Blood Pressure: Cuff Sizing, Technique, and Arm Contraindications

Normal Blood Pressure Ranges

Blood pressure is recorded as two numbers: systolic over diastolic. The systolic pressure is the force against the artery walls when the heart contracts; the diastolic is the force when the heart rests between beats. In an adult, the normal range is:

A reading of 120/78 is normal. A reading of 150/92 is hypertension and must be reported. A reading of 88/58 is hypotension and must be reported. The care plan may set tighter or looser thresholds for a specific resident - always compare to the care plan and the resident's baseline.

Blood pressure is documented in the TPR-BP order on the chart: temperature, pulse, respiration, then blood pressure. On the flowsheet, the blood pressure column is labeled "BP" and the reading goes in as "120/78."

The 5-Minute Rest Rule

Blood pressure rises with activity, anxiety, pain, a full bladder, talking, and recent caffeine or tobacco use. To get a true resting reading, the resident must sit quietly for at least 5 minutes before you inflate the cuff. This is a non-negotiable step on the skills evaluation.

During the 5-minute wait:

• The resident sits with feet flat on the floor (do not let the legs dangle - dangling increases the reading).
• The arm is supported at heart level, resting on a table or the bed armrest. If the arm hangs below heart level, the reading is falsely high; if above, falsely low.
• The resident does not talk. Talking raises the reading.
• You can use this 5 minutes to gather supplies, check the care plan, or prepare the thermometer for the next resident, as long as you stay in the room.

Cuff Sizing: The Most Common Source of Error

The blood pressure cuff must be the right size for the resident's arm. The cuff has an inflatable bladder inside; the bladder should cover about 80 percent of the upper arm circumference and the cuff width should be about 40 percent of the arm circumference. Most facilities stock three sizes: small adult, standard adult, and large adult.

The most tested cuff-sizing fact: a cuff that is too small gives a falsely high reading. If you use a standard cuff on a large arm, the bladder cannot compress the artery fully and the reading climbs. This is a common scenario on the written exam and a critical step on the skills evaluation. When in doubt, measure the arm and pick the cuff that covers 80 percent of the circumference.

The cuff goes on bare skin. Rolling up a sleeve creates a tourniquet effect above the cuff and gives a falsely high reading. If the sleeve cannot be removed or rolled up without bunching, use the other arm or ask the nurse for guidance.

Step-by-Step Technique

1. Wash hands. Confirm the resident has rested for 5 minutes.
2. Select the correct arm - check for contraindications (below).
3. Position the arm supported at heart level, palm up.
4. Select the correct cuff size and wrap it snugly around the upper arm, with the lower edge of the cuff about 1 inch above the antecubital crease (the inner elbow crease). The artery marker on the cuff (if present) lines up over the brachial artery, which runs along the inner arm.
5. Place the stethoscope diaphragm over the brachial artery in the antecubital crease. Do not place it under the cuff - it goes below the cuff edge.
6. Close the valve on the bulb and inflate the cuff to about 30 mmHg above the point where you can no longer feel the radial pulse.
7. Open the valve slowly (2-3 mmHg per second). Watch the gauge.
8. The first sound you hear is the systolic pressure (Korotkoff phase I) - a clear, tapping sound.
9. The sounds continue, then become muffled (phase IV), then disappear (phase V). The point where the sound disappears is the diastolic pressure.
10. Deflate the cuff fully and remove it. Document systolic over diastolic.

Korotkoff Sounds

The sounds you hear through the stethoscope as the cuff deflates are called Korotkoff sounds. They have five phases:

In most adult residents, the sound disappears cleanly at phase V and that is the diastolic. If the sound never disappears (common in some older adults, pregnant residents, or those with certain conditions), record the point where the sound muffled (phase IV) as the diastolic and note it - for example, "140/80 (muffled)." Follow facility policy; some facilities always record phase IV, others record phase V.

Arm Contraindications

Never take blood pressure on an arm that has any of the following:

If both arms are contraindicated, the nurse may order a leg blood pressure or use an alternate method. The CNA does not decide - notify the nurse.

The dialysis fistula rule is the most critical and most tested. An AV fistula is a surgical connection between an artery and a vein, usually in the forearm, created to provide access for hemodialysis. Compressing the fistula can cause it to clot, which can require surgery to fix or even cost the resident their dialysis access. Never apply a cuff to the fistula arm, never take a pulse on the fistula arm (use the other wrist), and never draw blood from the fistula arm. If you are unsure which arm has the fistula, ask the nurse before you start.

When to Report

Report immediately to the licensed nurse if:

• Systolic is below 90 or above 140 mmHg.
• Diastolic is below 60 or above 90 mmHg.
• The reading has changed significantly from the resident's baseline, even if still within range.
• You could not hear the sounds clearly (technical failure - do not guess the number).
• The resident reports dizziness, headache, chest pain, or visual changes during or after the measurement.

Never make up a number. If the reading is unclear or you lost the sound, deflate the cuff, wait 1-2 minutes, and repeat. If you still cannot get a clear reading, notify the nurse - the nurse may take the reading or use an automated device.

Common Skills Evaluation Errors

The Indiana CNA skills evaluation has a tolerance of plus or minus 8 mmHg for blood pressure readings. If the evaluator reads 120/78 and you read 128/86, you pass. If you read 110/60, you fail. Common errors that push the reading outside tolerance or fail a critical step:

• Using a cuff that is too small (falsely high reading) - check the arm size before selecting the cuff.
• Not resting the resident for 5 minutes - critical step failure.
• Placing the stethoscope under the cuff instead of below it - muffled or absent sounds.
• Inflating too slowly (the artery opens and closes unevenly) or deflating too fast (you miss the sounds).
• Taking the reading on a contraindicated arm (IV, fistula, mastectomy side) - critical step failure.
• Recording only one number (systolic without diastolic, or vice versa) - incomplete documentation.
• Not reporting an abnormal reading to the nurse - critical safety step.

Automated Blood Pressure Devices

Many Indiana LTC facilities use automated blood pressure cuffs that inflate and deflate on their own and display the reading. The same rules apply: correct cuff size, 5-minute rest, supported arm at heart level, correct arm selection, and report readings outside 90-140/60-90. The automated device does not change the technique - it only changes how you get the number. Some facilities also display a pulse reading from the automated cuff; you can use this as a cross-check for the radial pulse you counted, but the radial pulse count for a full 60 seconds is still the documented pulse.

The Resident Who Is Anxious

Anxiety raises blood pressure. A resident who is nervous about the reading, about being in the facility, or about a procedure that day may have a reading 10-20 mmHg above their baseline. If the reading is high and the resident is visibly anxious, note this in the documentation and tell the nurse. The nurse may recheck after the resident has calmed down. Do not dismiss a high reading as anxiety without reporting it - hypertension can also cause anxiety, and the nurse needs to make the call.

Orthostatic (Postural) Blood Pressure

Some residents have orders for orthostatic blood pressure - measured lying, then sitting, then standing, to check for a drop when position changes. The licensed nurse typically orders this and may supervise it. If you are assigned to do orthostatic readings, the technique is:

1. Resident lies flat for 5 minutes. Take BP and pulse.
2. Resident sits up. Take BP and pulse within 1-2 minutes of sitting.
3. Resident stands. Take BP and pulse within 1-2 minutes of standing.

A systolic drop of 20 mmHg or more, or a diastolic drop of 10 mmHg or more, between positions is orthostatic hypotension and must be reported. The resident may feel dizzy on standing - stay close and be ready to support. If the resident feels faint or cannot stand, do not force the standing reading; help them sit or lie down and report.