Acute Traumatic Coagulopathy vs. Disseminated Intravascular Coagulation
By Amy Newfield, CVT, VTS (ECC), Technician CE Coordinator, VETgirl.
In this VETgirl online veterinary continuing education blog, Amy Newfield, CVT, VTS (ECC) reviews acute traumatic coagulopathy (ATC) vs. Disseminated Intravascular Coagulation (DIC) in veterinary medicine. Both ATC and DIC are life-threatening coagulation disorders. While veterinary medicine is familiar with DIC it is less familiar with ATC. Let’s break down the difference between the two.
Acute Traumatic Coagulpathy (ATC)
Let’s start with ATC. As the name suggests an acute traumatic event is the Anticoagulation is the primary finding with ACT. In a study that was done in 2016 and published in the Journal of Veterinary Emergency Critical Care, it found that ACT occurred rarely in patients that experienced blunt trauma, affecting roughly 11% of the pets that presented to the hospital. ACT starts with hemorrhagic shock from blood loss. The blood loss that the patient experiences is acute and usually from a traumatic event. Regardless of what sets up the patient for ACT, it has to be an ablcute cause. ACT occurs very quickly after the inciting incident has occurred. This appears to be one of the key differences between ACT and DIC. DIC may take place 24 to 72 hours after the inciting cause. ACT occurs within hours. ACT affects the intrinsic pathway of the coagulation system. There are six key actors that are may predispose a patient to developing ACT: tissue injury, hypoperfusion, systemic inflammation, metabolic acidosis, hypothermia, and hemodilution. The main three causes are considered hypoperfusion, metabolic acidosis, and hypothermia which are sometimes referred to as the “triad of death.”
Disseminated Intravascular Coagulation (DIC)
Unlike ACT, there are a myriad of risk factors that could potentiate DIC in a patient. Anything that causes a major disruption in the intravascular system has the potential to cause DIC in a patient. This includes sepsis, infectious diseases, organ failure, fungal infections, heatstroke, pancreatitis, etc. It is generally associated with sepsis or systemic inflammatory response syndrome. There is not a clear cut path for the pathophysiology of DIC. Ultimately, the initial insult played the role in how that particular DIC in that patient started. For example, in the case of sepsis, bacteria causes endothelial injury which could inhibit thrombomodulin or cause a hypercytokinemia, which could then inhibit either the extrinsic pathway of the coagulation cascade leading to DIC. No matter the pathophysiology DIC eventually occurs because fibrin is deposited into the microvascular circulation, which results in a decrease or cessation of blood flow OR it occurs from a consumption of platelets and clotting factors. Microthrombi form in the microvascular circulation and they will contribute to the continued consumption of clotting factors in platelets. Because there is an acceleration of microthrombi forming, the patient can experience periods of hyper- and hypocoagulability. Platelet consumption or platelet exhaustion can contribute to a thrombocytopenia. A thrombocytopenia may also occur simply because platelets are entrapped in clots in the microvascular system.
Treatment for coagulopathies in veterinary medicine
With a patient experiencing ACT. the most important treatment is to control any hemorrhage. This may be either internal or external. Compressing or using tourniquets may be necessary. If bleeding is uncontrolled then surgery may be indicated to suture off or cauterize bleeding that is uncontrolled other ways. Because ACT occurs because of hemodilution, it has been suggested that providing large quantities of crystalloids may be contraindicated. Even administering blood will interfere with the body’s coagulation cascade. It is known that synthetic colloids cause platelet dysfunction, a decrease in von Willibrand factor in factor VIII.
The US Military has studied ACT and has settled on a protocol using less fluid resuscitation prior to the hospital and have shown it results in less hemorrhage and less acidemia. They also allow for permissive hypotension and aggressive patient rewarming. They also found that if they used a one-to-one ratio of RBC, FFP and platelets, they reduced the incidence of post-traumatic multi-organ failure. Blood pressure should be maintained above the mean arterial pressure of 60 mmHg. If it is below that organ failure will occur. There is obviously a fine line between resuscitation to increase blood pressure and giving too much where it now becomes detrimental to a patient with ACT.
Antifibrinolytics should be considered like aminocaproic acid and tranexamic acid. Ideally, they should be given as early on as possible. Certainly, caring for the trauma patient as a trauma patient is important as well. Pain medications, oxygen therapy, ECG monitoring are all important as well.
DIC is treated very similarly to ACT. Platelet rich plasma, fresh frozen plasma, and cryoprecipitate can all be given to help combat DIC. Most commonly in veterinary medicine fresh frozen plasma is provided. Platelet rich plasma and cryoprecipitate tend to be difficult to obtain and are not usually readily available in most hospitals. Both aminocaproic acid and tranexamic acid can be used as antifibrinolytic to decrease bleeding. There has been much debate about using heparin in the hypercoagulable state. There really is not a lot of evidence supporting it being a successful treatment. There is such a fine line between a state of hypercoagulability and hypo. Because there is a certain amount of ischemia that occurs in patients that have DIC, it is important to watch for signs and symptoms of pulmonary thromboembolism. Micro clots are being formed in the microvascular circulation and can certainly enter the primary circulation causing a devastating syndrome. In patients that start experiencing respiratory distress, oxygen supplementation needs to be provided.
Certainly more veterinary-related studies and data will help to drive the treatment of these very two different disorders. The discussion of how ATC presents in veterinary medicine is still relatively new. Understanding the differences between the two disorders will allow us to treat our patients appropriately.