What is anaphylaxis?
It is due to a severe Type I hypersensitvity reaction.
What is the main mediator of anaphylaxis?
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;
- Chemotactic factors
What are the physiological changes that occur when exposed to hypersensitivty mediators such as histamine?
• Smooth muscle spasm
• Chemotaxis and leukocyte invasion
• Mucous secretion
• Leaky vessels
What are the four stagings of sepsis?
1) SIRS - Severe Inflammatory Response Syndrome
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:
• Gram -ve:
- E Coli
What is the management plan for septic shock?
3) Fluids - At least 1.5L (Hartmanns?)
4) Blood cultures
5) Empirical ABx
7) Monitor - Urine output, temp, sats.
8) ECG and Radiology