Anesthesia and analgesia
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Anesthesia and analgesia · Aug 1998
Randomized Controlled Trial Comparative Study Clinical TrialTopical lidocaine-prilocaine cream (EMLA) versus local infiltration anesthesia for radial artery cannulation.
In a randomized trial, we compared topical anesthesia by a lidocaine-prilocaine cream (EMLA; Laboratorie ASTRA, Manterre, France) with subcutaneous local lidocaine infiltration for radial artery cannulation. Patients included 538 adults scheduled for coronary angiography using a radial approach. EMLA was applied 2 h before radial cannulation, and lidocaine infiltration was performed 5 min before cannulation. The primary end point was pain as assessed by a verbal numerical scale (0 = no pain, 10 = extreme pain). Pain was less severe in the EMLA group than in the lidocaine infiltration group (Score of 2 vs 7; P = 0.0001). Additional lidocaine infiltration was required significantly less frequently in the EMLA group (relative risk 0.19). The failure rate of cannulation was significantly lower in the EMLA group (relative risk 0.38), and insertion time was shorter (4 versus 6 min). We conclude that EMLA, compared with lidocaine infiltration, reduces pain associated with radial artery cannulation and improves the success rate of the procedure. Routine application of EMLA should be performed in awake patients 2 h before radial artery cannulation. ⋯ In a randomized trial, we compared topical anesthesia by a lidocaine-prilocaine cream (EMLA) with subcutaneous local lidocaine infiltration for radial artery cannulation in 538 adults patients. EMLA reduced pain associated with radial artery cannulation and improved the success rate of the procedure.
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Anesthesia and analgesia · Aug 1998
Minimum alveolar concentrations of noble gases, nitrogen, and sulfur hexafluoride in rats: helium and neon as nonimmobilizers (nonanesthetics)
We assessed the anesthetic properties of helium and neon at hyperbaric pressures by testing their capacity to decrease anesthetic requirement for desflurane using electrical stimulation of the tail as the anesthetic endpoint (i.e., the minimum alveolar anesthetic concentration [MAC]) in rats. Partial pressures of helium or neon near those predicted to produce anesthesia by the Meyer-Overton hypothesis (approximately 80-90 atm), tended to increase desflurane MAC, and these partial pressures of helium and neon produced convulsions when administered alone. In contrast, the noble gases argon, krypton, and xenon were anesthetic with mean MAC values of (+/- SD) of 27.0 +/- 2.6, 7.31 +/- 0.54, and 1.61 +/- 0.17 atm, respectively. Because the lethal partial pressures of nitrogen and sulfur hexafluoride overlapped their anesthetic partial pressures, MAC values were determined for these gases by additivity studies with desflurane. Nitrogen and sulfur hexafluoride MAC values were estimated to be 110 and 14.6 atm, respectively. Of the gases with anesthetic properties, nitrogen deviated the most from the Meyer-Overton hypothesis. ⋯ It has been thought that the high pressures of helium and neon that might be needed to produce anesthesia antagonize their anesthetic properties (pressure reversal of anesthesia). We propose an alternative explanation: like other compounds with a low affinity to water, helium and neon are intrinsically without anesthetic effect.
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Anesthesia and analgesia · Aug 1998
Involvement of nitric oxide in peripheral antinociception mediated by kappa- and delta-opioid receptors.
Nitric oxide (NO) has been reported to enhance the analgesic effect of the peripherally administered mu-opioid receptor agonists, but the role of NO on the analgesic effect of the peripherally administered kappa and delta opioid receptor agonists is still unclear. We examined the effects of peripherally applied kappa- and delta-opioid receptor agonists and of their interactions with the NO-releasing drug, FK409, on the behavioral response to intraplantar injection of formalin in rats (the formalin test). The formalin injection results in a biphasic appearance of agitation behavior, consisting of the early (Phase 1; 0-9 min) and late (Phase 2; 10-60 min) responses. The active enantiomer of kappa-opioid receptor agonist, (-)U50,488H, dose-dependently suppressed the agitation response in both phases of the formalin test when applied peripherally. A peripheral delta-opioid receptor agonist, [D-Pen(2,5)] enkephalin (DPDPE), suppressed only Phase 2 of the formalin test. Local application of FK409 after the administration of a subthreshold dose of each opioid resulted in a dose-dependent decrease in the Phase 1, but not Phase 2, response to the formalin test for both agonists. Interactions between peripheral opioids and FK409 were reversed with both naloxone and carboxy-PTIO (NO scavenger). Systemic injections of either a kappa- or delta-agonist had no interaction with peripherally applied FK409. Peripheral FK409 alone did not have any significant effect on the formalin test. These data indicate that the antinociceptive effects of peripherally applied kappa- and delta-opioid agonists on the formalin test are potentiated by the local action of NO. ⋯ The analgesic effects of peripherally applied kappa- and delta-opioid receptor agonists during inflammation induced by formalin injection in the rat are, at least partly, mediated by the NO-cGMP pathway.