Anesthesiology
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Randomized Controlled Trial Clinical Trial
Optimal dose of succinylcholine revisited.
The authors reappraised the conventional wisdom that the intubating dose of succinylcholine must be 1.0 mg/kg and attempted to define the lower range of succinylcholine doses that provide acceptable intubation conditions in 95% of patients within 60 s. ⋯ The use of 1.0 mg/kg of succinylcholine may be excessive if the goal is to achieve acceptable intubating conditions within 60 s. Comparable intubating conditions were achieved after 0.3, 0.5, or 1.0 mg/kg succinylcholine. In a rapid-sequence induction, 95% of patients with normal airway anatomy anesthetized with 2 mug/kg fentanyl and 2 mg/kg propofol should have acceptable intubating conditions at 60 s after 0.56 mg/kg succinylcholine. Reducing the dose of succinylcholine should allow a more rapid return of spontaneous respiration and airway reflexes.
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Clinical Trial
The "intubating dose" of succinylcholine: the effect of decreasing doses on recovery time.
The usually cited "intubation dose" of succinylcholine is 1.0 mg/kg. In the majority of patients, this dose will produce apnea of sufficient duration that significant hemoglobin desaturation may occur before neuromuscular recovery takes place in those whose ventilation is not assisted. This study was undertaken to examine the extent to which reducing this dose would decrease the duration of action of succinylcholine. ⋯ Reducing the dose of succinylcholine from 1.0 mg/kg to 0.60 mg/kg shortens the duration of effect at the adductor pollicis by more than 90 s. The authors believe that even this modest decrease in the duration of drug-induced paralysis is often worth pursuing.
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The mode of drug administration, blood sampling schedule, and sampling site affect the pharmacokinetic model derived. The present study tested the hypothesis that three-compartment pharmacokinetic model parameters derived from arterial drug concentrations obtained after rapid intravenous administration can be used to design a target-controlled drug infusion (TCI) that deviates minimally from the target. ⋯ Because three-compartment models based on drug concentration histories obtained after rapid intravenous administration do not characterize VC accurately, TCIs based on them produce concentrations exceeding the target. A model capable of producing TCIs deviating minimally from the target can be derived from data obtained during and after a brief drug infusion.
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Pharmacologic modulation of the state of consciousness is of interest for clinical practice and for a better understanding of anesthetic mechanisms. The cholinergic activating system is an important regulator of the state of consciousness during general anesthesia. Entropy of the electroencephalogram has been proposed as a promising measure of anesthetic depth. The authors have shown that volatile anesthetics decrease cross-approximate entropy (C-ApEn) of the bihemispheric frontal electroencephalogram in rats. The effect of cholinergic agents on C-ApEn has not been examined. Here, the authors test the hypothesis that cholinergic activation reverses the effect of isoflurane anesthesia on C-ApEn. ⋯ C-ApEn of the bihemispheric electroencephalogram correlates with the return of spontaneous motor signs but not with the nociceptive reflex. Cerebral cholinergic activation dissociates central and peripheral anesthetic effects. C-ApEn, a novel measure of interhemispheric electroencephalogram independence, is a promising correlate of depth of sedation and state of consciousness.