Sepsis and Septic Shock Flashcards
What is sepsis?
Life-threatening organ dysfunction caused by dysregulated host response to infection
What is septic shock?
Clinical construct of sepsis with persisting hypotension requiring vasopressors to maintain MAP >65mmHg and having serum lactate of >2mmol/L despite adequate volume resuscitation
How is organ dysfunction identified in sepsis?
Organ dysfunction identified as acute change in total SOFA score >2
What is sepsis caused by?
Is a systemic illness caused by microbial invasion of normally sterile parts of the body
Describe the traditional model of sepsis?
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What is qSOFA used for?
To identify if a patient is likely to require ICU or die in hospital
Score of 2 or more indicates greater risk of poor outcome
What does qSOFA look at?
- Hypotension systolic BP <100mmHg
- Altered mental state
- Tachypnea RR >22/min
What is survival in septic shock based on?
Survival in septic shock is based on antimicrobial delay:
- Each hour delay increases mortality by 7.6%
Remember “time is life”
What are some of the bodies defences against sepsis?
- Physical barrier
- Skin, mucosa, epithelial lining
- Innate immune system
- IgA in gastrointestinal tract, dendritic cells, macrophages
- Adaptive immune system
- Lymphocytes, immunoglobulins
Describe the pathophysiology of sepsis?
- Uncontrolled inflammatory response
- Features consistent with immunosuppression
- Loss of delayed hypersensitivity
- Inability to clear infection
- Predisposition to nosocomial infection
- Probably change of the sepsis syndrome over time
- Initially, increase in inflammatory markers
- Later, shift towards an anti-inflammatory immunosuppressive phase
What are the 3 phases of pathogenesis of sepsis?
-
Release of bacterial toxins
- Bacterial invasion into body tissues source of dangerous toxins
- May or may not be neutralised by existing immune system
- Commonly released toxins
- Gram negative
- Lipopolysaccharide (LPS)
- Gram positive
- Microbial-associated molecular pattern (MAMP)
- Lipoteichoic acid
- Murmyl dipeptides
- Superantigens
- Staphylococcal toxic shock syndrome toxin (TSST)
- Streptococcal exotoxins
- Microbial-associated molecular pattern (MAMP)
- Gram negative
-
Release of mediators
- Effects due to endotoxin release
- LPS needs an LPS-binding protein to bind to macrophages
- LTA do not need such proteins
- Effects due to exotoxin release
- Pro-inflammatory response
- Small amounts of superantigens cause a large amount of mediators to be secreted causing cascade effect
- Mediator role on sepsis
- Two types of mediators can be released
- Pro-inflammatory mediators – cause inflammatory response that characterises sepsis
- Compensatory anti-inflammatory reaction – can cause immunoparalysis
- Effects due to endotoxin release
-
Effects of specific excessive mediators
- Pro-inflammatory mediators
- Promote endothelial cell – leukocyte adhesion
- Release of arachidonic acid metabolites
- Complement activation
- Vasodilation of blood vessels by NO
- Increase coagulation by release of tissue factors and membrane coagulants
- Cause hyperthermia
- Anti-inflammatory mediators
- Inhibit TNF alpha
- Augment acute phase reaction
- Inhibit activation of coagulation system
- Provide negative feedback mechanism to pro-inflammatory mediators
- Balance between pro and anti-inflammatory mediators determines outcome
- Pro-inflammatory stronger causes septic shock with multiorgan failure and death
- Pro-inflammatory mediators
Anti-inflammatory stronger causes immunoparalysis with uncontrolled infection and multiorgan failure
What are commonly released toxins that cause sepsis?
- Gram negative
- Lipopolysaccharide (LPS)
- Gram positive
- Microbial-associated molecular pattern (MAMP)
- Lipoteichoic acid
- Murmyl dipeptides
- Superantigens
- Staphylococcal toxic shock syndrome toxin (TSST)
- Streptococcal exotoxins
- Microbial-associated molecular pattern (MAMP)
What are examples of superantigens that can cause sepsis?
- Staphylococcal toxic shock syndrome toxin (TSST)
- Streptococcal exotoxins
What are the 2 types of mediators that can be released in the pathogenesis of sepsis?
- Pro-inflammatory mediators – cause inflammatory response that characterises sepsis
- Compensatory anti-inflammatory reaction – can cause immunoparalysis
What do pro-inflammatory mediators cause in relation to sepsis?
