Are you a Health Professional? Jump over to the doctors only platform. Click Here

Blood Pressure

Doctor taking a patients blood pressure
Print Friendly, PDF & Email


What is blood pressure?

The heart pumps blood through the blood vessels in our bodies.  This is important for delivering oxygen and other nutrients to our tissues, and also for removing waste. The pumping action is caused by the heart muscle relaxing and contracting. When the heart muscle relaxes (called diastole) the heart is filled with blood. Subsequent contraction of the heart muscle (called systole) forces the blood from the heart into the blood vessels to circulate around the body. Blood pressure (BP) refers to the pressure created in the arteries by blood as the heart contracts and relaxes.


How do we measure blood pressure?

The most accurate, non-invasive method of measuring BP is the mercury sphygmomanometer used by your trained health professional. However, due to environmental concerns regarding heavy metal contamination, these may be phased out in the future. The accuracy of other devices varies widely. Digital devices should be checked and validated every 6 months.


How to measure blood pressure accurately

Your local general practitioner (GP) is able to measure and record your BP for you.

Occasionally, your GP may ask you to record BP measurements from home to complement those taken in the clinic. This allows multiple BP measurements to be taken over longer periods.

Self-measurement also helps you understand the changes in your BP and the effects of treatment.

Accurate self-measurement of BP requires:

  • An accurate, approved device, serviced regularly and re-calibrated every 6 months;
  • Practical instruction of good technique by a trained health professional;
  • Written instructions for home reference; and
  • Follow-up appointment to ensure the correct technique is being used.

Take note that patient-measured BP readings are usually lower than clinic BP readings.


Factors that influence blood pressure readings

Blood pressureSeveral factors can artificially raise blood pressure, including:

  • Caffeine – causes short term increases in BP
  • Smoking tobacco – causes short term increases in BP
  • Exercise – causes short term increases in BP, however, regular aerobic exercise can lower BP long term
  • Emotional responses – can cause increased BP
  • Changes in posture – can lead to decreases in BP as in orthostatic hypotension
  • Certain medications – many lower or increase BP


Preparing for blood pressure measurement

For at least two hours before getting your BP measured, you should avoid caffeine and tobacco smoke. These may cause your BP to rise, especially if they are taken together.

Try to relax in the waiting area, and seat yourself comfortably.

 


How are blood pressure results read?

BP results are given as two numbers. An example BP result may be 120 over 80 (written as 120/80).

The first number represents the systolic blood pressure – the maximum pressure exerted on the arterial walls when the heart is contracting.

The second number represents the diastolic blood pressure – the pressure exerted on the arterial walls when the heart is resting.


What do the results mean?

The diagnosis of hypertension should be based on several BP measurements taken on separate occasions. Table 1 shows the different diagnostic categories for various measurements of BP.

Table 1: Diagnostic categories for measured blood pressure.

Diagnostic category*

Systolic BP
(mmHg)

 Diastolic BP
(mmHg)

Normal

< 120

< 80

High-normal

120–139

80–89

Grade 1 (mild) hypertension

140–159

90–99

Grade 2 (moderate) hypertension

160–179

100–109

Grade 3 (severe) hypertension

> 180

> 110

Isolated systolic hypertension

> 140

< 90

Isolated systolic hypertension with widened pulse pressure

> 160

< 7

*If your systolic and diastolic BP fall into different categories, the higher diagnostic category applies.

All persons with a higher BP than normal should consider lifestyle changes, including regular daily exercise and quitting smoking. You can discuss these with your GP.

If your BP is elevated, it may also be appropriate to initiate blood pressure lowering medication. Once again, your local GP can advise you on this.

If you have a BP lower than normal your GP will determine if you suffer symptoms from the low blood pressure, which may then mean treatment or further investigation is required.

Blood Pressure Calculator
This risk assessment tool is based on data from the National Heart Foundation´s Guide to management of hypertension 2008. It puts your blood pressure measurement into one of the seven diagnostic categories specified in this guide.
Age years
Gender Male / Female
Blood pressure* / mmHg
*Use current blood pressure, regardless of whether the person is on antihypertensive therapy.

