Anesthesiology
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Review Meta Analysis
Effect of perioperative systemic α2 agonists on postoperative morphine consumption and pain intensity: systematic review and meta-analysis of randomized controlled trials.
Systemic α2 agonists are believed to reduce pain and opioid requirements after surgery, thus decreasing the incidence of opioid-related adverse effects, including hyperalgesia. ⋯ Perioperative systemic α2 agonists decrease postoperative opioid consumption, pain intensity, and nausea. Recovery times are not prolonged. Common adverse effects are bradycardia and arterial hypotension. The impact of α2 agonists on chronic pain or hyperalgesia remains unclear because valid data are lacking.
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Peripheral application of opioids reduces inflammatory pain but is less effective in noninflamed tissue of rats and human patients. Hypertonic solutions can facilitate the antinociceptive activity of hydrophilic opioids in noninflamed tissue in vivo. However, the underlying mechanisms are not well understood. We hypothesized that the enhanced efficacy of opioids may be because of opening of the perineurial barrier formed by tight junction-proteins like claudin-1. ⋯ Hypertonic saline opens the perineurial barrier via metalloproteinase activation and claudin-1 regulation, thereby allowing access of hydrophilic drugs to peripheral opioid receptors. This principle may be used to specifically target hydrophilic drugs to peripheral neurons.
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Randomized Controlled Trial
Spontaneous breathing during general anesthesia prevents the ventral redistribution of ventilation as detected by electrical impedance tomography: a randomized trial.
Positive-pressure ventilation causes a ventral redistribution of ventilation. Spontaneous breathing during general anesthesia with a laryngeal mask airway could prevent this redistribution of ventilation. We hypothesize that, compared with pressure-controlled ventilation, spontaneous breathing and pressure support ventilation reduce the extent of the redistribution of ventilation as detected by electrical impedance tomography. ⋯ Both pressure-controlled ventilation and pressure support ventilation induce a redistribution of ventilation toward the ventral region, as detected by electrical impedance tomography. Spontaneous breathing prevents this redistribution.