Laboratory Assessment of Raynaud’s Phenomenon

This chapter the reviews current and potential non-invasive laboratory (research) methods to assess the vascular dysfunction associated with Raynaud’s phenomenon (RP). Discussion encompasses prerequisites for imaging and measurement including the benefit of dynamic challenge in addition to baseline measurements. Techniques examined include laser Doppler modalities, infrared thermography, Doppler ultrasound, finger systolic pressure measurement and plethysmography. Each technique is described in terms of its theory, followed by a review of physiological and treatment studies in patients with RP. These techniques mainly assess blood flow (directly or indirectly) and oxygenation. These techniques are able to differentiate between patients with primary or secondary RP. Evidence suggests they are suitable techniques to monitor disease severity and response to treatment, although some require further validation. A more centralised approach to perfusion-based protocol design and analysis has enabled validation of certain methods paving the way for multicentre phase II clinical trials. Several new techniques offer further options for better differentiation between patient groups (recently with a focus on early secondary RP), ambulatory monitoring and measurement of other functional measures such as oxidative stress.