Blood Pressure Assessment for Student Nurses
Learn how to obtain an accurate blood pressure reading, understand systolic and diastolic pressure and recognise changes that may indicate circulatory compromise or patient deterioration.
What do systolic and diastolic pressure mean?
Blood pressure reflects the pressure exerted by circulating blood against the walls of the arteries. It is recorded as two values, measured in millimetres of mercury, or mmHg.
The upper number
Systolic blood pressure represents arterial pressure during ventricular contraction.
The lower number
Diastolic blood pressure represents arterial pressure while the heart relaxes between contractions.
Systolic BP
NEWS2 uses systolic blood pressure as one of its six physiological parameters.
How to obtain a reliable blood pressure reading
Technique can significantly affect the result. A poorly positioned patient or incorrectly sized cuff can produce a misleading reading.
Prepare the patient
Explain the procedure, ensure appropriate privacy and allow the patient to rest where clinically appropriate before measurement.
Position correctly
Support the arm appropriately and use the position recommended by your local procedure and equipment guidance.
Select the correct cuff
Use a cuff suitable for the patient's arm size. An inappropriate cuff can alter the accuracy of the reading.
Apply the cuff correctly
Place the cuff according to manufacturer instructions and local practice, avoiding unnecessary obstruction by clothing.
Measure the pressure
Use the approved automated or manual method in line with your competence, training and placement procedure.
Record and interpret
Document the result, compare it with previous readings and assess whether the value fits the patient's overall condition.
Unexpected result?
If the reading seems inconsistent with the patient's condition, consider technique, cuff size, movement and equipment. Repeat the measurement where appropriate, but do not delay escalation if the patient appears unwell.
Low and high blood pressure
Blood pressure terminology describes the observation, but the number alone does not tell you the underlying cause.
| Finding | What it describes | What else should you consider? |
|---|---|---|
| Hypotension | Blood pressure lower than expected for the patient or clinical situation. | Symptoms, pulse, perfusion, fluid status, bleeding, infection, medications and previous readings. |
| Hypertension | Blood pressure higher than the expected or target range. | Previous diagnosis, pain, anxiety, medication, symptoms and whether the elevation is persistent. |
| Falling systolic pressure | A downward trend in the upper blood pressure value. | This may be particularly important when associated with a rising pulse, poor perfusion or other signs of deterioration. |
| Postural change | Blood pressure changes associated with a change in position. | Dizziness, weakness or collapse may require further assessment according to local procedure. |
Look for the pattern
A blood pressure that is lower than usual becomes more concerning when accompanied by a rising pulse, altered consciousness, reduced urine output, cool peripheries or worsening respiratory observations.
Blood pressure is only part of the circulation assessment
A patient's circulation should be assessed using more than the blood pressure machine. Think about whether the tissues appear to be receiving adequate blood flow.
- Assess pulse rate, rhythm and strength.
- Consider skin colour and temperature.
- Look for cool or clammy peripheries.
- Assess capillary refill where clinically appropriate.
- Consider mental state and level of consciousness.
- Review urine output where relevant and available.
- Compare current blood pressure with previous observations.
- Consider symptoms such as dizziness, weakness or collapse.
Changes that deserve attention
- A significant fall in systolic blood pressure from the patient's baseline.
- Low blood pressure alongside tachycardia.
- Low blood pressure with cool, clammy or poorly perfused peripheries.
- New dizziness, collapse, weakness or altered consciousness.
- Blood pressure changes associated with suspected bleeding or fluid loss.
- Several NEWS2 parameters deteriorating at the same time.
- A patient who appears clinically unwell despite a blood pressure that does not initially seem dramatically abnormal.
Clinical concern overrides reassurance from one number
A blood pressure reading should support your assessment, not replace it. If the patient looks unwell or their condition is changing, communicate your concern.
Putting the observations together
Example
Earlier in the shift, your patient's blood pressure was 132/78 mmHg and their pulse was 76 bpm.
Several hours later their blood pressure is 98/62 mmHg and their pulse has increased to 108 bpm. They report feeling weak and dizzy, and their hands feel cool.
The significance comes from the trend and combination of findings: falling blood pressure, rising pulse and symptoms suggesting possible circulatory compromise.
As a student nurse, recognise the change, obtain accurate observations and promptly communicate your findings to the appropriate registered practitioner.
Blood pressure assessment errors to avoid
- Using the wrong cuff size. This may produce an inaccurate reading.
- Poor positioning. Support the patient and arm according to recommended technique.
- Accepting an unexpected result without checking it. Consider repeating the measurement where appropriate.
- Repeatedly checking while delaying escalation. If the patient appears unwell, seek help.
- Looking at blood pressure alone. Review pulse, perfusion, respiration, consciousness and the wider clinical picture.
- Ignoring trends. A significant change from the patient's baseline may be important even if the reading is not extreme.
Recognise β assess β communicate β escalate
Notice the change
Identify unexpected readings, downward trends or symptoms suggesting reduced circulation.
Build the picture
Confirm the blood pressure and review pulse, perfusion, symptoms, respiratory observations and previous readings.
Report clearly
Communicate the current result, trend and associated findings and follow local escalation procedures where necessary.
Further learning: Royal College of Physicians β National Early Warning Score (NEWS2) .
Temperature Assessment for Student Nurses
Learn how to measure body temperature, recognise pyrexia and hypothermia and understand why changes in temperature can be an important sign of infection and deterioration.
Continue to Temperature Assessment β