Clinical Skills: BP Measurement

Question 1

How is BP measured? (3)

Answer 1

BP is measured in mm of mercury (mmHg) and given as 2 figures:
- Systolic pressure: Pressure when your heart pushes blood out.
- Diastolic pressure: Pressure when your heart rests between beats.

Question 2

What is the systolic and diastolic BP range of hypertension? (2)

Answer 2

Systolic > 140 mmHg either/or
Diastolic > 90 mmHg

Question 3

What is the systolic and diastolic BP range of hypotension? (2)

Answer 3

Systolic < 90mmHg either/or
Diastolic < 60mmHg

Question 4

Explain how to measure a cuff. (2)

Answer 4

Cuff bladder length = 80% of arm circumference.

Bladder Width = 40% arm circumference.

Question 5

Explain the 5 phases of Korotkoff’s Sounds. (5)

Answer 5

Phase 1:
- First appearance of faint clear tapping sounds which gradually increases with intensity.
- Systolic pressure is heard for at least 2 consecutive beats and correlates well with intra-arterial pressure.

Phase 2:
- Softening of sounds become swishing.

Phase 3:
- Return of sharper sounds becoming crisper but never fully regains the intensity of phase 1 sounds.
- Neither phase 2 or 3 has clinical importance.

Phase 4:
- Distinct abrupt sound muffling becomes soft and blowing.

Phase 5:
- All sounds disappear completely.

Question 6

Perform a manual blood pressure reading of a patient. (14)

Answer 6

1. Ensure patient is rested and comfortable. Consider caffeine, exercise and stress factors. Ensure seated if possible and legs uncrossed.
2. Check equipment and identify which arm is to be used.
3. Support patient’s arm at about the level of the heart. (either arm can be used unless otherwise indicated.)
4. Select appropriate cuff size (80=20 rule)
5. Apply cuff to upper arm (2-3cm above brachial artery pulsation)
6. Palpate brachial /radial artery and measure (30 seconds regular and x 2 or 60 seconds for an irregular pulse) - record pulse rate.

7, Inflate cuff until pulse is impalpable.

8. Inflate cuff 10-20mmHg further
9. Deflate cuff until pulse returns (rough estimate of systolic)
10. Allow to rest for 15-30 sec before re-inflation of the cuff to level identified in step 7.
11. Place stethescope over brachial artery (Diaphragm)
12. Deflate cuff slowly (2-3mmHg/sec) until regular sounds are heart - systolic pressure (Korotkoff sound phase 1 - note gauge)
13. Continue to deflate cuff until sounds disappear completely - diastolic pressure (Korotkoff’s sounds phase 5 - note gauge). Record reading
14. Deflate cuff completely + thank patient.