Thrombotic Thrombocytopenic Purpura

Thrombotic thrombocytopenic purpura (TTP) is a thrombotic microangiopathy characterized by severe ADAMTS13 deficiency and formation of platelet-rich microvascular thrombi. The name holds the paradox that makes this disease so easy to mishandle. The patient has very few platelets and may be bruising, yet the danger is clotting, not bleeding. Platelets are low because they are being used up in thousands of tiny clots in small vessels. Hold on to that picture, because almost every nursing decision follows from it. A brain with blocked small vessels produces confusion or stroke. A heart with blocked small vessels leaks troponin, sometimes silently. Red cells forced past those clots break apart, which produces the anaemia and the haemolysis markers. Adding more platelets to this process may feed it, which is why the usual reflex to transfuse a very low platelet count is the wrong reflex here. Canada has a particular stake in this disease. The Canadian Apheresis Study Group ran the 1991 randomized trial of 102 patients showing that plasma exchange was more effective than plasma infusion, and that trial shaped the standard of...