Haematology, oncology and immunology

10 Haematology, oncology and immunology



Haematology: anatomy and physiology


The haematology system consists of the blood and the bone marrow.



Haematopoiesis


Is the production of new blood cells. The bone marrow creates multipotential stem cells (can become any type of blood cell) which become unipotential stem cells (a specific type of blood cell).



image Differentiated into three main types of blood cells:
• Erythrocytes—red blood cells (RBC)

• Leucocytes—white blood cells (WBC)
image Granulocytes—neutrophils, eosinophils, basophils

image Agranulocytes—lymphocytes, monocytes

• Platelets.


Red blood cells (RBC)



image Function only within blood vessels

image Contain haemoglobin, which carries O2 to body tissues and CO2 from body tissues

image Lifespan of 120 days

image Old RBCs are removed from circulation by the spleen

image Normal levels are:
• Male: 4.0–6.2 × 1012/L

• Female: 3.6–5.4 × 1012/L.


White blood cells (WBC)



image Are part of the immune system

image Act mainly outside blood vessels (in the body’s tissues)

image Normal levels are 3.9–12.7 × 109/L

image Granulocytes
• Neutrophils
image Live for 15 hours

image Phagocytic cells (ingest and digest foreign materials)

image Pass through capillary walls into the tissues to the site of infection

image Old neutrophils form the main component of pus

• Eosinophils
image Live for a few days

image Act in response to an allergic reaction

• Basophils
image Can live for 9–18 months

image Secrete histamine in response to immune stimuli, increasing the permeability of blood vessels

image Agranulocytes
• Monocytes
image Phagocytic cells that respond to inflammation

image Become macrophages and promote wound healing by ‘eating’ necrotic tissue

• Lymphocytes
image T-lymphocytes mature in the thymus and are responsible for cell-mediated immunity (direct attack)

image B-lymphocytes (humoral immunity) mature in bone marrow and are responsible for the production of antibodies.


Platelets



image Form plugs to injured vessels, causing clotting

image Lifespan of 10 days

image Normal levels are 150–396 × 109/L.
image

FIGURE 10.1 Clotting pathways


(Lewis S 2007 Medical–surgical nursing. 7th edn. Mosby, St Louis)



Clotting factors









































I Fibrinogen
II Prothrombin
III Thromboplastin (tissue factor)
IV Calcium ions
V Proaccelerin
VI Proconvertin
VII Antihaemophilic factor
VIII Plasma thromboplastin component
IX Stuart-Prower factor
X Plasma thromboplastin antecedent
XI Hageman factor
XII Fibrin stabilising factor


Blood groups


There are 26 discrete blood grouping systems.



image Examples are: ABO, Rh, Kell, Lewis

image ABO and Rh are commonly checked for a transfusion.


ABO system




image



image Type O is the universal donor and type AB is the universal recipient.



Rhesus system (Rh)



image If the antigen is present: Rh-positive, e.g. O+ve

image If the antigen is not present: Rh-negative, e.g. O−ve

image If possible, an Rh−ve person should only receive Rh−ve blood.



image An Rh−ve person can develop antigens if transfused with Rh+ve, and become Rh+ve.



Haematology disorders



Anaemia


Decreased circulating red blood cells (RBC).



Types



image Aplastic
• Stem cells in the bone marrow are destroyed

• Causes include drugs (e.g. cytotoxics), viral diseases and adverse drug reactions or interactions

image Folic acid (folate) deficiency
• When either the folate stores are low or the diet is inadequate

• Causes include increased folate requirements (e.g. pregnancy), alcohol abuse, poor diet and impaired gastric absorption

image Haemorrhagic
• RBC lost through bleeding

image Iron deficiency
• When either the iron stores are low or the diet is inadequate

• Causes include increased iron requirements (e.g. pregnancy), alcohol abuse, poor diet and impaired gastric absorption

image Pernicious
• Decreased intrinsic factor and production of hydrochloric acid (required for vitamin B12 absorption)

• Causes include genetic, diet (B12 deficiency) and gastric disorders, e.g. inflammation or surgery

image Sickle cell
• A congenital haemolytic disorder that occurs when a defective haemoglobin molecule causes a RBC to become ‘sickle shaped’, impairing circulation and increasing likelihood of haemolysis.


Signs and symptoms



image Pallor

image Weakness, fatigue

image Tachycardia, tachypnoea, dyspnoea

image Confusion.


Diagnosis



image Blood tests (full blood examination, serum iron, folate)

image Bone marrow biopsy (for aplastic anaemia).


Treatment



image Treat cause
• Iron and folate supplements, corticosteroids

• Bone marrow transplant (for aplastic or sickle cell)

image Treat symptoms
• Oxygen if hypoxic

• Transfusion of blood if symptomatic.


