Anesthesiology
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Regulation of blood flow to the right ventricle differs significantly from that to the left ventricle. The right ventricle develops a lower systolic pressure than the left ventricle, resulting in reduced extravascular compressive forces and myocardial oxygen demand. Right ventricular perfusion has eight major characteristics that distinguish it from left ventricular perfusion: (1) appreciable perfusion throughout the entire cardiac cycle; (2) reduced myocardial oxygen uptake, blood flow, and oxygen extraction; (3) an oxygen extraction reserve that can be recruited to at least partially offset a reduction in coronary blood flow; (4) less effective pressure-flow autoregulation; (5) the ability to downregulate its metabolic demand during coronary hypoperfusion and thereby maintain contractile function and energy stores; (6) a transmurally uniform reduction in myocardial perfusion in the presence of a hemodynamically significant epicardial coronary stenosis; (7) extensive collateral connections from the left coronary circulation; and (8) possible retrograde perfusion from the right ventricular cavity through the Thebesian veins. ⋯ The risk of right ventricular ischemia is also heightened during chronic elevations in right ventricular afterload because microvascular growth fails to match myocyte hypertrophy and because microvascular dysfunction is present. The right coronary circulation is more sensitive than the left to α-adrenergic-mediated constriction, which may contribute to its greater propensity for coronary vasospasm. This characteristic of the right coronary circulation may increase its vulnerability to coronary vasoconstriction and impaired right ventricular perfusion during administration of α-adrenergic receptor agonists.
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Randomized Controlled Trial
Morbidity and Mortality of Crystalloids Compared to Colloids in Critically Ill Surgical Patients: A Subgroup Analysis of a Randomized Trial.
WHAT THIS ARTICLE TELLS US THAT IS NEW: BACKGROUND:: The multicenter randomized Colloids versus Crystalloids for the Resuscitation of the Critically Ill (CRISTAL) trial was designed to test whether colloids altered mortality compared to crystalloids in the resuscitation of intensive care unit patients with hypovolemic shock. This preplanned analysis tested the same hypothesis in the subgroup of surgical patients. ⋯ The authors found no survival benefit when comparing crystalloids to colloids in critically ill surgical patients.
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Assessment of clinical competence is essential for residency programs and should be guided by valid, reliable measurements. We implemented Baker's Z-score system, which produces measures of traditional core competency assessments and clinical performance summative scores. Our goal was to validate use of summative scores and estimate the number of evaluations needed for reliable measures. ⋯ The Baker system produced moderately reliable measures at our institution, suggesting that it may be generalizable to other training programs. Raw absolute scores required few assessment occasions to achieve 90% reliable measurements.