This June 29, 2016 note was posted by Patricia Boyer, MS, MLS, Program Director, Zablocki VAMC School of Medical Technology to the American Society for Clinical Laboratory Science educators bulletin board:
I am working on my hemostasis curriculum, and I was wondering how many instructors teach coagulation using the multicomponent complexes–specifically the tenase and prothrombinase complexes concepts. This is my second year teaching the course, and previous versions of the course have never used these “newer” ways of explaining coagulation. I think that it is great for students to understand that the cascade as we know and use it in the laboratory is not really how things work physiologically, but I am afraid of presenting these complexes in case they muddy the waters of an already confusing topic. I teach in a program where we condense the preclinical courses into a short timeframe so that the students have all the didactic and student laboratory knowledge prior to starting their clinical rotations at the hospitals. So the coagulation course is intense. Anyone have specific pros and cons for me regarding this topic?
Here is George’s response: Hi, Patricia. Given your schedule, I recommend that for your undergraduates, cover Broze’s 1992 cascade model carefully, placing emphasis on the two main complexes, tenase and prothrombinase, or three, if you count the “extrinsic” complex, tissue factor and VIIa. The cascade model is what we still use to define our clot-based assays, PT, PTT, thrombin time, mixing studies, and factor assays, though in some ways it is obsolete.
The cell-based model, developed on the basis of several elegant experiments in the 1990s and 2000s by Duke’s Maureen Hoffman, MD and North Carolina’s Dougald Monroe, MD, is closer to the physiologic truth and it answers some questions that the cascade model leaves open, however it hasn’t been applied to our clinical testing methods. I’d save it for a special topic at the end of your course or for a graduate course. If you have limited time to cover coagulation, the cascade model with its control mechanisms and fibrinolysis is complex enough for your students to work on at an introductory level, and the cell-based model will help satisfy their curiosity about the physiology after they’ve gained a level of understanding.
Of course, George invites alternative recommendations, please append your comment to this entry.
In subsequent correspondence, Prof. Boyer asks whether questions about the cell-based mechanism may appear on the ASCP Board of Certification generalist examination. George forwarded the question to the a BOC official for clarification. If you have an answer to this question, please post your comment.
George also used this opportunity to promote our audio PowerPoint educational units, which are available for undergraduate, graduate, and continuing education.