Anesthesiology
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A rigorous study of the dose-response relation of rapacuronium has, to our knowledge, yet to be performed. In addition, there is little information available regarding the onset or offset profile of rapacuronium when administered in subparalyzing doses. These issues necessitate further study. ⋯ The authors found the ED95 of rapacuronium to be substantially less than suggested by previous estimates. Rapacuronium has an onset profile that is not different from that previously reported for succinylcholine. The rate of spontaneous recovery was faster after rapacuronium than the authors previously observed after mivacurium administration but was slower than after succinylcholine, using an identical protocol.
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Comparative Study
Addition of sodium bicarbonate to lidocaine decreases the duration of peripheral nerve block in the rat.
Adding sodium bicarbonate to lidocaine to enhance its efficacy during peripheral nerve block is controversial. The authors studied the effect of adding sodium bicarbonate to lidocaine with and without epinephrine versus equivalent alkalinization by sodium hydroxide (NaOH) on onset, degree, and duration of peripheral nerve block. ⋯ With 1% commercial lidocaine without epinephrine, sodium bicarbonate decreases the degree and duration of block. However, in solutions with epinephrine, sodium bicarbonate hastens onset, without effecting degree or duration.
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The spinal cord is an important anatomic site at which volatile agents act to prevent movement in response to a noxious stimulus. This study was designed to test the hypothesis that enflurane acts directly on motor neurons to inhibit excitatory synaptic transmission at glutamate receptors. ⋯ Enflurane exerts direct depressant effects on both alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid and NMDA glutamate currents in motor neurons. Enhancement of gamma-aminobutyric acid A and glycine inhibition is not needed for this effect. Direct depression of glutamatergic excitatory transmission by a postsynaptic action on motor neurons thus may contribute to general anesthesia as defined by immobility in response to a noxious stimulus.
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Comment Letter
Can epidural fentanyl induce selective spinal hyperalgesia?