Final answer:
The appropriate coverage of a blood pressure cuff on a patient's upper arm is 80% to 100% of its circumference, with the length coverage not directly mentioned in the provided resources, but typically 40% to 50% as per medical guidelines.
Step-by-step explanation:
The correct size of a blood pressure cuff should cover around 80% to 100% of the circumference of the patient's upper arm when properly sized. However, if expressed in terms of how much of the arm's length it should cover, the most appropriate coverage is 40% to 50%. This is not directly mentioned in the provided resources; however, it is a standard medical guideline. When the cuff is too small, it can yield falsely high blood pressure readings, whereas a cuff that's too big can give you a falsely low reading.
To ensure accurate blood pressure measurement, the cuff should be placed at the level of the heart, snugly wrapped so that it is evenly applied around the arm, with enough room to slide two fingertips underneath the top edge of the cuff. When using a blood pressure cuff on the leg, as mentioned in the reference, adjustments must be made to account for the additional hydrostatic pressure exerted by the column of blood in the leg below the level of the heart.