Anesthesiology
-
Uncontrolled increase in intracranial pressure is the most significant cause of mortality in patients with severe traumatic brain lesions, and the efficacy of common non-surgical treatments has been questioned. Pharmacologically induced cerebral vasoconstriction aiming at a decrease of cerebral blood volume and brain edema has recently been suggested as an alternative. Limited clinical experience with indomethacin as a cerebral vasoconstrictor has been reported but dose- or concentration-effect relationships were not investigated. In particular, there is a lack of data showing whether a therapeutic window exists in which risk of cerebral ischemia is minimized. ⋯ Indomethacin, which is known to constrict precapillary resistance vessels, caused a decrease in intracranial pressure during experimental intracranial hypertension. This was accompanied by signs of cerebral ischemia when indomethacin was used in a dose that has previously been suggested for the treatment of increased intracranial pressure in patients.
-
Up to 30% of all deaths attributable to anesthesia are related to difficulties with airway management. The purpose of this study was to determine whether anesthesiology residents are receiving specialized instruction in the various techniques and mechanical devices currently recommended for airway management in patients with anticipated or unanticipated difficult airways. ⋯ Based on the data obtained by the authors, formal instruction in difficult airway management is not offered by most residency programs. It is commonly taught as difficult clinical situations arise. Because these difficulties occur sporadically, opportunities for teaching are occasional. Learning based on sporadic and occasional occurrences risks incomplete and nonuniform training of residents.
-
Randomized Controlled Trial Clinical Trial
Desflurane slightly increases the sweating threshold but produces marked, nonlinear decreases in the vasoconstriction and shivering thresholds.
Shivering is rare during general anesthesia. This observation suggests that anesthetics profoundly impair shivering. However, the effects of surgical doses of volatile anesthetics on control of shivering have yet to be evaluated. Furthermore, the effects of desflurane on sweating and thermoregulatory vasoconstriction remain unknown. Accordingly, the authors determined the concentration-dependent effects of desflurane on sweating, vasoconstriction, and shivering. ⋯ The observed linear increase in the sweating threshold was similar in pattern and magnitude to that produced by most general anesthetics. The approximately 3 degrees C reduction in the vasoconstriction threshold by 0.8 MAC desflurane was similar to that observed previously during isoflurane and propofol anesthesia. However, the threshold was reduced less than expected at 0.5 MAC, suggesting that the dose-response relationship for vasoconstriction is nonlinear. Shivering was induced without difficulty in this study although the response is rare in surgical patients. It is likely that shivering during general anesthesia is rare because thermoregulatory vasoconstriction usually prevents body temperature from decreasing the required additional 1-1.5 degrees C.
-
It was hypothesized that stimulation of rapidly adapting airway receptors produces the transient (2-4 min) circulatory responses to rapid increases in desflurane concentrations greater than 6%. Accordingly, it was reasoned that increasing the concentration of desflurane in one lung, without altering the concentration of desflurane in systemic blood, should cause cardiovascular stimulation, whereas once the airway receptors had adapted to the stimulation, an initial increase in the systemic concentration of desflurane should have little effect. ⋯ It was concluded that at least two sites respond to a rapid increase in desflurane concentrations greater than 6%: one site in the airways and/or lungs, and at least one other in a highly perfused tissue(s). The systemic site contributes more importantly.