1. Blood Pressure
August 2015
Blood Pressure

2. Learning outcomes Understand common blood pressure terms
Describe the clinical significance of blood pressure variations
Discuss factors affecting blood pressure
Demonstrate correct use of equipment for taking a BP
Demonstrate the correct procedure for measuring and recording blood pressure using the palpation and auscultation method
August 2015
Blood Pressure

3. What is Blood Pressure? Blood pressure reflects:
The fluctuating force that blood exerts against arterial walls as the heart contracts and relaxes
Systolic reading reflects the maximum pressure exerted on the arterial wall when the left ventricle contracts.
Diastolic reading is the minimum arterial pressure that occurs when the left ventricle relaxes
August 2015
Blood Pressure

4. What is Blood Pressure? Blood pressure also reflects: Cardiac output
Peripheral vascular resistance
Blood volume
Blood viscosity
Arterial elasticity
August 2015
Blood Pressure

5. Blood Pressure Reading
Measurement:
Blood Pressure is measured in mm Hg (millimetres of mercury)
There are two blood pressure readings:
Systolic pressure - pressure within the artery when the heart contracts (contraction phase - systole)
Diastolic pressure – pressure within the artery when the heart relaxes (relaxation phase - diastole)
• Recorded as systolic/diastolic
eg. 120/80
August 2015
Blood Pressure

6. Blood Pressure Ranges Normal BP Adult Ranges: Systolic 100 - 160mmHg
Diastolic mmHg
In Children & Infants:
Systolic blood pressure is calculated as: (age x 2)
Examples:
1 year old = 80 + (1 x 2) = 82 mmHg
3 year old = 80 + (3 x 2) = 86 mmHg
8 year old = 80 + (8 x 2) = 96 mmHg
10 year old = 80 + (10x2) = 100 mmHg
August 2015
Blood Pressure

7. Equipment
Stethoscope
Sphygmomanometer
August 2015
Blood Pressure

8. Sphygmomanometer readings
The most common site for a blood pressure reading is the arm.
August 2015
Blood Pressure

9. Preparing the patient Explain and reassure Posture appropriately
Place arm straight
Place palm of hand facing up
Remove constrictive clothing
DO NOT take a BP on an arm with history of:
Venous fistula
Mastectomy
August 2015
Blood Pressure

10. Palpation method Locate radial pulse
Inflate cuff to 30 mmHg above cessation of peripheral pulse
Deflate cuff slowly until pulse returns
Note pressure level (systolic pressure)
Deflate cuff completely
August 2015
Blood Pressure

11. Auscultation method Locate & place diaphragm over brachial pulse
Face stethoscope ear pieces forward
Inflate cuff 30 mmHg higher than previous systolic reading
Deflate cuff slowly until pulse sounds begin
A “lub-dub” sound will be heard
Note systolic pressure at this point
Deflate slowly until pulse sounds disappears
Note diastolic pressure at this point
Deflate cuff completely & record BP
August 2015
Blood Pressure

12. Sphygmomanometer
Cuff should be at least 2/3 size of patient’s upper arm
Place cuff around arm, cm above site of brachial artery
Ensure arrows on cuff are in line with brachial artery
August 2015
Blood Pressure

13. Blood Pressure Inaudible blood pressure:
If you can’t obtain an audible blood pressure, palpate a reading.
This procedure will give you a systolic pressure, not a diastolic pressure.
Document BP e.g. 110/--- by palpation
Systolic BP most useful measurement in pre hospital trauma environment
August 2015
Blood Pressure

14. Factors affecting BP Hypertension ↑ Increase cardiac output
Heightened peripheral vascular resistance
Expanded blood volume
↑ Increase blood viscosity
↓ Decrease arterial elasticity
↑ Increase emotional state
Pain
Medications
August 2015
Blood Pressure

15. Factors affecting BP Hypotension ↓ decrease cardiac output
↓ decrease peripheral vascular resistance
Diminished blood volume
↓ decrease blood viscosity
↑ increase arterial elasticity
Orthostatic changes
Medications
August 2015
Blood Pressure

16. Subsequent BP Readings
Venous blood, which has accumulated in the arm, must be allowed to drain
• Wait one (1) minute for a second reading or a “false high” will be recorded
August 2015
Blood Pressure

17. Blood Pressure Measurement & Recording
Practical Activity
Blood Pressure Measurement & Recording
August 2015
Blood Pressure