Sepsis Flashcards
What is severe inflammatory response syndrome (SIRS)?
- Exaggerated repsonse to stressor
- May be infection, trauma, burns, ischaemia
- Not all SIRS is infection or sepsis
- Characterised by temperature dysregulation
- Can affect any organ system
What are the core diagnostic features for SIRS?
- Hyper/hypothermia
- Tachycardia
- Leukocytosis/penia
- Tachypnoea
2 or more required for diagnosis
What is shock?
- Life threatening circulatory failure
- With inadequate delivery or utility of oxygen to meet metabolic needs
How do we classify shock?
- Hypovolaemic
- Cardiogenic
- Obstructive
- Distributive
- Other: cytotoxic, anaemia, hypoxia
Why is there cardiovascular compromise in shock?
-
Loss of capillary integrity
- loss of intravascular volume
- preload reduced
-
Vasodilatation
- NO synthase induced by cytokines and endotoxin
- direct vasc sm muscle response to acidosis + hypoxia
- other vasodilatory mediators
-
Reduced cardiac output
- cardiac output often normal or high in sepsis
- some pts may have impaired cardiac fxn as a result of sepsis
What is infection?
Invasion of normally sterile tissue by organisms resulting in pathological effects
What is sepsis?
Life-threatening organ dysfunction caused by dysregulated host response to infection
What is septic shock?
- Sepsis with physiological disturbance so profound as to substantially increase mortality
- Inadequate tissue perfusion despite adequate fluid resuscitation
- Vasopressors required to maintain MAP > 65mmHg
- Lactate > 2mmol/L
What are risk factors for sepsis?
- Very young
- Frail/elderly
- Recent surgery or trauma < 6 wks
- Impaired immunity (illness/immunosuppression)
- Indwelling catheters/lines
- IV drug use
- Breaks in skin integrity
What are possible sources of infection, for sepsis?
- Upper resp tract
- Lower resp tract
- Urinary tract
- Skin
- Abdomen
- Central nervous system
What is the qSOFA score?
- Resp rate > 22
- Altered mentation
- SBP < 100 mmHg
Score _>_2 indicates increased mortality risk
What are examples of organ dysfunction, due to sepsis?
- Respiratory failure → ARDS
- Circulatory failure → MI, hypovolaemia
- Acute kidney injury
- Liver failure
- Haemostatic failure → DIC
- ‘Brain failure’ → encephalopathy
Biomarkers in sepsis: What are key features of CRP?
- Capsular-Reactive Protein (CRP)
- First pattern recognition protein discovered
- Binds to surface of dying cells + some bacteria
- Induces complement system, promoting phagocytosis
- Produced in the liver, in response to inflammation (IL-6)
- Not always the most useful as released in any inflammatory response (eg. SIRS)
Biomarkers in sepsis: What are key features of Pro-calcitonin (PCT)?
- Pre-cursor of calcitonin
- Acute phase reactant
- Produced in adipocytes in inflammatory states (IL-6)
- More specific to bacterial infection (sens 77%; spec 79%, ie will miss 1 in 5 infections if only PCT used)
- Use in decision making may reduce mortality and inappropriate antibiotics (not strong evidence)
How easy is diagnosing sepsis?
- Clear criteria for identifying the ‘dysregulated host response’ → qSOFA + SIRS
- But there’s no reliable biomarker
- Host response is dysregulated in a number of clinical conditions (burns, pancreatitis, major trauma)
Stevens et al → diagnosing infection (and sepsis) is really hard
How do you manage a patient with sepsis?
- ABC approach
- Sepsis 6
What are the sepsis 6?
- Take blood cultures
- Start broad spectrum antibiotics
- Give oxygen (aim 94-98%)
- Measure lactate and haemoglobin and accurate hourly urine output
- Give IV fluid challenges
- Source control also important, where applicable
Do these within 1 hour
Where does lactate come from in sepsis?
- Anaerobic metabolism: Pyruvate → lactate
- In presence of lack of oxygen
Lactate XS mechanisms:
- Increased anaerobic glycolysis
- Microvascular failure
- Mitochondrial dysfunction
Lactate production due to microvascular failure may be corrected with fluids, whereas the other two can’t
What are other causes of raised lactate?
-
Type A (inadequate oxygen delivery)
- tissue hypoperfusion (regional ischaemia eg. bowel)
- reduced O2 delivery (hypoxia, anaemia, CO poisoning)
-
Type B
- disease (pancreatitis, thiamine def, liver failure)
- drugs (venformin, metformin, cyanide, b-agonists)
- metabolic dysfunction
How useful is urine output as a feature for sepsis?
- Can be a useful marker of renal perfusion (as a surrogate of cardiac output)
- But can also be a useless marker of renal perfusion and cardiac output
When do you give fluids / what for?
Fluid resuscitation is important for sepsis
Which fluids are given for sepsis?
-
Sodium-based crystalloid
- Hartmann’s solution (sodium lactate, compound)
- Sodium chloride 0.9%
- Rarely a colloid
- Never glucose
- Never with ‘added’ potassium
What are principles for fluid resuscitation in sepsis?
- Administer fluid sufficient to increase cardiac filling
- Select a fluid and volume eg. Hartmann’s 250-500mL
- Administer as fast as possible - cardiac patients: reduce volume not rate
- Assess response (and discuss)
When prescribing, define a rate eg. 5 min (don’t write ‘stat’)
What drugs can be given if fluid resuscitation fails?
- Target mean arterial pressure = 65 mmHg
- First-line → vasopressors (adrenaline), alpha-adrenoreceptor agonist
- Second-line → vasopressin, V1 receptor agonism (inc vasc tone)
- Other drugs → adrenaline, increases chrono + inotropy alongside vasoconstriction, alpha + beta activity
- Other drugs → metaraminol, another alpha agonist, can be given peripherally
