Anesthesiology
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Randomized Controlled Trial Clinical Trial
Hemodynamic and analgesic profile after intrathecal clonidine in humans. A dose-response study.
Epidural clonidine produces effective postoperative analgesia in humans. Observed side effects include hypotension, bradycardia, sedation, and dryness of the mouth. A recent clinical study demonstrated that 150 micrograms intrathecal clonidine administered postoperatively as the sole analgesic agent was effective but produced hypotension and sedation. Animal studies have provided evidence of a biphasic effect on blood pressure after intrathecal clonidine administration, but no data concerning this effect in humans currently exist. This study was performed to evaluate the dose-response hemodynamic and analgesic profiles of intrathecal clonidine administered after a standard surgical intervention, without perioperative administration of additional analgesics, local anesthetics, or tranquilizers. ⋯ These results demonstrate dose-dependent analgesia after intrathecal clonidine at doses as great as 450 micrograms. The nearly immediate analgesic effect observed after intrathecal injection of 300 and 450 micrograms clonidine strongly argues for a spinal rather than a systemic site of action of this alpha 2-adrenergic agonist. After 300 and 450 micrograms intrathecal clonidine a relative hemodynamic stability is observed, suggesting a pressor effect at peripheral sites.
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Randomized Controlled Trial Clinical Trial
End-tidal sevoflurane concentrations for laryngeal mask airway insertion and for tracheal intubation in children.
Sevoflurane, a new inhalational anesthetic agent characterized by a low blood-gas partition coefficient and nonpungent odor, appears suitable as an induction agent for children. The laryngeal mask airway is a new device for maintaining airway patency during anesthesia. This study was conducted to determine the sevoflurane concentrations required for insertion of a laryngeal mask (MACLMI) and for tracheal intubation (MACTI) in children. ⋯ Laryngeal mask insertion can be performed at a lesser sevoflurane concentration than that required for tracheal intubation.
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Clinical Trial
Transesophageal echocardiographic monitoring of preoperative acute hypervolemic hemodilution.
Preoperative acute hypervolemic hemodilution is used in anesthesia to reduce the loss of blood cells during intraoperative bleeding. Indications for use of the technique might be broadened if it can be shown to be safe in older as well as younger patients. Few data are available describing heart function in humans subjected to hypervolemic hemodilution. ⋯ The described regimen of acute hypervolemic hemodilution is well tolerated during anesthesia by patients without heart disease and does not lead to cardiac failure. It leads to an increase in stroke volume that is generated initially from an increase in end-diastolic volume, followed in many patients by a decrease in end-systolic volume, the mechanism of which is as yet unclear.
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It is well known that endotoxin causes acute lung injury resulting in adult respiratory distress syndrome. Numerous cellular and humoral factors such as macrophages, neutrophils, platelets, and inflammatory mediators (e.g., activated complements, cytokines, and arachidonic acid metabolites) are thought to play a pivotal role in the pathogenesis of endotoxin-induced lung injury. Furthermore, pulmonary edema in acute lung injury is associated with an increase in vascular permeability that may arise from a perturbation of the endothelial cell surface membrane. Lidocaine has been shown to inhibit function of these cells and stabilize cell membranes. The aim of the current study was to determine whether pretreatment with intravenous lidocaine could attenuate acute lung injury induced by endotoxin in rabbits. ⋯ These results suggest that intravenous lidocaine pretreatment has a prophylactic effect on endotoxin-induced lung injury in rabbits. However, further studies are required to investigate the therapeutic (as an early posttreatment) effect of the drug given after lung injury because rabbits in the current study received lidocaine before endotoxemia.