Doctors often check your fingers and toes when doing a physical exam. They may gently squeeze each fingertip and toe tip, watching the color and how fast it returns to normal after squeezing. This simple test can reveal a lot about your health.
What is the fingertip squeezing test?
The fingertip squeezing test, also called capillary refill test, checks how well blood is circulating through your body. To do this test, the doctor firmly presses on one of your fingernails or toenails, pushing out the blood. When they release the pressure, they time how long it takes for color to return to that finger or toe.
In healthy people with good blood flow, the natural pink color returns within 2 seconds. Slower capillary refill can be a sign of poor circulation or dehydration. Abnormally fast refill may point to an overactive thyroid.
Why check capillary refill?
Doctors test capillary refill for a few key reasons:
- Screen for dehydration – Slow capillary refill can be an early sign of dehydration. Checking fingers and toes is a quick way to see if someone is dehydrated.
- Test circulation – Sluggish blood flow often causes delayed capillary refill. Finding slow refill may prompt further testing for circulatory problems.
- Spot shock – Very delayed capillary refill can indicate shock, a life-threatening condition where blood pressure drops severely. This test helps detect shock early.
- Monitor health status – Subtle changes in capillary refill time can signal improving or worsening health status in hospitalized patients.
Along with other vital signs like pulse and blood pressure, capillary refill gives doctors insight into how well your heart is pumping blood and how well your blood vessels are working.
What is a normal capillary refill time?
Normal capillary refill time is 2 seconds or less. Here are the reference ranges:
| Capillary Refill Time | Result |
|---|---|
| Less than 2 seconds | Normal |
| 2-3 seconds | Mildly delayed |
| Over 3 seconds | Severely delayed |
Doctors may consider capillary refill times up to 3 seconds as borderline normal in some cases. Significantly delayed refill over 3 seconds is always abnormal.
What causes delayed capillary refill?
Many conditions can temporarily slow capillary refilling after squeezing a finger. Common causes include:
- Dehydration – Fluid loss concentrates the blood, making it thicker and slower moving.
- Cold temperatures – Constricted blood vessels in cold fingers limit blood flow.
- Blood loss – Low blood volume from bleeding or donating blood reduces circulation.
- Shock – Critically low blood pressure impairs blood flow.
- Peripheral artery disease – Plaque narrows arteries reducing blood supply to extremities.
- Raynaud’s phenomenon – Spasms temporarily constrict blood vessels in fingers and toes.
- Scleroderma – Hardening and thickening of skin can restrict blood flow.
- Diabetes – Over time, high blood sugar damages blood vessels.
In most cases, warming the hands and increasing hydration can improve mildly delayed capillary refill. But consistent delays over 3 seconds often require medical treatment of an underlying health issue.
What does fast capillary refill mean?
Rapid capillary refill in under 1 second can sometimes be seen with:
- Fever – Warm body temperatures dilate blood vessels.
- Hyperthyroidism – Excess thyroid hormone increases metabolism and blood flow.
- Anemia – Low red blood cell counts allow faster blood flow.
- Medications – Such as vasodilators that open blood vessels.
Doctors mainly monitor for delayed capillary refill as a warning sign. But very brisk refill may provide clues in some cases, prompting thyroid tests or other evaluations as appropriate.
How is capillary refill assessed?
To test capillary refill, doctors typically:
- Press firmly on the tip of a finger or toe nailbed with their thumb for 5 seconds. This blanches or lightens the normal red color.
- Release pressure and start timing how long it takes for normal color to return.
- Repeat on other fingers or toes, testing on hands and feet if concerning delays are found.
- Note if color fails to return fully within 3 seconds. This indicates significantly reduced blood flow.
Skin temperature, hydration status, and use of vasoconstricting drugs can affect results, so doctors consider these factors. Testing warmer, well-hydrated fingers improves accuracy if circulation appears reduced.
Why fingertips and not palms?
Pressing and releasing fingernails gives the most precise gauge of capillary refill. Nails lack oil glands, so blanching happens more quickly and completely. Palms take longer to blanch and refill since they contain more blood vessels and capillaries.
Fingertips also provide visualization of the small capillaries that can reflect reduced peripheral circulation. Toenail beds offer another site far from the heart to check blood flow adequacy.
What’s the difference between light and deep palpation?
Doctors may use two pressures when testing capillary refill:
- Light palpation – Applies just enough pressure to blanch the fingernail. Assesses surface capillaries.
- Deep palpation – Firmly presses down on the nailbed. Checks deeper blood vessels.
Deep palpation gives longer blanching and better detection of delays from dehydration or shock. But pressing too hard can cause unnecessary pain and be difficult in children or the elderly.
How accurate is the fingertip squeezing test?
The capillary refill test provides a simple, fast way to broadly assess circulation. However, results have limitations:
- Subjective – Interpretation of “delayed” refill varies between practitioners.
- Inexact – Categorizes circulation as normal/abnormal but doesn’t quantify.
