Clinical evaluation of a bleeding patient (Proceedings) - Veterinary Healthcare
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Clinical evaluation of a bleeding patient (Proceedings)


CVC IN BALTIMORE PROCEEDINGS


Clinical assessment

An accurate history, thorough physical exam, and certain laboratory tests must be performed in order to properly evaluate a bleeding patient, determine a diagnosis, and define a therapeutic plan.

History

A complete history is critical in beginning a work-up for a hemostatic defect. In veterinary medicine, all pertinent information regarding patient history must be gathered from the owners. Obtaining and assessing a complete and detailed history will help define the nature, severity, and duration of clinical signs and aid in making a correct diagnosis. This attention to detail allows the clinician to establish probability for each possible differential early in the diagnostic process.

Questions should be very clear and thought provoking. Devising a list of questions for owners to review will hopefully help stimulate them to think of some very important, most likely not obvious facts. Does the animal have any previously diagnosed diseases? Is the animal currently on any medication? A list of any prescription or over-the-counter medications should be included as many drugs have potentially harmful or complicating side effects, resulting in a toxic effect on red blood cells, white blood cells, and platelets. Complete vaccination history should not be overlooked as a relationship between recent vaccination and onset of immune-mediated hemolytic anemia (IMHA) has been questioned. The animal's environmental history may suggest potential exposure to toxic or organic substances such as anticoagulant rodenticide poisons or lead. Tick exposure should also be investigated.

It is vital to evaluate the current bleeding episode and characterize the bleed as localized or multifocal. Is this the animal's first bleeding episode, or is there a history of bleeding tendency? These facts may help differentiate between an acquired or hereditary disorder. Specific breeds may suggest specific coagulopathies. Any information the owner may have regarding breed history could provide helpful clues.

Physical exam

A complete physical examination and multiple monitoring procedures may be required to properly assess the patient in a bleeding crisis. Optimal assessment cannot be based on the result of a single parameter, but is based on the results of several physical exam findings and monitored parameters which should always be evaluated in relation to one another.

Certain clinical signs found on physical exam may help determine the origin of the bleeding episode. Small surface bleeds (e.g., petechiation, ecchymosis, epistaxis, hematuria) are usually suggestive of platelet or vascular abnormalities. Larger bleeds or bleeding into body cavities (e.g., hematoma formation, hemarthroses, deep muscle hemorrhage) are suggestive of clotting factor deficiencies. A combination of these clinical signs is not uncommon.

In anemic patients, the development and progression of clinical signs depends on the rapidity of onset, degree, and cause of anemia, as well as the animal's physical activity. Common physical findings are those associated with a decrease in red cell mass: lethargy, weakness, pale mucous membranes, tachycardia, tachypnea, and bounding pulses. The cardiovascular and respiratory system should be carefully evaluated. Assessment of perfusion is based on mucous membrane color, capillary refill time (CRT), heart rate, and pulse rate, strength, and character. In a severe anemic state, a low-grade systolic flow murmur may occur secondary to decreased blood viscosity. Mucous membrane color can be used to monitor the patient's response to therapy or indicate the development of a problem. Prolonged CRT is suggestive of compromised tissue perfusion and shock, but may be difficult to assess in an anemic patient. Weak and rapid pulses suggest severe dehydration and poor perfusion; bounding pulses suggest anemia. Assessment of respiratory rate and effort, as well as careful auscultation, may help differentiate between decreased oxygen carrying capability and possible pulmonary thromboembolism. Monitoring all parameters in unison with one another will lend information regarding bleed severity and potentially life-threatening complications.

Laboratory tests

Although information obtained from the history and specific clinical signs may suggest a diagnosis, certain laboratory tests are necessary for definitive diagnosis. Laboratory tests should be performed ASAP and therapy instituted promptly after test samples are obtained.

Serial hematocrit determinations may help demonstrate progression or stabilization of bleeding, taking into account the body takes a certain amount of time to equilibrate following an acute bleeding episode. Anemia is suggested when one or more of the red cell parameters are below normal for the age, sex and breed of the species concerned. Of these parameters, PCV provides a simple, quick, and accurate means of detecting anemia, and allows classification of the anemia as mild, moderate, or severe. Dehydration and splenic contraction may mask anemia, whereas hemodilution may cause a temporary reduction in red cell parameters. Evaluating both PCV and total plasma protein (TPP) levels may help in differentiating these variables. Dehydration is associated with increases in both PCV and TPP, while PCV elevation alone is seen with splenic contraction . Decreases in both PCV and TPP are associated with hemodilution following acute blood loss or fluid therapy, whereas a reduction in PCV only is usually associated with hemolytic anemias.

Normal platelet count is 150,000-400,000/l. Abnormal bleeding may occur with platelet counts below 40,000/l, although each patient varies and some animals may not exhibit clinical signs associated with bleeding with a platelet count of 2,000/l. The thrombocytopenic patient requires special care (e.g., extra cage padding, avoidance of central vessels for blood collection, extended application of pressure to venipuncture sites). In an animal exhibiting signs of surface bleeding with a normal platelet count, consideration should be given to the function of the platelets.

Certain tests are available to monitor coagulation in patients with suspected coagulopathies. Prothrombin time (PT) measures extrinsic and common clotting pathway activity, whereas activated partial thromboplastin time (aPTT) measures intrinsic and common pathway activity. Prolongation of PT/aPTT will be seen when clotting factors are depleted below 30% of normal. PT and aPTT samples must be collected and processed carefully to avoid potential sample errors. Atraumatic venipuncture and smooth blood flow into collection tubes are necessary to avoid extraneous clotting mechanism activation. Samples should be processed immediately after collection and frozen if being sent to an outside laboratory.

Elevation in FSPs occurs with excessive bleeding and fibrinolysis, and in animals with severe liver dysfunction. Interpreted in conjunction with the PT, aPTT, and platelet count, elevated FSP levels are useful as a diagnostic indicator of DIC.


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Source: CVC IN BALTIMORE PROCEEDINGS,
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