European journal of anaesthesiology
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A series of 52 patients in whom 0.5% bupivacaine was used to produce spinal analgesia for awake Caesarean section is described. Analgesia tended to be asymmetrical and of limited extent until the patients were turned from the left lateral to the right lateral position immediately after injecting the spinal solution. This movement produced a more symmetrical block with better cephalic spread. ⋯ The mean +/- SEM time to achieve maximal spread of analgesia was 17.5 +/- 0.6 min. The mean- +/- SEM time to the administration of the first postoperative analgesic was 163.5 +/- 7.0 min. The disadvantages of the technique were hypotension and the unpredictable spread of analgesia.
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Review Comparative Study
Multiple opioid receptor systems in brain and spinal cord: Part 2.
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The biological activity of opioid agents reflects their interaction with specific membrane sites. The fact that the drug interaction resulting in physiological responses shows distinguishing characteristics with regard to rank order of agonist potency, affinity of the antagonist for the site acted upon by the agent to produce the effect, tolerance and cross-tolerance, may be interpreted as indicating that different opioids produce their effects by an action on distinctive receptors. Examination of the literature provides support for the hypothesis proposed by different investigators that the physiological effects of the several opioid ligands may be parsimoniously explained in terms of several possibly overlapping receptor classes including mu, delta, kappa, sigma and epsilon. ⋯ Though not reviewed, it is likely that a similar complexity underlies the interaction of opioids with neural substrates mediating other functions. Thus different opioid receptors may modulate the same physiological phenomenon because they are on different systems which have a similar output (e.g. spinal reflex inhibition) or they may co-exist on the same neurone. In short, it appears likely that there are discriminable populations of opioid receptors and that no single receptor can be said to modulate a given physiological effect.
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Comparative Study
Differential sensory and motor blockade after spinal cocaine in the rat and marmoset.
Various concentrations of local anaesthetic agents have been injected into the rat and marmoset via a chronically implanted cannula in the subarachnoid space. In the rat, cocaine at a concentration of 0.125% produced analgesia without motor blockade whereas higher concentrations produced motor blockade in some animals. ⋯ It would appear that differential blockade of sensory function without motor loss can be achieved by cocaine. New local anaesthetics based on cocaine or similar chemical structures would seem potentially valuable.
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A programmable microprocessor has been developed to control a nerve stimulator, to accept electromyographic potentials and to process them to produce derivatives related to neuromuscular function which can then be stored and displayed. Examples are given of its use to assess the physiological state of the neuromuscular junction and to quantify the degree of blockade in clinical situations.