Anesthesiology
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The direct thrombin inhibitor argatroban is indicated for the treatment of heparin-induced thrombocytopenia II, but it is also used off-label to treat critically ill patients presenting with heparin resistance, severe antithrombin deficiency, or hypercoagulability. Direct drug monitoring is not routinely available, and argatroban dosing is mainly based on global coagulation assays such as activated partial thromboplastin time (PTT) or diluted thrombin time (TT), both of which have limitations in patients with hypercoagulability. ⋯ Although activated PTT monitoring of argatroban is the most commonly used test, in critically ill patients, diluted TT provides more precise measurements. Alternately, point-of-care viscoelastic ecarin clotting time also provides guidance for argatroban dosing to identify overdosing if available. The data also suggested that patients with sepsis are at greater risk for argatroban overdosing.
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Perioperative oliguria is an alarm signal. The initial assessment includes closer patient monitoring, evaluation of volemic status, risk-benefit of fluid challenge or furosemide stress test, and investigation of possible perioperative complications.
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Observational Study
The effect of extracerebral contamination on near infrared spectroscopy as revealed during organ donation: A prospective observational study in brain dead organ donors.
Near-infrared spectroscopy (NIRS) has been utilized widely in anesthesia and intensive care to monitor regional cerebral oxygen saturation (rScO2). A normal oxygenation of extracerebral tissues may overlay and thereby mask cerebral desaturations, a phenomenon known as extracerebral contamination. The authors investigated the effect of a cessation of extracerebral tissue perfusion on rScO2 in patients with anoxic brains. ⋯ The abrupt end of extracerebral contamination, caused by aortic clamping, affected both NIRS monitors to a considerable extent. Both the INVOS and the ForeSight monitor were unable to detect severe cerebral hypoxia or anoxia under conditions of normal extracerebral oxygenation. While both NIRS monitors may guide measures to optimize arterial oxygen supply to the head, they should not be used with the intention to detect isolated cerebral desaturations.
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The optimal consciousness level required for general anesthesia with surgery is unclear, but in existing practice, anesthetic oblivion, may be incomplete. This article discusses the concept of consciousness, how it is altered by anesthetics, the challenges for assessing consciousness, currently used technologies for assessing anesthesia levels, and future research directions. ⋯ In agreement with Sanders et al. (2012), the authors propose that a state of disconnected consciousness is the optimal level of anesthesia, as it likely avoids both awareness and the possible dangers of oversedation. However, at present, there are no reliably tested indices that can discriminate between connected consciousness, disconnected consciousness, and complete unconsciousness.