An updated concept of coagulation with clinical implications

Resident: Cho

Author(s): Romney et al.

Journal: JADA

Year. Volume (number). Page #’s: 2009. 140. 567-574.

Major topic: Coagulation cascade

Minor topic: PT/INR, PTT

Type of Article: Literature Review

Main Purpose: To describe the flaws of previously proposed coagulation cascade and discuss how a cell-based model better describe the coagulation in vivo.

Overview of method of research: PubMed database was used to do a literature search using the words “coagulation”, “hemostasis”, “bleeding”, “coagulation factors”, “models”, “prothrombin time”, “activated partial thromboplastin time”, “international normalized ratio”, “anticoagulation therapy” and “hemophilia” separately and in combination.

Findings: The coagulation cascade provides a logical application of the clotting reaction in vitro. However, it fails to explain findings in vivo. Ex. Deficiency of FXII results in fewer bleeding tendencies than deficiency of FVIII (the opposite should be true if following the coagulation cascade since FXII is higher in the cascade).

The cell-based model of coagulation is presented in three overlapping phases: initiation, amplification and propagation. This new model explains why FXII deficiencies do not require modifications to dental protocol, FXI may require modification, and FVIII and FIX deficiencies need to be cared for with specific treatments.

PT/INR may be relevant only when patient is taking anticoagulant agents since its calibration is based on patients taking vitamin K antagonists.

Key points/Summary: By understanding the underlying mechanisms of the development of potential bleeding tendencies, providers will be able to render more appropriate and safer dental care.

Assessment of Article: This article did not have much clinical applications to dentistry.