Results

Normal
Your blood pressure should be rechecked within 2 years or earlier depending on your risk of developing cardiovascular disease. Your General Practitioner can advise you about this risk and also on lifestyle risk reduction.
High-Normal
Your blood pressure is elevated. It should be rechecked within 12 months or earlier depending on your risk of developing cardiovascular disease. Your General Practitioner can advise you about this risk and also on lifestyle risk reduction.
Grade 1 (mild) Hypertension
Your blood pressure is elevated. It should be confirmed within 2 months. Your General Practitioner should advise you about lifestyle risk reduction and/or medication to lower your blood pressure.
Grade 2 (moderate) Hypertension
Your blood pressure is elevated. It should be confirmed within 1 month and you may also need to see a specialist in this time. Your General Practitioner can advise you about lifestyle risk reduction and/or medication to lower your blood pressure.
Grade 3 (severe) Hypertension
Your blood pressure is elevated. It should be confirmed within 1 week and you may also need to see a specialist in this time. Your General Practitioner can advise you about lifestyle risk reduction and/or medication to lower your blood pressure.
Isolated systolic hypertension
Your systolic blood pressure is elevated. Depending on the level it needs to be confirmed within a certain time (140-159mmHg - 2 months; 160-179mmHg - 1 month; >180mmHg - 1-7 days).You may also need to see a specialist. Your General Practitioner can advise you about lifestyle risk reduction and/or medication to lower your blood pressure.
Isolated systolic hypertension with widened pulse pressure
Your blood pressure is elevated. It should be confirmed within 1 week and you may also need to see a specialist in this time. Your General Practitioner can advise you about lifestyle risk reduction and/or medication to lower your blood pressure.
Hypotension
Your blood pressure is lower than normal. Your General Practitioner will ask you about symptoms that you may be experiencing and determine if you require treatment or further investigation.


References
  1. National Heart Foundation of Australia. Guide to Management of Hypertension 2008- Assessing and Managing Raised Blood Pressure in Adults. Updated 2010. [cited 3 December 2014] Available from: http://www.heartfoundation.org.au/SiteCollectionDocuments/HypertensionGuidelines2008to2010Update.pdf

This information will be collected for educational purposes, however it will remain anonymous.


Conditions associated with a change in blood pressure

There are several conditions associated with changes in BP.

Hypertension (or high blood pressure) is associated with a greater risk of:

Hypotension (or low blood pressure) is seen in cases of:


Summary

  • Blood pressure is most accurately measured using a mercury sphygmomanometer.
  • There are several key steps that should be followed to measure BP accurately.
  • If properly demonstrated and practised, patient self-measurement can be a valuable addition to measurements performed by a health professional.
  • Before having your BP measured, avoid caffeine and tobacco smoke (up to 2 hours prior).
  • Early detection of high blood pressure is critical in the prevention of future cardiovascular and kidney disease.

More information

Blood
For more information on blood, blood types, blood tests, and blood donation and transfusion, see Blood
.

 

Hypertension
For more information on high blood pressure, including investigations and treatments, as well as some useful animations, videos and tools, see Hypertension (High Blood Pressure)
.

 

References

  1. Your blood pressure 2008 [online]. Canberra, ACT: National Heart Foundation of Australia; 19 August 2008 [cited 15 November 2008]. Available from: URL link
  2. Guide to management of hypertension 2008: Assessing and managing raised blood pressure in adults [online]. Canberra, ACT: National Heart Foundation of Australia; 1 August 2008 [cited 15 November 2008]. Available from: URL link
  3. Chesnut RM, Marshall LF, Klauber MR, et al. The role of secondary brain injury in determining outcome from severe head injury. J Trauma. 1993;34(2):216-22. [Abstract]
  4. Low PA. Prevalence of orthostatic hypotension. Clin Auton Res. 2008;18(Suppl 1):8-13. [Abstract]
  5. Vincent JL, Gerlach H. Fluid resuscitation in severe sepsis and septic shock: An evidence-based review. Crit Care Med. 2004;32(11 Suppl):S451-4. [Abstract]
  6. Chiara O, Bucci L, Sara A, et al. Quality and quantity of volume replacement in trauma patients. Minerva Anestesiol. 2008;74(6):303-6. [Abstract | Full text]
  7. Nieman LK, Chanco Turner ML. Addison’s disease. Clin Dermatol. 2006;24(4):276-80. [Abstract]
Print Friendly, PDF & Email

Dates

Posted On: 20 November, 2008
Modified On: 26 November, 2010

Tags



Created by: myVMC