Anesthesiology
-
Clinical Trial
Differential contribution of sodium channel subtypes to action potential generation in unmyelinated human C-type nerve fibers.
Multiple voltage-dependent sodium channels (Na(v)) contribute to action potentials and excitability of primary nociceptive neurons. The aim of the current study was to characterize subtypes of Na(v) that contribute to action potential generation in peripheral unmyelinated human C-type nerve fibers. ⋯ These data indicate that more than one type of Na(v) contributes to the generation of action potentials in unmyelinated human C-type nerve fibers. The peak height of an action potential produced by a short electrical impulse is dependent on the activation of tetrodotoxin-resistant ion channels. In contrast, membrane threshold and action potential peak height at the end of a slow membrane depolarization are regulated by a subtype of Na(v) with high sensitivity to low concentrations of tetrodotoxin, lidocaine, and mexiletine. The electrophysiologic and pharmacologic characteristics may indicate the functional activity of the Na(v) 1.7 subtype of voltage-dependent sodium channels.
-
Mechanical ventilation (MV) may activate the innate immune system, causing the release of cytokines. The resulting proinflammatory state is a risk factor for ventilator-induced lung injury. Cytokine increase results from direct cellular injury but may also result from cyclic stretch alone as demonstrated in vitro: mechanotransduction. To study mechanotransduction in vivo, the authors used an animal MV model with clinically relevant ventilator settings, avoiding alveolar damage. ⋯ Mechanical ventilation induces reversible cytokine increase and leukocyte influx with preserved tissue integrity. This model offers opportunities to study the pathophysiologic mechanisms behind ventilator-induced lung injury and the contribution of MV to the "multiple-hit" concept.
-
Randomized Controlled Trial
Continuous preperitoneal infusion of ropivacaine provides effective analgesia and accelerates recovery after colorectal surgery: a randomized, double-blind, placebo-controlled study.
Blockade of parietal nociceptive afferents by the use of continuous wound infiltration with local anesthetics may be beneficial in a multimodal approach to postoperative pain management after major surgery. The role of continuous preperitoneal infusion of ropivacaine for pain relief and postoperative recovery after open colorectal resections was evaluated in a randomized, double-blinded, placebo-controlled trial. ⋯ Continuous preperitoneal administration of 0.2% ropivacaine at 10 ml/h during 48 h after open colorectal resection reduced morphine consumption, improved pain relief, and accelerated postoperative recovery.
-
Randomized Controlled Trial
Median frequency revisited: an approach to improve a classic spectral electroencephalographic parameter for the separation of consciousness from unconsciousness.
In the past, several electroencephalographic parameters have been presented and discussed with regard to their reliability in discerning consciousness from unconsciousness. Some of them, such as the median frequency and spectral edge frequency, are based on classic spectral analysis, and it has been demonstrated that they are of limited capacity in differing consciousness and unconsciousness. ⋯ A more general approach of the design of spectral parameters leads to a new electroencephalographic spectral parameter that separates consciousness from unconsciousness significantly better than the Bispectral Index.
-
Chronic pain models are commonly defined as either nerve-injury or inflammation models, but recent work suggests inflammatory processes are important in nerve injury-induced pain. ⋯ Several components of the spinal nerve injury model are responsive to corticosteroid, suggesting inflammatory processes are important in the development of neuropathic pain. The observation that TA was effective when given starting at the time of injury suggests that steroid treatment might alter the development of chronic pain after surgical procedures that involve nerve injury, such as amputation or hernia repair.