Sepsis Flashcards
is sepsis an infection
no
but it does not occur in the absence of infection
define sepsis
Life-threatening organ dysfunction due to dysregulated host response to infection
what is septic shock
sepsis in which the underlying circulatory and cellular and / or metabolic abnormalities are marked enough to substantially increase mortality
clinically defined as sepsis with persisting hypotension
what is SOFA
wide range of tests done on organs involving lab tests
has to be in a hospital environment
what is qSOFA
quick SOFA
• A tool is clinically characterise patients at risk of sepsis (at risk of prolonged ICU or death)
This criteria does not need lab tests and can be used in the community
what are the criteria in qSOFA
- respiratory > or equal to 22 breaths per minute (elevated respiratory rate)
- altered mentation (glasgow coma scale < 15)
- systolic blood pressure < or equal to 100mmHg
what is baseline qSOFA
• Baseline qSOFA = 0 unless patient has pre-existing organ dysfunction BEFORE onset of infection
○ If you have a patient presenting who is diabetic or diagnosed with a CVS disease or liver disease before they get infection then they will immediately score 1
what does a qSOFA score of > or equal to 1 tell you
overall 10% mortality risk - requires prompt medical intervention
what criteria remains important to aid diagnosis of infection
SIRS criteria
helps with identifying infection in general and the source of infection
what are the 3 criteria looked for in the glasgow coma scale / GCS?
3 criteria looking for - Eye opening - Verbal - Motor response Maximum score is 15
what causes sepsis
Any infection can trigger sepsis examples: - Meningitis - Small infected cut - UTI
what are common sites of infection to trigger sepsis?
Lungs - 64%
Abdomen - 20%
Bloodstream - 15%
Urinary system - 14%
what sort of micro-organism infections trigger sepsis
○ Gram positive bacteria - 47% § Staph aureus - 20% ○ Gram negative bacteria - 62% ○ Fungal - 19% § Candida- 17% □ Candida blood stream infections associated with higher ICU mortality compared with bacterial infections
what factors cause some infections to progress to sepsis
Mechanisms not fully understood
Involves a combination of microbial and host factors
what microbial factors cause some infections to progress to sepsis
Microbial factors Factors that help microbes to attach colonise and invade our tissues and cause disease ○ Virulence factors § LPS § Lipoteichoic acid § Peptidoglycan § Pili, fimbriae, capsule etc ○ Virulence contributes to pathogenicity Ability to cause disease
what host factors cause some infections to progress to sepsis
○ Innate immunity ○ Adaptive immunity ○ Immuno-compromised § HIV/AIDS § Cancer § Autoimmunity § organ transplantation § Immune function impaired in any way will affect the body's ability to fight infection ○ Pre-existing chronic conditions § Diabetes § Cirrhosis § CKD ○ Age ○ Genetics
what is the outcome of infection (pathogenicity) determined by?
Outcome of infection (pathogenicity) is determined by interactions between microbes and host immune response
what is involved in host-microbial interactions
microbial colonisation
- antigens
- virulence factors
immune response
- innate
- adaptive
what happens when the host has a weakened / compromised immune response
the microbial colonisation uses it’s competitive advantage and are more pathogenc
what population are more likely to get sepsis?
• Most common among aging population ○ 65% of sepsis cases in US • Sepsis disproportionately affects medically and immune compromised patients ○ Cancer ○ Cirrhosis ○ Autoimmunity ○ HIV / AIDS ○ Organ transplantation ○ Diabetes
what is included in the pathophysiology of sepsis
• Dysregulated, excessive systemic inflammation
○ Leads to organ dysfunction
• Body wide blood clotting and leaky vessels
○ Leaks into tissues
• One or more organs begin to fail (sepsis - 10% in hospital mortality)
• Persistent hypotension (septic shock - 40% in hospital mortality)
what is acute inflammation in response to localised infection
- A protective immune reaction to invading micro-organisms or endogenous signals from damaged cells
- Gives rise to cardinal signs of inflammation - localised to the site of infection
- Leading to clearance of the source of injury and necrotic tissues
- Followed by tissue repair and return to homeostasis
what happens with the innate immune system?
- Innate immune system recognises PAMPs (and DAMPs) through PRRs
- Responding cells trigger inflammation through release of cytokines and chemokines
- Cytokines activate endothelial cells, vasodilation and vascular permeability
- Large amounts of cytokines (eg TNFa) activate acute phase proteins in the liver, platelet activation and symptoms of fever
- Activation of complement
what happens in the resolution of inflammation
• In most cases, the pathogen is eliminated
• Resolution of inflammation is an active process
• Involving several regulatory mechanisms
• Immune suppression via anti-inflammatory mediators
○ IL-10
○ TGF-beta
§ Activated during this period
• In sepsis, the immune response fails to eliminate the pathogen
○ Pathogen persists and can spread through the blood
• Localised acute inflammation progresses to acute systemic inflammation
