Anesthesiology
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Comparative Study
Severe bradycardia during spinal and epidural anesthesia recorded by an anesthesia information management system.
Bradycardia and asystole can occur unexpectedly during neuraxial anesthesia. Risk factors may include low baseline heart rate, first-degree heart block, American Society of Anesthesiologists physical status 1, beta-blockers, male gender, and high sensory level. Anesthesia information management systems automatically record large numbers of physiologic variables that are combined with data input from the anesthesiologist to form the anesthesia record. Such large databases can be scanned for episodes of bradycardia. ⋯ Moderate or severe bradycardia may occur at any time during neuraxial anesthesia, regardless of the duration of anesthesia. Low baseline heart rate increases the risk for bradycardia.
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The C50 of remifentanil for ventilatory depression has been previously determined using inspired carbon dioxide and stimulated ventilation, which may not describe the clinically relevant situation in which ventilatory depression occurs in the absence of inspired carbon dioxide. The authors applied indirect effect modeling to non-steady state Paco2 data in the absence of inspired carbon dioxide during and after administration of remifentanil. ⋯ Remifentanil is a potent ventilatory depressant. Simulations demonstrated that remifentanil concentrations well tolerated in the steady state will cause a clinically significant hypoventilation following bolus administration, confirming the acute risk of bolus administration of fast-acting opioids in spontaneously breathing patients.
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Cannabinoid receptor agonists inhibit inflammatory hyperalgesia in animal models. Nonselective cannabinoid receptor agonists also produce central nervous system (CNS) side effects. Agonists selective for CB2 cannabinoid receptors, which are not found in the CNS, do not produce the CNS effects typical of nonselective cannabinoid receptor agonists but do inhibit acute nociception. The authors used the CB2 receptor-selective agonist AM1241 to test the hypothesis that selective activation of peripheral CB2 receptors inhibits inflammatory hyperalgesia. ⋯ Local, peripheral CB2 receptor activation inhibits inflammation and inflammatory hyperalgesia. These results suggest that peripheral CB2 receptors may be an appropriate target for eliciting relief of inflammatory pain without the CNS effects of nonselective cannabinoid receptor agonists.
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The clinical efficacy of the noncompetitive N-methyl-d-aspartate receptor antagonist ketamine for treating orofacial pain has already been reported. Side effects related to psychotomimetic disturbances, however, limit ketamine use as an analgesic. Theoretically, this limitation could be minimized by using low doses of ketamine in combination with other analgesics. In the present study, the potential synergistic antinociceptive interaction between ketamine and morphine in the orofacial capsaicin test in rats was investigated. ⋯ These results indicate that ketamine and morphine have antinociceptive effects on the orofacial capsaicin test. Furthermore, their combination produces synergistic antinociception. It is therefore suggested that, used together, ketamine and morphine might be clinically efficient at lower doses than those currently used when administered separately. This could provide a useful strategy for the clinical management of orofacial pain.
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Randomized Controlled Trial Comparative Study Clinical Trial
Use of a continuous local anesthetic infusion for pain management after median sternotomy.
The use of large doses of opioid analgesics to treat pain after cardiac surgery can prolong the time to tracheal extubation and interfere with recovery of bowel and bladder function in the postoperative period. Therefore, the authors investigated the efficacy of a continuous infusion of bupivacaine 0.25% or 0.5%, at the median sternotomy site, for 48 h after cardiac surgery in reducing the opioid analgesic requirement and improving the recovery process. ⋯ A continuous infusion of bupivacaine 0.5% at 4 ml/h is effective for decreasing pain and the need for opioid analgesic medication as well as for improving patient satisfaction with their pain management after cardiac surgery. Patients in the bupivacaine-0.5% group were able to ambulate earlier, leading to a reduced length of hospital stay.