This patient was bitten by a rattlesnake.
Hand edema was present upon arrival at the hospital, and proximal progression of edema was measured at regular intervals. Rattlesnakes are a member of the Crotalinae subfamily of snakes. Crotalid venom has multiple effects on human tissues.
The measurements in this image are being used to follow compartment swelling in the forearm.
See more cases like this on Figure 1.