Canadian journal of anaesthesia = Journal canadien d'anesthésie
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Randomized Controlled Trial
A randomized controlled trial demonstrates that a novel closed-loop propofol system performs better hypnosis control than manual administration.
The purpose of this randomized control trial was to determine the performance of a novel rule-based adaptive closed-loop system for propofol administration using the bispectral index (BIS(R)) and to compare the system's performance with manual administration. The effectiveness of the closed-loop system to maintain BIS close to a target of 45 was determined and compared with manual administration. ⋯ The closed-loop system for propofol administration showed better clinical and control system performance than manual administration of propofol. (Clinical Trials gov. NCT 01019746).
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Clinical studies demonstrate that anemia increases the risk of morbidity and mortality. Tissue hypoxia is an attractive but incompletely characterized candidate mechanism of anemia-induced organ injury. Physiological responses that optimize tissue oxygen delivery (nitric oxide synthase-NOS) and promote cellular adaptation to tissue hypoxia (hypoxia inducible factor-HIF) may reduce the risk of hypoxic organ injury and thereby improve survival during anemia. The presence of vascular diseases would likely impair the efficacy of these physiological mechanisms, increasing the risk of anemia-induced organ injury. In all cases, biological signals that indicate the activation of these adaptive mechanisms could provide an early and treatable warning signal of impending anemia-induced organ injury. Thus, we review the evidence for tissue hypoxia during acute hemodilutional anemia and also explore the novel hypothesis that methemoglobin, a measurable byproduct of increased NOS-derived nitric oxide (NO), may serve as a biomarker for "anemic stress". ⋯ Evidence continues to demonstrate that anemia increases morbidity and mortality, possibly via hypoxic mechanisms. A potential strategy for assessing "anemic stress" was derived from experimental data based on a readily measurable biomarker, methemoglobin. New methods for measuring real-time hemoglobin and methemoglobin levels in patients may provide the basis to translate this idea into clinical practice. Further mechanistic studies are required to determine if the impact of reduced tissue oxygen delivery and activation of hypoxic cellular mechanism can be linked to measurable changes in biomarkers and clinical outcomes in acutely anemic patients.