CNA · Basic Nursing Skills · 6 min read
Measuring Blood Pressure, Height and Weight
- Identify the normal ranges, equipment, and proper procedure for measuring and documenting a resident's blood pressure.
- Recognize the safety guidelines, positioning requirements, and arm restrictions necessary for accurate blood pressure measurement.
- Describe the standardized techniques and safety guidelines for measuring resident height and weight using various types of scales and bed measurements.
Understanding Blood Pressure Basics and Equipment
Blood pressure measures the force of blood against the walls of the arteries. Every time the heart beats, it moves blood through the circulatory system. Systolic pressure is the pressure in the arteries when the heart muscle contracts. In contrast, diastolic pressure is the pressure in the arteries when the heart muscle relaxes. Blood pressure is recorded as systolic pressure over diastolic pressure in millimeters of mercury, written as mm Hg.
To provide safe care, the nurse aide needs to know what typical healthy numbers look like. A typical normal systolic reading for a healthy adult is less than 120 mm Hg. A typical normal diastolic reading for a healthy adult is less than 80 mm Hg. When values fall outside expected limits, specific terms apply. Hypertension is the medical term for high blood pressure, while hypotension is the medical term for low blood pressure. The nurse aide must report any unusually high or low blood pressure reading to the nurse immediately rather than attempting to interpret what the numbers mean.
The equipment used to measure manual blood pressure includes a sphygmomanometer and a stethoscope. The sphygmomanometer consists of an inflatable cuff, a bulb with a control valve, and a pressure gauge. To maintain proper infection control, the nurse aide must clean the earpieces and diaphragm of the stethoscope with an alcohol wipe before and after use. When putting the stethoscope on, the earpieces of the stethoscope should point forward into the ears to provide clear sound and fit comfortably.
| Measurement Phase | Heart Action | Typical Normal Reading |
|---|---|---|
| Systolic Pressure | Pressure in the arteries when the heart muscle contracts | Less than 120 mm Hg |
| Diastolic Pressure | Pressure in the arteries when the heart muscle relaxes | Less than 80 mm Hg |
Common mistakes
- Applying the blood pressure cuff over clothing instead of placing it directly on a bare arm.
- Measuring blood pressure on an arm with an intravenous infusion, dialysis shunt, or fistula, or failing to check with the nurse when a resident has had a mastectomy, paralysis, cast, or injury.
- Forgetting to balance or zero the scale before weighing, or failing to tare the weight of the wheelchair and equipment on a wheelchair scale.
- Attempting to force the limbs straight when measuring a bed-bound resident with severe contractures instead of reporting the situation to the nurse.
Key points
- Blood pressure measures the force of blood against the walls of the arteries and is recorded as systolic (contraction) over diastolic (relaxation) in mm Hg, with healthy adult readings typically less than 120 mm Hg systolic and less than 80 mm Hg diastolic.
- A blood pressure cuff that is too small causes a falsely high reading, while a cuff that is too large causes a falsely low reading.
- Clean the stethoscope earpieces and diaphragm with an alcohol wipe before and after use, ensure earpieces point forward into the ears, and position the cuff bare-arm about one inch above the elbow with the arrow over the brachial artery.
- Release cuff pressure at 2 to 4 mm Hg per second, identify the first clear tapping sound as systolic and the point where sound disappears as diastolic, and wait 1 to 2 minutes before repeating on the same arm.
- Weigh residents at the same time of day with an empty bladder and similar lightweight clothing, balance or zero the scale beforehand, and tare wheelchair weight when using a wheelchair scale.
- Measure standing height without shoes, or measure bed-bound residents by marking the sheet from head to heels, always reporting severe contractures to the nurse rather than forcing limbs straight.
- Promptly document all measurements, and report any unusually high or low blood pressure readings or significant, unexpected weight changes to the nurse immediately.
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