Raynaud's Syndrome Diagnosis

What is Raynaud's Syndrome?

Raynaud’s Syndrome is a disorder of the blood vessels, usually in the fingers or toes, causing blood vessels to narrow when exposed to cold temperatures or during periods of stress. This narrowing, or vasoconstriction, leads to reduced blood perfusion to the affected sites.
Raynaud's Syndrome

This condition is also known as Raynaud’s Disease or Primary Raynaud’s when not accompanied by arterial obstruction. In cases where it is accompanied by arterial obstruction, it is referred to as Raynaud’s Phenomenon or Secondary Raynaud’s.

The terms “Raynaud’s syndrome,” “Raynaud’s disease,” “Raynaud’s phenomenon,” and “Raynaud’s disorder” are often used interchangeably.

When Raynaud’s occurs, blood cannot reach the surface of the skin, resulting in areas turning white or blue. In severe cases, this reduced blood flow can lead to sores or tissue death1.

Prevalence and Risk Factors of Raynaud's Syndrome

Raynaud’s Syndrome affects approximately 5% of the population2, with a higher occurrence in females. It is more prevalent in regions with cold climates. 

The risk factors for this condition include smoking and alcohol consumption.

How to Test for Raynaud's

To diagnose Raynaud’s Disease, physiological tests are typically performed. Such tests include measuring of photoplethysmography (PPG) waveforms with or without blood pressure in the fingers or toes, both at room temperature and after cold immersion. 

Required Equipment


Learn More
Falcon Toeclips PPG


Falcon Inflatable Cuffs

Inflatable Cuffs

Temperature Sensor

Temperature Sensor

Here is an example of a step-by-step guide for performing Raynaud’s Syndrome Test based on PPG (it is also possible to perform the test with pressure cuffs and PPG sensors):

  1. Preparation: Ensure a suitable testing environment with controlled temperature conditions. Make sure the room temperature is comfortable and consistent throughout the test.

  2. Explanation and Consent: Explain the procedure to the patient, including its purpose and potential sensations they might experience during the test. Obtain informed consent from the patient before proceeding.

  3. Positioning: Ask the patient to sit in a relaxed position, with their hands or feet comfortably placed on a surface.

  4. Baseline Measurement: Before any cold exposure, measure the patient’s baseline photoplethysmography (PPG) waveform and/or blood pressure in the fingers or toes at room temperature. Record these measurements as the baseline values for later comparison.

  5. Cold Immersion: Remove the PPG sensor from the patient’s digits or toes. Prepare a container filled with cold water. Ask the patient to immerse their hand or foot (depending on the area being tested) into the cold water for a specified duration. The cold immersion should be long enough to elicit a response but not to the point of discomfort or pain.

  6. Observation and Measurements: While the hand or foot is immersed in cold water, closely observe the color changes in the affected area. Note any visible signs of blanching or discoloration. 

  7. Recovery Period: After the specified cold immersion duration, instruct the patient to remove their hand or foot from the cold water and allow it to return to room temperature. Reattach the PPG sensors and measure the recovery of the PPG waveforms or blood pressure as the affected area returns to its baseline state.

  8. Analysis and Interpretation: Compare the PPG waveforms or blood pressure measurements taken during the cold immersion and the recovery period with the baseline values. Look for any significant changes, such as delayed recovery or abnormal patterns, which may indicate Raynaud’s Syndrome or other related conditions.

  9. Documentation and Reporting: Record the test results accurately, including the measurements, observed responses, and any notable observations. Prepare a comprehensive report summarizing the findings and interpretations for further analysis or consultation with a healthcare professional.

This step-by-step guide for performing a Raynaud’s test is for informational purposes only. Healthcare professionals should rely on their expertise, clinical judgment, and institutional protocols for accurate administration and interpretation. Additional clinical information, patient history, physical examination, and other diagnostic tests may be necessary for comprehensive evaluation.

Using the Falcon for Raynaud's Measurements​

The Falcon/PRO vascular machine offers significant advantages for Raynaud’s diagnosis: 

  1. Enhanced Efficiency: Dedicated protocols for Raynaud’s testing, allowing for rapid and simultaneous measurement of photoplethysmography (PPG) waveforms and systolic blood pressure in all 5 fingers or toes at the same time. This significantly reduces the time and effort required for performing the test compared to traditional methods that require separate measurements for each digit.
  2. Improved Patient Experience: The 5 independent PPG sensors also eliminate the need for patients to repeat the cumbersome and sometimes painful process of immersing each finger or toe individually in cold water.
  3. Comprehensive Measurements: Perform simultaneously 5 PPG measurements and 10 Pulse Volume Recordings (PVR) on the digits or toes.
  4. Integrated Temperature Monitoring: An integrated temperature sensor is essential in documenting the skin temperature during cold immersion and continuously monitoring the skin temperature during the recovery period.
  5. Streamlined Analysis and Reporting: Various print and report options specifically designed for a detailed comparison between pre- and post-immersion results.

Expected Results

During a Raynaud’s Syndrome test, several expected results and observations can be noted. First, during the cold immersion phase, the affected area may exhibit color changes, turning white or blue due to vasoconstriction and reduced blood flow. This discoloration serves as a characteristic sign of Raynaud’s Syndrome. 

Additionally, the focus of the test is on the time it takes for the PPG waveforms to return to their pre-immersion amplitude levels after exposure to cold temperatures. 

It is expected that the PPG waveforms will gradually recover and return to their baseline levels within approximately 10 minutes or so. This recovery time can vary depending on individual factors and the severity of the condition. A longer duration for the waveforms to return to pre-immersion levels may indicate the presence of a disease condition related to Raynaud’s Phenomenon.

Systolic blood pressure measurements can provide further insights into the diagnosis. In cases of secondary Raynaud’s, a decrease in systolic blood pressure compared to primary Raynaud’s is typically observed. This difference in blood pressure readings can help distinguish between primary and secondary forms of the condition.

To summarize, the expected results of a Raynaud’s Syndrome test include color changes in the affected area, gradual recovery of the PPG waveforms to their baseline levels within approximately 10 minutes, and potential variations in systolic blood pressure readings between primary and secondary Raynaud’s cases. These observations serve as important indicators for diagnosing and assessing the condition.

Selected Literature

Wigley FM. Clinical practice. Raynaud’s Phenomenon. N Engl J Med. 2002;347(13):1001-1008.

Assessment of upper extremity arterial occlusive disease, Steven R. Talbot, in “Introduction to Vascular Ultrasonography”, Ed. Pellerito and Polak, Elsevier Health Sciences, 2012, Ch 15, pp 262-280

Herrick AL. Pathogenesis of Raynaud’s phenomenon. Rheumatology (Oxford). 2005 May;44(5):587-96

Three-Grade Classification of Photoplethysmography for Evaluating the Effects of Treatment in Raynaud Phenomenon, Shin-Seok Yang et al., Angiology 64(8) 609-613, 2012

Multifinger photoplethysmography and digital blood pressure measurement in patients with Raynaud’s phenomenon of the hand, J H Tordoir, L B Haeck, H Winterkamp, W Dekkers, J Vasc Surg, 1986 Mar;3(3):456-61.

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