Intravenous Fluids

Question 1

Define diffusion

Answer 1

movement of solute from high concentration to low concentration. Membrane has to be solute permeable

Question 2

Define osmosis

Answer 2

movement of water from high concentration to low concentration. membrane has to be solute impermeable

Question 3

Define osmolarity

Answer 3

the measure of solute concentration per unit volume of solvent

Question 4

Define osmolality

Answer 4

the measure of solute concentration per unit mass of solvent

Question 5

Define tonicity

Answer 5

the measure of the osmotic pressure gradient between two solutions

Question 6

Describe the fluid components of a 70kg man

Answer 6

42 l water
2/3 28l intracellular
1/3 14l extracellular - 3l is intravascular

Question 7

what solutes are found in plasma

Answer 7

HPO4^2-
Cl-
protein
bilirubin
Mg2+
K+
Na+
urea

Question 8

daily requirement of water

Answer 8

25-30ml/kg

Question 9

daily requirement of sodium

Answer 9

1mmol/kg

Question 10

daily requirement of potassium

Answer 10

1mmol/kg

Question 11

daily requirement of glucose

Answer 11

50-100g

Question 12

what questions do you need to ask before prescribing fluids?

Answer 12

patients volume status
do they need IV fluids
how much
type of fluid

Question 13

describe a euvolaemic patient

Answer 13

feels well, not thirsty
veins well filled
warm extremities
mild sweat
normal BP and HR
normal urine

Question 14

describe a hypovolaemic patient

Answer 14

feels nauseous, thirsty
flat veins
cool peripheries 
no sweat
low or postural BP and high HR
concentrate oliguria
responds to SLR

Question 15

what are the fluid needs in a hypovolaemic patient?

Answer 15

low BP - resus fluids

rehydration fluids

Question 16

describe a hypervolaemic patient

Answer 16

feels breathless, not thirsty
veins distended
warm and oedematous extremities
sweaty
high BP and HR
dilute urine - may be oliguric or polyuric

Question 17

what are the fluid needs in a hypervolaemic patient?

Answer 17

no more fluids
possibly diuretics if resp compromise
haemofiltration (if anuric)

Question 18

how can you work out the water deficit of a patient?

Answer 18

catheters, drains
input charts
vomit bowls
sputum pots
stool charts and stoma losses

Question 19

how do you work out the insensible losses?

Answer 19

sepsis - sweat
ventilation
open wounds
burns
bleeding

Question 20

what is a resuscitation fluid?

Answer 20

IV fluids urgently to restore circulation with hypovolaemia

Question 21

what are routine maintenance fluids?

Answer 21

IV fluids if cannot take orally or enterally to meet patient maintenance requirements

Question 22

what are replacement fluids?

Answer 22

some don’t need IV resus but do need IV additional to maintenance to correct existing deficit or ongoing abnormal external losses e.g. diarrhoea, fever

Question 23

what are redistribution fluids?

Answer 23

some patients have abnormal internal fluid redistribution or abnormal fluid handling, particularly with sepsis, or major illness, cardiac, liver or renal disease e.g. tissue oedema, GIT/thoracic/peritoneal collection

Question 24

describe dextrose and its uses

Answer 24

total body water
moves through all compartments - not useful for blood volume expansion
0 Na load, isotonic
useful - chronic dehydration, hypernatraemia

Question 25

when is dextrose NOT useful?

Answer 25

resus

low albumin

Question 26

describe crystalloids and their uses

Answer 26

utilitarian, comes in various combinations
remain in ECF
usually high Na load - can cause problems over time
uses - acute dehydration, AKI, resus

Question 27

when are crystalloids NOT useful?

Answer 27

long term maintenance,

hypernatraemia

Question 28

decribe the colloids (plasma expanders) and their uses

Answer 28

stay in IVS
Blood and TPN are colloids
IV albulin sometimes used in cirrhosis
liver patients
select intraoperative