Anesthesiology
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Randomized Controlled Trial Comparative Study Clinical Trial
Hyperbaric spinal ropivacaine: a comparison to bupivacaine in volunteers.
Ropivacaine is a newly introduced local anesthetic that may be a useful alternative to low-dose bupivacaine for outpatient spinal anesthesia. However, its relative potency to bupivacaine and its dose-response characteristics are unknown. This double-blind, randomized, crossover study was designed to determine relative potencies of low-dose hyperbaric spinal ropivacaine and bupivacaine and to assess the suitability of spinal ropivacaine for outpatient anesthesia. ⋯ Ropivacaine is half as potent and in equipotent doses has a similar profile to bupivacaine with a higher incidence of side effects. Low-dose hyperbaric spinal ropivacaine does not appear to offer an advantage over bupivacaine for use in outpatient anesthesia.
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Randomized Controlled Trial Clinical Trial
Effects of prophylactic nalmefene on the incidence of morphine-related side effects in patients receiving intravenous patient-controlled analgesia.
Opioid-related side effects associated with intravenous patient-controlled analgesia can be reduced by a low-dose naloxone infusion. The influence of nalmefene, a pure opioid antagonist with a longer duration of action, on opioid-related side effects has not been evaluated. This study was designed to determine the dose-response relation for nalmefene for the prevention of morphine-related side effects in patients receiving intravenous patient-controlled analgesia. ⋯ Compared with placebo, prophylactic administration of nalmefene significantly decreased the need for antiemetics and antipruritic medications in patients receiving intravenous patient-controlled analgesia with morphine.
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Cardiac output (CO) is likely to influence the pharmacokinetics of anesthetic drugs and should be accounted for in pharmacokinetic models. The influence of CO on the pharmacokinetic parameters of alfentanil in pigs was evaluated using compartmental and recirculatory models. ⋯ Cardiac output markedly influences the pharmacokinetics of alfentanil in pigs. Therefore, accounting for CO enhances the predictive value of pharmacokinetic models of alfentanil.