Sepsis and Septic Shock Flashcards
Define sepsis
Lifethreatening organ dysfunction caused by a dysregulated host immune response to an infection
Define organ dysfunction as referred to in the definition of sepsis
An acute change in SOFA score >2 due to infection
Define septic shock
Sepsis & persisting hypotension requiring vasopressors to maintain MAP >65mmHg and lactate >2mmol/L despite adequate fluid resus
What is the mortality associated with sepsis?
10%
What mortality is associated with septic shock?
40%
What are the SOFA variables?
PaO2, FiO2 Platelet count Bilirubin MAP/administration of vaspressor (type/dose) Serum creatnine/OU GCS
What does SOFA stand for?
Sequential (sepsis related) organ failure assessment score
How can you quickly screen someone for sepsis?
qSOFA
What does the qSOFA determine?
qSOFA score of 2 or more is associated with longer hospital stays, increased risk of admission to UTI and death
Score of 2 or more should be followed up by completing SOFA score
Describe the variables in qSOFA
Hypotension (<100mmHg systolic)
Altered mental status
Tachypnoea (>22RR)
Why is sepsis so important?
3rd biggest killer
Each delay in hour of giving antibiotics to someone with sepsis increases their mortality by 7.6%
What are the body’s barriers against sepsis?
Physical: skin, mucosa, epithelial lining
Innate immune system: IgA in GIT, dendritic cells/macrophages
Adaptive immune system: lymphocytes, Ig
What does sepsis originate from?
A breach in the integrity of a host barrier (physical or immunological)
Organism enters blood –> septic state
Patients with sepsis have features consistent with what other group of individuals? Give examples of how this is so.
Immunocompromised patients
They have loss of delayed hypersensitivity, inability to clear infections and are predisposed to nosocomial infection
True or false:
Originally there is an initial increase in inflammatory mediators but then this shifts into an anti-inflammatory suppressive phase (but this depends on the health of the individual)
True
What are the three phases of pathogenesis of sepsis?
- Release of bacterial toxins
- Release of mediators
- Effects of specific excessive mediators
Phase 1: release of bacterial toxins
Toxins may or may not be cleared by the immune system
Commonly released toxins:
Gram -ve: LPS
Gram +ve: microbial-associated molecular pattern (MAMP - lipoteichoic acid, muramyl dipeptides), superantigens (TSST, streptococcal exotoxins)
What are endotoxins?
LPS complex associated with the outer membrane of gram -ve bacteria
What does LPS need to bind to macrophages?
LPS-binding protein
What happens when LPS binds to macrophages?
Triggers release of mediators
What are exotoxins?
Proteins actively secreted by gram positive and negative bacteria that create a pro-inflammatory response
How do superantigens differ in the way they trigger the host immune respones?
Only a small amount of superantigens is required to produce a huge number of mediators - this is due to a cascade effect.
Distinguish pro-inflammatory mediators from anti-inflammatory mediators
Pro-inflammatory mediators cause the inflammatory response that causes sepsis, they are produced by Th1 cells and examples include TNFa, interferon gamma, IL-1b, IL-2
Anti-inflammatory mediators counteract the pro-inflammatory mediators and these are produced by Th2 cells, examples include IL-4, IL-5, IL-13
What can happen if there is too many anti-inflammatory mediators?
Immunoparalysis, organ failure and death