Anesthesia and analgesia
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Anesthesia and analgesia · Jun 2005
Clinical TrialThe electrophysiological effect of dextrose 5% in water on single-shot peripheral nerve stimulation.
When performing regional anesthesia, a small volume of local anesthetic or normal saline abolishes a motor response induced by a low current (0.5 mA). In this case series we describe the electrophysiological effect of a nonconducting (dextrose 5% in water, D5W) injectate on a motor response elicited by low current electrical stimulation. Twenty-nine peripheral nerve blocks were performed in 20 patients using insulated needles. ⋯ In all cases, the motor response was at least maintained or augmented (96%) immediately after the injection of D5W. All motor responses diminished after the injection of local anesthetic (100%). All blocks were considered clinically successful.
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Anesthesia and analgesia · Jun 2005
Case ReportsPropofol infusion syndrome associated with short-term large-dose infusion during surgical anesthesia in an adult.
In this case report we describe a case of propofol infusion syndrome in an adult after a short-term infusion of large-dose propofol during a neurosurgical procedure. Large-dose propofol (9 mg.kg(-1).h(-1)) was given for only 3 h during surgery and was followed by a small-dose infusion (2.3 mg.kg(-1).h(-1)) for 20 h postoperatively. ⋯ There were no other evident causes of lactic acidosis as documented by laboratory data. We believe this is the first report of reversible lactic acidosis associated with a short duration of large-dose propofol anesthesia.
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Anesthesia and analgesia · Jun 2005
Propofol dose-dependently reduces tumor necrosis factor-alpha-Induced human umbilical vein endothelial cell apoptosis: effects on Bcl-2 and Bax expression and nitric oxide generation.
We investigated whether propofol can inhibit tumor necrosis factor (TNF)-alpha-induced apoptosis in cultured human umbilical vein endothelial cells (HUVECs). Isolated HUVECs were cultured in Dulbecco's modified Eagle medium supplemented with 20% bovine calf serum. HUVECs in untreated and propofol control groups were cultured at 37 degrees C for 24.5 h. ⋯ This was accompanied by increases in nitric oxide production. There is an inverse correlation between the ratio of Bcl-2/Bax expression and AI (P = 0.0009). These results suggest that propofol, at clinical relevant concentrations, can reduce TNF-induced HUVEC apoptosis.
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Anesthesia and analgesia · Jun 2005
Oxygen consumption with mechanical ventilation in a field anesthesia machine.
Field anesthesia machines (FAM) with gas-powered ventilators have been developed for remote locations that may not have a central supply of oxygen. These ventilators may rapidly deplete oxygen cylinders, especially in patients with decreased pulmonary compliance. Our goal in this study was to determine oxygen consumption rates with a contemporary FAM in models of high (HC) and low (LC) pulmonary compliance. ⋯ Oxygen consumption varied directly with Vt and inversely with compliance, increasing from 4.8 +/- 0.07 L/min with the HC-500 mL Vt model to 6.2 +/- 0.05 L/min with the LC-1000 mL Vt model. D cylinder duration ranged from 56.8 +/- 0.4 to 73.6 +/- 1.0 minutes. Assuming oxygen fresh gas flow of 1 L/min, calculating tank duration with the fastest consumption rate underestimated the tank duration for more compliant and smaller Vt models but provided a greater margin of patient safety.
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Anesthesia and analgesia · Jun 2005
Molecular properties important for inhaled anesthetic action on human 5-HT3A receptors.
Although inhaled anesthetics have diverse effects on 5-hydroxytryptamine type 3 (5-HT3A) receptors, the mechanism accounting for this diversity is not understood. Studies have shown that modulation of 5-HT3A receptor currents by n-alcohols depends on molecular volume, suggesting that steric interactions between n-alcohols and their binding sites define their action on this receptor. Electrostatic interactions also play an important role in anesthetic action on other ligand-gated receptors. ⋯ However, only agents smaller than 0.120 nm3 shifted the 5-HT3A receptor's serotonin concentration-response curve to the left, whereas larger anesthetics shifted them to the right. Modulation of human 5-HT3A-mediated currents by volatile anesthetics exhibits a dependence on molecular volume consistent with the n-alcohols, suggesting that both classes of agents may enhance 5-HT3A receptor function via the same mechanism. Furthermore, the enhancing but not inhibiting effects of anesthetic compounds on 5-HT3A receptor currents are modulated by electrostatic interactions.