Sepsis Flashcards
1
Q
Sepsis - Definition
A
- Infection = the detrimental colonization of a host organism by a microbe
- SIRS (systemic inflammatory response syndrome)
- Defined as two or more of:
- Temperature >38°C or <36°C
- Heart rate >90bpm
- Respiratory rate >20 or Pa CO2 <4.3 kPa
- White cell count >12 or < 4 x 109 cells/L
- Defined as two or more of:
- Sepsis =
- Clincal evidence of an infection plus evidence of a systemic reponse to infection (i.e. SIRS)
2
Q
Sepsis - Defining Severity
A
- Infection + SIRS ==>
- Sepsis
- Sepsis + hypoperfusion or organ dysfunction **or **hypotension ==>
- Sever sepsis
- Severe sepsis + hypotension refractory to fluid ==>
- Septic shock
3
Q
Sepsis - Initial Pathogenesis
A
- Immune system cells bind bacteria via toll-like pattern recognition receptors
- ==> Release of inflammatory mediators:
- Lipid mediators of inflammation:
- Prostaglandins
- Leukotrienes
- Platelet activation factor (PAF)
- Pro-inflammatory cytokines e.g.:
- TNFalpha
- IL-1
- IL-6
- Activation of secondary mediators (amplified response):
- Complement system
- Coagulation cascade
- Nitric oxide
- Acute phase protein
- Activation of secondary mediators (amplified response):
- Lipid mediators of inflammation:
- ==> Release of inflammatory mediators:
- Also complement activated directly by interaction with bacteria via alternative pathway (complement pathogen binding) ==>
- Opsonisation of pathogen
- Lysis of pathogen
- Recruitment of inflammatory cells
4
Q
Sepsis - Vascular Changes
A
- Platelet activation factor (PAF) causes increased platelet aggregation and adhesion
- TNF-alpha & C5a cause increased vascular permeability
- Nitric oxide causes loss of contractility of vascular smooth muscle
5
Q
Sepsis - Coagulopathy
A
- Increased PAF leads to platelet adhesion to vascular endothelium
- TNF-alpha and IL-1 cause release of tissue factor (thromboplastin) from endothelial cells leading to activation of the coagulation cascade ==> disseminated intravascular coagulation
- Together ==> occlusion of microcirculation causing hypoperfusion and then organ failure
6
Q
Sepsis - Cardiac Changes
A
- Initial high cardiac output
- ==> Classic ‘bounding pulse’ of sepsis
- As cardiac muscle becomes affected by organ hypoperfusion and toxic products cardiac output falls
- Patient becomes cold, clammy, resembling patient with cardogenic shock
7
Q
Sepsis - Immunosuppression
A
- Initial release of cytokines ==> intense inflammation
- Later compensatory rise in anti-inflammatory cytokines e.g. IL-10 brings inlammation and immunity down to a sub-normal state
8
Q
Sepsis - Tissue Damage
A
- Toxic substances released by cells of the immune system
- Nitric oxide
- Oxygen radicals
- Enzymes
- Toxic substances released by pathogens
9
Q
Sepsis - Epidemiology
A
- Accounts for 2-11% of all admissions to hospital
- Principal cause of death on Intensive Care Units
- Mortality
- Severe sepsis 30%
- Septic shock 60%
10
Q
Sepsis - Risk Factors for Severe Sepsis
A
- Immunosuppression
- Comrobidity
- Extremes of age: old or young
- Invasive devices
- Vascular
- Surgical
- Ventilatory
- Use of antimicrobials
11
Q
Sepsis - Signs And Symptoms - Systemic Inflammatory Response Syndrome
A
- 4 criteria:
- Temperature >38ºC or <36ºC
- Tachycardia
- Tachpnoea
- WCC >12 or <4
- Other markers:
- Raised CRP
- Decreased platelets
- Future markers
- Procaltinonin
- Differentiates response to bacterial infection from response to other pathogens
- Procaltinonin
12
Q
Sepsis - Signs and Symptoms - Hypoperfusion
A
- Early signs
- Respiratory alkalosis
- Oliguria
- Later signs
- Increased lactate - metabolic acidosis
- Decreased capillary refill
13
Q
Sepsis - Signs and Symptoms - Organ Dysfunction Due To Hypoperfusion
A
- Brain:
- Altered consciousness
- Confusion
- Lethargy
- Psychosis
- Agression/agitation
- Heart:
- (Tachycardia)
- Hypotension
- (Reduced capillary refill time)
- Respiratory:
- (Tachpnoea)
- Hypoxia
- Acute respiratory distress syndrome
- Liver:
- Jaundice
- Raised LFTs
- Decreased albumin
- Raised prothrombin time
- Kidneys:
- Oliguria
- Raised creatinine
- Raised urea
- GI:
- Abdominal pain
- Ileus
14
Q
Sepsis - Golden Hour
A
- Early recognition and intervention is associated with a reduced mortality due to sepsis
- In the golder hour:
- Optimise oxygen delivery to the tissues
- Interupt the cycle of hypoperfusion⇔tissue damage
15
Q
Sepsis - Treatment - Resuscitation
A
- Fluid resuscitation
- Oxygen +/- ventilation
- Vasopressor agents (in high cardiac output phase)
- Inotropic agents (in cardiac depression stage)
