National Registry Paramedic Exam: Hematological Emergencies

Hematological emergencies can fall into 1 of 2 categories: hemolytic disorders and hemostatic disorders.

In hemolytic disorders, blood cells break down or fail to function properly, and transport of O2 is impaired.

Hemostatic disorders refer to any problem related to abnormal clotting, which could mean both prolonged bleeding and clots forming in places they are not needed. This section discusses the physiology of the blood and the clotting cascade. It will focus on problems related to the red blood cells and clotting; issues of the white blood cells and the immune system were covered in the section on immunological emergencies. Continuous movement of blood throughout the body is essential to the health of the body.

What does blood do?

- Transports O2 from the lungs to all tissues.
- Carries nutrients dissolved in the plasma for use in cells.
- Carries wastes such as CO2 and urea away from cells to the lungs and kidneys, respectively, for excretion.
- Contains defense mechanisms including antibodies and white blood cells.
- Carries hormones from the endocrine gland in which they are produced to their target organs.

Anatomy and Physiology
Blood is composed of primarily 2 components: the plasma and the formed elements. The plasma is the watery fluid in which the formed elements are carried and makes up about 55% of the circulating volume. The plasma contains dissolved O2, CO2, proteins, hormones, glucose, and electrolytes. The formed elements and information about each follows.

- Red Blood Cells. These cells make up about 44% of the circulating volume. They do not contain a nucleus (except in mononucleosis, mentioned earlier), so they have as much room as possible inside to carry as much hemoglobin as possible. Hemoglobin is the O2-carrying molecule, all of which is found within red blood cells. The hematocrit is the term given to the proportion of the circulating red blood cells in the blood. Hematocrit should be roughly 3 times the value of the hemoglobin number. 

- Normal Hemoglobin: Women: 12–16; Men: 14–18
- Normal Hematocrit: Women: 35–45; Men: 40–50- Platelets. Also called thrombocytes, they are integral in clot formation.

ABO Classification System and Rh factor
The red blood cells have on the exterior surface of the plasma membrane markers called antigens. Antigens cause antibodies to be formed. Here is a way to remember that: ANTIGENS are ANTIbody GENerating. These antigens can have the designation A or B. The cells can have any combination of antigen on their surface. People who have only A antigens are said to have the A blood type; people who have only B antigens have the B blood type; people who have both A and B antigens have the AB blood type; and, finally, people who have neither A nor B antigens on their blood cells have the O blood type.
If a person has type A blood, then he or she has anti-B antibodies, which means that if the patient’s blood comes in contact with type B blood, antibodies will attack it like a foreign invader. People with type AB blood do not have antibodies to either anti-A or anti-B blood, so they can receive any blood type from a donor. People with type O blood can donate to any other blood type because there are no antigens on the surfaces of their red blood cells for the antibodies of the recipients to attack.

Blood Types and Donors
 

Blood also may contain a 2nd antigen called the Rh factor. This antigen is located on the surface of the red blood cells. People either have the antigen Rh positive (Rh+) or Rh negative (Rh-). The Rh designation is needed as well to ensure full compatibility of the blood donor with the recipient. Here, the Rh- person can donate to either Rh+ or Rh-; however, an Rh+ person can donate only to other Rh+ people.
Determining the Rh factor is of particular importance in pregnant women and the unborn fetus to prevent hemolytic disease of the newborn. If an RH- mother has an Rh+ fetus, the mother’s body may develop antibodies to the Rh+ blood. If at any time the baby’s blood comes in contact with the mother’s blood during gestation, the mother will get sensitized to the Rh+ blood and produce antibodies against it. Those antibodies can cross the placental barrier and attack the baby’s red blood cells as a foreign invader. The baby’s red blood cells would be lysed or broken down, resulting in hemolytic disease, also called hemolytic anemia. This results in an inability to transport O2 in the infant, leading to illness, brain damage, or death of the fetus.

Hemostasis Hemostasis is a highly complex process of stopping bleeding anywhere in the body. The 1st step in this process is localized vasoconstriction, which clamps off a large amount of the blood flow heading to that area. The 2nd step is the action of platelets plugging the hole. The blood is exposed to collagen fibers surrounding the vessel. When platelets come in contact with the collagen, they become activated. Activated platelets become sticky and release other chemicals that begin aggregation of more platelets at the site of the injury. Finally, about a dozen different clotting factors arrive at the area of injury to further seal off the wound. There are 2 pathways: the intrinsic pathway initiated by damage to the vessel itself, and the extrinsic pathway activated when blood comes in contact with tissues outside the lumen of the vessel.
Coagulopathies are any of a variety of problems that interfere with the body’s ability to form a clot. They can lead to heavy or prolonged bleeding, even from a wound that should not otherwise be life threatening.

Hemolytic Emergencies

Sickle Cell Crisis
Sickle cell disease is an inherited disorder that affects the shape of red blood cells. The mutation is on the gene that codes for adult-type hemoglobin, designated HbA. The disease has to be inherited from both parents to exhibit symptoms of the disease; therefore, both parents must have at least 1 copy of the gene (be a carrier but not express symptoms of the disease) to pass it on. In this disease, the malformed hemoglobin causes the cells to change shape from a smooth biconcave disk to a curved shape resembling a gardener’s sickle. These cells are no longer capable of transporting O2, and their shape now causes them to get stuck trying to transit the smallest capillaries, leading to a clot in the area. If enough capillaries in that area get clogged with sickled cells and clots form, necrosis and tissue death could begin in that area.


