Anesthesiology
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Although volatile anesthetics such as isoflurane can depress sensory and motor neurons in the spinal cord, movement occurring during anesthesia can be coordinated, involving multiple limbs as well as the head and trunk. However, it is unclear whether volatile anesthetics depress locomotor interneurons comprising central pattern generators or disrupt intersegmental central pattern generator coordination. ⋯ Isoflurane disrupts motor output by reducing interneuronal central pattern generator activity in the spinal cord. The effects of isoflurane on motor output outside the site of isoflurane application were presumably independent of effects on sensory or motor neurons.
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This study investigated the effect of varying concentrations of propofol on upper airway collapsibility and the mechanisms responsible for it. ⋯ Increasing depth of propofol anesthesia is associated with increased collapsibility of the upper airway. This was associated with profound inhibition of genioglossus muscle activity. This dose-related inhibition seems to be the combined result of depression of central respiratory output to upper airway dilator muscles and of upper airway reflexes.
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Atelectasis results in impaired compliance and gas exchange and, in extreme cases, increased microvascular permeability, pulmonary hypertension, and right ventricular dysfunction. It is not known whether such atelectasis-induced lung injury is due to the direct mechanical effects of lung volume reduction and alveolar collapse or due to the associated regional lung hypoxia. The authors hypothesized that addition of supplemental oxygen to an atelectasis-prone ventilation strategy would attenuate the pulmonary vascular effects and reduce the local levels of vasoconstrictor eicosanoids. ⋯ Although supplemental oxygen worsened atelectasis in this model, it prevented the pathologic effects of atelectasis, including microvascular leak and pulmonary hypertension. Atelectasis-induced lung injury seems to be mediated by hypoxia rather than by the direct mechanical effects of atelectasis.