Q11

How are thermal burns classified?

  • According to depth of injury:
    • Superficial – confined to epidermis
    • Partial thickness – extends to dermis
    • Full thickness – involves subcutaneous tissue

Pass Criteria:

  • Bold to pass

What are the potential complications of thermal burns?

  • Early
    • Hypovolaemic shock (especially with >20% BSA)
    • Compartment syndrome (circumferential lower limb burn)
    • Associated injuries (e.g. inhalational burn, CO poisoning)
    • Airway compromise
    • Hypermetabolic state
  • Late
    • Infection/sepsis (Pseudomonas)
    • ARDS
    • Multi-organ failure
    • Skin grafting, scarring/cosmetic
    • Psychological

Pass Criteria:

  • 2 early
  • 2 late

How do you determine the extent of burns?

  • TBSA calculation notoriously inaccurate. Does not include superficial burns
  • Wallace “rule of nines”
  • Lund & Browder diagram

Pass Criteria:

  • Mention 1 method

Q12

An 80 year old woman is transferred to your ED following a motor vehicle accident 12 hours ago, where she sustained serious chest injuries. She has multiple wounds oozing blood due to Disseminated Intravascular Coagulation (DIC). On a full blood count and coagulation profile, what would you expect to find?

  • Decreased Hb (MAHA – microangiopathic haemolytic anaemia)
  • Increased WCC
  • Decreased platelets
  • Decreased fibrinogen
  • Increased PT/INR
  • Increased a/PTT
  • Increased fibrin degradation products

Pass Criteria:

  • Bold to pass

What are the pathological consequences of DIC?

  • DIC – major trauma releases tissue thromboplastins. Both sides of clotting cascade are activated.
  • 2 major consequences
    • Deposition of fibrin within microcirculation leading to ischaemia/microthrombosis of vulnerable organs
    • Consumptive coagulopathy – platelets and clotting factors leading to a bleeding diathesis

Pass Criteria:

  • 3/3 bold to pass

What are the causes of DIC?

  • Obstetric
    • Fetal Death In Utero
    • Amniotic fluid embolism
    • Pre-eclampsia
  • Sepsis
  • Malignancy
    • Acute promyelocytic leukaemia
    • Adenoma of lung, pancreas, stomach and colon
  • Trauma
    • Multi/burns/environmental/snakebite

Pass Criteria:

  • Must get 3 categories

Q13

What is the definition of a neoplasm?

  1. Abnormal growth of a tissue
  2. Growth exceeds and is uncoordinated with that of the original tissue
  3. Growth continues in the absence of stimuli which evoked the change
  • (Preys on host and serves no purpose)

Pass Criteria:

  • Must get gist of all 3

How may a malignant tumour affect the 'host'?

PROMPT – What is meant by paraneoplastic syndrome? Give examples of paraneoplastic endocrinopathies.

  • Local and metastatic direct effects
    • Pressure
    • Bleeding
    • Ulceration
    • Rupture
    • Infarction
  • Cachexia
  • Hormonal
  • Paraneoplastic
    • Endocrinopathy with 3 examples (Cushing’s, SIADH, Ca++ up, hypoglycaemia, Carcinoid syndrome, polycythaemia)
    • Nerve and muscle – myasthenia
    • Skin – acanthosis nigricans, dermatomyositis
    • Bone – HPOA and clubbing
    • Blood/vascular – anaemia, venous thrombosis

Pass Criteria:

  • 3 of 4 bold to pass
  • 3 examples of paraneoplastic syndrome

Q14

What is sickle cell disease?

PROMPT – Is it congenital or acquired?

  • Hereditary blood disorder
  • Haemoglobinopathy

Pass Criteria:

  • Bold to pass

What are the major pathological manifestations of sickle cell disease?

  • Haemolysis/Haemolytic anaemia
  • Microvascular occlusions (crises/tissue ischaemia = severe pain in affected organs e.g. bones, lungs, liver, spleen)
  • Splenic enlargement, infarct and dysfunction (Increased susceptibility to infection – encapsulated organisms [e.g. strep pneumonia, haemophilus influenza])

Pass Criteria:

  • 2 of 3 to pass

In general how are haemolytic anaemias classified?

  • Inherited genetic defects
    • RBC membrane {Spherocytosis)
    • Enzyme deficiencies (G6PD)
    • Haemoglobinopathies (Thalassaemia, SIckle Cell Disease)
  • Antibody mediated destruction
    • Transfusion reactions
    • Autoimmune
  • Mechanical trauma
    • Microangiopathic haemolytic anaemias (HUS, DIC, TTP)
    • Cardiac valves
  • Infections of red cells
    • Malaria
  • Toxic
    • Envenomation

Pass Criteria:

  • 2 of 5 bold to pass

Q15

What are the sequence of events in haemostasis after a vascular injury?
Prompt: Is there any particular sequence to the events?

