Medical Definition of central line
: an IV line that is inserted into a large vein (as the superior vena cava) typically in the neck or near the heart for therapeutic or diagnostic purposes (as to administer medicines or fluids or withdraw blood) <I had trained in the intensive care unit. I could start a central line, intubate a patient in respiratory failure, and insert a pacemaker.—Margaret Seton, The New England Journal of Medicine, 29 Sept. 2011>
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