Anesthesiology
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Randomized Controlled Trial Clinical Trial
A double-blind, placebo-controlled trial of transdermal fentanyl after abdominal hysterectomy. Analgesic, respiratory, and pharmacokinetic effects.
A randomized, double-blind, placebo-controlled trial was conducted to assess the analgesic, pharmacokinetic, and clinical respiratory effects of 72-h application of two transdermal fentanyl (TTSF) patch sizes in patients undergoing abdominal hysterectomy. ⋯ Application of TTSF patches 2 h preoperatively is associated with moderate supplementary opioid requirements for analgesia in the early postoperative period and ongoing opioid supplementation for at least 72 h. Although good analgesia is the result of this combination therapy, it is associated with a high incidence of respiratory depression requiring intensive monitoring oxygen supplementation, removal of the TTSF patches in approximately 11% of the patients and opioid reversal with naloxone in approximately 8% of the patients.
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Despite the widespread use of epidurally administered corticosteroids in the treatment of sciatica and the failure of animal studies to demonstrate neurotoxicity from epidermally administered corticosteroids, controversy remains regarding the mechanism of action as well as the safety of this treatment. The goal of this study was to determine whether spinally administered corticosteroids have any analgesic effects, and whether repeated intrathecal administration causes any neuronal damage to the spinal cord. ⋯ Intrathecal steroid injections have no analgesic effect and do not suppress spinal sensitization when administered acutely. After chronic administration, there is a mild effect on nociceptor-driven spinal sensitization (phase 2 of the formalin test), but no analgesic effect on an acute noxious stimulus (phase 1 of the formalin test). Repeated intrathecal administration of triamcinolone diacetate (0.8 mg/kg) is not associated with spinal neurotoxic effects during the time period studied.
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Injection of formalin in the hindpaw of the rat induces intense C-fiber activity accompanied by brief flinching of the injected paw (phase 1) and gives rise to facilitated spinal processing characterized by renewed flinching beginning 15 min after injury and lasting 40 min or more (phase 2). In previous work, isoflurane, administered during phase 1, slightly reduced phase-2 activity, whereas the addition of intrathecal morphine dramatically inhibited phase 2, even with naloxone reversal 6 min after the formalin injection. We used a similar model to determine whether intrathecal morphine could block spinal sensitization in the absence of inhalation anesthetic. ⋯ Intrathecal morphine, administered before formalin injection but antagonized before the onset of phase 2 of the formalin test, significantly suppresses sensitization of dorsal horn neurons. This suppression is significantly increased by coadministration of halothane anesthesia.
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Manual ventilators (resuscitators) are used primarily to ventilate the lungs of patients lacking spontaneous ventilatory effort. However, in many settings patients are allowed to breathe through the manual ventilator. Although many aspects of manual ventilator function have been studied, very little has been reported on the use of manual ventilators during spontaneous breathing. The purpose of this study was to evaluate inspiratory and expiratory imposed work of breathing and oxygen delivery during spontaneous breathing through disposable manual ventilators. ⋯ Adult disposable manual ventilators produce a substantial imposed work of spontaneous breathing, which is increased with the addition of positive end-expiratory pressure. With some manual ventilators, a high oxygen concentration may not be delivered during spontaneous breathing. We recommend that patients not be allowed to spontaneously breathe through disposable manual ventilators.
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Comparative Study
Sevoflurane and isoflurane protect against bronchospasm in dogs.
Halothane and isoflurane have been shown to be effective in reversing bronchoconstriction; however, the effects of sevoflurane have not been well defined. We studied whether sevoflurane, compared with isoflurane, attenuates bronchospasm in dogs. ⋯ Sevoflurane is as effective as isoflurane in attenuating bronchoconstriction associated with anaphylaxis in dogs. Sevoflurane may be a useful alternative to halothane, enflurane, or isoflurane in the treatment of bronchospasm in asthma or anaphylaxis.