Fluid Resuscitation Flashcards
1
Q
define hypotension
A
it is difficult to classify but generally
- a BP <90/60 mmHg
- >40 mmHg below normal
2
Q
how does hypotension occur in sepsis
A
- bacteria produce toxins which stimulate the immune system to produce cytokines eg TNF alpha
- these increase NO production in vascular smooth muscle which causes vasodilation
- fall in TPR, leads to a fall in BP = TPR x CO(=HR x SV)
- endothelial dysfuntion and capillary leak leads to decreased intravascular volume
3
Q
NO production
A
- continuously produced by vascular endothelium from amino acid L-arginine through NOS enzyme
- potent vasodilator, short action
- shear stress on vascular endothelium stimulates calcium release from vascular endothelial cells and activation of NOS
4
Q
consequences of hypotension
A
- Leads to hypoperfusion in tissues which causes hypoxia and organ dysfunction
- Hypoxia leads to anaerobic metabolism, which produces lactic acid as a byproduct
- This causes a progressive metabolic acidosis with a raised anion gap, which leads to detrimental effects:
5
Q
detrimental effects of metabolic acidosis
A
- exacerbates vasodilatation , reducing TPR further
- decreased myocardial contractility, reducing CO
- generalised impaired function of cells
6
Q
what does hypoperfusion cause in kidneys
A
acute kidney injury
7
Q
immediate fluid management - sepsis 6
A
- 500ml 0.9% saline STAT
- repeat boluses of fluid as required
8
Q
signs of hypovolaemia
A
- Cool peripheries (though may be warm)
- Clammy
- Dry mucous membranes
- Decreased JVP
- Tachycardia
- Hypotension, postural drop is evident first
- Skin turgor
- Mottling of skin
- Poor urine output
9
Q
monitoring of fluid
A
- HR, BP, RR
- Sepsis 6: serum lactate and urine output
10
Q
what is the normal serum lactate level
A
<1.8 mmol/L
11
Q
what does elevated lactate suggest
A
- tissue hypoperfusion/hypoxia - anaerobic metabolism
- in the context of sepsis, suggests severe illness or organ dysfunction as a result of tissue hypoperfusion
12
Q
how is urine output best monitored
A
- urinary catheter - more accurate and can give hourly volumes
- also option of recording urine volume
13
Q
normal urine output
A
should be at least 0.5ml/kg/hr
(heavier patients produce more)
anything less than this is oliguria
14
Q
what does oliguria indicate in sepsis
A
renal hypoperfusion
15
Q
crystalloid fluids
A
- eg 0.9% NaCl and Hartmanns solution
- cheap and widely available
