Week 140 - Collapse

Question 1

What is anaphylaxis?

Answer 1

It is due to a severe Type I hypersensitvity reaction.

Question 2

What is the main mediator of anaphylaxis?

Answer 2

Mast cells.

Question 3

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

Answer 3

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.

Question 4

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

Answer 4

• 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.

Question 5

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

Answer 5

• 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

Question 6

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

Answer 6

• Smooth muscle spasm
• Vasodilation
• Chemotaxis and leukocyte invasion
• Mucous secretion
• Leaky vessels

Question 7

What are the four stagings of sepsis?

Answer 7

1) SIRS - Severe Inflammatory Response Syndrome
2) Sepsis
3) Severe Sepsis
4) Septic Shock

Question 8

What are the clinical signs of SIRS?

Answer 8

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

Question 9

What are the characteristics of Sepsis?

Answer 9

• 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.

Question 10

What are the characteristics of Severe Sepsis?

Answer 10

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

+

Hypoperfusion, hypotension and Organ dysfunction

Question 11

What are the characteristics of Septic Shock?

Answer 11

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

+

Refractory hypotension, resistant to fluids.

Question 12

What are the main causative organisms of Sepsis?

Answer 12

• Gram +ve:

• Streptococcus
• Staphylococcus

• Gram -ve:

• E Coli
• Pseudomonnas
• Proteus
• Kilbsiella

Question 13

What is the management plan for septic shock?

Answer 13

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