Week 3 Acute Sepsis Flashcards
What is the difference to sepsis, bacteraemia and septicaemia?
Sepsis- systemic response to infection- can be defined as SIRS + infection
Bacteraemia- presence of bacteria in the blood
Septicaemia- generalised sepsis
What are the features of neisseria meningitidis and meningococcal disease- presentation, spread,?
Gram -ve diplococcus
Spread by direct contact with respiratory secretions- aerosols and nasopharyngeal secretions
Most people harmlessly colonised- 25% young people carriers
Photophobia, purpuric rash- non blanching
What is the typical presentation of a pt with acute sepsis?
Non specifically unwell- temp etc which quickly turns into pt being acutely unwell- fever, severe headaches, nausea, weakness, muscle aches, abdo pain and eye pain (photophobia)
Tachynea- high respiratory rate
What are the common investigations used to diagnose acute sepsis?
FBC, urea and electrolytes (renal function), Blood sugars- changes in homeostasis, Liver function test CRP- measure of inflammation Clotting studies- increased coagulation Blood gases
What is systemic inflammatory response syndrome (SIRS) and how is it diagnosed?
Response to a non specific insult- eg ischaemia, trauma, infection Diagnosed by two or more of: Temp 38 HR >90/min Respiratory rate >20/min
How does sepsis affect coagulation?
Cytokines initiate production of thrombin and therefore coagulation - leads to microvascular thrombosis (poor blood supply) and therefore organ ischaemia, dysfunction and failure
- major cause of shock and multi organ failure
Also inhibit fibrinolysis
What is involved in the sepsis bundle (sepsis 6)?
- Deliver high flow O2- prevents ischaemia organs
- Take blood cultures and others- consider source control
- Administer empirical IV ABs
- Measure serum lactate- common measure of acute metabolic derangement- may have rapid rise if acutely unwell
- IV fluid resuscitation p- may have low BP
- Commence accurate urine output measurement- monitor renal function
What is severe sepsis?
SIRS + organ dysfunction or organ hypo perfusion- often affects kidneys- hypotension- decreased urine output
Test with creatinine and urea
What is septic shock?
Severe sepsis + persistently low blood pressure despite administration of IV fluids
How do microorganisms trigger the inflammatory cascade?
Endotoxins eg LPS on surface bind to macrophage
LOCAL RESPONSE- cytokines released (TNFa and IL1)- stimulate inflammatory response to promote wound healing
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SYSTEMIC RESPONSE- cytokines released int circulation- stimulate growth factor, macrophages and platelets
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SIRS- immune response over played- homeostasis not restored- cytokines lead to activation of humoural cascade
Describe the important first line of defence barriers of the host to infection (4)?
Physical barriers:
- skin,
- mucous membranes (mouth, rest tract, GI, urinary),
- bronchial cilia - damage increases susceptibility to infection
Physiological barriers:
- diarrhoea- food poisoning
- vomiting- food poisoning, hepatitis, meningitis
- coughing- pneumonia
- sneezing- sinusitis
Chemical barriers:
- low pH- kills bacteria- skin, stomach, vagina
- antimicrobial molecules
Biological barriers:
-normal flora- skin, nasopharynx
Prevent entry and limit growth of pathogens
What are the components of the innate immune system and what role does it have in preventing infection?
Immediate protection:
- fast
- lack of specificity
- lack of memory
- no change in intensity- always the same response
Buys time before adaptive kicks in
What’s involved in the second lines of defence in innate immunity- phagocytes, chemicals?
Phagocytes
- PAMPS on microbes (LPS) recognised by PRR of phagocytes (toll like receptors)
- opsonisation - enhances attachment and clearance (c3b)
- respiratory burst or oxygen independent- lysozyme
Chemicals- complement- alternative and MBL pathways, cytokines
Inflammation
- contain and clear infections
