Anesthesiology
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Erythrocytes are transfused to prevent or treat inadequate oxygen delivery resulting from insufficient hemoglobin concentration. Previous studies failed to find evidence of inadequate systemic oxygen delivery at a hemoglobin concentration of 5 g/dl. However, in those studies, sensitive, specific measures of critical organ function were not used. This study tested the hypothesis that acute severe decreases of hemoglobin concentration alters human cognitive function. ⋯ Acute reduction of hemoglobin concentration to 7 g/dl does not produce detectable changes in human cognitive function. Further reduction of hemoglobin level to 6 and 5 g/dl produces subtle, reversible increases in reaction time and impaired immediate and delayed memory. These are the first prospective data to demonstrate subtle degraded human function with acute anemia of hemoglobin concentrations of 6 and 5 g/dl. This reversibility of these decrements with erythrocyte transfusion suggests that our model can be used to test the efficacy of erythrocytes, oxygen therapeutics, or other treatments for acute anemia.
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Volatile anesthetic-induced preconditioning is mediated by adenosine triphosphate-dependent potassium (KATP) channels; however, the subcellular location of these channels is unknown. The authors tested the hypothesis that desflurane reduces experimental myocardial infarct size by activation of specific sarcolemmal and mitochondrial KATP channels. ⋯ Desflurane reduces myocardial infarct size in vivo, and the results further suggest that both sarcolemmal and mitochondrial KATP channels could be involved.
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Succinylcholine causes immediate and severe arterial hypotension in swine with the malignant hyperthermia phenotype. The underlying mechanisms are unknown. ⋯ Succinylcholine-induced hypotension occurred before muscle hypermetabolism in MHS swine. Succinylcholine had no differential physiologic effects on either the isolated heart or on isolated arteries. This hypotension could not be prevented by dantrolene but was prevented by pretreatment with high-dose vecuronium. Thus, an indirect mechanism such as the release of a cardiac depressant from skeletal muscle may have caused this hypotensive response.
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The ratio of ventricular end-systolic elastance (Ees) to effective arterial elastance (Ea) is known to reflect not only ventricular mechanical performance but also energetic performance. Despite these useful features, technical difficulties associated with estimating Ees make the clinical application of Ees/Ea impractical. We developed a framework to estimate Ees/Ea without measuring ventricular volume or altering the loading condition. ⋯ The proposed framework is capable of estimating Ees/Ea from ventricular and aortic pressure.
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MPV-2426 is a novel alpha2-adrenoceptor agonist developed for spinal pain therapy. It has proved to be effective in physiologic and neuropathic conditions. In the current study its effectiveness on mechanical hyperalgesia was assessed in a rat model of postoperative pain. ⋯ Intrathecal MPV-2426 dose-dependently attenuates postoperative hyperalgesia to mechanical stimulation because of an action on alpha2 adrenoceptors. Its antihyperalgesic action is as effective as that produced by dexmedetomidine and is considerably stronger than that produced by clonidine. However, preoperative treatment with MPV-2426 does not prevent the development of postoperative hyperalgesia.