kymograph

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun An instrument for recording variations in pressure, as of the blood, or in tension, as of a muscle, by means of a pen or stylus that marks a rotating drum.

from The Century Dictionary.

• noun An instrument by means of which variations of fluid pressure, as of the blood in some one of the vessels of a living animal, can be measured and graphically recorded.

from the GNU version of the Collaborative International Dictionary of English.

• noun (Physiol.) An instrument for measuring, and recording graphically, the pressure of the blood in any of the blood vessels of a living animal; -- called also kymographion.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun A device that gives a graphical representation of a variation in a phenomenon such as blood pressure over time, using a pen on a rotating drum.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun scientific instrument consisting of a rotating drum holding paper on which a stylus traces a continuous record (as of breathing or blood pressure)