Anesthesiology
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Brief episodes of ischemia during early reperfusion after coronary occlusion reduce the extent of myocardial infarction. Phosphatidylinositol-3-kinase (PI3K) signaling has been implicated in this "postconditioning" phenomenon. The authors tested the hypothesis that isoflurane produces cardioprotection during early reperfusion after myocardial ischemia by a PI3K-dependent mechanism. ⋯ Isoflurane acts during early reperfusion after prolonged ischemia to salvage myocardium from infarction and reduces the threshold of ischemic postconditioning by activating PI3K.
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Rapacuronium, a nondepolarizing muscle relaxant that was proposed as a replacement for succinylcholine for rapid intubation, was withdrawn from clinical use as a result of fatal bronchospasm, but the mechanism of this effect is not known. Preferential antagonism of presynaptic M2 muscarinic receptors versus postsynpatic M3 muscarinic receptors can facilitate bronchoconstriction. The authors questioned whether rapacuronium preferentially antagonized M2 versus M3 muscarinic receptors in intact airway. ⋯ These findings are consistent with the hypothesis that rapacuronium may precipitate bronchoconstriction by selective antagonism of the M2 muscarinic receptor on parasympathetic nerves, enhancing acetylcholine release to act upon unopposed M3 muscarinic receptors on airway muscle. An additional mechanism of rapacuronium-induced bronchoconstriction is suggested by increases in baseline muscle tension.
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Regional anesthesia is increasing in popularity for ambulatory surgical procedures. Concomitantly, the prevalence of obesity in the United States population is increasing. The objective of the present investigation was to assess the impact of body mass index (BMI) on patient outcomes after ambulatory regional anesthesia. ⋯ The present investigation shows that obesity is associated with higher block failure and complication rates in surgical regional anesthesia in the ambulatory setting. Nonetheless, the rate of successful blocks and overall satisfaction remained high in patients with increased BMI. Therefore, overweight and obese patients should not be excluded from regional anesthesia procedures in the ambulatory setting.
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Mechanical hyperalgesia and allodynia associated with chemical irritant application are mediated by spinal high-threshold (HT) as well as wide-dynamic-range neurons as a result of "central sensitization." Because the pathophysiology of pain is thought to differ depending on the type of injury and may vary between hairy and glabrous skin, the authors examined changes in properties of spinal dorsal horn neurons after surgical incisions in hairy skin of rats to obtain insights into the mechanisms of postoperative pain. ⋯ The results suggest that wide-dynamic-range neurons are responsible for behavioral hyperexcitability after surgical incision but that HT neurons are not involved in the hyperexcitability, despite the fact that HT neurons are capable of responding to innocuous stimuli by reversal of gamma-aminobutyric acid-mediated inhibition.
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Acceleromyography is regularly used as an isolated test to detect residual paralysis. The performance of acceleromyography, however, has not been investigated for the setting where calibration is impossible. This study first evaluated the reliability of a single acceleromyographic train-of-four (TOF) ratio (T4/T1) to detect residual paralysis and compared it with tactile estimation of fade after double-burst stimulation and 100-Hz, 5-s tetanus. The second part of the study investigated whether uncalibrated acceleromyographic TOF ratio can predict time to complete recovery. ⋯ Acceleromyographic TOF performed better than double-burst stimulation or 100 Hz tetanus, but it did not reliably detect low degrees of residual paralysis when used as an isolated test at the end of surgery. The uncalibrated acceleromyographic TOF ratio, however, did predict the time to complete recovery.