Cause inflammatory response that characterises sepsis
What do anti-inflammatory mediators cause in relation to sepsis?
Can cause immunoparalysis
What are the specific effects of pro-inflammatory mediators?
- Promote endothelial cell – leukocyte adhesion
- Release of arachidonic acid metabolites
- Complement activation
- Vasodilation of blood vessels by NO
- Increase coagulation by release of tissue factors and membrane coagulants
- Cause hyperthermia
What are the specific effects of anti-inflammatory mediators?
- Inhibit TNF alpha
- Augment acute phase reaction
- Inhibit activation of coagulation system
- Provide negative feedback mechanism to pro-inflammatory mediators
Balance of pro and anti-inflammatory markers determines outcome of sepsis, what does pro-inflammatory being stronger cause?
- Pro-inflammatory stronger causes septic shock with multiorgan failure and death
Balance of pro and anti-inflammatory markers determines outcome of sepsis, what does anti-inflammatory being stronger cause?
- Anti-inflammatory stronger causes immunoparalysis with uncontrolled infection and multiorgan failure
What are toxins use endotoxin release?
LPS, lipopolysaccharide (needs an LPS-binding protein to bind to macrophages)
LTA, lipoteichoic acid (does not need such a protein)
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Which of LPS and LTA needs a binding protein before binding to macrophage?
LPS
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A common gram negative toxin with endotoxin release is?
LPS
A common gram positive toxin with endotoxin release is?
LTA
What toxins have exotoxin release?
Superantigens
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What are some examples of pro-inflammatory markers?
What are some examples of anti-inflammatory markers?
What do the clinical features of sepsis depend on?
- Host
- Organism
- Environment
What are some signs of organ dysfunction?
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What are some general features of sepsis?
- Fever
- Presenting as chills, rigors, flushes, cold sweats, night sweats etc
- Hypothermia
- Especially in elderly and young children (remember the immunosuppressed)
- Tachycardia
- Tachypnoea
- Altered mental state
- Especially in elderly
- Hyperglycaemia in absence of diabetes
What are some diagnostic markers of sepsis?
- Inflammatory
- Leucocytosis (WCC > 12,000/ml)
- Leucopenia (WCC < 4,000/ml)
- Normal WCC with greater than 10% immature forms
- High CRP
- High procalcitonin
- Haemodynamic
- Arterial hypotension (systolic <90mmHg or MAP <70mmHg)
- SvO2 >70%
- Organ dysfunction
- Arterial hypoxaemia (PaO2/FiO2 < 50mmHg)
- Oliguria (<0.5ml/kg/h)
- Creatinine increase compared to baseline
- Coagulation abnormalities (PT >1.5 or APTT >60s)
- Ileus
- Thrombocytopenia (<150,000/ml)
- Hyperbilirubinaemia
- Tissue perforation
- High lactate
- Skin mottling and reduced capillary perfusion
What are some effects of the host on sepsis?
- Age
- Co-morbidities
- Immunosuppression
- Acquired such as HIV/AIDS
- Drug induced such as steroids, chemotherapy agents, biologics
- Congenital
- Previous surgery
- Such as splenectomy
What are some effects of the organism on sepsis?
- Gram positive vs gram negative
- Virulence factors
- Such as MRSA, toxin secretion etc
- Bioburden
What are some effects of the environment on sepsis?
- Occupation
- Travel
- Hospitalisation
In general, what is the process for recognising and managing sepsis?
- Recognise clinical presentation of sepsis
- Identify source of infection
- Treat with antibiotics, fluids and oxygen
What is the sepsis 6 used for management of sepsis?
- Give 3
- Blood cultures
- Blood lactate
- Marker of hypoperfusion/severe sepsis/poorer prognosis
- Measure urine output
- Low urine output is marker of renal dysfunction
- Take 3
- Oxygen aim sats 94-98%
- IV antibiotics
- IV fluid challenge
- 30ml/kg
When should you consider HDU referal?
- Low BP responsive to fluids
- Lactate >2 despite fluid resuscitation
- Elevated creatinine
- Oliguria
- Liver dysfunction, Bil, PT, Plt
- Bilateral infiltrates, hypoxaemia
When should you consider ITU?
- Septic shock
- Multi-organ failure
- Requires sedation, intubation and ventilation