Quincke's test

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Quincke's test is done to determine whether there is an increase in pulse pressure.
   A bright light is placed against the pad of a finger. Gentle pressure is then applied to the tip of the nail, compressing the capillary bed. The pressure is gradually reduced while one looks for pulsation of the capillary bed. This resembles a neon light flashing on and off.
   Relative darkness is required from optimal testing. This can be accomplished by having a helper shield the test finger with their hands.