Homesleeping healthBsc Nursing NotesShock, Immunity, Hypersensitivy, -Nursing notes

Shock, Immunity, Hypersensitivy, -Nursing notes


  • the life-threatening clinical syndrome of cardiovascular collapse
  • characterized by hypotension and hypoperfusion
  • An acute reduction of effective circulating blood volume (hypotension)
  • Inadequate perfusion of cells and tissues (hypoperfusion)
  • If uncompensatedàlead to impaired cellular metabolism and death

Shock Definition

  • clinical state of circulatory collapse resulting in hypo-perfusion of tissues with subsequent impaired tissue oxygenation

Types of Shock- 5 types

Hypovolemic Shock

  • Due to acute reduction in circulating blood volume or inadequate circulatory blood volume
  • Causes
  • severe hemorrhage (loss of red cell mass and plasma) or
  • massive loss of fluid
  • dehydration

Pathophysiology of Hypovolemic Shock

  • Severity à clinical features
  • The severity of clinical features depends upon the degree of blood volume
  • Less than 1000 ml: Compensated
  • 1000-1500 ml: Mild
  • 1500-2000 ml: Moderate
  • Greater than 2000 ml: Severe

Hypovolemic Shock Clinical Features

  • increased heart rate (tachycardia),
  • hypotension,
  • low urinary output,
  • altered mental state (agitated to confused to lethargic)
  • Restlessness
  • Sweating and cold
  • Rapid shallow breathing

Cardiogenic shock

  • No actual reduction of blood volume
  • Caused due to Heart disease like severe left ventricular dysfunction such as myocardial damage
  • Acute circulatory failure Due to decreased cardiac output

Septic/Toxaemic Shock-septicimia

  • Caused by systemic microbial or bacterial infection in a whole system
  • Two types of shock
  • Endotoxic shock or Gram negative septicemia
  • Exotoxic shock or gram positive septicimia

Neurogenic Shock

  • Associated with accident or spinal cord injury, severe trauma
  • Results from causes of interruption of sympathetic vasomotor supply
  • Neurogenic Shock  pathophysiology

Anaphylactic Shock

  • It is hypersensitivity reactions
  • It is initiated by generalized by IgE mediated hypersensitivity reaction leading to systemic vasodilatation and increased vascular permeability
  • Pathophysiology of Anaphylytic Shock
  • 3 Stages of shock
  • Progressive disorder that leads to death if uncorrected
  • Compensated  Shock/ Non-progressive/ Initial/ Reversible
  • If good treatment recovery and becomes normal
  • Compensatory mechanism activatedà perfusion of vital organs maintained
  • Activation of various neuro-hormonal mechanisms
  •  widespread vasoconstriction and
  •  fluid conservation by the kidney
  • The purpose is to maintain adequate  cerebral and coronary blood supply by redistribution of blood so that the vital organs (brain and heart) are adequately perfused and oxygenated
  • Widespread vasoconstriction
  • Fluid conservation by the kidney
  • To compensate for the actual loss of blood volume in hypovolaemic shock, the following factors may assist in restoring the blood volume and improving venous return to the heart
  • Release of aldosterone from the hypoxic kidney by activation of the renin-angiotensin-aldosterone mechanism
  • Release of ADH due to decreased effective circulating blood volume
  • Shifting of tissue fluids into plasma due to lowered capillary hydrostatic pressure (hypotension)

Stimulation of adrenal medulla

  • In response to low cardiac output, adrenal medulla is stimulated to release excess of catecholamines (epinephrine and non-epinephrine)
  • This increases heart rate as well as increase cardiac output

Progressive decompensated shock

When the patient suffers from some other stress or risk factors (e.g pre-existing cardiovascular and lung diseases) besides the persistence of the shock there is a progressive deterioration

  • It worsens pulmonary perfusion (pulmonary hypoperfusion) and increase vascular permeability resulting in tachyponea and ARDS
  • Impaired tissue perfusion causes switch from aerobic to anaerobic glycolysis resulting in metabolic lactic acidosis
  • Lactic acidosis lowers the tissue pH which cause vasomotor response ineffective. This results in vasodilatation and peripheral pooling of blood
  • Clinically, patient develops confusion and worsening of renal function

Irreversible decompensated shock

  • When the shock is severe that in spite of compensatory mechanisms and despite therapy and control of etiology agent (shock) and no recovery takes place


  • Types of Immunity
  • Natural or innate immunity

Non-specific Immnity

  • Considered as the first line of defense without antigenic specificity

Specific  immunity or adaptive immunity

  • Characterized by antigenic specificity

Immune deficiency disorders

  • Deficiencies of host defense systems result in an immunologic imbalance that can lead to a susceptibility to infection, an autoimmune disease, or a predisposition to malignancies
  • Characterized by deficient cellular and/or humoral immune functions
  • Includes
  • Primary immune deficiency disorder
  • Secondary immune deficiency disorder

