Anesthesiology
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The ventilatory response to hypoxia is composed of the stimulatory activity from peripheral chemoreceptors and a depressant effect from within the central nervous system. Morphine induces respiratory depression by affecting the peripheral and central carbon dioxide chemoreflex loops. There are only few reports on its effect on the hypoxic response. Thus the authors assessed the effect of morphine on the isocapnic ventilatory response to hypoxia in eight cats anesthetized with alpha-chloralose-urethan and on the ventilatory carbon dioxide sensitivities of the central and peripheral chemoreflex loops. ⋯ Morphine depresses ventilation at hyperoxia but does not depress the steady-state increase in ventilation due to hypoxia. The authors speculate that morphine reduces the central depressant effect of hypoxia and the peripheral carbon dioxide sensitivity at hyperoxia.
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Protamine is currently the most widely used drug for the reversal of heparin anticoagulation. Heparinase 1 (heparinase) is being evaluated as a possible alternative to protamine for the reversal of heparin anticoagulation. The authors evaluated the effects of equivalent doses of heparinase and protamine on platelet reactivity by measuring agonist-induced P-selectin expression. ⋯ At dosages that reverse the anticoagulant effects of heparin, heparinase has minimal effects on platelets, whereas platelet reactivity was markedly inhibited by protamine.
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Randomized Controlled Trial Clinical Trial
Concentration-effect relations for intravenous lidocaine infusions in human volunteers: effects on acute sensory thresholds and capsaicin-evoked hyperpathia.
Preclinical studies have emphasized that persistent small afferent input will induce a state of central facilitation that can be regulated by systemically administered lidocaine. The authors extended these preclinical studies to human volunteers by examining the concentration-dependent effects of intravenous lidocaine on acute sensory thresholds and facilitated processing induced by intradermal capsaicin. ⋯ These studies suggest that the facilitated state induced by persistent small afferent input human pain models may predict the activity of agents that affect components of nociceptive processing that are different from those associated with the pain state evoked by "acute" thermal or mechanical stimuli. Such insight may be valuable in the efficient development of novel analgesics for both neuropathic and post-tissue-injury pain states.
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Randomized Controlled Trial Clinical Trial
Effects of concentration and volume of 2-chloroprocaine on epidural anesthesia in volunteers.
Effect of local anesthetic concentration and volume on the spread and density of epidural anesthesia is unclear. This study was performed to delineate effects of a threefold difference in concentration and volume of 2-chloroprocaine on epidural anesthesia. ⋯ Intensity of sensory and motor block from epidural anesthesia with 2-chloroprocaine appears to depend primarily on total milligram dose.