Background The influence of psychoactive drugs on the central nervous system has been investigated with positron emission tomography and task-related functional magnetic resonance imaging. However, it is not known how these drugs affect the intrinsic large-scale interactions of the brain (resting-state functional magnetic resonance imaging connectivity). In this study, the effect of low-dose...
Consciousness is subjective experience. During both sleep and anesthesia, consciousness is common, evidenced by dreaming. A defining feature of dreaming is that, while conscious, we do not experience our environment; we are disconnected. Besides inducing behavioral unresponsiveness, a key goal of anesthesia is to prevent the experience of surgery (connected consciousness), by inducing either...
BACKGROUND: Chronic pain is associated with depression. In rodents, pain is often assessed by sensory hypersensitivity, which does not sufficiently measure affective responses. Low-dose ketamine has been used to treat both pain and depression, but it is not clear whether ketamine can relieve depression associated with chronic pain and whether this antidepressant effect depends on its...
Dartmouth Medical School, Dartmouth College, Lebanon, New Hampshire. edgar.a.romero-sandoval@dartmouth.eduA LARGE population of patients concomitantly experiences chronic pain and depression or symptoms of depression (52% in pain clinics, or 85% in chronic facial pain dental clinics, for example).1How these two syndromes coexist, interact, reinforce each other, and/or are maintained is poorly...
AnesthesiologyJune 1, 2011Daniela Hauer, Patrizia Ratano, Maria Morena et al.
Propofol is associated with postoperative mood alterations and induces a higher incidence of dreaming compared with other general anesthetics. These effects might be mediated by propofol's inhibitory action on fatty acid amide hydrolase, the enzyme that degrades the endocannabinoid anandamide. Because propofol is also associated with a higher incidence of traumatic memories from perioperative...
Background: There is poor experimental evidence concerning the effects of anesthetic doses of the noncompetitive N-methyl-D-aspartate receptor antagonist ketamine on rodents' memory abilities. The current study was designed (1) to investigate the consequences of posttraining administration of anesthetic ketamine (100 mg/kg intraperitoneally) on rats' recognition memory and (2) to evaluate the...
Background: Loss of consciousness is an essential feature of general anesthesia. Although alterations of neural networks during anesthesia have been identified in the spatial domain, there has been relatively little study of temporal organization. Methods: Ten healthy male volunteers were anesthetized with an induction dose of propofol on two separate occasions. The duration of network...
BACKGROUND: Mechanisms of anesthesia-induced loss of consciousness remain poorly understood. Resting-state functional magnetic resonance imaging allows investigating whole-brain connectivity changes during pharmacological modulation of the level of consciousness. METHODS: Low-frequency spontaneous blood oxygen level-dependent fluctuations were measured in 19 healthy volunteers during...
Pharmacologic actions of CI-581, a chemical derivative of phencyclidine, were determined in 20 volunteers from a prison population. The results indicate that this drug is an effective analgesic and anesthetic agent in doses of 1.0 to 2.0 mg per kilogram. With intravenous administration the onset of action is within 1 min and the effects last for about 5 to 10 min, depending on dosage level and...
BACKGROUND: Low-dose ketamine behaves as an analgesic in the treatment of acute and chronic pain. To further understand ketamine's therapeutic profile, the authors performed a population pharmacokinetic-pharmacodynamic analysis of the S(+)-ketamine analgesic and nonanalgesic effects in healthy volunteers. METHODS: Ten men and ten women received a 2-h S(+)-ketamine infusion. The infusion was...
Dream recall is reportedly more common after propofol than after volatile anesthesia, but this may be due to delayed emergence or more amnesia after longer-acting volatiles. The electroencephalographic signs of dreaming during anesthesia and the differences between propofol and desflurane also are unknown. The authors therefore compared dream recall after propofol- or desflurane-maintained...
AnesthesiologyMay 2007Adelchi Toscano, Carlo Pancaro, Vito Aldo Peduto
Dreaming during anesthesia is not a well-understood phenomenon. Anticholinergic drugs are used in anesthesia as premedication, but their use to decrease the incidence of dreams and psychological adverse reactions after anesthesia is not well established. The authors therefore studied the efficacy of intramuscular atropine and scopolamine for the prevention of dreams during general anesthesia...
