Anesthesia and analgesia
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Anesthesia and analgesia · Nov 2016
Physostigmine and Methylphenidate Induce Distinct Arousal States During Isoflurane General Anesthesia in Rats.
Although emergence from general anesthesia is clinically treated as a passive process driven by the pharmacokinetics of drug clearance, agents that hasten recovery from general anesthesia may be useful for treating delayed emergence, emergence delirium, and postoperative cognitive dysfunction. Activation of central monoaminergic neurotransmission with methylphenidate has been shown to induce reanimation (active emergence) from general anesthesia. Cholinergic neurons in the brainstem and basal forebrain are also known to promote arousal. The objective of this study was to test the hypothesis that physostigmine, a centrally acting cholinesterase inhibitor, induces reanimation from isoflurane anesthesia in adult rats. ⋯ Unlike methylphenidate, physostigmine does not accelerate time to emergence from isoflurane anesthesia and does not restore righting during continuous isoflurane anesthesia. However, physostigmine consistently decreases BSP during deep isoflurane anesthesia, whereas methylphenidate does not. These findings suggest that activation of cholinergic neurotransmission during isoflurane anesthesia produces arousal states that are distinct from those induced by monoaminergic activation.
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Anesthesia and analgesia · Nov 2016
An Investigation Into the Effects of In Vitro Dilution With Different Colloid Resuscitation Fluids on Clot Microstructure Formation.
Balancing the beneficial effects of resuscitation fluids against their detrimental effect on hemostasis is an important clinical issue. We aim to compare the in vitro effects of 3 different colloid resuscitation fluids (4.5% albumin, hydroxyethyl starch [Voluven 6%], and gelatin [Geloplasma]) on clot microstructure formation using a novel viscoelastic technique, the gel point. This novel hemorheologic technique measures the biophysical properties of the clot and provides an assessment of clot microstructure from its viscoelastic properties. Importantly, in contrast to many assays in routine clinical use, the measurement is performed using unadulterated whole blood in a near-patient setting and provides rapid assessment of coagulation. We hypothesized that different colloids will have a lesser or greater detrimental effect on clot microstructure formation when compared against each other. ⋯ We show that dilution with all 3 fluids has a significant effect on coagulation at even relatively low dilution volumes (20% and 40%). Furthermore, we quantify, using a novel viscoelastic technique, how the physiochemical properties of the 3 colloids exert individual changes on clot microstructure.
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Anesthesia and analgesia · Nov 2016
Structural Integrity of a Simple Method to Repair Disrupted Tracheal Tube Pilot Balloon Assemblies.
An intact pilot balloon assembly is crucial to the proper function of a cuffed tracheal tube. Disruption of the pilot balloon, transection of the inflation line, or valve incompetence results in cuff deflation, which may lead to inadequate ventilation and aspiration of secretions. Such failures typically result in tracheal tube replacement, but this may be a safety risk if a difficult reintubation is anticipated. We recently encountered such a patient who remained intubated postoperatively and in whom the inflation line was transected, causing a large leak. We describe a method to reconstitute the inflation line and report on the structural integrity of the repair. We hypothesized that the repaired assembly would maintain cuff pressure not statistically different from an intact device, but that the inflation line would be weaker. ⋯ Repairing a disrupted pilot balloon assembly using an IV catheter as a stent inside the inflation line is an effective temporizing measure in situations where ventilation is impaired and where tracheal tube replacement may present an excessive patient risk.
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Anesthesia and analgesia · Nov 2016
δGABAA Receptors Are Necessary for Synaptic Plasticity in the Hippocampus: Implications for Memory Behavior.
Extrasynaptic γ-aminobutyric acid type A (GABAA) receptors that contain the δ subunit (δGABAA receptors) contribute to memory performance. Dysregulation of δGABAA receptor expression, which occurs in some neurological disorders, is associated with memory impairment. Mice lacking δGABAA receptors (Gabrd) exhibit deficits in their ability to distinguish between similar memories, a process which is referred to as pattern separation. The CA3 and dentate gyrus subfields of the hippocampus regulate pattern separation, raising the possibility that synaptic plasticity is impaired in these regions in Gabrd mice. Although long-term potentiation (LTP), the most widely studied form of synaptic plasticity, is normal in the dentate gyrus of Gabrd mice, LTP in the CA3 subfield has not been studied. Here, we tested the hypothesis that LTP is reduced in the CA3 subfield of Gabrd mice. ⋯ Both genetic deletion and pharmacological blockade of δGABAA receptors impair MF-CA3 LTP, suggesting that δGABAA receptors are necessary for synaptic plasticity in the CA3 subfield. Drugs that enhance δGABAA receptor function may reverse deficits in synaptic plasticity in the CA3 subfield and improve pattern separation in neurological disorders.