### Instruction:
Given a reference text about the blood hammer phenomenon, tell me the background of the term "blood-hammer".

### Input:
The blood hammer phenomenon is a sudden increase of the upstream blood pressure in a blood vessel (especially artery or arteriole) when the bloodstream is abruptly blocked by vessel obstruction. The term "blood-hammer" was introduced in cerebral hemodynamics by analogy with the hydraulic expression "water hammer", already used in vascular physiology to designate an arterial pulse variety, the "water-hammer pulse". Complete understanding of the relationship between mechanical parameters in vascular occlusions is a critical issue, which can play an important role in the future diagnosis, understanding and treatment of vascular diseases.

### Response:
The term "blood-hammer" was introduced by analogy with the hydraulic expression "water hammer" that was already used in vascular physiology.