Introduction
Hematology is the study of blood and its components, including red blood cells (RBCs), white blood cells (WBCs), platelets, and proteins involved in clotting and bleeding processes. It also includes the hematopoietic system, which consists of the organs and tissues responsible for producing blood cells.
Hematologic emergencies involve disorders affecting the blood, excluding severe blood loss from trauma. True hematologic emergencies are relatively uncommon in EMS and are often related to chronic medical conditions. A hematologic disorder refers to any disease or abnormality involving the blood or blood-forming tissues.
Although EMS treatment options are usually limited in the field, understanding these disorders helps providers deliver better assessments, supportive care, and patient advocacy.
Anatomy and Physiology Review
Blood
Blood is a connective tissue suspended in plasma and made up of cells and cellular fragments. It accounts for approximately 5–6 liters, or about 8% of total body weight, in the average adult.
Major Functions of Blood
- Delivers oxygen and nutrients to tissues
- Removes carbon dioxide and waste products
- Transports hormones throughout the body
- Regulates body temperature and pH balance
- Maintains electrolyte balance
- Supports immune defenses through WBC transport
- Forms clots to control bleeding
Plasma
Plasma is the liquid portion of blood and consists mostly of water along with:
- Electrolytes
- Proteins
- Glucose
- Clotting factors
- Solutes
Plasma makes up about half of total blood volume, while the remaining portion consists of formed elements such as RBCs, WBCs, and platelets.
Blood-Forming Organs
Liver
The liver helps produce clotting factors, filters waste from the blood, breaks down old RBCs into bile, and stores blood within its vascular system.
Spleen
The spleen filters old RBCs, assists with WBC production, and stores about one-third of the body’s platelet supply.
Bone Marrow
Bone marrow is a major site of blood cell production, especially RBC formation. Active marrow is commonly found in long bones, the pelvis, skull, and vertebrae.
Red Blood Cells (RBCs)
RBCs, also called erythrocytes, originate from stem cells. Their production is stimulated by erythropoietin, a hormone released by the kidneys.
RBC Lifecycle
- Mature over approximately 5 days
- Circulate for about 120 days
RBC Function
Their main role is oxygen transport through hemoglobin, the iron-containing protein that gives blood its red color.
Gas exchange occurs through the Bohr effect, where oxygen is released and carbon dioxide is absorbed depending on concentration gradients.
White Blood Cells (WBCs)
WBCs are essential components of the immune system. They develop from stem cells and specialize into different cell types designed to defend the body against infection and foreign substances.
Immunity
The immune system protects the body from pathogens and harmful substances.
Types of Immunity
Cellular Immunity
Also called cell-mediated immunity, this process uses cells such as T-cells and macrophages to directly attack pathogens.
Humoral Immunity
This form relies on antibodies (immunoglobulins) that recognize specific antigens and help the immune system “remember” threats.
Autoimmune Disorders
Autoimmune diseases occur when the immune system mistakenly attacks the body’s own tissues.
Examples include:
- Type 1 Diabetes: Targets the pancreas
- Lupus: Affects multiple organs and body systems
Blood Types
RBCs are classified according to surface antigens using the ABO system:
- Type A
- Type B
- Type AB
- Type O
The Rh factor is another antigen marker:
- Rh-positive: Rh antigen present
- Rh-negative: Rh antigen absent
Matching blood types correctly is critical during transfusions to avoid immune reactions.
Hemostasis
Hemostasis is the body’s natural process for stopping bleeding.
Stages of Hemostasis
1. Vascular Spasm
Damaged blood vessels constrict to reduce blood flow.
2. Platelet Plug Formation
Platelets adhere to the injury site and form a temporary seal.
3. Coagulation
Clotting factors activate fibrin formation, strengthening the clot and forming a thrombus.
Assessment Findings
Assessment of hematologic emergencies follows standard patient evaluation principles, but several findings are especially important.
Common Signs and Symptoms
Neurological
- Altered mental status
- Stroke-like symptoms
- Headache
- Visual disturbances
Skin
- Excessive bruising
- Petechiae
- Delayed clotting
- Pallor
Gastrointestinal
- Nosebleeds
- Bleeding gums
- Bloody stool or vomit
- GI bleeding
Musculoskeletal
- Joint stiffness
- Bone pain
- Generalized body pain
Cardiorespiratory
- Dyspnea
- Tachycardia
- Chest pain
- Hemoptysis
- Arrhythmias
Genitourinary
- Hematuria
General Management
Airway, Breathing, Circulation
Management priorities remain focused on:
- Oxygenation
- Ventilation support
- Bleeding control
- Shock management
External bleeding should be treated with direct pressure and bandaging. Internal bleeding may require fluid support according to local protocols.
