8.3 Blood Pressure Measurement (INACE Skill)
Key Takeaways
- Normal blood pressure: 90-120 systolic / 60-80 diastolic mmHg
- Place the cuff 1 inch above the antecubital fossa, arrow over the brachial artery
- Systolic = first sound heard; Diastolic = sounds disappear; deflate at 2-3 mmHg/second
- Never take BP on an arm with an IV, AV fistula, or mastectomy on that side
- Arm must be bare, at heart level, with the resident resting for at least 5 minutes
- Wrong cuff size is the most common source of error — too small reads falsely HIGH
Last updated: March 2026
Blood Pressure Measurement (INACE Skill)
Measuring and recording blood pressure is one of the 21 mandated INACE performance skills and one of the most important vital signs a CNA measures. Blood pressure reflects the force of blood against arterial walls and is a key indicator of cardiovascular health.
Understanding Blood Pressure
| Component | Description | Normal Range |
|---|---|---|
| Systolic (top number) | Pressure during heart contraction | 90-120 mmHg |
| Diastolic (bottom number) | Pressure during heart relaxation | 60-80 mmHg |
| Pulse Pressure | Difference between systolic and diastolic | 30-50 mmHg |
| mmHg | Millimeters of mercury — the unit of measurement | Standard unit |
Blood Pressure Categories
| Category | Systolic | Diastolic |
|---|---|---|
| Hypotension | Below 90 | Below 60 |
| Normal | 90-120 | 60-80 |
| Elevated | 120-129 | Less than 80 |
| Hypertension Stage 1 | 130-139 | 80-89 |
| Hypertension Stage 2 | 140+ | 90+ |
| Hypertensive Crisis | Above 180 | Above 120 |
Equipment
| Equipment | Description |
|---|---|
| Sphygmomanometer | Blood pressure cuff with gauge (aneroid or digital) |
| Stethoscope | Used with manual cuff to hear Korotkoff sounds |
| Proper cuff size | Bladder should cover 80% of the arm circumference |
Manual Blood Pressure Procedure (INACE Tested)
Before the Measurement:
- Wash your hands and identify the resident
- Explain the procedure
- Ensure the resident has been resting for at least 5 minutes
- Position the resident sitting or lying with arm at heart level
- Ensure the arm is bare — roll up sleeves (do not take BP over clothing)
- Select the correct cuff size
- Identify the brachial artery — inner aspect of the elbow (antecubital fossa)
Taking the Blood Pressure:
- Apply the cuff 1 inch above the antecubital fossa (inner elbow)
- The cuff arrow or marker should align over the brachial artery
- Place the stethoscope earpieces in your ears (pointing forward)
- Place the stethoscope diaphragm over the brachial artery (do not tuck under the cuff)
- Close the valve and inflate the cuff to 180 mmHg (or 30 mmHg above expected systolic)
- Slowly release the valve, deflating at about 2-3 mmHg per second
- Systolic reading = the first Korotkoff sound you hear (first thump)
- Diastolic reading = when the sounds disappear completely (last thump)
- Fully deflate the cuff and remove it
- Record the reading immediately
Common Blood Pressure Errors
| Error | Effect on Reading | How to Avoid |
|---|---|---|
| Cuff too small | Falsely HIGH reading | Use proper cuff size (80% of arm) |
| Cuff too large | Falsely LOW reading | Use proper cuff size |
| Cuff over clothing | Inaccurate reading | Always on bare arm |
| Arm below heart level | Falsely HIGH reading | Support arm at heart level |
| Arm above heart level | Falsely LOW reading | Support arm at heart level |
| Deflating too fast | Missed sounds | Deflate at 2-3 mmHg/second |
| Resident talking | Falsely HIGH reading | Ask resident to remain still and quiet |
| Repeated inflation | Falsely HIGH reading | Wait 1-2 minutes before reinflating |
| Wrong arm | Varies | Do not use an arm with IV, fistula, or mastectomy on that side |
Arms to Avoid for Blood Pressure
Do NOT take blood pressure on an arm with:
- IV line — pressure could dislodge the IV
- AV fistula (dialysis) — could damage the fistula
- Mastectomy on that side — lymphedema risk
- Fracture or injury — could cause pain or further injury
- Paralysis (stroke-affected side) — may give inaccurate readings
Orthostatic (Postural) Hypotension
Orthostatic hypotension is a significant drop in blood pressure when changing from lying to sitting or standing:
| Measurement | Definition of Orthostatic Hypotension |
|---|---|
| Systolic drop | ≥20 mmHg from lying to standing |
| Diastolic drop | ≥10 mmHg from lying to standing |
| Symptoms | Dizziness, lightheadedness, fainting |
| Action | Have resident sit on bed edge before standing; report to nurse |
Test Your Knowledge
Where should the blood pressure cuff be placed on the arm?
A
B
C
D
Test Your Knowledge
The first sound you hear when deflating the blood pressure cuff represents:
A
B
C
D
Test Your Knowledge
On which arm should you NOT take a blood pressure reading?
A
B
C
D