Anesthesia and analgesia
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Anesthesia and analgesia · Oct 2008
Composite auditory evoked potential index versus bispectral index to estimate the level of sedation in paralyzed critically ill patients: a prospective observational study.
Electromyographic activity (EMG) has been reported to elevate the Bispectral Index (BIS) in patients not receiving neuromuscular blockade while under sedation in the intensive care unit (ICU). We investigated the change of the composite A-line autoregressive index (AAI) and BIS after administration of muscle relaxants in sedated surgical ICU patients. ⋯ This study demonstrated that, in sedated ICU patients, BIS and AAI markedly decreased after administration of myorelaxant, and the decreased BIS and AAI values after neuromuscular blockade were correlated to those usually seen in the state of surgical anesthesia, respectively.
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Anesthesia and analgesia · Oct 2008
The effect of injectate conductivity on the electric field with the nerve stimulator needle: a computer simulation.
Electrical neural stimulation is commonly used to localize neural structures and place local anesthetic for regional anesthesia. The sharp tip of the stimulating needle gives rise to an electric field which is highly localized. The electrostatic effect of the injected solution on the field distribution and strength has not previously been modeled. ⋯ The electric field magnitude in the vicinity of the needle tip decayed more slowly with distance than predicted by Coulomb's law. This was independent of the presence of injectate. The near instantaneous abolition of muscle twitch with injection of small volumes of local anesthetic is consistent with an electrostatic effect, rather than a pharmacological or mechanical one. The change in field strength depended upon the volume of the injectate and its conductivity relative to that of the surrounding tissue. In this simulation, even tiny volumes of injectate lead to significant changes in field and therefore threshold current, which may have clinical implications.
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Anesthesia and analgesia · Oct 2008
Case ReportsAcute neck cellulitis and mediastinitis complicating a continuous interscalene block.
We report a case of acute neck cellulitis and mediastinitis complicating a continuous interscalene brachial plexus block. A 61-yr-old man was scheduled for an elective arthroscopic right shoulder rotator cuff repair. A continuous interscalene block was done preoperatively and 20 mL of 0.5% bupivacaine and 20 mL of 2% mepivacaine were injected through the catheter. ⋯ The infection was treated with surgery, the site was surgically debrided, and a 2-mo course of vancomycin, imipenem, and oxacilline. The technique of drawing local anesthetic from the bottle and filling the elastomeric pump was the most likely cause of infection. This case emphasizes the importance of strict aseptic conditions during puncture, catheter insertion, and management of the local anesthetic infusate.
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Anesthesia and analgesia · Oct 2008
Spatial memory is intact in aged rats after propofol anesthesia.
We have previously demonstrated that aged rats have persistent impairment of spatial memory after sedation with nitrous oxide or general anesthesia with isoflurane-nitrous oxide. Propofol has different receptor mechanisms of action and a favorable short-term recovery profile, and it has been proposed that propofol is devoid of enduring effects on cognitive performance. No studies have investigated this question in aged subjects, however, so we designed an experiment to examine the long-term effects of propofol anesthesia on spatial working memory. ⋯ In aged rats, propofol anesthesia is devoid of the persistent memory effects observed with other general anesthetics in this model. Thus, while it appears that the state of general anesthesia is neither necessary nor sufficient for development of postanesthetic memory impairment, the choice of anesthetics may play a role in late cognitive outcome in the aged.
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Anesthesia and analgesia · Oct 2008
Propofol attenuates the decrease of dynamic compliance and water content in the lung by decreasing oxidative radicals released from the reperfused liver.
Remote pulmonary injuries after hepatic reperfusion are frequently caused by reactive oxygen species (ROS)-induced damage. The choice of anesthetics may affect the balance between oxidants and antioxidants, and propofol, a commonly used anesthetic, has an antioxidant effect. In this study, we developed a model to study pulmonary function with hepatic ischemia/reperfusion (I/R) manipulation, with the aim of defining remote pulmonary dysfunction after hepatic reperfusion and determining if propofol affects this dysfunction by altering ROS production from the liver or lungs. ⋯ Remote pulmonary dysfunction and reperfusion injury in the liver were demonstrated in our rat model, as well as massive ROS production and lipid peroxidation. Propofol infusion attenuated remote pulmonary injury by lessening oxidative injury from the reperfused liver.