EEG electrodes placed along the scalp (commonly called "scalp EEG") using the International 10–20 system, or variations of it. Electrocorticography, involving surgical placement of electrodes, is sometimes called "intracranial EEG". Clinical interpretation of EEG recordings is most often performed by visual inspection of the tracing or quantitative EEG analysis. Voltage fluctuations measured by the EEG bio amplifier and electrodes allow the evaluation of normal brain activity. As the electrical activity monitored by EEG originates in neurons in the underlying brain tissue, the recordings made by the electrodes on the surface of the scalp vary in accordance with their orie ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anaesthetist
Anesthesiology, anaesthesiology or anaesthesia is the medical specialty concerned with the total perioperative care of patients before, during and after surgery. It encompasses anesthesia, intensive care medicine, critical emergency medicine, and pain medicine. A physician specialized in anesthesiology is called an anesthesiologist, anaesthesiologist, or anaesthetist, depending on the country. In some countries, the terms are synonymous, while in other countries, they refer to different positions and ''anesthetist'' is only used for non-physicians, such as nurse anesthetists. The core element of the specialty is the prevention and mitigation of pain and distress using various anesthetic agents, as well as the monitoring and maintenance of a patient's vital functions throughout the perioperative period. Since the 19th century, anesthesiology has developed from an experimental area with non-specialist practitioners using novel, untested drugs and techniques into what is now a hi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Consciousness
Consciousness, at its simplest, is awareness of a state or object, either internal to oneself or in one's external environment. However, its nature has led to millennia of analyses, explanations, and debate among philosophers, scientists, and theologians. Opinions differ about what exactly needs to be studied or even considered consciousness. In some explanations, it is synonymous with the mind, and at other times, an aspect of it. In the past, it was one's "inner life", the world of introspection, of private thought, imagination, and volition (psychology), volition. Today, it often includes any kind of cognition, experience, feeling, or perception. It may be awareness, awareness of awareness, metacognition, or self-awareness, either continuously changing or not. The disparate range of research, notions, and speculations raises a curiosity about whether the right questions are being asked. Examples of the range of descriptions, definitions or explanations are: ordered distinc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spectral Entropy
''Spectral'' is a 2016 Hungarian-American military science fiction action film co-written and directed by Nic Mathieu. Written with Ian Fried & George Nolfi, the film stars James Badge Dale as DARPA research scientist Mark Clyne, with Max Martini, Emily Mortimer, Clayne Crawford, and Bruce Greenwood in supporting roles. The film is set in a civil war-ridden Moldova as invisible entities slaughter any living being caught in their path. The film was released worldwide on December 9, 2016 on Netflix. On February 1, 2017, Netflix released a prequel graphic novel of the film called ''Spectral: Ghosts of War'' which was made available digitally through the website ComiXology. Plot DARPA researcher Mark Clyne is sent to a US military airbase on the outskirts of Chișinău, to consult his created line of hyperspectral imaging goggles issued to US Army Special Forces led by Army General James Orland, who is covertly supporting the Moldovan government in an ongoing civil war agains ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Blood Pressure
Blood pressure (BP) is the pressure of Circulatory system, circulating blood against the walls of blood vessels. Most of this pressure results from the heart pumping blood through the circulatory system. When used without qualification, the term "blood pressure" refers to the pressure in a brachial artery, where it is most commonly measured. Blood pressure is usually expressed in terms of the systolic pressure (maximum pressure during one Cardiac cycle, heartbeat) over diastolic pressure (minimum pressure between two heartbeats) in the cardiac cycle. It is measured in Millimetre of mercury, millimetres of mercury (mmHg) above the surrounding atmospheric pressure, or in Pascal (unit), kilopascals (kPa). The difference between the systolic and diastolic pressures is known as pulse pressure, while the average pressure during a cardiac cycle is known as mean arterial pressure. Blood pressure is one of the vital signs—together with respiratory rate, heart rate, Oxygen saturation (me ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
