Anesthesiology
-
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.
-
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.
-
Lumbar facet nerve (medial branch) block for pain relief in facet syndrome is currently performed under fluoroscopic or computed tomography scan guidance. In this three-part study, the authors developed a new ultrasound-guided methodology, described the necessary landmarks and views, assessed ultrasound-derived distances, and tested the clinical feasibility. ⋯ Ultrasound guidance seems to be a promising new technique with clinical relevance and the potential to increase practicability while avoiding radiation in lumbar facet nerve block.
-
Management strategies conceived to improve patient safety in anesthesia have rarely been assessed prospectively. The authors undertook a prospective evaluation of a predefined algorithm for unanticipated difficult airway management. ⋯ When applied in accordance with a predefined algorithm, the gum elastic bougie and the ILMA are effective to solve most problems occurring during unexpected difficult airway management.