Anesthesiology
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Randomized Controlled Trial Comparative Study Clinical Trial
Effects of a circulating-water garment and forced-air warming on body heat content and core temperature.
Forced-air warming is sometimes unable to maintain perioperative normothermia. Therefore, the authors compared heat transfer, regional heat distribution, and core rewarming of forced-air warming with a novel circulating-water garment. ⋯ The circulating-water system transferred more heat than forced air, with the difference resulting largely from posterior heating. Circulating water rewarmed patients 0.4 degrees C/h faster than forced air. A substantial peripheral-to-core tissue temperature gradient with each device indicated that peripheral tissues insulated the core, thus slowing heat transfer.
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Comparative Study
Effects of dopamine, dobutamine, and dopexamine on microcirculatory blood flow in the gastrointestinal tract during sepsis and anesthesia.
Insufficient blood flow to the splanchnic organs is believed to be an important contributory factor for the development of organ failure after septic shock. It has been suggested that increasing systemic flow also may improve splanchnic blood flow in septic patients. The aim of this study was to compare the effects of three commonly used inotropic agents, dopamine, dobutamine, and dopexamine, on systemic (cardiac index), regional (superior mesenteric artery), and local (micro-circulatory) blood flow during septic shock in pigs. ⋯ All the inotropic agents markedly increased cardiac output in this sepsis model. However, increased systemic flow did not reach the microcirculation in the gastrointestinal tract. This may in part explain why some of the clinical trials, in which systemic oxygen delivery was deliberately increased by administration of inotropic drugs, have failed to improve survival in critically ill patients.
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Comparative Study
Propofol modulates gamma-aminobutyric acid-mediated inhibitory neurotransmission to cardiac vagal neurons in the nucleus ambiguus.
Although it is well recognized that anesthetics modulate the central control of cardiorespiratory homeostasis, the cellular mechanisms by which anesthetics alter cardiac parasympathetic activity are poorly understood. One common site of action of anesthetics is inhibitory neurotransmission. This study investigates the effect of propofol on gamma-aminobutyric acid-mediated (GABAergic) and glycinergic neurotransmission to cardiac parasympathetic neurons. ⋯ Propofol may vary heart rate by modulating GABAergic neurotransmission to cardiac parasympathetic neurons. At clinically relevant concentrations (> or =1.0 microm), propofol facilitated GABAergic responses in cardiac vagal neurons by increasing decay time, which would increase inhibition of cardioinhibitory cardiac vagal neurons and evoke an increase in heart rate. At higher supraclinical concentrations (> or =50 microm), propofol inhibits GABAergic neurotransmission to cardiac vagal neurons, which would evoke a decrease in heart rate.
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Intrathecal adenosine has antinociceptive effects under conditions of hypersensitivity. T62 (2-amino-3-(4-chlorobenzoyl)-5,6,7,8-tetrahydrobenzothiophen) is an allosteric adenosine receptor modulator that enhances adenosine binding to the A1 receptor. Intrathecal T62 reduces hypersensitivity to mechanical stimuli in a rat model of neuropathic pain by a circuit that totally relies on activation of alpha2 adrenoceptors. Here, the authors tested whether this same dependence was present in the acute setting of hypersensitivity after surgery. ⋯ Intrathecal T62 is effective for postoperative hypersensitivity. The synergy of T62 with clonidine and its only partial antagonism by idazoxan suggest that T62 does not rely entirely on activation of alpha2 adrenoceptors. These results indicate that, after surgery, T62 acts via a mechanism different from that of spinal nerve ligation, a model of chronic neuropathic pain.