3- Sepsis Flashcards
(36 cards)
Define sepsis
Life threatening organ dysfunction due to a dysregulated host response to infection
Describe the mechanism of sepsis
when a microbe enters the body, host defence systems produce mediators to activate the immune system to limit spread of microbes
- activation of inflammatory cascade leads to activation of coagulation and fibrin deposition
- body responds to infection by injury to its own tissues/ organs
What 2 things does sepsis cause?
- shock
- multiple organ failure and death
What is the MAIN cause of sepsis?
gram negative bacteria eg E. coli
-have lipopolysaccharides eg LPS
main cause of developing sepsis
How do gram negative bacteria cause sepsis?
- their LPS activates macrophages and natural killer cells
- macrophages and NK cells activate a positive feedback loop which AMPLIFIES immune response so that innate immune system can respond quickly and strongly to local infection
What are the 3 main steps of managing sepsis ( general)
1) Identify sepsis
2) Categorise sepsis
3) Initiate treatment
How do you categorise sepsis?
RHLRBV
Royal High Lilacs Robust Brew Venture
by the SOFA criteria
Sequential Organ Failure Assessment ( in ITU patients)
SOFA= suspected infection+ change in more than 2 of below from baseline:
1) RESP: pO2/ FiO2 ratio
2) HAEMATOLOGY: platelet count
3) LIVER: serum bilirubin
4) RENAL: serum creatinine eg urine output
5) BRAIN: Glasgow Coma Scale
6) CVS: hypotension
vasopressor requirement
What is SIRS?
Why is it no longer recommended?
Systemic Inflammatory Response Syndrome
- certain abnormalities of vital signs and lab results
- used previously to identify early sepsis
-no longer recommended because
poor sensitivity
poor specificity
How do you initiate treatment for sepsis? ie within 3 HOURS
MOAA
should complete within 3 hours
1) Measure lactate level
2) Obtain blood cultures prior to admin of antibiotics
3) Administer broad spectrum antibiotics
4) Administer 30 ml/kg crystalloid if
-hypotension
or
-lactate 4mmol/L or more
What treatment steps do you follow up within 6 HOURS
5) App vasopressors for hypotension that does not respond to initial fluid resuscitation
to maintain MAP> 65mmHg
6) if hypotension is persistent, re-assess volume status and tissue perfusion
7) Re-measure lactate if initial lactate is elevated
What is septic shock?
- severe abnormalities of circulation and/or cellular metabolism
- persistent hypotension
- high mortality
What 2 processes are involved in sepsis?
Immune sytem
Coagulation cascade
What role does the immune response play in sepsis? ( 5 steps)
-activation of signalling cascade
-recruitment
-increased expression of cytokines
-causes acute inflammation
and stimulation of adaptive immunity
What vascular changes occur in sepsis?
- vasodilation
- vascular permeability
- increased adhesion of WBC’s
What cellular events occur in sepsis?
cellular recruitment and activation of neutrophils (PMN’s)
-neutrophil migration to injury site and therefore vascular permeability increases
What happens overall from sepsis to arteries?
- warm shock
- arteries and arterioles dilate,
- decreasing peripheral arterial resistance
- cardiac output typically increases
What is ABSOLUTE HYPOVOLAEMIA?
- reduction in circulating volume relating to blood or plasma loss
- blood volume is smaller
What results from absolute hypovolaemia?
MAP= TPR X CO ( HR X SV)
-decrease in systemic vascular resistance
(remember MAP formula)
-thus decrease in BP
baroreceptors get activated and thus you get
COMPENSATORY TACHYCARDIA
How do you get organ failure from sepsis?
- poor capillary flow and capillary obstruction by micro thrombi
- therefore decreased oxygen delivery
- impaired CO2 and waste removal
- decreased perfusion causes organ dysfunction
How does decompensated shock occur?
-reduced circulating volume caused by capillary leakage
ie reduced venous return
therefore:
-reduced cardiac output
-reduced BP falls even FURTHER
-reduced flow to organs
typical features of shock appear
Describe the effect of shock on the lungs?
-increased resp rate ie tachypnoea
-rapid breathing
-SOB ie dyspnoea
-surfactant dries out——–> stiffening of lungs——>ARDS
(diffusion in alveoli also decreases)
What is ARDS?
Acute Respiratory Distress Syndrome
How does sepsis affect tissues?
-you get anaerobic respiration in tissues
cells use pyruvate therefore lactic acid builds up
-decreased pH
-metabolic acidosis
-body responds by increasing resp rate
How does sepsis affect the brain? (6)
- confusion
- raised blood sugar
- increased gluconeogenesis and insulin resistance
- inhibition of tissues’ ability to uptake glucose
- caused by CRP; inflammation marker
- Low blood volume; increased vascularisation ; can lower body temperature ( not always raise it)