Dreaming reported after anesthesia remains a poorly understood phenomenon. Dreaming may be related to light anesthesia and represent near-miss awareness. However, few studies have assessed the relation between dreaming and depth of anesthesia, and their results were inconclusive. Therefore, the authors tested the hypothesis that dreaming during anesthesia is associated with light anesthesia, as...
THE mechanism by which general anesthetics prevent consciousness remains unknown largely because the mechanism by which brain physiology produces consciousness is unexplained. But the two mysteries seem to share a critical feature—both consciousness and actions of anesthetic gases are mediated through extremely weak London forces (a type of van der Waals force) acting in hydrophobic pockets...
BACKGROUND: Remifentanil-induced secondary hyperalgesia has been documented experimentally in both animals and healthy human volunteers, but never clinically. This study tested the hypotheses that increased pain sensitivity assessed by periincisional allodynia and hyperalgesia can occur after relatively large-dose intraoperative remifentanil and that small-dose ketamine prevents this...
AnesthesiologyNovember 2003Marko Fiege, Frank Wappler, Ralf Weisshorn et al.
3,4-Methylenedioxymethamphetamine (MDMA, "ecstasy") can mediate acute toxic effects such as muscle rigidity, metabolic acidosis, and hyperthermia. Because of close clinical similarities, an association between MDMA intoxication and malignant hyperthermia (MH) was suggested. The aim of this study was to investigate whether MDMA is a trigger of MH in susceptible swine. MH-nontriggering general...
Background: Ketamine is increasingly used in pain therapy but may impair brain functions. Mood and cognitive capacities were compared after equianalgesic small-dose S(+)-, R(-)-, and racemic ketamine in healthy volunteers. Methods: Twenty-four subjects received intravenous 0.5 mg/kg racemic, 0.25 mg/kg S(+)-, and 1.0 mg/kg R(-)-ketamine in a prospective, randomized, double-blind, crossover...
Background Ketamine has been associated with a unique spectrum of subjective "psychedelic" effects in patients emerging from anesthesia. This study quantified these effects of ketamine and related them to steady-state plasma concentrations. Methods Ketamine or saline was administered in a single-blinded crossover protocol to 10 psychiatrically healthy volunteers using computer-assisted...
Sevoflurane is a volatile general anesthetic that differs in chemical nature from the gaseous anesthetic nitrous oxide. In a controlled laboratory setting, the authors characterized the subjective, psychomotor, and analgesic effects of sevoflurane and nitrous oxide at two equal minimum alveolar subanesthetic concentrations. A crossover design was used to test the effects of two end-tidal...
BACKGROUND: Ketamine, a noncompetitive N-methyl-D-aspartate antagonist, has psychotomimetic side effects. Recent studies have shown that noncompetitive N-methyl-D-aspartate antagonists cause morphologic damage to the cingulate and retrosplenial cortices and induce c-fos protein (c-Fos) in the same regions. Although benzodiazepines are effective in preventing these side effects, the neural basis...
Michael Faraday (1791-1867) was a protégé of Humphry Davy. He became one of Davy's successors as Professor of Chemistry at the Royal Institution of Great Britain. Of Faraday's many brilliant discoveries in chemistry and physics, probably the best remembered today is his work on electromagnetic induction. Faraday's contribution to introduction of anesthesia was his published announcement in 1818...
Ketamine and midazolam can produce analgesia following intrathecal administration in rabbits. However, neurotoxicity studies are required before these agents can be considered safe for clinical use. The aim of this study was to evaluate by histologic and blood-brain barrier (BBB) studies whether ketamine or midazolam could be used as an alternative to local anesthetics or opioids to produce...
AnesthesiologyAugust 1988D W Davis, A M Mans, J F Biebuyck et al.
The purpose of this study was to determine the effect of different doses of ketamine on cerebral function at the level of individual brain structures as reflected by glucose use. Rats received either 5 or 30 mg/kg ketamine intravenously as a loading dose, followed by an infusion to maintain a steady-state level of the drug. An additional group received 30 mg/kg as a single injection only, and...