Anesthesiology
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Randomized Controlled Trial Clinical Trial
Pharmacology of epidural fentanyl, alfentanil, and sufentanil in volunteers.
Despite a large number of clinical investigations in postoperative patients, the pharmacology of epidural fentanyl, alfentanil, and sufentanil has not been well characterized in a human laboratory setting. In this double-blind, placebo-controlled crossover study, we evaluated analgesia and side effects produced by epidural fentanyl (30 and 100 micrograms), alfentanil (300 and 1,000 micrograms), and sufentanil (3 and 10 micrograms) in volunteers. ⋯ Lumbar epidural fentanyl, alfentanil, and sufentanil produce selective lower-extremity analgesia. Low plasma opioid concentrations measured after small epidural opioid doses suggest a spinal mechanism for analgesia. Larger doses of epidural opioids result in systemic absorption and are likely to produce supraspinal analgesia and other side effects.
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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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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.
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Randomized Controlled Trial Comparative Study Clinical Trial
Onset and duration of rocuronium and succinylcholine at the adductor pollicis and laryngeal adductor muscles in anesthetized humans.
Rocuronium, a new nondepolarizing muscle relaxant, has a rapid onset of activity and may be suitable as a component of a rapid-sequence induction of anesthesia. We evaluated a range of doses on onset and duration of effect at the larynx and the adductor pollicis and compared these characteristics with those of succinylcholine. ⋯ The laryngeal adductors are more resistant to the action of rocuronium than is the adductor pollicis. Consequently, the onset of effect of rocuronium, in doses greater than 0.8 mg/kg, is similar to that of succinylcholine at the adductor pollicis but is significantly delayed compared with that of succinylcholine at the laryngeal adductors.