Anesthesiology
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Activation of A1 adenosine receptors (A1Rs) causes antinociception after nerve injury and inflammation. However, the role of A2a adenosine receptors (A2aRs) for pain processing is less clear. In the current study, the authors investigated the role of spinal adenosine A1Rs and A2aRs for the maintenance of mechanical hyperalgesia in an animal model for postoperative pain. ⋯ Spinal A1Rs but not A2aRs play an important role in the maintenance of nonevoked and evoked pain behaviors after an incision. Furthermore, A1R-induced spinal antinociception is mediated by interactions with pertussis toxin-sensitive G proteins. In addition, the opening of adenosine triphosphate-sensitive K channels but not of calcium-activated potassium channels and voltage-gated Kv1.3 or Kv1.6 channels contribute to the antinociceptive effect of A1R agonists.
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Randomized Controlled Trial Comparative Study
Effect of equiosmolar solutions of mannitol versus hypertonic saline on intraoperative brain relaxation and electrolyte balance.
The purpose of the study was to compare the effect of equiosmolar solutions of mannitol and hypertonic saline (HS) on brain relaxation and electrolyte balance. ⋯ Mannitol and HS cause an increase in cerebrospinal fluid osmolality, and are associated with similar brain relaxation scores and arteriovenous oxygen and lactate difference during craniotomy.
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Inhibition of N-methyl-D-aspartate (NMDA) receptors by anesthetic gases and vapors may play an important role in anesthesia and neuroprotection. However, the site of action of these agents on the NMDA receptor is unknown. The authors show that xenon and isoflurane compete for the binding of the coagonist glycine on the NMDA receptor NR1 subunit. ⋯ Xenon and isoflurane inhibit NMDA receptors by binding at the same site as the coagonist glycine. This finding may have important implications for general anesthesia and neuroprotection. Neuroprotectants that act at the glycine site of the NMDA receptor antagonists are well tolerated in patients, being devoid of psychotomimetic side effects, and the mechanism of inhibition may play a role in their clinical profile.
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Mechanical ventilation is delivered to sedated patients during anesthesia, but also to nonsedated patients (ventilator weaning, noninvasive ventilation). In these circumstances, patient-ventilator asynchrony may occur, provoking discomfort and unduly increasing work of breathing. In certain cases, it is associated with an increased inspiratory load. Inspiratory loading in awake humans activates the premotor cortical regions, as illustrated by the occurrence of electroencephalographic premotor potentials. In normal humans during noninvasive ventilation, the authors used an experimental model of patient-ventilator asynchrony to determine whether premotor cortical activation occurs in this setting. ⋯ This study indicates that "ventilator fighting" in healthy humans is associated with an activation of higher cerebral areas. Premotor potentials could thus be markers of patient-ventilator asynchrony at the brain level. Both corroboration in patients and the elucidation of the causative or reactive nature of the association are needed before determining clinical implications.