Pathophysiological Mechanisms
Thrombocytopenia may arise because of decreased
production or increased destruction (immune
or nonimmune) of platelets, as well as from
sequestration in the spleen. Among patients who
are admitted to an ICU, the condition occurs in
about 20% of medical patients and a third of surgical
patients. The cause of this condition is often
multifactorial. Patients with thrombocytopenia
tend to be sicker, with higher illness-severity
scores, than those who are admitted with normal
platelet counts.29 Table 3 lists the differential diagnoses
of thrombocytopenia in the critical care
setting. Given the long list, it is important to identify
patients in whom thrombocytopenia requires
specific and urgent action (e.g., heparin-induced
thrombocytopenia and thrombotic thrombocyto