Figure: Sickle-Shaped and Normal Red Blood Cells

Sickle cell crisis can occur in any of a variety of ways:

- Aplastic Crisis. Suspension of the production of red blood cells leads to the patient becoming weak, pale, and short of breath.
- Hemolytic Crisis. Excessive red blood cell destruction in the liver leads to an overproduction of bilirubin, which is characterized by a jaundice in a patient.
- Vaso-occlusive Crisis. This most common complication of sickle cell disease, it occurs when capillaries clot off and tissue starts to become ischemic. This presents as often intractable pain in the area of the clotted capillaries, which typically lasts about a week.
- Splenic Sequestration Crisis. Red blood cells get trapped in the spleen, which results in painful enlargement of the spleen. The organ can swell to the point it ruptures. Patients present with a sudden onset of LUQ pain, weakness, pallor, tachycardia, and shortness of breath with tachypnea.
- Acute Chest Syndrome. This is a specific type of vaso-occlusive crisis associated with pneumonia. In addition to shortness of breath and a productive cough from pneumonia, the patient also may have severe chest pain.

Patients in sickle cell crisis often are in serious condition. The patient may be in severe systemic pain from areas being clotted off now getting hypoxic. He or she may be short of breath from pneumonia, systemic hypoxia, or clots forming in the lungs or any combination of all 3. Patients also will complain of pain in the joints.
It is important for these patients to administer high-flow O2 to help prevent further destruction of red blood cells. In this case, the SpO2 reading is not helpful because it is impossible to know how many normal-shaped red blood cells the patient has. Have the patient remain as comfortable as possible while initiating an intravenous line and running fluids to help flush out the sickled cells and prevent further dehydration. Keep the patient warm because that may help prevent further sickling of the cells, whereas cold can accelerate it. Provide analgesia as needed, beginning with 1 mcg/kg fentanyl. Patients may have built-in tolerance to pain medications, so doses may need to be repeated.

Anemia
Anemia is a deficiency in red blood cells or hemoglobin. Iron deficiency anemia is the most common and is most frequently associated with some other disease process. It can be from slow, long-term blood loss, a decrease in overall production of cells, or an increase in red blood cell recycling in the liver or spleen. Red blood cells also can be destroyed in an autoimmune disorder.
Patients with anemia will complain of feeling weak, tired, and possibly short of breath, especially with even minimal exertion. They may appear pale in color. Patients also may have chest pain, depending on the few red blood cells they have and the ongoing myocardial O2 demand. Treat these patients with high-flow O2, and if it is not possible to completely rule out ACS concurrently with the anemia, treat the patient as if he or she is having an ischemic cardiac event. Closely monitor the vital signs and ECG throughout transport and treat other symptoms as they arise.

Polycythemia
Polycythemia is a condition where the patient has an excess of red blood cells. The overproduction could be caused by external conditions of hypoxia, such as what might happen at high altitudes. Internal conditions of hypoxia, such as in COPD, also could lead to an increased production of red blood cells. Another possible reason is that the patient is overproducing or is “doping” with erythropoietin (EPO)—the hormone produced in the kidneys that tells the bone marrow to make more red blood cells—to gain a competitive advantage, particularly in endurance sports. The overall result is a thickening of the blood. Because of the thicker blood, several problems can develop. The patient becomes more prone to abnormal clotting, which puts them at risk for strokes, MI, and DVT, and PE.
Essentially, the patient the paramedic will treat is not the one who complains of polycythemia, but rather the CVA or MI. There is no prehospital treatment directly targeting the condition, so proper treatment of the patient’s other symptoms, such as chest pain and headache, would be most appropriate for the patient. Short of having red blood cell count paperwork along with the patient, which may be available at a skilled nursing facility, no particular symptom would indicate that a patient has this condition.

Disseminated Intravascular Coagulopathy
Disseminated intravascular coagulopathy (DIC) is a life-threatening event that involves systemic activation of the clotting cascade in all areas of the body, not just those with blood vessel damage. It does not typically occur as its own distinct condition but rather is a complicating factor of other disease processes. DIC may occur as a result of massive trauma accompanied by massive blood loss, severe late stage sepsis, and obstetrical hemorrhage. In the first stage of the condition, fibrin and thrombin in the blood cause platelets to begin to get sticky and form clots throughout the body. Now that some, if not all, of the body’s thrombin and fibrin have been used up in what amounts to pointless clots, severe, uncontrollable hemorrhage worsens because of the lack of clotting factors.
Treatment for these patients begins with aggressive fluid therapy and rapid transport to the most appropriate medical facility, in many cases, a trauma center. Early administration of O2 and treatment for shock is essential in these patients. Monitor the ECG and treat any dysrhythmias.

Hemophilia
Hemophilia is a genetic disorder that results in poor or no clotting. It is far more common in men than in women because it is X-linked. Any bleeding in a hemophiliac should be treated as severe until proven otherwise because even small lacerations or abrasions can bleed them into a life-threatening situation. Falls and other accidents can be catastrophic for a person with hemophilia. Spontaneous intracranial hemorrhage is a relatively common problem and often leads to death.
Assessment of the hemophiliac is related to the symptoms found and centers on working to control bleeding. Bleeding will not likely stop until a hemostatic agent is introduced or the patient receives clotting factors at the hospital, so the paramedic should be dedicated to the manual control of external hemorrhage. Missing an intravenous line on these patients could mean that a crew member is dedicated to holding pressure on the failed intravenous site, so use every precaution before attempting a line. Even an intramuscular or subcutaneous injection can have unintended consequences of bleeding. Treatment is otherwise symptomatic.