Assessing Coagulation
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Introduction
Normally, blood clots in response to vascular damage to form a local seal. The damage
is repaired and the clot lysed to restore vascular patency. The original cascade or
waterfall theories proposed in the 1960s by MacFarlane and Davie were enthusiastically
embraced. The mechanisms involved were artificially divided into vasoconstriction,
platelet adhesion and aggregation, fibrin formation and stabilisation and fibrinolysis.
These subdivisions were then measured "independently" by various bedside and
laboratory tests, allowing us to pinpoint a specific deficiency in the system. However all
the processes are intimately related and are initiated simultaneously, so although
presented as a step wise "cascade" it must be remembered that an explosion is
occurring. A firm grasp of the normal physiology and insight into the techniques used in
evaluation helps in understanding why we are misled by routine testing.
Web page author: lara@anaesthetist.com