Assessing skin color is a foundational practice for individuals with limited mobility or those confined to a bed or chair for extended periods. When the body rests on a surface, the soft tissues overlying bony prominences are exposed to pressure, which can impede blood flow. Localized damage to the skin and underlying tissue, often called a pressure injury, begins with subtle changes in color and texture. Differentiating between temporary skin irritation and sustained tissue damage is crucial for preventing wound progression. The simple application of the skin blanching test provides caregivers and medical professionals with the information needed to determine the severity of the redness and take appropriate preventative measures.
How to Perform the Skin Blanching Test
The test is a straightforward physical assessment requiring light pressure and careful observation. Ensure the area being examined is well-lit for accurate detection of color changes, especially on darker skin tones. The area of concern is typically a reddened or discolored spot over a bony part of the body, such as the heel, hip, or tailbone.
Apply gentle pressure directly onto the discolored skin using a fingertip or a clear plastic disc. Maintain the pressure for three to five seconds. The immediate goal is to observe if the skin turns white or pale while the pressure is applied.
Quickly remove the finger or disc and immediately note the skin’s color response. This assessment focuses solely on the physical response of the tissue to external force.
Understanding Blanchable Redness
A positive blanching response, where the skin turns white under pressure, is considered the better scenario in a skin assessment. This temporary pallor occurs because the external force briefly squeezes the blood out of the superficial capillaries. When the pressure is released, the skin quickly returns to its original red color, ideally within a few seconds.
This rapid return of color is known as reactive hyperemia, indicating a healthy, functional microcirculation. Reactive hyperemia is a physiological mechanism where the blood vessels dilate to compensate for the momentary restriction of blood flow, delivering an increased volume of blood to the affected area. The quick rush of blood shows that the capillaries are intact and capable of refilling, effectively repaying the temporary oxygen debt the tissue incurred.
A blanchable area of redness typically suggests temporary irritation or inflammation, rather than deep cellular destruction. Because the blood vessels are still responding appropriately, the tissue has likely received sufficient oxygen and nutrients to avoid permanent damage. This is a sign that the damage is superficial and reversible.
Non-Blanchable Redness and Pressure Injury Risk
Non-blanchable redness is a finding that warrants immediate attention, as it indicates a more serious underlying issue. The skin remains red, or discolored, even when gentle pressure is applied and then released. This lack of color change is a sign that the capillaries have been damaged and can no longer be emptied of blood. The trapped blood and fluid prevent the skin from turning pale, signifying localized damage to the vascular structure.
This persistent discoloration is the defining characteristic of a Stage 1 Pressure Injury, which represents the most superficial level of tissue damage. The injury occurs when the external pressure exerted on the tissue over a prolonged period exceeds the internal pressure needed to maintain normal blood flow, leading to tissue ischemia and subsequent cell death. Although the skin is still intact at this stage, the redness is a strong warning that the underlying tissue has been compromised.
Non-blanchable redness can present differently depending on the individual’s natural skin tone. On darker skin, the damage may manifest as persistent blue, purple, or maroon discoloration, rather than a distinct red hue. For these individuals, the assessment must also include checking for changes in texture, such as increased firmness or sponginess, or differences in temperature compared to the surrounding healthy skin. A Stage 1 classification signals that sustained tissue damage has occurred and that deeper structures may be at risk.
Taking Action After Skin Assessment
Discovering a non-blanchable area requires an immediate response to prevent the injury from progressing. The first action is to remove all pressure from the affected site by immediately repositioning the individual to redistribute the load. Proper positioning often involves using the 30-degree side-lying position to avoid placing weight directly on the bony prominence.
Maintaining skin integrity involves diligently keeping the area clean and dry. Applying a moisture barrier cream helps protect the skin from excessive wetness, which can cause further breakdown. Adequate nutritional support is also necessary, requiring sufficient intake of protein, vitamins (such as C and Zinc), and hydration to support the body’s repair processes.
The area must be continuously monitored for signs of worsening damage, such as blistering or an open wound. If the non-blanchable redness persists after 30 minutes of complete pressure relief, or if the skin begins to break down, consultation with a healthcare professional is necessary.