Page 54 - Libro 2

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PART 1 — INTRODUCTION TO THE VASCULAR SYSTEM
SUMMARY
Understanding some of the factors that play a role in the movement of blood within the vein will be helpful when performing venous ultrasound. Venous capacitance, transmural pressure, hydrostatic pressure, as well as other anatomic and physiologic components help to govern venous flow. Venous physiology affects what is observed on the ultrasound image as well as the venous Doppler signals obtained during a duplex ultrasound examination.
Critical Thinking Questions
1. You are examining a patient’s calf veins with ultrasound, and the veins ap- pear small and difficult to visualize. The patient is lying supine, with their head slightly elevated. What is one simple change not involving the ultra- sound system that can be done to make the veins easier to image?
2. Is the venous pressure higher or lower than normal in a common femoral vein that demonstrates a continuous venous Doppler signal with no respira- tory phasicity?
3. A patient presents for a venous examination with clinically evident varicose veins and no history of a deep vein thrombosis or venous ulceration. Would venous insufficiency be more likely in the deep or superficial system or both?
SUGGESTED READINGS
1. CarterSA.Hemodynamicconsiderationsinperipheralvascularandcerebrovasculardisease.In: Zwiebel WJ, Pellerito JS, eds. Introduction to Vascular Ultrasonography. 5th ed. Philadelphia, PA: Elsevier Saunders; 2005:3–17.
2. Eberhardt RT, Raffetto JD. Chronic venous insufficiency. Circulation. 2005;111(18):2398–2409.
3. Guyton AC, Hall JE. Textbook of Medical Physiology. 11th ed. Philadelphia, PA: Saunders; 2005.
4. Koeppen BM, Stanton BA. Berne & Levy Physiology. 6th ed. St. Louis, MO: Mosby; 2009.
5. Kupinski AM. Dynamics of venous syndrome. Vascular US Today. 2006;11:1–20.
6. Meissner, MH. Venous anatomy and hemodynamics. In: Zierler RE, ed. Strandness’s Duplex Scanning in Vascular Disorders. 4th ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2010:56–60.
7. Mohrman DE, Heller LJ, eds. Cardiovascular Physiology. New York, NY: McGraw-Hill; 1997.
8. Oates C. Cardiovascular Haemodynamics and Doppler Waveforms Explained. Cambridge,
NY: Cambridge University Press; 2001.