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Flashcards in Week 140 - Collapse Deck (14):

What is anaphylaxis?

It is due to a severe Type I hypersensitvity reaction.


What is the main mediator of anaphylaxis?

Mast cells.


What are the two stages required for a Type I hypersensitivity reaction?

1) Prior sensitisation, to enable bonding of IgE to mast cells.

2) Secondary exposure to antigen, resulting in cross linking between antigen and mast-cell-cound-IgE causing mast cell degranulation.


What occurs during the sensitisation stage that preceeds a Type 1 hypersensitivity reaction?

• Antigen picked up by dendritic cell, which activates Th2 cell, which activates B-cell to produce IgE.

• The IgE binds to receptors on the mast cell.


How does the hypersensitivity reaction occur once the mast cell has been primed with IgE?

• The same antigen is exposed again and forms cross links with the mast-cell-bound-IgE.

• This causes degranulation of the mast cell releasing;
- Histamine
- Proteases
- Chemotactic factors


What are the physiological changes that occur when exposed to hypersensitivty mediators such as histamine?

• Smooth muscle spasm

• Vasodilation

• Chemotaxis and leukocyte invasion

• Mucous secretion

• Leaky vessels


What are the four stagings of sepsis?

1) SIRS - Severe Inflammatory Response Syndrome

2) Sepsis

3) Severe Sepsis

4) Septic Shock


What are the clinical signs of SIRS?

• Tachycardia, Tachypnoea, High or low temperature, High or low white cell count.


What are the characteristics of Sepsis?

• Same as SIRS - Tachypnoea, Tachycardia, High/low temperature and high/low white cell count.


A confirmed infection through blood cultures +/- radiological evidence and clinical features.


What are the characteristics of Severe Sepsis?

As with sepsis; tachycardia, tachypnoea, high/low temp., high/low WCC and confirmed infection.


Hypoperfusion, hypotension and Organ dysfunction


What are the characteristics of Septic Shock?

• As with Severe sepsis; tachypnoea, tachycardia, high/low temp., high/low WCC, confirmed infection, hypoperfusion, hypotension, organ dysfunction.


Refractory hypotension, resistant to fluids.


What are the main causative organisms of Sepsis?

• Gram +ve:
- Streptococcus
- Staphylococcus


• Gram -ve:
- E Coli
- Pseudomonnas
- Proteus
- Kilbsiella


What is the management plan for septic shock?

1) ABCs
2) O2
3) Fluids - At least 1.5L (Hartmanns?)
4) Blood cultures
5) Empirical ABx
6) Bloods
7) Monitor - Urine output, temp, sats.
8) ECG and Radiology