PubMed · 8305087
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B Bonke, M Jelicic, A E Bonebakker, A De Roode, J G Bovill. 1993. Information processing under anaesthesia.. https://pubmed.ncbi.nlm.nih.gov/8305087/
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Spindle oscillations (7-14 Hz) appear in the thalamus and cortex during early stages of sleep. They are generated by the combination of intrinsic properties and connectivity patterns of thalamic neurons and distributed to cortical territories by thalamocortical axons. The corticothalamic feedback is a major factor in producing coherent spatiotemporal maps of spindle oscillations in widespread thalamic territories. Here we have investigated the spatiotemporal patterns of spontaneously occurring and evoked spindles by means of multisite field potential and unit recordings in intact cortex and decorticated animals. We show that (1) spontaneous spindle oscillations are synchronized over large cortical areas during natural sleep and barbiturate anesthesia; (2) under barbiturate anesthesia, the cortical coherence is not disrupted by transection of intracortical synaptic linkages; (3) in intact cortex animals, spontaneously occurring barbiturate spindle sequences occur nearly simultaneously over widespread thalamic territories; (4) in the absence of cortex, the spontaneous spindle oscillations throughout the thalamus are less organized, but the local coherence (within 2-4 mm) is still maintained; and (5) spindling propagation is observed in intact cortex animals only when elicited by low intensity cortical stimulation, applied shortly before the initiation of a spontaneous spindle sequence; propagation velocities are between 1 and 3 mm/sec, measured in the anteroposterior axis of the thalamus; increasing the intensity of cortical stimulation triggers spindle oscillations, which start simultaneously in all leads. We propose that, in vivo, the coherence of spontaneous spindle oscillations in corticothalamic networks is attributable to the combined action of continuous background corticothalamic input initiating spindle sequences in several thalamic sites at the same time and divergent corticothalamic and intrathalamic connectivity.
PURPOSE: Many patients with sepsis require surgery for their management, often on an urgent or emergency basis. Anaesthetists are commonly required to manage patients with sepsis and septic shock in the operating room, past anaesthesia recovery area, and the intensive care unit. Since little has been written in the Anaesthesia literature on sepsis and septic shock, a review of this topic was considered appropriate. SOURCE: References were obtained from computerized searches on the National Library of Medicine (English language), recent review articles and personal files. PRINCIPLES FINDINGS: Septic shock is a common cause of morbidity and mortality. Its presentation may be subtle or catastrophic. Successful management depends on an understanding of the pathophysiology of the syndrome, allowing rapid, appropriate resuscitation. This often requires aggressive correction of volume deficit, maintenance of adequate perfusion pressure with inotropic and vasopressor therapy, mechanical ventilation and correction of coagulopathy. Appropriate cultures must be taken and antibiotic therapy started, often empirically. Anaesthetic management should include careful haemodynamic monitoring. Anaesthesia induction and maintenance must be tailored to the haemodynamically unstable patient. CONCLUSIONS: The management of the septic patient in the perioperative period presents a challenge for the anaesthetist. Haemodynamic and respiratory instability should be anticipated. Management requires multisystem intervention and careful anesthetic management.
The real-time measurement of electrically evoked dopamine was established in brain extracellular fluid of freely moving rats. Dopamine was monitored by fast-scan cyclic voltammetry at carbon fiber microelectrodes lowered into the striatum by means of a detachable micromanipulator. A stimulating electrode, previously implanted in the substantia nigra, was used to evoke striatal dopamine efflux. Evoked extracellular dopamine was both current and frequency dependent. When low current intensities (+/-125 microA) and frequencies (10-20 Hz) were applied, detectable levels of dopamine were elicited without a perceptible behavioral response. Reproducible concentrations of extracellular dopamine could be evoked in the same rat for at least 2 months. These concentrations, moreover, were significantly higher in freely moving rats compared with rats anesthetized with Equithesin. Analysis of measured curves for dopamine uptake and release rates revealed that anesthesia inhibits release but does not affect uptake. It is concluded that (a) fast-scan cyclic voltammetry at carbon fiber microelectrodes is a viable technique for the measurement of electrically evoked dopamine in brain extracellular fluid of freely moving rats, (b) it is possible to determine in situ rate constants for dopamine release and uptake from these temporally and spatially resolved measurements of levels of dopamine, and (c) transient changes in extracellular dopamine levels elicited by electrical stimulation are affected by anesthesia.