What is the evaluation of pallor?

From the Guidelines

Pallor is a late and unreliable sign of compartment syndrome and other underlying conditions.

Evaluation of Pallor

• Pallor is often associated with arterial occlusion and is indicative of a late diagnosis of acute compartment syndrome (ACS) 1.
• The presence of pallor, along with other signs such as pulselessness, is a late indicator of compartment syndrome, and its absence does not rule out the condition 1.
• In the context of cardiovascular evaluation, pallor can be an indicator of underlying disease or coronary artery disease (CAD), but it is a non-specific sign that requires further investigation 1.
• A thorough physical examination, including assessment of vital signs, cardiovascular examination, and examination of the extremities, is essential for evaluating patients with suspected compartment syndrome or other conditions that may present with pallor 1.
• The 6 Ps of ACS, which include pain, paresthesia, paresis, pain with stretch, skin examination, and pink color, are more reliable indicators of compartment syndrome than pallor 1.

From the Research

Evaluation of Pallor

The evaluation of pallor is a complex process that involves assessing the presence or absence of pallor at different anatomical sites, including the conjunctivae, face, nails, palms, and palmar creases.

• The true-positive rates (sensitivities) for pallor at any one of three sites (ie, the conjunctivae, face, or palms) were found to be 0.65 2.
• The true-negative rates (specificities) were best for palmar creases (1.00), for pallor at conjunctivae, face, and palms (all three in combination; 0.95), and for the face (0.90) 2.
• The examination of the nailbeds was found to be inferior to all other sites or combinations 2.

Anatomical Sites for Pallor Assessment

Different anatomical sites have been assessed for pallor, including:

• Conjunctivae: Pallor at this site was found to be associated with a significantly lower hemoglobin concentration 3.
• Palms: Pallor at this site was found to have a sensitivity of 0.53 for detecting anemia 2.
• Nailbeds: The examination of the nailbeds was found to be inferior to all other sites or combinations 2.
• Tongue: Severe tongue pallor was found to yield a likelihood ratio of 9.87 for detecting severe anemia 4.

Diagnostic Accuracy of Pallor

The diagnostic accuracy of pallor for detecting anemia has been found to be:

• Sensitivity: 50% 3
• Specificity: 92% 3
• The area under the receiver operating characteristic curve (ROC area) for tongue pallor was found to be 0.84 for detecting severe anemia 4.
• The use of pallor to screen and treat severe anemia by primary care providers is feasible and worthwhile where severe anemia is common 3.

Limitations of Pallor Assessment

There are several limitations to the assessment of pallor, including:

• Inter-observer variability: The agreement between observers for detection of anemia was found to be poor (kappa values = 0.07 for conjunctival pallor and 0.20 for tongue pallor) 4.
• Spectrum bias: Previous studies addressing the usefulness of pallor in anemia are deficient because of observer or spectrum bias 2.
• Iron overload: The presence of iron overload can affect the validity of pallor in detecting anemia 5.