Capillary Refill Assessment for Student Nurses
Learn how capillary refill can contribute to assessment of peripheral perfusion and why it should always be interpreted alongside pulse, blood pressure, skin temperature and the wider clinical picture.
What is capillary refill time?
Capillary refill time, often shortened to CRT, describes how quickly colour returns to tissue after pressure has temporarily reduced blood flow in the small vessels.
Peripheral perfusion
CRT can contribute to assessment of how well blood is reaching peripheral tissues.
Colour return
A return of colour within around two seconds is commonly used as a teaching reference in adults.
Think wider
Temperature, age, lighting, peripheral circulation and technique can all affect interpretation.
How to assess capillary refill
Follow your local procedure and clinical teaching. A consistent technique makes the observation more useful when comparing findings.
Assess the patient first
Look at skin colour, temperature, consciousness, pulse, blood pressure and overall clinical appearance.
Select the assessment site
Use the site recommended in your clinical area and according to local teaching.
Apply pressure
Apply firm pressure for the recommended period until the area blanches.
Release pressure
Observe the tissue as blood flow returns after pressure is removed.
Time the colour return
Assess how quickly normal colour returns, using a consistent method rather than estimating casually.
Interpret the finding
Consider CRT alongside pulse, blood pressure, skin temperature, consciousness and other evidence of perfusion.
Environment matters
Cold surroundings and cold extremities can affect peripheral blood flow and therefore influence capillary refill. Interpret the result in context.
What else should you assess?
Capillary refill becomes more meaningful when combined with other signs of circulation and tissue perfusion.
| Observation | What to look for | Why it matters |
|---|---|---|
| Pulse | Rate, rhythm and strength. | A fast or weak pulse may add to evidence of circulatory stress. |
| Blood pressure | Current reading and trend from baseline. | Falling blood pressure may become particularly concerning when accompanied by signs of poor perfusion. |
| Skin | Colour, temperature, moisture and mottling. | Cool, pale, clammy or mottled skin may suggest altered peripheral circulation. |
| Consciousness | Alertness, confusion or reduced responsiveness. | Changes can occur when circulation or oxygen delivery is compromised. |
| Urine output | Recent output where relevant and available. | Reduced urine output may form part of a wider picture of poor perfusion or acute illness. |
Think perfusion, not just CRT
A prolonged capillary refill alongside a rising pulse, falling blood pressure, cool peripheries and altered mental state is much more significant than the CRT result considered alone.
Changes that deserve attention
- Capillary refill becoming slower than on previous assessment.
- Cool, pale or clammy extremities.
- A weak or increasingly rapid pulse.
- A falling blood pressure or significant change from baseline.
- New confusion, drowsiness or reduced responsiveness.
- Reduced urine output where this is being monitored.
- Increasing respiratory rate or other signs of physiological stress.
- A combination of several signs suggesting worsening perfusion.
Do not wait for hypotension
Changes in peripheral perfusion can occur before a dramatic fall in blood pressure. Assess trends and the patient's whole clinical picture rather than waiting for one severe abnormality.
Putting the observations together
Example
A patient's capillary refill was previously brisk. During your next assessment you notice that their hands are cool and CRT appears prolonged.
Their pulse has increased from 80 to 112 bpm and their systolic blood pressure is lower than earlier in the shift.
They also say they feel weak and light-headed.
The concern is the combined pattern suggesting worsening circulation, rather than the capillary refill result alone.
As a student nurse, recognise the change, obtain accurate observations and communicate your concern promptly to the appropriate registered practitioner.
Capillary refill errors to avoid
- Using CRT as a diagnosis. It is one observation within a wider assessment.
- Ignoring cold extremities. Peripheral temperature can affect the result.
- Estimating casually. Use a consistent assessment technique.
- Ignoring other circulation findings. Review pulse, blood pressure, skin and consciousness.
- Focusing on one isolated reading. Compare with previous observations where possible.
- Delaying escalation. A concerning pattern of poor perfusion requires appropriate clinical review.
Recognise → assess → communicate → escalate
Notice poor perfusion
Identify prolonged refill, cool skin, pallor or a change in the patient's general condition.
Build the picture
Review pulse, blood pressure, skin, consciousness, respiration and other relevant observations.
Report the pattern
Describe the current findings, change from baseline and associated observations and follow local escalation procedures.
Recognising Hypoxia for Student Nurses
Learn the signs and symptoms of hypoxia, understand why oxygen saturation is only part of the assessment and recognise when a patient's oxygenation may be deteriorating.
Continue to Recognising Hypoxia →