Continuous blood flow in the veins

Introduction The vein is the conduit that guides and transports blood back to the heart in the cardiovascular system. The vein begins at the capillaries and ends at the atria. The venules originate from the capillaries and gradually merge into the middle veins and large veins during the return process, and finally into the atrium.

Cause

Intravenous venous valve damage is not tightly closed, resulting in continuous blood flow in the venous blood vessels.

an examination

Related inspection

Venous auscultation deep vein patency test center venous pressure measurement (CVP)

Swelling, fatigue. Volumetric load test - can be used as a treatment reference for patients with higher CVP but still have insufficient cardiac output. If 500ml of fluid is quickly input within 20 minutes, CVP rise is not obvious, or even decreased, while blood pressure rises and heart rate decreases, indicating that the patient has absolute or relative insufficient capacity, and the heart has the potential to continue to receive large amounts of infusion.

Differential diagnosis

1. The venule venule is irregular, the diameter is 50-200m, the smooth muscle outside the endothelium is with or without, and the outer membrane is thin. The venules of the capillaries are called the posterior venules of the capillaries. The wall structure is similar to that of the capillaries, but the tube diameter is slightly thicker and the gap between the endothelial cells is larger, so the permeability is larger and there is also a substance exchange function. The posterior venules in lymphoid tissues and lymphoid organs also have special structures and functions.

2. The small veins of small veins have a diameter of more than 200m, and there is a relatively complete smooth muscle outside the endothelium. The medial membrane of the larger venule has one to several layers of smooth muscle. The outer membrane is also thicker and thicker.

3. In addition to the large veins in the middle vein, all veins with anatomical names belong to the medium-sizde vein. The diameter of the middle vein is 2 to 9 mm, the inner membrane is thin, and the inner elastic membrane is not developed or is not obvious. The middle membrane is much thinner than the middle artery accompanying it, and the annular smooth muscle is sparsely distributed. The outer membrane is generally thicker than the middle membrane, there is no outer elastic membrane, which is composed of connective tissue, and some middle venous adventitia may have longitudinal smooth muscle bundle.

4. Large veins have a diameter of more than 10 mm. The superior vena cava, inferior vena cava, innominate vein and jugular vein belong to this category. The inner membrane of the wall is thin, and the middle membrane is very underdeveloped. It is a layer of loose annular muscles, sometimes without smooth muscle. The outer membrane is thicker, and there are often more longitudinal smooth muscle bundles in the connective tissue.

5. Veins with a venous valve diameter of 2 mm or more often have valves. The valve is a two-and-a-half-shaped sheet, opposite each other, with the root connected to the intima and its free edge facing the direction of blood flow. The valve is formed by the intima protruding into the lumen of the lumen, and the center is a connective tissue containing elastic fibers, and the surface is covered with an endothelium, and its function is to prevent blood from flowing backward. Swelling, fatigue.

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