Page 44 - Virtual Vascular Vol 10

Cold Stimulation Test

Laboratory tests included a raised C-reactive protein (CRP), positive anti-double

stranded DNA antibodies, positive cardiolipin IgG levels, and positive anti-Ro and
Anti-La antibodies.

Anti-double stranded DNA (Anti-dsDNA) antibodies are a group of anti-nuclear
antibodies (ANA) that are are highly diagnostic of systemic lupus erythematosus
(SLE) and are implicated in the pathogenesis of lupus nephritis. Anti-cardiolipin

antibodies are positive in patients with antiphospholipid syndrome, livedoid
vasculitis, Behçet's syndrome, idiopathic spontaneous abortion, and systemic lupus
erythematosus. Autoantibodies directed against Ro/SSA and La/SSB autoantigens

are common in patients with Sjögren's syndrome and systemic lupus
erythematosus, and other autoimmune diseases.

ECHOcardiogram and Holter tape investigations were negative, ruling out proximal
emboli source from the heart.

We further perform a cold stimulation test, which is designed to trigger and
simulate Raynauld’s symptoms: i.e. pallor on exposure to cold with
vasoconstriction and rubor or rewarming due to vasodilatation. The waveform and

pressure of each finger are measured by photophlethysmography (PPG), using
infrared signals to monitor blood flow before and after the cold challenge.

The PPG probe is fixed onto a fleshy part of the finger whilst a pressure cuff is
wrapped around the base of the finger. The principle is similar to the measurement
of ankle-brachial pressure index. The cuff is inflated until a wavefore is no longer

detected, and gradually deflated. The pressure at which the signal reappears is the
digital pressure. Small pneumatic cuffs are used to determine finger perfusion using photoplethysmography
sensors before and after immersion in cold water. The test can be used to determine vasos-

With this patient suffering from ischaemia on her right ring finger, the PPG pastic diseases.
waveform is notably diminished compared to the left.

The process is repeated with her hands immersed in ice-cold water for 2 minutes.
In this case, the right ring finger did not have a signal after 30 minutes, indicating
profound vasoconstriction of the digital artery. As he finger rewarmed, the signal

returned.
A complete version of the COLD STIMULATION TEST

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