- Transient – Can be temporarily altered by temperature, hydration status, etc.
- Insensitive – Mild circulatory deficits may not affect such a basic test.
While convenient at the bedside, capillary refill lacks accuracy and precision. Doctors rely on it for screening purposes, but if abnormalities are found, direct blood pressure measurements and blood tests better evaluate circulation.
What are normal blood pressure ranges?
Normal blood pressure ranges according to recent American Heart Association guidelines are:
| Blood Pressure Category | Systolic mm Hg | Diastolic mm Hg |
|---|---|---|
| Normal | Less than 120 | Less than 80 |
| Elevated | 120-129 | Less than 80 |
| Hypertension Stage 1 | 130-139 | 80-89 |
| Hypertension Stage 2 | 140 or higher | 90 or higher |
These ranges apply to adults ages 18 and over who do not have short-term serious illnesses. Standards vary slightly for ages under 18 and during pregnancy.
How are blood pressure and circulation related?
Blood pressure and circulation are closely linked. Arterial blood pressure reflects the force exerted as blood pumps from the heart and moves through blood vessels. Higher pressures allow blood to overcome resistance and circulate to the body’s tissues.
A healthy blood pressure enables good peripheral circulation detected through fast capillary refill. Meanwhile, low blood pressure reduces circulation causing delayed refill. Checking capillary refill provides an indirect screen for potentially unhealthy blood pressure.
Why does temperature affect capillary refill time?
Body temperature impacts capillary refill in a few key ways:
- Cold temperatures constrict blood vessels, slowing blood flow.
- Warm temperatures dilate vessels, increasing circulation speed.
- Fever raises metabolism and heart rate, improving blood flow.
Colder hands and feet often have slower initial refill after squeezing. Doctors may warm up these extremities before retesting if circulation seems reduced. Monitoring refill on warm forehead skin can give the most accurate assessment when temperature is a factor.
How can doctors evaluate circulation besides capillary refill?
If capillary refill suggests poor circulation, doctors can confirm and evaluate causes through other tests like:
- Blood pressure – Low blood pressure reduces peripheral circulation.
- Pulse – Checks heart rate and rhythm.
- Blood tests – Assess oxygen and nutrient levels.
- Doppler ultrasound – Measures blood flow in arteries.
- Angiography – Visualizes blood vessels via imaging and dye.
These provide more direct, quantitative data on circulation than the simple capillary refill test. But that test offers a quick first screen prompting further evaluation if warranted.
What conditions cause poor circulation?
Delayed capillary refill can result from circulatory system conditions such as:
- Peripheral artery disease – Plaque narrows arteries in limbs.
- Blood clots – Clots block blood flow through vessels.
- Varicose veins – Twisted veins improperly circulate blood.
- Atherosclerosis – Hardened arteries resist blood flow.
- Heart failure – Weak heart muscle can’t pump out blood well.
- Arrhythmias – Irregular heartbeat disrupts blood flow.
Poor circulation can also stem from low fluid volume, as with dehydration or blood loss. Evaluating patients with delayed refill aims to identify treatable causes like these.
How is poor circulation treated?
Boosting weak circulation involves treating the underlying cause, which may include:
- Raising blood pressure if too low.
- Balancing thyroid hormone levels if off.
- Administering fluids if dehydrated.
- Surgery to open blockages from plaque or clots.
- Medications to improve heart function.
- Compression stockings to prevent blood pooling.
Lifestyle changes like quitting smoking, exercising regularly, and eating a heart-healthy diet also support healthy circulation for the long term.
Can you improve circulation naturally?
Along with medical treatment, people can potentially optimize their circulation naturally in certain ways. Some methods that may help include:
- Exercise – Aerobic activity and strength training benefit circulation.
- Stretching – Loosens muscles to allow better blood flow.
- Massage – Kneads tissues to help move blood through the body.
- Warm baths – Warms extremities to dilate blood vessels.
- Compression garments – Prevent blood pooling in limbs.
- Quit smoking – Allows blood vessels to open up.
A healthy lifestyle supports the body’s circulatory system. But medical evaluation is still needed to identify and properly treat any underlying conditions causing poor blood flow.
Takeaways
- Doctors squeeze fingertips to briefly push out blood and test capillary refill time.
- Delayed refill over 3 seconds often signals dehydration or circulation problems.
- Fast refill under 1 second may occur with fever, hyperthyroidism, or anemia.
- Skin temperature, hydration, and blood pressure can all impact results.
- While convenient, capillary refill has limitations in precision and accuracy.
- Further testing like blood pressure checks are needed if abnormal delays are seen.
- Treating underlying causes can help optimize circulation.
Conclusion
The simple fingertip squeezing test provides a quick screen of circulation as part of a routine physical exam. Delayed capillary refill may prompt further evaluation for low blood pressure, dehydration, or vascular conditions affecting blood flow. Doctors can then treat the cause to restore optimal circulation. Patients can also partner with their provider to improve circulation through medications, surgeries if needed, and healthy lifestyle choices.