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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Case Reports Comparative Study
A clinical grading scale to predict malignant hyperthermia susceptibility.
The diagnosis of an acute malignant hyperthermia reaction by clinical criteria can be difficult because of the nonspecific nature and variable incidence of many of the clinical signs and laboratory findings. Development of a standardized means for estimating the qualitative likelihood of malignant hyperthermia in a given patient without the use of specialized diagnostic testing would be useful for patient management and would promote research into improved means for diagnosing this disease. ⋯ The malignant hyperthermia clinical grading scale is recommended for use as an aid to the objective definition of this disease. It use may improve malignant hyperthermia research by allowing comparisons among well-defined groups of patients. This clinical grading system provides a new and comprehensive clinical case definition for the malignant hyperthermia syndrome.
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Editorial Comment Review
Do low-dose inhalational anesthetic agents alter ventilatory control?
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Combined spinal-epidural anesthesia is a technique growing in popularity. However, there have been no attempts to investigate the risk of epidural drug reaching the subarachnoid space in high concentration by passing through the meningeal hole left by the spinal needle. This study begins to address this question by quantitating the flux of morphine and lidocaine through the spinal meninges of the monkey in vitro after puncture with three different-sized needles. ⋯ Epidural anesthesia after accidental or intentional puncture of the spinal meninges has occasionally resulted in high spinal blocks and total spinal anesthesia. This study suggests that drug movement through the meningeal hole is responsible for this complication and that the risk may be decreased by using the smallest possible needle to puncture the meninges.