Journal of clinical anesthesia
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Randomized Controlled Trial Clinical Trial
Propofol and alfentanil for sedation during placement of retrobulbar block for cataract surgery.
To determine if the addition of alfentanil to propofol is more effective than propofol alone to provide adequate conditions for placement of a retrobulbar block prior to cataract surgery. ⋯ The combination of alfentanil and propofol may be used to sedate patients in order to limit movement and provide a cooperative, alert patient with stable hemodynamics and limited respiratory depression during placement of retrobulbar block prior to ophthalmic surgery. However, excessive dosage of these drugs may result in hazardous respiratory depression in this patient population.
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Opioids decrease the sympathetic and somatic responses to noxious stimulation and can be given in high doses without negative inotropic effects, even in patients with impaired cardiac function. With currently available opioids, precise titration of dose to effect is difficult, and high doses result in drug accumulation and prolonged respiratory depression. Remifentanil is a new synthetic opioid with direct action on mu-opioid receptors. ⋯ The hydrolysis of remifentanil produces a metabolite with very weak opioid receptor activity that does not contribute to the effects of remifentanil. Possible disadvantages of the drug include (1) the need to mix the lyophilized drug with a diluent, (2) administration as a continuous infusion, (3) risk of rapid loss of analgesic and anesthetic effects if the infusion is interrupted accidentally, and (4) difficulty in judging the dose of another, longer lasting opioid that will be required to control postoperative pain without producing excessive ventilatory depression. Remifentanil is likely to be more expensive than other opioids, but its use may reduce overall costs if prompt recovery from its effects results in shorter stays in the operating room and recovery units.
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Multiple reports of cauda equina syndrome and transient radicular nerve root irritation have suggested that lidocaine spinal anesthesia may be responsible. In this case report, a patient with a preexisting diabetic neuropathy received a partial block following a tetracaine spinal, which was followed by a lidocaine spinal. ⋯ The preexisting diabetic neuropathy may have predisposed this patient to neurologic injury. The choice of a different local anesthetic drug with less neurotoxic potential such as bupivacaine may have prevented this injury.
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An abrupt decrease in end-tidal carbon dioxide (CO2) occurred in an anesthetized male who was placed in the head down position during radical perineal prostatectomy. The end-tidal CO2 was restored after insertion of a wet pack into the operative site, which strongly indicated venous air embolism as the cause. Predisposing factors, detection, and treatment of venous air embolism in this setting are discussed.