Primary Immune deficiency disorder

  • -Causes in immune system component
  • a. According of component
  • i) Complements
  • ii) Phagocytic
  • iii) B cells (Humoral)
  • iv) T Cells (cellular)
  • b. According to the etiology
  • i) Congenital (X-linked disease)
  • ii) Acquired (AIDS)
  • iii) Embryogenesis (Digoerge syndrome)
  • iv) Idiopathic

Secondary immune deficiency disorder

  • -Non Immunogenic causes
  • Prematurity
  • Mal nutrition
  • Malignancy
  • Injury, Burns, Splenectomy
  • Drugs

Hypersensitivity reactions

  • Defined as the state of exaggerated immune response to an antigen
  • Characterized by hyperfunction of the immune system and cover the various mechanisms of immunologic tissue injury

Types of hypersensitivity reactions

Type I hypersensitivity reactions

  • Known as Anaphylactic reaction
  • Defined as a state of rapidly developing or anaphylactic type of immune response to an antigen to which the individual is previously sensitized
  • Reaction occurs within 15-30 minutes of exposure to antigen
  • IgE mediated reactions
  • Associated with allergens such as bee stings, peanuts

Type II hypersensitivity reactions

  • Known as cytotoxic reaction
  • Defined as reactions by humoral antibodies that attack cell surface antigens on the specific cells and tissues and cause lysis of target cells
  • Reaction occurs within hours to days of exposure to antigen
  • IgG or IgM mediated reactions
  • Examples- autoimmune haemolytic anaemia, transfusions reaction, myasthenia gravis

Type III hypersensitivity reactions

  • Known as Immune Complex Mediated Reaction
  • Result from deposition of antigen-antibody complexes on tissues which is followed by activation of the complement system and inflammatory reaction, resulting in cell injury
  • Reaction occurs within 1-3 weeks of exposure to antigen
  • Immune complex mediated reactions
  • Examples- SLE, Immune complex glomerulonephritis
  • Type IV Hypersensitivity Reactions
  • Known as delayed hypersensitivity reaction
  • Defined as a tissue injury by cell mediated immune response without formation of antibodies but a slow and prolonged response of specifically sensitized T lymphocyctes
  • Reaction occurs after 24 hours to days and weeks of exposure to antigen
  • T cell mediated reactions
  • Examples- tuberculin reaction, leprosy (reaction against mycobacterial infection), transplant rejection

Auto immune disorders

  • Normally lymphocytes recognize body’s own proteins, so antibodies are not developed against them
  • However, sometimes body suffer from antibody or cell mediated attack against its own, causing damage of normal cells and their function leading to autoimmune disease
  • example- rheumatic heart disease
  • Defined as a state in which the body’s immune system fails to distinguish between ‘self’ and ‘non self’ and reacts by formation of autoantibodies against one’s own tissue antigens
  • There is loss of tolerance to one’s own tissues (autoimmunity)
  • Caused by immunological factors, genetic factors and microbial factors

Types of autoimmune diseases

Organ specific diseases

  • Autoantibodies formed react specifically against an organ or target tissue component and cause its chronic inflammatory destruction
  • Example-thyroid, pancreatic islets of langerhans

Organ non-specific (systemic) diseases

  • Autoantibodies formed which reacts with antigens in many tissues and thus causes systemic lesions
  • Example- Systemic lupus erythematous, Rheumatoid arthritis, Sjogren’s syndrome

Genetic disorders

  • Genetic disorder is due to inherited defects in chromosomes

Classification of genetic disorders

  • Single gene defect
  • Multifactorial disorder
  • Cytogenetic (Karyotypic) disorder or chromosomal abnormalities

Single gene disorders

  • Know as mendelian disorders
  • These disorders are due to defect in a single gene or result of mutation of a single gene
  • Example- sickle cell anemia, Beta thalassaemia

Multifactorial genetic/inheritance disorders

  • Those disorders which result from the combined effect of genetic composition and environmental influences
  • Example- congenital heart disease, diabetes mellitus, cleft palate, congenital heart disease
  • Cytogenetic or chromosomal disorders
  • This disorder may be due to aberrations in the number of structure of chromosomes
  • A chromosomes number which is an exact multiple of the haploid number and exceeds the diploid number is called polypoidy and which is not an exact multiple is called aneuploidy
  • Examples Down’s syndrome (Trisomy 21), Edward’s syndrome (Trisomy 18)


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