Disseminated intravascular coagulation in cats Flashcards
Give a definition of DIC
DIC is a consequence of severe infection (especially bacterial sepsis), inflammation, trauma or neoplasia and ultimately causes systemic microvascular thrombosis and consequent multi-organ failure (often leading to the death of the patient)
What is the main pathomechanism for the development of DIC
The main pathomechanism for the development of DIC is unrestricted and excessive thrombin generation on widespread cellular surfaces
- this is likely due to exposure of large amounts of tissue factor (=tissue thromboplastin) in the extravascular space and/or circulating cells and “micro-particles” shed mostly by activated platelets
- these micro-particles can spread throughout the circulation, which allows the process to propagate systemically
The process then follows the usual exttrinsic coagulation pathway culminating in the generation of fibrin (and hence thrombi)
- other compounds such as snake venom or cancer proteases can directly activate coagulation factors
Concurrently, specific inhibitory factors such as anti-thrombin, active protein C and tissue factor pathway inhibitor are consumed during the process, which results in further progression of DIC
What is an important prognosis factor for DIC
Fibrinolysis is concurrently activated (although this process becomes impaired as DIC progresses)
It is the increased concentrations of fibrin-split products that can be detected in DIC cases
The absence of elevations of these factors has a high negative predictive value for DIC
What are the 3 different stages of DIC
DIC can be conceptually divided into different stages:
- “Non-overt” DIC where coagulation has been activated, however thrombin generation is constrained by inhibitors
- "Controlled overt" DIC which reflects an uncompensated hemostatic system, where inhibitors have become overwhelmed and thrombosis begins to cause organ dysfunction
- however the process is considered temporary and can be subverted by removal of the inciting cause
- "Uncontrolled overt" DIC, in which reversal of the underlying cause does not result in resolution of the process
What is the main problem in DIC diagnosis
The clinical signs of DIC and the detection of coagulation abnormalities on routine tests such as PT and aPTT are only really indicative of advanced stage DIC
- it is likely that the window of opportunity for therapeutic intervention has most likely passed once these parameters become abnormal
Explain why is it more difficult to diagnose DIC in cats than in dogs
The tests often used to detect DIC in dogs (low anti-thrombin activity and/or incresaed D-dimer concentration) may not be as reliable for detecting DIC in cats
Moreover, unlike dogs, cats with DIC might not be thrombocytopenic
Even RBC fragmentation is so non-specific in cats that it is not a reliable indicator of DIC
What exam could help detect early DIC in future days
Thromboelastography may provide a sensitive means of detecting early hyper-coagulability in critical care patients
What are the most common underlying disorders causing DIC
According to one study, the most common underlying disorders were lymphoma, other forms of neoplasia, pancreatitis, and sepsis