  • Vasoconstriction:
    • Arteriolar
    • Reflex neurogenic
    • Enhanced by endothelin
  • Primary haemostasis
    • Extracellular matrix exposed
    • Platelet adherence/activation
    • Platelet aggregates and forms plug
  • Secondary Haemostasis
    • Tissue factors exposed
    • Factor III
    • Thromboplastin
    • Factor VII
    • Platelet plug consolidated – thrombin/fibrin generated
  • Thrombus & antithrombotic effect
    • Fibrin polymerises to form permanent plug, tPA regulates

Pass Criteria:

  • Identify 3/4 steps of haemostasis (Bold) in correct sequence

What laboratory tests are used to assess the function of the different pathways of the coagulation cascade?
Prompt: Which one is vitamin K dependent?

  • Prothrombin time – extrinsic pathway
    • Factors VII, X, II, V, fibrinogen (including vit K dependent factors)
  • Partial thromboplastin time – intrinsic pathway
    • Factors XII, XI, IX, VIII, X, V, II, fibrinogen

Pass Criteria:

  • To pass identify test, what pathway it is testing and identify which one is vit K dependent

Q16

Coagulation Profile

What is the abnormality on this coagulation profile?

  • Delayed clot formation in both the extrinsic (PT/INR) and intrinsic (APTT) systems
  • Fibrinogen low
  • Consistent with a consumptive coagulopathy/DIC

Pass Criteria:

  • Must state coagulopathy / DIC

What could cause this?

  • Sepsis
  • Liver failure
  • Malignancy
  • Trauma
  • Envenoming (Brown/Tiger/Taipan)
  • etc

Pass Criteria:

  • One example of possible cause

Q17

List some common triggers of DIC.

  • Sepsis (Bacterial endotoxins and AgAb complexes)
  • Major trauma/burns/surgery
  • Certain cancers (promyelocytic AML, adenocarcinoma of the lung, colon, stomach and pancreas)
  • Obstetric complications (placental abruption, amniotic fluid embolism, dead retained fetal tissue)

Pass Criteria:

  • 3 of 4 categories required to pass. Examples are accepted.

How does endothelial injury initiate DIC?

  • Exposure of subendothelial matrix activates platelets and the coagulation cascade
  • TNF causes tissue factor to be expressed from endothelial cells
  • TNF up-regulates the expression of adhesion molecules on endothelial cells to allow leukocytes to bind and damage endothelial cells
  • Direct trauma to endothelial cells from AgAb complexes, temperature extremes, or microorganisms

Pass Criteria:

  • 3 points required to pass.

(Bonus question) Draw the extrinsic pathway of the coagulation cascade.

Diagram of the coagulation cascade.


Q18

Define hyperplasia.

Hyperplasia is an increase in the number of cells in an organ or tissue resulting in increased mass.

Pass Criteria:

  • Bold to pass.

What are the different types of hyperplasia and give some examples for each of them?

  • Physiologic hyperplasia
    • Hormonal – female breast at puberty, and during pregnancy
    • Compensatory – post partial hepatectomy
  • Pathologic hyperplasia
    • Excess hormones – benign prostatic hyperplasia, dysfunctional uterine bleeding
    • Response to viral infection – papillomavirus

Pass Criteria:

  • Bold and one example of each to pass.

Q19

Describe the sequence of events that occur in reversible ischaemic cellular injury.
Prompt: What occurs within the cell after delivery of oxygen and substrate is compromised?

  • Decreased oxydative phosphorylation and decreased ATP production leads to failure of the Na+/K+ membrane pump (K efflux, and Na influx)
  • Cellular swelling which results in Ca2+ influx
  • Further decrease in ATP production activates enzymes that decrease glycogen and decrease protein synthesis
  • Changes in the cellular cytoskeleton:
    • Loss of microvilli
    • Bleb‘ formation
    • Myelin figures‘ from degenerating cell membranes, leads to mitochondrial swelling

Pass Criteria:

  • 3 of 4 bold to pass.

List the morphological changes of irreversible cellular injury.

  • Severe mitochondrial swelling
  • Extensive damage to plasma membrane (including ‘myelin figures‘)
  • Lysosomal swelling
  • Necrosis or apoptosis

Pass Criteria:

  • Any 2 to pass.

Describe reperfusion injury (time permitting).

  • Increased injury to ischaemic cells with restoration of perfusion
  • Due to generation of reactive O2 and nitrogen species
  • Ca2+ re-enters cells and activates inflammatory and complement cascades

Pass Criteria:

  • At least 1 concept to pass.