What is the definition of hypotension?
BP too low to perfuse tissues
< 90 / 60 mmHg or 40 below normal
How does hypotension come about in sepsis?
Bacteria produce toxins
Toxins cause cytokine production
Cytokines cause VASODILATION and leaky capillaries > REDUCED BLOOD VOLUME
BP = CO x TPR
What is a cytokine which causes hypotension in sepsis?
What does hypotension cause in sepsis?
Hypoperfusion of organs
=> ORGAN DAMAGE due to ISCHAEMIA and LACTIC ACIDOSIS
How does lactic acidosis exacerbate sepsis?
Reduces cardiac output by reducing contractility of heart muscle
Cells can't function outwith their optimum pH
What is a renal problem caused by hypoperfusion in sepsis?
Acute kidney injury (AKI)
What are clinical signs of hypovolaemia?
Cold peripheries, skin turgor, clammy
Hypotension (including postural)
Dry mucuous membranes
Poor urine output
Why does heart rate increase in sepsis?
Attempt to compensate for reduced BP
Why does respiratory rate increase in sepsis?
Increased oxygen requirement of cells
Attempt to compensate for metabolic acidosis
What is the normal level of lactate in the blood?
< 1.8 mmol/l
What does an elevated lactate indicate?
Widespread anaerobic respiration
i.e widespread hypoperfusion --> hypoxia
A lactate level of > ___ mmol/l is abnormal.
> 4 mmol/l
How is urine output measured?
Directly (less accurate)
Catheter bag (more accurate)
What is the minimum healthy urine output for a patient?
which translates to about 30ml/hr in an adult
In sepsis, ____ suggests renal hypoperfusion.
< 0.5 ml/kg/hr
What fluids are given to patients with sepsis?
0.9% NaCl, Hartmann's solution
Crystalloids (gelofusin, blood transfusions) - don't redistribute into soft tissue, "maintain oncotic pressure"
What is a small risk of using colloid fluids e.g gelofusin?
What are some risks of blood transfusions?
Infection - e.g Hepatitis C
Transfusion reactions - Type II hypersensitivity, antibody-mediated reaction against RBCs
What is a fluid challenge?
Initial resuscitation to replace water and salt
Repeat 500ml boluses of 0.9% NaCl or Hartmann's, reassess vitals until resuscitated
How much fluid is usually required to resuscitate someone?
It's always better to give too ___ than too ___ fluid.
What are the risks of
a) fluid overload
a) Pulmonary oedema, treat with diuretics
b) Organ hypoperfusion, failure and death
What changes in monitoring should be seen after fluid resuscitation?
Increased urine output
If a patient is still hypotensive after fluid resuscitation, what are they in?
What is the cause of the persistent hypotension?
Low TPR due to vasodilation
Rx: vasopressors (adrenaline, noradrenaline) which cause vasoconstriction and increased myocardial contractility
What receptors do
b) noradrenaline act on?
Adrenaline is a mixed alpha/beta agonist
Noradrenaline acts on alpha receptors only
What is the target MAP in septic shock?
> 65 mmHg
How are inotropes given to someone in septic shock?
Central venous catheter
What is the target urine output for someone in septic shock?
> 30 ml/hr
i.e > 0.5ml/kg/hr in a 60kg person