LECTURE OUTLINE Week 3

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LECTURE OUTLINEWeek 3
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Topic 1. STRESS AND PATHOPHYSIOLOGY

• Stress and adaptation of body systems
• Stress and adaptation of cells
• Cellular injury - reversible - irreversible ---
  death
• Causes of cell injury
• hypoxia, physical, chemical
• Gangrene

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STRESS PATHOPHYSIOLOGY

• Stress refers to a condition of the body when not
  in homeostasis.
• Stressors are all those factors that contribute
  to change the steady state of the body.

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ADAPTATION RESPONSE

• General Adaptation Syndrome
• alarm stage
• stage of resistance
• stage of exhaustion
• Stress Response
• nervous system (fight-flight response)
• endocrine (cortisol)
• immune (suppression of immune response)

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CELLULAR ADAPTATION

• ATROPHY - decrease in cell size
• HYPERTROPHY - increase in cell size
• HYPERPLASIA -increase in cell number
• METAPLASIA - substitution of better cells
• DYSPLASIA - deranged cell growth

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CELL INJURY

• DEGENERATION
• MECHANISMS
• free-radical injury
• hypoxia
• physical agents (T, electricity, radiation)
• chemical (corrosives, CO)
• biologic agents
• nutritional imbalances

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Cell Injury

• REVERSIBLE
• swelling
• fatty changes

• IRREVERSIBLE
• liquefaction
• coagulation
• caseous

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GANGRENE

• Considerable tissue undergoes necrosis
• Dry gangrene - interference of blood supply
• Wet gangrene - interference with venous return
• Gas gangrene - infection by Clostridium

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Topic 2. PROCESSES OF INFLAMMATION

• Functions of the inflammatory response
• Chemical mediators of inflammation
• Vascular and cellular aspects of the inflammatory
  response
• Acute and chronic inflammation

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Functions of the Inflammatory Response

• Preparation for wound healing
• Minimise tissue damage
• Contain minor infections

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Cardinal Signs

• Redness
• Swelling
• Heat
• Pain
• Loss of function

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Chemical Mediators

• Histamine
• Plasma proteases (kinins)
• Prostaglandins
• Leukotrienes
• Platelet Activating Factor

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Vascular and Cellular Phase

• Short vasoconstriction-vasodilation (redness and
  warmth)-increased permeability (swelling-pain and
  impaired function)-localising effects of injury
• Leukocytes move in- margination, emigration,
  chemotaxis, phagocytosis

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Acute vs Chronic Inflammation

• Rapidly controlled vs self-perpetuating
• Neutrophils vs mononuclear cells (macrophages,
  lymphocytes and plasma cells)
• Proliferation of exudates vs fibroblasts
  (scarring and deformity)
• burn/infection vs low-grade irritants (talc,
  silica, microbes, tumour)

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Topic 3. INFLAMMATION AND WOUND HEALING

• Resolution of inflammation
• stages of repair
• delayed and aberrant wound healing
• Soft tissue injury
• strains
• sprains
• Fracture and complications
• compartment syndrome
• fat embolisms

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WOUND HEALING

• Inflammatory phase
• Proliferative phase
• Remodelling phase

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Factors affecting healing

• Localised factors
• Generalised factors

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STRAINS AND SPRAINS

• Soft Tissue Injury
• contusion
• haematoma
• laceration
• Strain - stretching injury
• Sprain - excessive joint movement, ligaments may
  be completely or incompletely ruptured

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FRACTURES

• Break in the continuity of bones
• Classifications (type, pattern, location)
• Characteristics (pain, tenderness, swelling,
  deformity, abnormal mobility, loss of function)
• Healing involves haematoma formation, cellular
  proliferation, callus formation, ossification and
  remodelling
• Diagnosis and treatment

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FRACTURE COMPLICATIONS

• COMPARTMENT SYNDROME
• depression of nerve and blood vessel
• important to reduce compression
• FAT EMBOLISMS
• fat released from marrow or alteration of lipid
  stability
• IMPAIRED HEALING
• delayed union, malunion, nonunion

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Topic 4. BRAIN INJURY AND INTRACRANIAL PRESSURE

• Types of brain injury
• Results of raised intracranial pressure
• Loss of consciousness
• Brain death

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BRAIN INJURY

• PRIMARY OR DIRECT
• SECONDARY (swelling, haematomas, infection,
  hypoxia, ischaemia)
• SEVERITY / DIFFUSED (mild-severe)
• CONCUSSION
• CONTUSION
• DIFFUSED AXONAL INJURY (TEARING/SHEARING OF
  BRAIN)
• COUP/CONTRECOUP

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RAISED INTRACRANIAL PRESSURE

• BLOOD, BRAIN TISSUE, CSF
• ICP - 0-15mmHg
• Compliance change in volume / change in
  pressure (see curve)
• CPP MABP - ICP
• With increased ICP, tissue perfusion is
  inadequate, hypoxia, decreased level of
  consciousness --- neuronal death
• Direct and indirect monitoring

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LOSS OF CONSCIOUSNESS

• Consciousness --- Reticular Activating System
• Rostral-caudal progression of coma (sequential
  event - level of brain structures)
• level of consciousness, pupil reaction, muscle
  tone and respiration
• Glasgow Coma Scale

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BRAIN DEATH

• DIAGNOSIS OF DEATH
• cessation of all brain functions (EEG) and
  irreversibility
• absence of brain stem reflexes
• absence of responsiveness and respiratory effort