Anesthesiology
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Randomized Controlled Trial Comparative Study Clinical Trial
A double-blind, randomized comparison of i.v. lorazepam versus midazolam for sedation of ICU patients via a pharmacologic model.
Benzodiazepines, such as lorazepam and midazolam, are frequently administered to surgical intensive care unit (ICU) patients for postoperative sedation. To date, the pharmacology of lorazepam in critically ill patients has not been described. The aim of the current study was to characterize and compare the pharmacokinetics and pharmacodynamics of lorazepam and midazolam administered as continuous intravenous infusions for postoperative sedation of surgical ICU patients. ⋯ The pharmacology of intravenous infusions of lorazepam differs significantly from that of midazolam in critically ill patients. This results in significant delays in emergence from sedation with lorazepam as compared with midazolam when administered for ICU sedation.
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Randomized Controlled Trial Clinical Trial
Role of the atrial natriuretic factor in obstetric spinal hypotension.
In recent years, the concept of prophylactic volume expansion to prevent hypotension caused by spinal anesthesia has been challenged. Investigators have reevaluated the concept of prehydration in the obstetric patient and the physiologic mechanisms involved. This article addresses whether the hypotensive effects attributed to the atrial natriuretic factor are the reason for the apparent failure of prehydration. ⋯ Atrial natriuretic factor is a potent endogenous diuretic in the pregnant patient but does not appear to be involved in short-term cardiovascular homeostasis after spinal anesthesia. Prehydration appears to be an ineffective measure to prevent post spinal hypotension in the obstetric patient [corrected].
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Although ether, alcohol, and halogenated alkane anesthetics potentiate agonist actions or increase the apparent agonist affinity of ligand-gated ion channels at clinically relevant concentrations, the effects of nonhalogenated alkane anesthetics on ligand-gated ion channels have not been studied. The current study assessed the abilities of two representative nonhalogenated alkane anesthetics (cyclopropane and butane) to potentiate agonist actions or increase the apparent agonist affinity of two representative ligand-gated ion channels: the nicotinic acetylcholine receptor and y-aminobutyric acid type A (GABA(A)) receptor. ⋯ Our results suggest that the in vivo central nervous system depressant effects of nonhalogenated alkane anesthetics do not result from their abilities to potentiate agonist actions on ligand-gated ion channels. Other targets or mechanisms more likely account for the anesthetic activities of nonhalogenated alkane anesthetics.
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Newborn neuromuscular junctions are more sensitive to d-tubocurarine than more mature preparations. It is unclear whether the same modifications occur with newer nondepolarizing agents and depolarizing agent succinylcholine. The purpose of this study was to determine the relative sensitivity of newborn neuromuscular junctions to succinylcholine and five nondepolarizing agents. ⋯ The newborn neuromuscular junction of the rat shows an increased sensitivity to all neuromuscular blocking agents tested, including succinylcholine. However, the potency ratio was greater for nondepolarizing than depolarizing drugs. The optimal dose of these agents for certain situations such as cesarean section and anesthesia in neonates should be reassessed.
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Randomized Controlled Trial Clinical Trial
A new model of electrically evoked pain and hyperalgesia in human skin: the effects of intravenous alfentanil, S(+)-ketamine, and lidocaine.
The authors used the analgesics alfentanil, S(+)-ketamine, and systemic lidocaine to examine a new human model of experimental pain and hyperalgesia. ⋯ A new model of electrically induced pain and hyperalgesia was established, which enabled assessment of the time course of analgesic and antihyperalgesic effects with high temporal resolution and minimum tissue damage and which was further validated by use of common intravenous anesthetics.