Invented by Stephen Hales in the eighteenth century, a hemostat, also called a hemostatic clamp is a surgical tool which resembles a pair of needle nosed pliers with a locking clamp. The hemostat characteristically has long handles and small clamping pliers that can be held in place by the locking mechanism. The locking mechanism is typically a series of interlocking teeth, a few on each handle, that allow the user to adjust the clamping tension of the pliers. A set of hemostats comes in several different sizes and types, for example, Kelly, Crile, and Halsted; and any given surgery may require the use of a number of hemostats.
A hemostat is commonly used in both surgery and emergency medicine to control bleeding, especially from a torn blood vessel, until the bleeding can be repaired by sutures or other surgical techniques. The process of halting bleeding is called hemostasis. Hemostats may also be used during surgery to hold open the incision.
Hemostats are part of the first aid kit carried by combat lifesavers and paramedics.
Another "hemostat" has been used in the surgical field. The microfibrillar collagen hemostat (MCH) is a topical agent composed of resorbable microfibrillar collagen. It attracts platelets and allows for the formation of a blood clot when it comes into contact with blood. Unlike the hemostatic clamp, no mechanical action is involved. The surgeon presses the MCH against a bleeding site and the collagen attracts and helps with the clotting process to eventually stop bleeding.
The practical application for MCH is different from that of the hemostatic clamp. It is not possible, for example, to stop a severed artery from gushing blood by using a patch of MCH and wait for the clotting process. The blood vessel must be mechanically clamped and repaired.
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