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Báo cáo y học: "Understanding cardiac output"

Tuyển tập các báo cáo nghiên cứu về y học được đăng trên tạp chí y học Critical Care giúp cho các bạn có thêm kiến thức về ngành y học đề tài: Understanding cardiac output. | Available online http ccforum.eom content 12 4 174 Commentary Understanding cardiac output Jean-Louis Vincent Department of Intensive Care Erasme Hospital Université libre de Bruxelles Route de Lennik 808 1070-B Brussels Belgium Corresponding author Jean-Louis Vincent jlvincen@ulb.ac.be Published 22 August 2008 This article is online at http ccforum.com content 12 4 174 2008 BioMed Central Ltd Critical Care 2008 12 174 doi 10.1186 cc6975 Abstract Cardiac output is the amount of blood the heart pumps in 1 minute and it is dependent on the heart rate contractility preload and afterload. Understanding of the applicability and practical relevance of each of these four components is important when interpreting cardiac output values. In the present article we use a simple analogy comparing cardiac output with the speed of a bicycle to help appreciate better the effects of various disease processes and interventions on cardiac output and its four components. Introduction Cardiac output expressed in liters minute is the amount of blood the heart pumps in 1 minute. Cardiac output is logically equal to the product of the stroke volume and the number of beats per minute heart rate . Easy enough one may think but the term cardiac in cardiac output is potentially misleading - with clinician s sometimes assuming that to interpret cardiac output they must focus on the heart. The heart is just one part of the much larger cardiovascular system however and the amount of blood it pumps is dependent on both cardiac and extracardiac factors. Although most clinicians should will be able to recite the four determinants of cardiac output - heart rate contractility preload and afterload - understanding of the applicability and practical relevance of each of these four components is all too often less well ingrained. To try to clarify the individual roles and the combined roles of these four factors in generating cardiac output and hence to facilitate our understanding of the effects of .