Anesthesiology
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Comparative Study
Capsaicin combined with local anesthetics preferentially prolongs sensory/nociceptive block in rat sciatic nerve.
Transient receptor potential vanilloid 1 channels integrate nociceptive stimuli and are predominantly expressed by unmyelinated C-fiber nociceptors, but not low-threshold mechanoreceptive sensory or motor fibers. A recent report showed that the transient receptor potential vanilloid 1 channel agonist capsaicin allows a hydrophilic quaternary ammonium derivative of lidocaine, QX-314, to selectively block C fibers without motor block. The authors tested whether a similar differential block would be produced using amphipathic N-methyl amitriptyline, amitriptyline, bupivacaine, or lidocaine, either alone or together with 0.05% capsaicin, in a rat sciatic nerve block model. ⋯ Both tertiary amine local anesthetics and their quaternary ammonium derivatives can elicit a predominantly sensory/nociceptor selective block when followed by injection of capsaicin. The combined application of transient receptor potential vanilloid 1 channel agonists and various local anesthetics or their quaternary ammonium derivatives is an appealing strategy to achieve a long-lasting differential block in regional analgesia.
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Clinicians, including anesthesiologists, surgeons, and intensivists, are frequently called on to correct coagulopathy in patients receiving oral anticoagulation therapy. Before elective surgery, anticoagulation reversal may be undertaken over several days by discontinuing warfarin or vitamin K treatment, but rapid correction is required in an emergency. European and American guidelines recommend prothrombin complex concentrates (PCCs) for anticoagulation reversal in patients with life-threatening bleeding and an increased international normalized ratio. ⋯ Although there are historic concerns regarding potential infectious and thrombotic risks with PCCs, current PCC formulations are much improved. Recombinant activated factor VII is a potential alternative to PCCs, but preclinical comparisons suggest that PCCs are more effective in correcting coagulopathy. Although many patients who require rapid reversal of warfarin are currently treated with fresh frozen plasma, PCCs should be considered as an alternative therapy.
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Selective blockade of spinal sigma(1) receptors (Sig-1R) suppresses nociceptive behaviors in the mouse formalin test. The current study was designed to verify whether intrathecal Sig-1R antagonists can also suppress chronic neuropathic pain. ⋯ These results demonstrate that spinal Sig-1Rs play a critical role in both the induction of mechanical allodynia and the activation of spinal N-methyl-d-aspartate receptors in CCI rats and suggest a potential therapeutic role for the use of Sig-1R antagonists in the clinical management of neuropathic pain.
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Comparative Study
Metoclopramide does not attenuate cricoid pressure-induced relaxation of the lower esophageal sphincter in awake volunteers.
The authors examined the influence of metoclopramide on cricoid pressure-induced relaxation of the lower esophageal sphincter (LES) in awake human volunteers. ⋯ The current investigation demonstrates that cricoid pressure reflexly decreases LES tone and barrier pressure in awake subjects. Although metoclopramide increased LES and barrier pressures, it did not attenuate cricoid pressure-induced relaxation of the LES and barrier pressures and thus seems to have no value in preventing gastroesophageal reflux during cricoid pressure. Metoclopramide may be useful in preventing reflux when there is need to release or discontinue cricoid pressure.