Final answer:
The result of using a blood pressure cuff that is too small is a falsely high blood pressure reading, due to the need for more pressure to compress the artery. Correct cuff size and placement are crucial for accurate readings, and the position of the arm or leg relative to the heart during measurement can also affect readings.
Step-by-step explanation:
Using a blood pressure cuff that is too small can result in a falsely high blood pressure reading. This occurs because the smaller cuff may require additional pressure to compress the artery, leading to an overestimation of blood pressure. When measuring blood pressure, it's important for the cuff to be the correct size and placed at the level of the heart for the most accurate results. Additionally, when the cuff is positioned on the upper arm, the measured pressures are transmitted to a mercury-filled manometer, which is used because mercury is denser than water, making it more sensitive and providing more accurate measurements for the typical arterial blood pressures encountered in medical situations.
Regarding the effects of arm positioning and cuff placement: lowering the manometer below the heart level could lead to a falsely high reading because of the added hydrostatic pressure of the column of blood. Raising the arm above the shoulder level can result in a falsely low reading, due to the decreased hydrostatic pressure affecting the measurement. Placing the cuff on the upper leg while a person is standing can give a higher reading since the blood pressure in the legs generally needs to be higher to overcome gravity and ensure blood flow back to the heart.