Complications



image Hypoxia

image Cellular damage from ischaemia.


Disseminated intravascular coagulation (DIC)


A condition where clotting and haemorrhage occur at the same time. It is initiated by damage to the endothelium, which triggers the clotting cascade.



image Excess fibrin is formed, which joins with platelets to form clots, decreasing blood flow to tissues

image Circulating thrombi activate fibrinolysis, which causes microthrombi to break down, leading to haemorrhage.


Causes



image Obstetric complications, e.g. postpartum haemorrhage, eclampsia

image Burns

image Trauma

image Toxic reactions, e.g. snake bite, drug reactions, incompatible blood reactions

image Infection, e.g. septicaemia

image Neoplastic disease, e.g. leukaemia, carcinoma, lymphoma

image Anorexia

image Shock.


Signs and symptoms



image Abnormal bleeding within a significant past history, e.g. bleeding from GI tract and IV/injection sites

image Confusion

image Pain, e.g. muscles, abdominal, back.


Diagnosis



image Decreased platelets and fibrinogen

image Increased prothrombin time (PT)

image Increased activated partial thromboplastin time (APTT)

image Positive D-dimer test.


Treatment



image Treat symptoms

image Pain relief

image Blood products, e.g. FFP, packed cells (PC), cryoprecipitate

image Heparin (if used early)

image Close observations of vital signs, as there is potential for haemorrhagic shock.


Complications



image Organ necrosis (especially renal and liver, due to increased haemolysis)

image Multisystem organ failure

image Death (if untreated).


Haemophilia


A genetic (X-linked recessive) bleeding disorder due to a deficiency of clotting factors.



Types



image Haemophilia A
• Also known as ‘classic’ haemophilia

• Most common (about 80% of cases)

• Deficiency in factor VIII (antihaemophilic factor)

image Haemophilia B
• Also know as Christmas disease

• Deficiency in factor IX.


Signs and symptoms



image Bruising

image Bleeding, e.g. epistaxis or bleeding into joints.


Diagnosis



image Factor assays (VIII and IX)

image Baseline coagulation (PT, APTT, INR).


Treatment



image Factors (either VIII or IX)

image Fresh frozen plasma (FFP)

image Desmopressin (will increase factor VIII)

image Aminocaproic acid (if actively bleeding).


Neutropaenia


An abnormally low count of neutrophils causing increased susceptibility to bacterial infections and, if untreated, it can be life-threatening. It is caused by decreased production of bone marrow (e.g. congenital disorders, cancer, medications) or increased destruction of bone marrow (e.g. chemotherapy, autoimmune diseases).



Polycythaemia


Increased number of circulating RBC due to the rapid production and maturation of RBC, causing the blood to become viscous (thick), resulting in impaired blood flow to microcirculation, formation of microthrombi and hypoxia, and cellular damage. Usually occurs between 40 and 60 years of age.



Causes



image Hyperplasia of the bone marrow.


Signs and symptoms



image Reddened complexion

image Hypertension

image Dizziness

image Hepatomegaly and splenomegaly.


Diagnosis



image Blood test (increased RBC)

image Bone marrow biopsy.


Treatment



image Minimise iron- and folate-rich foods

image Donate blood each month (to reduce RBC in circulation)

image Anticoagulants, e.g. aspirin, warfarin

image Medications to reduce blood cell production, e.g. hydroxyurea, radioactive phosphorus.


Thalassaemia


A hereditary (autosomal recessive) disease in which the haemoglobin is fragile and breaks down sooner than normal. This results in an excessive destruction of red blood cells, which leads to anaemia.



image Thalassaemia minor
• Also know as heterozygous beta-thalassaemia

• Patients have one normal gene and one thalassaemic gene
image Can become carriers of thalassaemia major

image Thalassaemia major
• Also know as homozygous beta-thalassaemia

• Patients have two thalassaemic genes

• These patients usually die at a young age.


Signs and symptoms



image Thalassaemia minor
• Usually asymptomatic

image Thalassaemia major
• Splenomegaly

• Hepatomegaly

• Jaundice—from the increased haemolysis

• Retardation—both physical and mental

• Tachycardia

• Systolic murmur


Treatment



image Thalassaemia minor
• No treatment necessary, as the body will adapt to lowered haemoglobin levels

Related posts:

  1. Documentation
  2. Medication administration
  3. Survival tactics
  4. Operative care

Stay updated, free articles. Join our Telegram channel
Tags:
Oct 22, 2016 | Posted by in NURSING | Comments Off on Haematology, oncology and immunology

Full access? Get Clinical Tree
Get Clinical Tree app for offline access