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Vascular resistance refers to the resistance that must be overcome to push blood through the circulatory system and create flow. The resistance offered by the peripheral circulation is known as the systemic vascular resistance (SVR) or may sometimes be referred to the antiquated term total peripheral resistance (TPR), while the resistance offered by the vasculature of the lungs is known as the pulmonary vascular resistance (PVR). Systemic vascular resistance is used in calculations of blood pressure, blood flow, and cardiac function. Vasoconstriction (i.e., decrease in blood vessel diameter) increases SVR, whereas vasodilation (increase in diameter) decreases SVR. Units for measuring vascular resistance are dyn·s·cm−5, pascal seconds per cubic metre (Pa·s/m³) or, for ease of deriving it by pressure (measured in mmHg) and cardiac output (measured in l/min), it can be given in mmHg·min/l. This is numerically equivalent to hybrid reference units (HRU), also known as Wood units, frequently used by pediatric cardiologists. To convert from Wood units to MPa·s/m3 you must multiply by 8, or to dyn·s·cm−5 you must multiply by 80.〔Fuster, V.; Alexander, R.W.; O'Rourke, R.A. (2004) ''Hurst's the heart, book 1''. 11th Edition, McGraw-Hill Professional, Medical Pub. Division. Page 513. ISBN 978-0-07-143224-5.〕 ==Calculation of vascular resistance== The basic tenet of calculating resistance is that flow is equal to driving pressure divided by resistance. : where *R is Resistance *ΔP is the change in pressure across the circulation loop (systemic / pulmonary) from its beginning (immediately after exiting the left ventricle / right ventricle) to its end (entering the right atrium / left atrium) *Q is the flow through the vasculature (when discussing SVR this is equal to cardiac output) 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Vascular resistance」の詳細全文を読む スポンサード リンク
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