Acute Disseminated Intravascular Coagulation is a serious physiological condition which, if left untreated, can lead to hemorrhage and ultimately death. Learn how to recognize potential signs and provide the proper care when necessary.
Case Study
Critical care transport has been arranged for a 28 year-old male admitted to the four-bed ICU of a local hospital three days ago with weakness and hypotension. Four days prior, the patient reported sustaining a bite while hiking in the woods. A large hematoma exists on his left arm. He has no prior medical history, no drug allergies and takes no medications.
Upon arrival of the transport team, the patient is awake and alert in moderate respiratory distress. He is oozing blood from both vascular access sites, his nose, and his urinary catheter. His skin is cool and mildly jaundiced. Vital signs include a heart rate of 110 beats per minute and regular blood pressure of 92/44, slightly labored respiratory rate of 22 breaths per minute, and a pulse oximetry reading of 91 percent. He has received 2 liters of IV crystalloid, 1 unit of type-specific packed red blood cells (PRBC), and is on dopamine at 5 mcg/kg/min.
Laboratory studies drawn an hour ago were abnormal for a hematocrit of 35 percent, platelet count of 70,000, prothrombin time (PT) of 28 seconds, partial thromboplastin time (PTT) of 71 seconds, an international normalized ratio (INR) of 2.4, fibrinogen of 92 mg/dL and D-Dimer of 3.1 micrograms/mL. Other pertinent results include a blood urea nitrogen (BUN) of 38 mg/dL, creatinine of 0.9 mg/dL and anion gap of 18 mEq/ L.
Interpretation of Laboratory Studies
The BUN/creatinine ratio is elevated, suggesting the possibility of dehydration or acute renal failure. An elevated anion gap in this instance is possibly suggestive of a metabolic acidosis. Thrombocytopenia, low fibrinogen (a protein produced in the liver to help with blood coagulation), and increased bleeding times (PT/PTT) suggest coagulapathy. The D-Dimer level is increased, suggesting an increase in the products of coagulation.
Pathophysiology
Acute Disseminated Intravascular Coagulation (DIC)
Also known as “consumptive coagulopathy,” DIC is a syndrome in which the coagulation cascade is activated to the point in which normal mechanisms of clotting are exhausted, which in turn produces unchecked hemorrhage.
Typically, hemostasis is maintained by maintaining a balance between clot formation (i.e. coagulation) and breakdown (i.e. fibrinolysis). Thrombin is produced through the activation of the coagulation cascade. Thrombin converts fibrinogen to fibrin (the final product of clotting). Fibrinolysis is the breakdown of fibrinogen and fibrin. In the presence of thrombin, a substance called plasmin is generated, breaking down formed clots. Fibrin degradation products (FDPs) or fibrin split products (FSPs) are produced as a result. Thrombin plays a key role in hemostasis, in both coagulation and fibrinolysis.1
Secondary to various etiologies, a massive activation of the coagulation cascade can occur and results in a marked increase in thrombin production. Excess circulating thrombin results in multiple clots and tissue ischemia. Platelet aggregation happens at the sites of these clots and tissue ischemia occurs. Impaired organ perfusion and end-organ damage results from this impaired microcirculation. Consumption of platelets, fibrinogen, prothrombin, and factors V and VIII (involved in the coagulation cascade) in the presence of unchecked coagulation results in bleeding.2 The formation of increased amounts of FDPs contribute to excessive bleeding secondary to its anticoagulant properties. In addition to its role in fibrinolysis, excess plasmin activates the complement and kinin systems which affect vascular tone and permeability.3
Etiology
Potential inciting factors, which create the same common pathway of excess coagulation, tissue ischemia, organ damage, and hemorrhage include, but are not limited to:
• Trauma / burns
• Sepsis
• Shock
• Rhabdomyolysis
• Malignancy
• Obstetrical complications (e.g., Amniotic Fluid Embolus: see last month’s column)
• Envenomations from rattle snakes (specifically coral snakes and pit vipers) and poisonous spiders.
