Anesthesiology
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Randomized Controlled Trial Clinical Trial
Anesthetic doses of sevoflurane to block cardiovascular responses to incision when administered with xenon or nitrous oxide.
The authors' previous study demonstrated that xenon (Xe) and nitrous oxide (N2O) in combination with sevoflurane can attenuate cardiovascular responses to skin incision. To quantitatively evaluate their suppressive effects on cardiovascular responses, the authors compared the MAC-BAR (minimum alveolar concentration that blocks adrenergic or cardiovascular response to incision) values of sevoflurane when administered with Xe or N2O. ⋯ Although 1 MAC Xe has a more potent suppressive effect on cardiovascular responses to incision than 0.7 MAC Xe or N2O, Xe and N2O have a similar suppressive effect at 0.7 MAC.
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Ulnar nerve pressure: influence of arm position and relationship to somatosensory evoked potentials.
Although the ulnar nerve is the most frequent site of perioperative neuropathy, the mechanism remains undefined. The ulnar nerve appears particularly susceptible to external pressure as it courses through the superficial condylar groove at the elbow, rendering it vulnerable to direct compression and ischemia However, there is disagreement among major anesthesia textbooks regarding optimal positioning of the arm during anesthesia. ⋯ Extrapolating these results to the clinical setting, the supinated arm position is likely to minimize pressure over the ulnar nerve. With the forearm in neutral orientation, pressure over the ulnar nerve decreases as the arm is abducted between 30 degrees and 90 degrees. In addition, up to one half of male patients may fail to perceive or experience clinical symptoms of ulnar nerve compression sufficient to elicit SSEP changes.
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Randomized Controlled Trial Clinical Trial
Analgesic and hemodynamic effects of intrathecal clonidine as the sole analgesic agent during first stage of labor: a dose-response study.
Intrathecal clonidine produces dose-dependent postoperative analgesia and enhances labor analgesia from intrathecal sufentanil. The authors evaluated the dose-response potency of intrathecally administered clonidine by itself during first stage of labor with respect to analgesia and maternal and fetal side effects. ⋯ Fifty to 200 microg intrathecal clonidine produces dose-dependent analgesia during first stage of labor. Although duration and quality of analgesia were more pronounced with 100 and 200 microg than with 50 microg, the high incidence of hypotension requires caution with the use of 200 microg for labor analgesia.