Anesthesiology
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Randomized Controlled Trial Multicenter Study Comparative Study Clinical Trial
Assessment of low-flow sevoflurane and isoflurane effects on renal function using sensitive markers of tubular toxicity.
Carbon dioxide absorbents degrade sevoflurane, particularly at low gas flow rates, to fluoromethyl-2,2-difluoro-1-(trifluoromethyl)vinyl ether (compound A). Compound A causes renal proximal tubular injury in rats but has had no effect on blood urea nitrogen (BUN) or creatinine concentrations in patients. This investigation compared the effects of low-flow sevoflurane and isoflurane on renal tubular function in surgical patients using conventional (BUN and creatinine) and finer indices of renal injury, specifically those biomarkers sensitive for compound A toxicity in rats (glucosuria, proteinuria, and enzymuria [N-acetyl-beta-D-glucosaminidase (NAG) and alpha-glutathione-S-transferase (alpha GST)]). ⋯ The renal tubular and hepatic effects of low-flow sevoflurane and isoflurane were similar as assessed using both conventional measures of hepatic and renal function and more sensitive biochemical markers of renal tubular cell necrosis. Moderate duration low-flow sevoflurane anesthesia, during which compound A formation occurs, appears to be as safe as low-flow isoflurane anesthesia.
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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.
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Randomized Controlled Trial Clinical Trial
Alfentanil, but not amitriptyline, reduces pain, hyperalgesia, and allodynia from intradermal injection of capsaicin in humans.
Intradermal injection of capsaicin produces brief pain followed by hyperalgesia and allodynia in humans, and the latter effects are mediated by spinal N-methyl-D-aspartate mechanisms. Amitriptyline recently was shown to antagonize N-methyl-D-aspartate receptors, and in this study, the authors sought to determine the effect of amitriptyline alone and with the opioid alfentanil on hyperalgesia and allodynia produced by intradermal injection of capsaicin. ⋯ These data correspond with previous studies in volunteers demonstrating reduction in hyperalgesia and allodynia after intradermal injection of capsaicin by systemically administered opioids, and they suggest that this reduction may be secondary to reduced nociceptive input by acute analgesia. These data do not support the use of acute systemic administration of amitriptyline for acute pain, hyperalgesia, and allodynia, although the roles of chronic treatment and spinal administration are being investigated.
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Randomized Controlled Trial Clinical Trial
The effect of isoflurane, halothane, sevoflurane, and thiopental/nitrous oxide on respiratory system resistance after tracheal intubation.
After tracheal intubation, lung resistance and therefore respiratory system resistance (R[rs]) routinely increase, sometimes to the point of clinical bronchospasm. Volatile anesthetics generally have been considered to be effective bronchodilators, although there are few human data comparing the efficacy of available agents. This study compared the bronchodilating efficacy of four anesthetic maintenance regimens: 1.1 minimum alveolar concentration (MAC) end-tidal sevoflurane, isoflurane or halothane, and thiopental/nitrous oxide. ⋯ After tracheal intubation in persons without asthma, sevoflurane decreased R(rs) as much or more than isoflurane or halothane did during a 10-min exposure at 1.1 MAC.