Anesthesia and analgesia
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Anesthesia and analgesia · Nov 2016
ReviewMesopontine Switch for the Induction of General Anesthesia by Dedicated Neural Pathways.
We review evidence that the induction of anesthesia with GABAergic agents is mediated by a network of dedicated axonal pathways, which convey a suppressive signal to remote parts of the central nervous system. The putative signal originates in an anesthetic-sensitive locus in the brainstem that we refer to as the mesopontine tegmental anesthesia area (MPTA). This architecture stands in contrast to the classical notion that anesthetic molecules themselves directly mediate anesthetic induction after global distribution by the vascular circulation. ⋯ Known connectivity of the MPTA provides a scaffold for defining the specific projection pathways that mediate each of the functional components of anesthesia. Because MPTA lesions do not induce coma, the MPTA is not a key arousal nucleus essential for maintaining the awake state. Rather, it appears be a "gatekeeper" of arousal function, a major element in a flip-flop switching mechanism that executes rapid and reversible transitions between the awake and the anesthetic state.
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Anesthesia and analgesia · Nov 2016
Clinical TrialNeuraxial Anesthesia Reduces Lymphatic Flow: Proof-of-Concept in First In-Human Study.
Dilation of lymphatic vessels may contribute to iatrogenic dissemination of cancer cells during surgery. We sought to determine whether neuraxial anesthesia reduces regional lymphatic flow. Using nuclear lymphoscintigraphy, 5 participants receiving spinal anesthesia for brachytherapy had lower extremity lymph flow at rest compared with flow under conditions of spinal anesthesia. ⋯ All analyzed limbs showed reduced lymph flow washout from the pedal injection site (range 62%-100%) due to neuraxial anesthesia. Lymph flow was abolished in 3 limbs. We report proof-of-concept that neuraxial anesthesia reduces lymphatic flow through a likely mechanism of sympathectomy.
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Anesthesia and analgesia · Nov 2016
Case ReportsPausing With the Gauze: Inhibition of Temporary Pacemakers by Radiofrequency Scan During Cardiac Surgery.
Radiofrequency identification (RFID) detection systems are used to detect retained surgical sponges and may cause electromagnetic interference (EMI), altering intended function of cardiac pacing systems. Three pediatric patients requiring temporary pacing for postoperative atrioventricular block experienced transient inhibition of ventricular pacing during the use of RFID detection system. Bench testing was performed to evaluate the mechanism of pacemaker inhibition. ⋯ Normal operation of RFID detection systems may cause inhibition of temporary pacing systems consistent with oversensing from EMI. Precaution should be taken, including considering pacing asynchronously to avoid effects of inhibition.
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Anesthesia and analgesia · Nov 2016
Observational StudyHemodynamic Instability Following Airway Spray Cryotherapy.
Spray cryotherapy (SCT) of airway lesions is used to effectively palliate respiratory symptoms related to airway obstruction, but significant intraoperative hemodynamic complications have been noted. We reviewed the experience at a single institution using SCT for the treatment of obstructive airway tumors. ⋯ Unpredictable life-threatening hemodynamic instability can follow endobronchial SCT. We propose that the most likely cause is pulmonary venous gaseous emboli entering the right heart, the coronary arteries, and the systemic circulation. Although SCT may offer advantages over airway laser therapy (such as no risk of fire and rapid hemostasis), further study is needed to delineate the relative likelihood of therapeutic benefit versus catastrophic complications.
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Air injection is carefully avoided during IV solution administration; however, ambient air is dissolved in all liquids used for intravenous (IV) therapy. A portion of this gas will come out of solution in the form of bubbles as the solution is warmed to body temperature in a fluid warming system and/or within the body. We sought to quantify the proportion of the gas theoretically dissolved in room temperature crystalloid and 4°C blood products that comes out of solution in the IV tubing on warming to 37°C. ⋯ A significant and potentially clinically relevant amount of the resident dissolved gas in room temperature crystalloid, and 4°C packed red blood cells and plasma solutions comes out of solution on warming to body temperature. A nontrivial fraction of this outgassing is also expected to occur within the body circulation based on the results of this study. This can be substantially prevented by prewarming.