Anesthesiology
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There is limited information on the regional inflammatory effects of mechanical ventilation and endotoxemia on the production of acute lung injury. Measurement of F-fluorodeoxyglucose (F-FDG) uptake with positron emission tomography allows for the regional, in vivo and noninvasive, assessment of neutrophilic inflammation. The authors tested whether mild endotoxemia combined with large tidal volume mechanical ventilation bounded by pressures within clinically acceptable limits could yield measurable and anatomically localized neutrophilic inflammation. ⋯ Mild short-term endotoxemia in the presence of heterogeneous lung aeration and mechanical ventilation with pressures within clinically acceptable limits produces marked spatially heterogeneous increases in pulmonary neutrophilic inflammation. The dependence of inflammation on aeration and perfusion suggests a multifactorial basis for that finding. F-FDG uptake may be a sensitive marker of pulmonary neutrophilic inflammation in the studied conditions.
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Comparative Study
Neurally adjusted ventilatory assist increases respiratory variability and complexity in acute respiratory failure.
Neurally adjusted ventilatory assist (NAVA) is a partial ventilatory support mode where positive pressure is provided in relation to diaphragmatic electrical activity (EAdi). Central inspiratory activity is normally not monotonous, but it demonstrates short-term variability and complexity. The authors reasoned that NAVA should produce a more "natural" or variable breathing pattern than other modes. This study compared respiratory variability and complexity during pressure support ventilation (PSV) and NAVA. ⋯ Compared with PSV, NAVA increases the breathing pattern variability and complexity of flow, whereas the complexity of EAdi is unchanged. Whether this improves clinical outcomes remains to be determined.
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Tramadol is an analgesic drug, and its mechanism of action is believed to be mediated by the mu-opioid receptor. A further action of tramadol has been identified as blocking the reuptake of serotonin (5-HT). One of the most recently identified subtypes of 5-HT receptor is the 5-HT7 receptor. Thus, the authors aimed to examine the potential role of serotonergic descending bulbospinal pathways and spinal 5-HT7 receptors compared with that of the 5-HT2A and 5-HT3 receptors in the antinociceptive and antihyperalgesic effects of tramadol and its major active metabolite O-desmethyltramadol (M1) on phasic and postoperative pain models. ⋯ These findings suggest that the descending serotonergic pathways and spinal 5-HT7 receptors play a crucial role in the antinociceptive and antihyperalgesic effects of tramadol and M1.