On the other hand, an embolism in an artery may lead to hypoxia in a tissue. Why is blood drawn from vein and not from artery during blood donation? Surya K. Mar 14, See below. Explanation: Veins have lower pressure than arteries. Another reason is that veins have thinner walls. Therefore, they must have more blood. They have thinner walls much less smooth muscle surrounding them than arteries, and have less innervation, so piercing them with a needle requires less force and doesn't hurt as much.
Venous pressure is also lower than arterial pressure, so there is less of a chance of blood seeping back out through the puncture point before it heals. Because of their thinner walls, veins tend to be larger than the corresponding artery in the area, so they hold more blood, making collection easier and faster.
Finally, it is somewhat safer if a small embolism bubble in the blood is introduced into a vein rather than an artery. Blood flow in an artery, on the other hand, always moves into smaller and smaller vessels, eventually ending in capilllaries, and there is a chance that a bubble introduced by a blood draw generally rare or more commonly an intravenous line IV could block a small blood vessel, potentially leading to hypoxia in the affected tissues.
Right of the bat, veins are superficial so it is much easier to hit a vein than an artery. Arterial sticks are very difficult if you are not practiced at them while veins are much much easier. Also arterial sticks have a very specific purpose usually for example arterial blood gas. Also veins are low pressure compared to the higher pressure of arteries so less chance of bleeding. Blood is not always drawn from the veins depending on the medical need and situation.
For example critically ill ICU patients will often have an arterial catheter placed to provide an accurate measure of blood pressure. Blood is sometimes sampled from this line to provide a more accurate measure of blood gases and cardiac performance. Sign up to join this community. The best answers are voted up and rise to the top. Stack Overflow for Teams — Collaborate and share knowledge with a private group. The cellular portion is made up mainly of red blood cells, but it also includes white blood cells and platelets.
Because blood has many functions, tests on the blood or its components may give valuable clues to help providers diagnose many medical conditions. Blood in the arteries arterial blood differs from blood in the veins venous blood mainly in its content of dissolved gases.
Testing arterial blood shows the makeup of the blood before any of its contents are used by the body tissues. Normal value ranges may vary slightly among different laboratories. Talk to your provider about the meaning of your specific test results. An arterial stick is done to get blood samples from arteries.
Blood samples are mainly taken to measure gases in the arteries. Abnormal results may point to breathing problems or problems with the body's metabolism. Sometimes arterial sticks are done to get blood culture or blood chemistry samples.
There is little risk in having your blood taken. Veins and arteries vary in size from one person to another and from one side of the body to the other. Taking blood from some people may be more difficult than from others. Other risks associated with having blood drawn are slight but may include:. There is a slight risk for damage to nearby tissues when the blood is drawn.
Blood can be taken from lower-risk sites, and techniques can be used to limit tissue damage. Eiting E, Kim HT. Arterial puncture and cannulation. Philadelphia, PA: Elsevier; chap
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