6b.) Fluid Replacement Therapy Flashcards
Describe distribution of bodily fluids in average male and female adult; explain the difference
Men have more muscle (whereas women have more fat) and muscle holds more water than fat
Describe the composition of electrolytes in:
- Plasma
- Interstitial fluid
- Intracellular fluid
What is tonicity?
A measure of the effective osmotic gradient between two fluids separated by a semi permeable membrane. Influenced only be solutes that cannot cross membrane.
It is describing what a fluid will do to cells.
Why can’t you give pure water as an IV fluid?
Osmolality of pure water is 0mOsm/kg.Osmolality of plasma 275 - 295 mOsm/Kg. Pure water would therefore be a hypotonic solution and cause water to move from plasma into RBC and cause swelling which will lead to haemolysis
State one key difference between tonicity and osmolality in terms of particles in solute
- Tonicity: dependent just upon those particles which exert osmotic force (e.g. those which can’t penetrate membrane)
- Osmolallity: dependent on all particles in solute
e.g. Everywhere except in kidneys (where urea is an effective osmole) urea contributes to osmolality but not to tonicity as it can freely move across membranes
Osmolality in intracellular, interstitial and intravascular space must be equal at any one time as water moves freely between the compartments; true or false
True
What happens if you give a patient isotonic saline fluids?
Isotonic fluids- there is no osmotic pressure gradient between the fluid and intracellular space- henc eno water moves into intracellular space.
Saline fluid is only added to extracellular space; distributes itself evenly between interstitium and plasma in proportion to their starting volumes
What is colloid IV fluid?
IV fluid containing osmotic/oncotic pressure due to presence of large molecules.
If oncotic pressure in infused fluid exceeds that in plasma it can pull water from interstitial space into intravascular space
What % of body weight is accounted forby water in infants?
Why?
73%
Dehydration more of an issue and hard to treat
?WHY??
What % of body weight is accounted for by water in the elderly?
45%
Once older, distribution for men and women usually same. Amount decreases as muscle mass decreases
Why do patients need intravenous fluids?
- NBM
- Malfunction GI tract
- Dehydration
- Abnormal electrolytes
Maintenance fluids need to replace standard daily losses; state the standard daily losses for:
- Urine
- Sweat
- Water
- Sodium
- Potassium
- Chloride
- Glucose
What is the maximum amount of potassium chloride you can give per hour?
10mmol
State 4 main types of IV fluid and discuss whether each is good for increasing intravascular volume
- Crystalloid: relatively low tendancy to stay intravascular
- Colloid: relatively high tendancy to stay intravascular
- Electrolyte free water: (contains glucose) spreads evenly between all 3 so bad at increasing intravascular volume- use to quickly bring down serum osmolality or hypoglycaemia
- Blood
What is the normal osmolality of normal saline/0.9% saline?
308mOsm/kg
Considered isotonic
If someone is hypotenisve due to hypovolaemia what IV fluid would we give them?
0.9% saline
What is Hartmann’s solution?
IV fluid solution that is most similar to plasma
Describe the fluid distribution if you give a patient Hartmann’s solution
Hartman’s is isotonic to plasma hence stays extracellular
Describe the fluid distribution if you give a patient D5W (1000ml with 5% dextrose)
Desribe the fluid distribution if you give 1000ml of 4% dextrose/0.18% saline
NOTE: effectively 200ml 0.9% saline, 800ml of 4% dextrose
For the following fluids state osmolality
- 5% dextrose
- 4% dextrose/0.18% saline
- 0.9% saline
- Hartmann’s solution
State whether 5% glucose is:
- Hypertonic, isotonic or hypotonic
- Hyperosmolar, isosmolar or hyposmolar
- Isotonic
- Isosmolar
State whether 0.45% NaCl/4% glucose is:
- Hypertonic, isotonic or hypotonic
- Hypertonic
State whether NaCl 0.9% is:
- Hypertonic, isotonic or hypotonic
- Isotonic