Medications
EMS interventions are often supportive and may include:
- Analgesics for pain
- Antiemetics
- Oxygen therapy
- IV fluids
Comfort measures and accurate patient assessment are also essential.
Sickle Cell Disease
Sickle cell disease is the most common inherited blood disorder in the United States and occurs more frequently among individuals of African descent.
The disorder causes RBCs to become sickle-shaped instead of round, reducing oxygen-carrying ability and causing chronic anemia.
Sickle cells also have a shorter lifespan than normal RBCs.
Sickle Cell Emergencies
Vaso-Occlusive Crisis
Blocked blood flow causes severe pain, ischemia, and possible organ damage.
Acute Chest Syndrome
Presents similarly to pneumonia with:
- Chest pain
- Fever
- Cough
- Respiratory distress
Acute Splenic Sequestration Syndrome
Common in children. Sickled cells become trapped in the spleen, causing swelling, anemia, and hypovolemia.
Signs include:
- Abdominal pain
- Pallor
- Tachycardia
- Tachypnea
Sickle Cell Management
Treatment focuses on symptom relief and stabilization.
EMS Care Includes
- High-flow oxygen
- IV fluids
- Pain management
- Keeping the patient warm
- Rapid transport
Other Hematologic Disorders
Anemia
Anemia is a reduction in RBCs or hemoglobin, decreasing oxygen delivery.
Common Causes
- Iron deficiency
- GI bleeding
- Heavy menstrual bleeding
- Chronic disease
Leukopenia
Leukopenia is a decreased WBC count, reducing the body’s ability to fight infection.
Common causes include:
- Chemotherapy
- HIV
- Bone marrow disorders
- Autoimmune diseases
Thrombocytopenia
Low platelet levels impair clotting and increase bleeding risk.
Leukemia
Leukemia is a cancer affecting blood-forming tissues and WBC production.
Symptoms
- Weakness
- Dyspnea
- Headache
- Hypotension
- Tachycardia
Patients are often immunocompromised and vulnerable to infection.
Lymphoma
Lymphoma is cancer of the lymphatic system.
Symptoms
- Enlarged lymph nodes
- Night sweats
- Weight loss
- Fatigue
- Pain
EMS care is generally supportive.
Polycythemia
Polycythemia causes excessive RBC production, thickening the blood and increasing clot risk.
Possible complications include:
- Stroke
- Pulmonary embolism
- DVT
- Myocardial infarction
Disseminated Intravascular Coagulation (DIC)
DIC is a severe condition involving widespread abnormal clotting followed by bleeding.
Common causes include:
- Sepsis
- Trauma
- Obstetric emergencies
Mortality is high due to bleeding and poor perfusion.
Hemophilia
Hemophilia is a hereditary clotting disorder causing impaired coagulation.
Types
- Hemophilia A: Factor VIII deficiency
- Hemophilia B: Factor IX deficiency
Patients are at high risk for internal and external bleeding.
Multiple Myeloma
Multiple myeloma is a cancer affecting plasma cells in bone marrow.
Complications may include:
- Anemia
- Infection risk
- Bone lesions
- Platelet abnormalities
EMS care remains primarily supportive.
Blood Transfusion Complications
Blood transfusions may produce several reactions.
Hemolytic Reactions
Occurs when incompatible blood types trigger destruction of RBCs.
Febrile Reactions
Common and usually mild fever-related reactions.
Allergic Reactions
May progress to anaphylaxis due to preservatives or donor proteins.
Transfusion-Related Lung Injury
Can cause pulmonary edema from capillary permeability changes.
Circulatory Overload
Occurs when blood products are infused faster than the patient can tolerate.
Bacterial Infection
Poor blood handling can introduce infection and potentially cause sepsis.
Key Points
- Hematologic emergencies often involve chronic disorders
- Assessment should focus on bleeding, perfusion, oxygenation, and neurologic status
- EMS treatment is usually supportive
- Sickle cell disease is one of the most important hematologic emergencies encountered in prehospital care
- Patients with clotting disorders are at high risk for internal bleeding
- Patients with immune disorders or blood cancers are highly susceptible to infection
Apperture Labs 