Pathophysiology of Sepsis Flashcards
Define sepsis?
Life-threatening organ dysfunction caused by a dysregulated hose response to infection
What is septic shock?
A subset of sepsis in which a profound circulatory, cellular, metabolic abnormalities are associated with a great risk of mortality than sepsis alone.
What is the population that are at greater risk of sepsis?
- Very young and very old,
- Impaired immune system due to illness/meds
- Surgery/invasive procedure in the last 6 weeks,
- Breach of skin integrity
- IV drug misuse
- Indwelling lines or catheters
- Pregnant women, or those who have miscarried or terminated in past 6 weeks,
- Neonates
What types of infections cause sepsis?
It can be from any sort of infection and any sort of pathogen, like respiratory tract, UTI but 1/3 are of an unknown source
What are some breaches of host barrier integrity?
Physical barriers like skin and mucous membranes. May be from catheters, wounds, burns, thorn pricks, insect bites or epithelial cell damage.
What are the main factors affecting infection?
- Virulence of pathogen (if they release endotoxins),
- The bioburden (more colonary forming units, the more severe infection will be)
- Portal of energy (some entry points will produce more severe symptoms)
- Host susceptibility (Fit adults are less likely to be affected than the elderly).
- Temporal evolution (if it is caught early, ther will be better outcomes than if its caught late)
The first line of defence conprises of what?
Many immune molecules such as:
- Complement,
- Mannose-blinding lectin,
- Phagocytes,
- Toll like receptors and
- Nucleotide-binding oligomerisation domain receptors.
Immune molecules may trigger what?
Production of inflammatory markers such as interleukins, tumour necrosis factor alpha and reactive oxygen species.
What recognises the pathogens? and what parts of the pathogens do they recognise.
Toll like receptors and NLRs. They detect lipopolysaccharides.
What the cytokines and effector molecules that occur in response?
Tumour necrosis factor alpha, interleukins, platelet activating factor and prostaglandins.
What increases as a result of the production of cytokines and effector molecules?
Increased coagulation, this prevents more entry of pathogen through breach but can cause clotting. Increased stress hyperglycaemia which gives cells energy. There is increased cytopathic dysoxia which is decreased oxygen, this can lead to cell death and organ failure.
What decreases as a result of the production of cytokines and effector molecules
Decreased fibrinolysis (can breakdown clots). Decreased circulatory control and decreased endothelial integrity which causes a loss of blood and increases transmission.
What are the effects of tumour necrosis factor alpha and interleukin one on the body?
Acute phase response:
- Fever
- Hypertension
- Increased HR (due to increased baroreceptor firing)
- Corticosteroid and Adrenocorticotropic hormone,
- Release of neutrophils,
What are the effects of TNF alpha and IL-1 on the cardiovascular system?
- Generalised vasodilation by nitric oxide,
- Increased vascular permeability due to impaired endothelium
- Intravascular fluid loss (as loss in albumin proteins causes a change in starlings forces and loss of fluid),
- Myocardial depression (decreases cardiac output)
- Circulatory shock due to poor perfusion of the heart.
Patient with sepsis must have 2 or more of what criteria?
Temperature above 38 or below 36, - Heart rate over 100bmp - Respiration - Over 20/min - Leukocyte count over 16,000 or under 4000. AND documented site of infection.
