Anesthesiology
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Randomized Controlled Trial Comparative Study Clinical Trial
Rate and gender dependence of the sweating, vasoconstriction, and shivering thresholds in humans.
The range of core temperatures not triggering thermoregulatory responses ("interthreshold range") remains to be determined in humans. Although the rates at which perioperative core temperatures vary typically range from 0.5 to 2 degrees C/h, the thermoregulatory contribution of different core cooling rates also remains unknown. In addition, sweating in women is triggered at a slightly greater core temperature than in men. However, it is unknown whether the vasoconstriction and shivering thresholds are comparably greater in women, or if women tolerate a larger range of core temperatures without triggering thermoregulatory responses. Accordingly, the authors sought to (1) define the interthreshold range; (2) test the hypothesis that, at a constant skin temperature, the vasoconstriction and shivering thresholds are greater during rapid core cooling than during slowly induced hypothermia; and (3) compare the sweating, vasoconstriction, and shivering thresholds in men and women. ⋯ Our findings confirm the existence of an interthreshold range and document that its magnitude is small. They also demonstrate that the interthreshold range does not differ in men and women, but that women thermoregulate at a significantly higher temperature than do men. Typical clinical rates of core cooling do not alter thermoregulatory responses.
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Randomized Controlled Trial Comparative Study Clinical Trial
Head extension and laryngeal view during laryngoscopy with cervical spine stabilization maneuvers.
Direct laryngoscopy frequently is modified in patients with known or suspected cervical spine injury. The goals of this study were to measure the degrees of head extension required to expose the arytenoid cartilages and glottis if neck flexion were not possible and to determine whether in-line stabilization maneuvers alter the amount of head extension. ⋯ Head immobilization reduced head extension necessary for laryngoscopy. If head extension is construed to be potentially dangerous in patients with cervical spine injuries, head immobilization without traction might be the preferable stabilization technique.