Anesthesia and analgesia
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Anesthesia and analgesia · Mar 2011
Randomized Controlled Trial Comparative StudyForced-air and a novel patient-warming system (vitalHEAT vH2) comparably maintain normothermia during open abdominal surgery.
The vitalHEAT vH(2) (Dynatherm Medical, Inc., Fremont, California) system transfers heat through a single extremity using a combination of conductive heat (circulating warm water within soft fluid pads) with mild vacuum, which improves both vasodilation and contact between the heating element and the skin surface. We tested the hypothesis that core temperatures were not >0.5°C lower in patients warmed with the vitalHEAT system than with forced air. ⋯ The 2 systems thus apparently transfer comparable amounts of heat. Both appear suitable for maintaining normothermia even during large and long operations.
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Anesthesia and analgesia · Mar 2011
Comparative StudyDoes anesthetic additivity imply a similar molecular mechanism of anesthetic action at N-methyl-D-aspartate receptors?
Isoflurane and carbon dioxide (CO(2)) negatively modulate N-methyl-d-aspartate (NMDA) receptors, but via different mechanisms. Isoflurane is a competitive antagonist at the NMDA receptor glycine binding site, whereas CO(2) inhibits NMDA receptor current through extracellular acidification. Isoflurane and CO(2) exhibit additive minimum alveolar concentration effects in rats, but we hypothesized that they would not additively inhibit NMDA receptor currents in vitro because they act at different molecular sites. ⋯ In contrast to our hypothesis, NMDA receptor inhibition by CO(2) and isoflurane is additive. Possibly, CO(2) acidification modulates a pH-sensitive loop on the NMDA receptor that in turn alters glycine binding affinity on the GluN1 subunit. However, ketamine plus either CO(2) or H(+) synergistically inhibits NMDA receptor currents. Drugs acting via different mechanisms can thus exhibit additive or synergistic receptor effects. Additivity may not robustly indicate commonality between molecular anesthetic mechanisms.
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Anesthesia and analgesia · Mar 2011
Comparative StudyPredicting lumbar plexus depth in children and adolescents.
Lumbar plexus block provides effective analgesia for hip, thigh, and knee surgery. A simple measurement that accurately predicts lumbar plexus depth would be invaluable for clinicians performing this block in children, in whom plexus depth varies with age. ⋯ PSIS-ICL distance provides an accurate, patient-specific predictor for lumbar plexus depth in children over a wide range of age and body habitus. The strong linear relationship obviates the need for complex calculations. This measurement can be used as a guide for ultrasound location, to choose an appropriate needle length, and may reduce complications associated with this block.
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Anesthesia and analgesia · Mar 2011
Case ReportsChallenging lung isolation secondary to aberrant tracheobronchial anatomy.
Aberrant tracheobronchial anatomy is reported at an incidence of approximately 10% and most frequently involves the segmental and subsegmental bronchi. The most relevant abnormality to the practice of anesthesiology is the presence of a tracheal bronchus. Although typically an asymptomatic finding during bronchoscopy, a tracheal bronchus has important implications for airway management and lung isolation. ⋯ We describe a patient with a tracheal bronchus, coexisting with a left-shifted carina and apically retracted left mainstem bronchus, presenting for right extrapleural pneumonectomy. Attempts to place a left-sided double-lumen endotracheal tube were unsuccessful. We discuss our solution, review the literature, and present potential solutions for lung isolation in patients with a tracheal bronchus.
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Anesthesia and analgesia · Mar 2011
Comparative StudyLack of beneficial effect for preemptive analgesia in postoperative pain control: verifying the efficacy of preemptive analgesia with N-methyl-D-aspartate receptor antagonists in a modified animal model of postoperative pain.
In previous animal studies, preemptive treatments with N-methyl-d-aspartate (NMDA) antagonists were ineffective at preventing incision-induced allodynia. It is very likely that the model was not clinically relevant for testing treatment effects on postoperative pain. The beneficial effects of preemptive treatment can be verified only by treatments with a pharmacologically proven effect in a specific pain type or animal model. We previously showed that NMDA receptor antagonists effectively alleviate enhanced mechanical hyperalgesia after plantar incision in adult rats that had been given an intraplantar injection of carrageenan as neonates. Here, using this modified model, we tested the efficacy of preemptive treatment with the NMDA antagonist MK-801. ⋯ Under conditions of proven analgesic action of an NMDA antagonist, we demonstrated that preincisional treatment is not more beneficial than postincisional treatment for postoperative pain relief in the modified animal model. Increasing the duration of administration and/or total dosage had an incremental analgesic effect in comparison with a single injection.