Anesthesia and analgesia
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Anesthesia and analgesia · Nov 2003
Randomized Controlled Trial Clinical TrialDoes a single intravenous injection of the 5HT3 receptor antagonist ondansetron have an analgesic effect in neuropathic pain? A double-blinded, placebo-controlled cross-over study.
Neurokinin-1-expressing neurones in lamina I to III of the spinal cord are intimately involved in the regulation of ascending and spino-bulbal pathways that regulate excitatory transmission. In experimental animals, ablation of these neurones reduces the responses to a variety of nociceptive stimuli. Furthermore, in animals, spinal application of the selective 5HT3 receptor antagonist ondansetron mimics these effects, indicating that 5HT3 receptors play a pronociceptive role and mediate descending excitatory controls that allow spinal neurones to fully code peripheral stimuli. In this study, we examined the potential analgesic effect of a single IV injection of ondansetron in humans with chronic neuropathic pain. Each consenting subject received a single IV injection of 8 mg ondansetron and placebo in varying order at least 1 wk apart with pain scores being recorded for the 48 h preceding and after each injection. Pain scores were significantly reduced 2 h after ondansetron injection (but at no other time point). This suggests that ondansetron can have an analgesic effect in neuropathic pain. Side effects were minor and infrequent. ⋯ The selective 5HT3 receptor antagonist ondansetron, currently used as an antiemetic, may also have analgesic properties. Side effects with a single IV injection are infrequent and usually mild.
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Anesthesia and analgesia · Nov 2003
Randomized Controlled Trial Comparative Study Clinical TrialThe relative motor blocking potencies of bupivacaine and levobupivacaine in labor.
Minimum local analgesic concentrations (MLAC) have been used to determine the epidural analgesic potencies of bupivacaine and its levo- counterpart. There are no reports of the motor blocking potencies of these drugs. In this study we sought to determine the motor block MLAC of both drugs and determine the relative potency ratio. Sixty ASA physical status I-II parturients were randomized. The first woman in each group received 0.25% wt/vol. Up-down sequential allocation was used to determine subsequent concentrations at a testing interval of 0.025% wt/vol. Effective motor block was defined as a Bromage score <4 within 30 min. The up-down sequences were analyzed with the Dixon and Massey method and probit regression. Two-sided P < 0.05 defined significance. The motor block MLAC for bupivacaine was 0.27% wt/vol (95% confidence interval [CI], 0.25-0.30) and for levobupivacaine was 0.31% wt/vol (95% CI, 0.29-0.34) (P = 0.024), with a levobupivacaine/bupivacaine potency ratio of 0.87 (95% CI, 0.77-0.98). This is the first study to estimate the motor-blocking potency ratio of bupivacaine and levobupivacaine in labor. This study demonstrates that the S-enantiomer of bupivacaine is less potent at motor block than the racemate. ⋯ We estimated the motor-blocking potency ratio of bupivacaine and levobupivacaine in labor and demonstrated that the S-enantiomer of bupivacaine is less potent at motor block than the racemate.
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Anesthesia and analgesia · Nov 2003
ReviewAn update on bronchial blockers during lung separation techniques in adults.
Techniques for one-lung ventilation (OLV) can be accomplished in two ways: The first involves the use of a double-lumen endotracheal tube (DLT). The second involves blockade of a mainstem bronchus (bronchial blockers). Bronchial blockade technology is on the rise, and in some specific clinical situations (e.g., management of the difficult airway during OLV or selective lobar blockade) it can offer more as an alternative to achieve OLV in adults. ⋯ Also this review describes placement, positioning, complications, ventilation modalities, and airflow resistances of all three bronchial blockers. Finally, the bronchial blockers can be used in many cases that require OLV, taking into consideration that bronchial blockers require longer time for placement, assisted suction to expedite lung collapse, and the use of fiberoptic bronchoscopy. The current use of bronchial blockers, supported by scientific evidence, dictates that bronchial blockers should be available in any service that performs lung separation techniques.