Of particular interest to the previously described case is envenomation. Some venoms contain substances that affect coagulation. For example, a phenomenon reported in Australian literature known as venom-induced consumptive coagulapthy (VICC) results from the secretion of venom containing a potent procoagulant toxin. When mammals are exposed to the toxin, the coagulation cascade is activated.4 While quite rare, initial indications possibly suggest that the young man in the case is suffering from an acute consumptive coagulopathy secondary to envenomation. Tanos et al. suggest that clotting factor consumption occurs quite rapidly following envenomation.5
Diagnosis of Acute DIC
Clinical diagnosis is typically made based upon a history of present illness and laboratory data. Severe thrombocytopenia (platelet count less than 100,000) accompanied by the following abnormal coagulation studies confirm the diagnosis:6
• Increased fibrinolysis, as evidenced by an increase in D-Dimer value or FSPs.
• Decreased fibrinogen levels
• Prolonged bleeding times (i.e., elevated PT and PTT)
Clinical Manifestations
Signs and symptoms of acute DIC result from bleeding and ischemia to affected organs. Bleeding causes oozing of blood from various orifices, ecchymosis, and petichiae. Hypoperfusion and shock result from hemorrhage and changes in vascular tone. Acute renal failure occurs as a result of shock and hypoperfusion as well as ischemia. Skin may be jaundiced as a result of hepatic dysfunction and hemolysis.7 Pulmonary symptoms such as dyspnea and hemoptysis can occur from sepsis and pulmonary hemorrhage. Pulmonary emboli are possible as a result of hypercoagulation. Central nervous system dysfunction occurs as a result of coagulation, hemorrhage, and shock, and is manifested by stroke, coma, and focal neurologic deficits.8
Management Goals
Management goals for air medical transport providers caring for a patient in Acute DIC include:
• Correction of underlying disease process
• Airway and hemodynamic management
• Blood product administration with the goals of:
o Correcting severe thrombocytopenia (<20,000)9
o Hemorrhage management
o Coagulation factor replacement
• Mitigation of hypercoagulation
Without question, maintenance of vital functions is paramount. Airway management, when indicated, is imperative. Keys to hemodynamic management include hemorrhage control, crystalloid infusion, and administration of packed red blood cells (PRBCs).
Blood products are administered to address specific coagulation disorders. Fresh frozen plasma and cryoprecipitate are used to replace certain key coagulation factors and fibrinogen, respectively.10 Interruption of hypercoagulation can be accomplished with the use of anticoagulants such as heparin, although its mechanism is not effective in envenomations.11
Conclusion
Acute DIC, if left undiagnosed or untreated, has a considerably high mortality rate. Knowledge of pathophysiology, laboratory interpretation, and management priorities is an extremely important skill set for the air medical transport provider.
References
1. Leung, LK. “Pathogenesis and Etiology of Disseminated Intravascular Coagulation.” UpToDate Online, licensed to the University of Michigan. Accessed 1 April 2009 <http://www.uptodate.com>.
2. Ibid.
3. Parillo, JE and RP Dellinger. Critical Care Medicine: Principles of Diagnosis and Management in the Adult 3rd ed. Philadephia: Mosby Elsevier, 2008: 1644-1646.
4. Tanos, PP, GK Isbister, DG Lalloo, CMJ Kirkpatrick and SB Duffull. “A Model for Venom-Induced Consumptive Coagulapthy in Snake Bite.” Toxicon 52 (2008): 769-780.
5. Ibid.
6. Leung, LK. “Clinical Features, Diagnosis and Treatment of Disseminated Intravascular Coagulation in Adults.” UpToDate Online, licensed to the University of Michigan. Accessed 1 April 2009 <http://www.uptodate.com>.
7. Ibid.
8. Ibid.
9. Ibid.
10. Parillo, JE and RP Dellinger.
11. Leung, LK. “Pathogenesis and Etiology of Disseminated Intravascular Coagulation.”
