Anesthesiology
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Comparative Study
Intraoperative tidal volume as a risk factor for respiratory failure after pneumonectomy.
Respiratory failure is a leading cause of postoperative morbidity and mortality in patients undergoing pneumonectomy. The authors hypothesized that intraoperative mechanical ventilation with large tidal volumes (VTs) would be associated with increased risk of postpneumonectomy respiratory failure. ⋯ Mechanical ventilation with large intraoperative VT is associated with increased risk of postpneumonectomy respiratory failure.
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Does perioperative myocardial ischemia lead to postoperative myocardial infarction? By Stephen Slogoff and Arthur S. Keats. Anesthesiology 1985; 62:107-14. ⋯ Although neither single nor multiple preoperative patient characteristics related to PMI, suboptimal quality of operation and prolonged ischemic cardiac arrest increased the likelihood of PMI independent of the occurrence of myocardial ischemia. The authors conclude that perioperative myocardial ischemia is common in patients undergoing CABG, occurs randomly as well as in response to hemodynamic abnormalities, and is one of three independent risk factors the authors identified as related to PMI. PMI is unrelated to preoperative patient characteristics such as ejection fraction and left main coronary artery disease, and its frequency will relate primarily to perioperative management rather than patient selection.
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Comparative Study
Selective gamma-aminobutyric acid type A receptor antagonism reverses isoflurane ischemic neuroprotection.
Isoflurane provides protection against severe forebrain ischemia in the rat. The authors hypothesized that this is attributable to interaction with the gamma-aminobutyric acid type A (GABAA) receptor resulting in altered time to onset of ischemic hippocampal depolarization. ⋯ These studies are consistent with the hypothesis that the GABAA receptor serves as a major site of action for isoflurane neuroprotection both in vitro and in vivo. However, the mechanism by which this interaction confers in vivo protection cannot be attributed to effects on the duration of ischemic depolarization.
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Spinal cord damage during interscalene brachial plexus block has been attributed to needle entry into the spinal canal. The purpose of this study was to identify the angles and depths of needle insertion that increase the likelihood of such an event, using the traditional classic interscalene approach and two more proximal entry points. ⋯ With the classic approach to the interscalene block, there is a greater possibility of the needle passing through the intervertebral foramen if the needle is advanced too deeply. More proximal entry points and techniques that use a more steeply angled needle may reduce the risk of entry into the spinal space.
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Comparative Study
Painful peripheral nerve injury decreases calcium current in axotomized sensory neurons.
Reports of Ca(2+) current I(Ca) loss after injury to peripheral sensory neurons do not discriminate between axotomized and spared neurons. The spinal nerve ligation model separates axotomized from spared neurons innervating the same site. The authors hypothesized that I(Ca) loss is a result of neuronal injury, so they compared axotomized L5 dorsal root ganglion neurons to spared L4 neurons, as well as neurons from rats undergoing skin incision alone. ⋯ Axotomy is required for I(Ca) loss. I(Ca) loss correlated with changes in the biophysical properties of sensory neuron membranes during action potential generation, which were due to I(Ca) loss leading to decreased outward Ca(2+)-sensitive K currents. Taken together, these results suggest that neuropathic pain may be mediated, in part, by loss of I(Ca) and the cellular processes dependent on Ca(2+).