This week I saw a lady who has already lost one leg due to ischemia. Now her right foot has been “turning red” (her words) and she’s started sleeping in a chair due to foot pain. I showed her the way her foot changes color from dependency (photo 1) to elevation (photo 2). This color change takes only a few seconds.

Photo 1 is classic “ischemic rubor.” I thought I’d review exactly WHY dependency causes redness in some ischemic limbs and discovered that there’s debate about the mechanism of ischemic rubor. I think I found about three different explanations. Most of the literature focuses on the importance of recognizing this physical finding and its predictive value with regard to future limb loss, but I remain curious. I thought I’d let you guys explain the mechanism of ischemic rubor to me!