Anesthesiology
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Comparative Study
Comparison between respiratory variations in pulse oximetry plethysmographic waveform amplitude and arterial pulse pressure during major abdominal surgery.
To assess preload dependence, the variation of the plethysmographic waveform of pulse oximetry (ΔPOP) has been proposed as a surrogate of the pulse pressure variation (ΔPP). The aim of the study was to assess the ability of the pulse oximeter-derived plethysmographic analysis to accurately trend ΔPP in patients undergoing major abdominal surgery by using standard monitors. ⋯ The wide limits of agreement between ΔPP and ΔPOP and the weak correlation between both values cast doubt regarding the ability of ΔPOP to substitute ΔPP to follow trend in preload dependence and classify respiratory cycles as responders or nonresponders using standard monitor during anesthesia for major abdominal surgery.
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Randomized Controlled Trial
Metabolomic profiling of children's brains undergoing general anesthesia with sevoflurane and propofol.
We recently applied proton magnetic resonance spectroscopy (HMRS) to investigate metabolic consequences of general anesthesia in the rodent brain, and discovered that isoflurane anesthesia was characterized by higher concentrations of lactate, glutamate, and glucose in comparison with propofol. We hypothesized that the metabolomic differences between an inhalant and intravenous anesthetic observed in the rodent brain could be reproduced in the human brain. ⋯ Our results demonstrating higher glucose and lactate with sevoflurane in the human brain compared with propofol could reflect greater neuronal activity with sevofluane resulting in enhanced glutamate-neurotransmitter cycling, increased glycolysis, and lactate shuttling from astrocytes to neurons or mitochondrial dysfunction. Further, the association between emergence delirium and lactate suggests that anesthesia-induced enhanced cortical activity in the unconscious state may interfere with rapid return to "coherent" brain connectivity patterns required for normal cognition upon emergence of anesthesia.
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Inflammation of the dorsal root ganglia (DRG) may contribute to low back pain, postherpetic neuralgia, and neuropathic pain. The mineralocorticoid receptor (MR) plays a proinflammatory role in many nonrenal tissues, but its role in peripheral pain at the DRG level is not well studied. ⋯ The MR may have a pronociceptive role in the DRG. Some of its effects may be mediated by neuronal MR. The MR may represent a novel therapeutic target in some pain syndromes.
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The role of the hypovolemic component secondary to the microcirculatory changes in the onset of inaugural anaphylactic hypotension remains debated. We investigated the microcirculatory permeability in a model of anaphylactic shock using a fluorescence confocal microscopy imaging system. ⋯ During anaphylaxis, interstitial capillary leakage occurs within minutes after shock onset. Compared with controls, the mesenteric microcirculation showed at least 8-fold-increased macromolecular capillary leakage. The inflammation-induced microcirculatory changes with subsequent intravascular fluid transfer might be involved in the onset of the inaugural hypotension during anaphylactic shock.
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Propofol in the early postnatal period has been shown to cause brain cell death. One proposed mechanism for cognitive dysfunction after anesthesia is alteration of neural stem cell function and neurogenesis. We examined the effect of propofol on neural precursor or stem cells (NPCs) grown in vitro. ⋯ Only supraclinical concentrations of propofol or Diprivan kill NPCs in culture by a non-γ-aminobutyric acid type A, noncaspase-3 mechanism. Clinically relevant doses of propofol increase neuronal fate choice by a non-γ-aminobutyric acid type A mechanism.