Recognising Hypotension for Student Nurses
Learn how to recognise low or falling blood pressure, assess the patient's circulation and identify associated changes that may indicate poor perfusion, shock or wider deterioration.
What is low blood pressure?
Hypotension describes blood pressure that is lower than expected for the patient or clinical situation. The significance depends on baseline blood pressure, symptoms and whether tissue perfusion appears to be affected.
Look beyond one value
A fall from the patient's normal blood pressure may be significant even before a very low reading is reached.
Perfusion
Pulse, capillary refill, skin temperature and consciousness can help build the circulation picture.
How do they feel?
Weakness, dizziness, collapse or altered consciousness can make a low blood pressure more concerning.
How to assess a low blood pressure reading
Confirm the measurement
Ensure the cuff size, patient position and measurement technique are appropriate and repeat the reading where clinically indicated.
Compare with baseline
Review previous blood pressures and identify whether there has been a significant downward trend.
Assess the pulse
Look for tachycardia, bradycardia, an irregular rhythm or a weak peripheral pulse.
Assess perfusion
Review capillary refill, peripheral temperature, skin colour and the patient's overall appearance.
Ask about symptoms
Consider dizziness, weakness, fainting, chest discomfort, breathlessness and changes in mental state.
Review the wider observations
Assess respiratory rate, oxygen saturation, temperature, consciousness and urine output where relevant.
Why might blood pressure fall?
| Possible context | Other clues | Clinical thinking |
|---|---|---|
| Dehydration | Poor intake, vomiting, diarrhoea or reduced urine output. | Reduced circulating volume can contribute to falling blood pressure. |
| Blood loss | Known or suspected bleeding, pallor, tachycardia or weakness. | Falling blood pressure may form part of a developing circulatory emergency. |
| Severe infection | Abnormal temperature, tachycardia, altered respiration or confusion. | Hypotension can occur in severe infection and circulatory deterioration. |
| Medication | Recent or ongoing medicines that may affect blood pressure. | Medication history is relevant, but do not assume medication explains an acutely deteriorating patient. |
| Postural change | Dizziness or faintness after standing or changing position. | Postural symptoms may require further assessment according to local procedure. |
| Cardiovascular problems | Chest symptoms, abnormal pulse or other circulatory findings. | Low blood pressure may reflect impaired cardiovascular function and requires appropriate clinical review. |
Think about change from normal
A patient whose systolic pressure is usually around 140 mmHg but has fallen progressively to 105 mmHg may be showing an important physiological change even though 105 does not initially sound dramatically low.
What makes hypotension more concerning?
- A rising pulse or weak peripheral pulse.
- Cool, pale, clammy or mottled skin.
- Prolonged capillary refill.
- New dizziness, weakness or collapse.
- New confusion, agitation or reduced responsiveness.
- Reduced urine output.
- Increasing respiratory rate.
- Known or suspected bleeding or significant fluid loss.
- Several NEWS2 parameters deteriorating together.
Blood pressure is only one part of circulation
A low systolic reading accompanied by tachycardia, prolonged capillary refill and altered consciousness is much more concerning than the blood pressure number considered alone.
When should you escalate promptly?
Blood pressure is falling
A progressive downward trend can indicate worsening circulation even before severe hypotension develops.
The patient is affected
Collapse, marked dizziness, chest discomfort, severe weakness or altered consciousness require prompt attention.
Circulation looks poor
Cool skin, weak pulses, delayed capillary refill and low urine output can increase concern.
Putting the observations together
Example
Earlier in the shift, your patient's blood pressure was 134/78 mmHg with a pulse of 78 bpm.
It is now 96/60 mmHg and their pulse has risen to 116 bpm.
They are pale, their hands feel cool, capillary refill is prolonged and they report feeling weak and dizzy.
The concern is not simply a blood pressure of 96/60. It is the combined pattern of falling blood pressure and worsening perfusion.
As a student nurse, recognise the deterioration, obtain accurate observations and communicate the findings promptly to the appropriate registered practitioner.
Hypotension assessment errors to avoid
- Looking only at the absolute BP. Compare it with the patient's baseline and previous readings.
- Ignoring the pulse. Tachycardia with falling BP can indicate worsening circulation.
- Repeatedly checking without escalating. Confirm an unexpected result, but do not delay help if the patient is unwell.
- Ignoring symptoms. Dizziness, weakness and collapse can make a low BP much more significant.
- Assuming medication is the cause. Consider the whole clinical picture.
- Waiting for profound hypotension. Earlier downward trends may already warrant assessment.
Recognise → assess → communicate → escalate
Notice the fall
Identify hypotension or a meaningful downward trend from the patient's previous blood pressure.
Review circulation
Assess pulse, capillary refill, skin, symptoms, consciousness and relevant fluid status.
Report the pattern
Give the current blood pressure, previous values and associated changes clearly.
Recognising New Confusion for Student Nurses
Learn how to recognise acute confusion, distinguish a new change from a patient's usual baseline and understand why altered mental state can be an important sign of deterioration.
Continue to Recognising New Confusion →