Week 5: IV Fluids

Question 1

What is the O2 dissociation curve of blood?

Answer 1

Relationship between PaO2 and Sa O2
Amount of O2 dissolved in blood (PaO2), compared to O2 saturation
PaO2 80 or above does not increase SaO2 much (>95%), however below 60-70 causes a precipitous drop

Question 2

What is the function of water in the body?

Answer 2

Transport: nutrients, O2, CO2, electrolytes, metabolic waste, etc between fluid compartments, cells, organs
Blood plasma (main component)
Temperature regulation
Lubrication
Shock absorption

Question 3

What are cations?

Answer 3

Positively charged ions

Na+, K+, Ca+2

Question 4

What are anions?

Answer 4

Negatively charged ions

HCO3-, Cl-

Question 5

How do electrolytes move between cells?

Answer 5

Diffusion
Facilitated diffusion
Active transport

Question 6

What is diffusion?

Answer 6

Movement of molecules from an area of high to low concentration

Question 7

What is facilitated diffusion?

Answer 7

Movement of a molecule down its concentration gradient assisted by a protein carrier (e.g insulin and glucose)

Question 8

What is active transport?

Answer 8

Movement of molecules against its concentration gradient. This process requires energy (ATP) e.g. sodium/potassium pump

Question 9

How does water move between fluid compartments?

Answer 9

Osmosis

Filtration

Question 10

What is osmolality?

Answer 10

Osmolality is a measure of the concentration of particles in plasma

Question 11

What is the normal serum osmolality?

Answer 11

275 –295 mOsm/kg

Question 12

What is osmosis?

Answer 12

Osmosis is the movement of water across a semi permeable membrane from an area of high water concentration to an area of lower water concentration

Question 13

How does protein relate to osmosis?

Answer 13

Albumin found in intravascular space
Major determinant for movement of water from interstitial space to intravascular compartment
Low albumin –> water moves into interstitial space (oedema)

Question 14

What is an isotonic solution?

Answer 14

Concentration inside and outside cell is the same
No net movement of fluid inside or outside cell
Osmolarity: 270 -300 mOsm/L

Question 15

What is a hypotonic solution?

Answer 15

Higher soluter concentration inside cell
Water moves form IVS to ICS
Cell swells
Osmolarity: < 270 mOsm/L

Question 16

What is a hypertonic solution?

Answer 16

Higher solute concentration outside cell
Fluid shifts from ICS to IVS
Cell shrinks
Osmolarity: >300 mOsm/L

Question 17

What is hydrostatic pressure?

Answer 17

Water moves between compartments by filtration
Filtration: water moves from areas of high pressure to low
Arterial end of capillaries: water moves out of capillary into interstitial and intracellular compartment

Question 18

How does hydrostatic pressure cause pulmonary oedema?

Answer 18

HF –> build up of blood in pulmonary capillaries –> increased hydrostatic pressure –> fluid forced into interstitial compartment –> PO

Question 19

How does hydrostatic pressure cause peripheral oedema?

Answer 19

Venous insufficiency in lower limbs –> increased hydrostatic pressure –> fluid forced into interstitial compartment –> peripheral oedema

Question 20

What is oncotic pressure/colloid osmotic pressure?

Answer 20

Protein molecules attract water, pulling fluid into vascular space

Question 21

What is net filtration pressure?

Answer 21

The added up pressure of net hydrostatic pressure and net oncotic pressure. Can be positive (arterial) or negative (venous)

Question 22

How is water balance controlled?

Answer 22

Water homeostasis: balance between fluid intake and excretion
Controlled by neurohormonal systems: ADH, RAAS system, ANF

Question 23

What are types of crystalloid IV fluids?

Answer 23

0.9% NaCl
5% dextrose
Glucose 4% in 0.18% NaCl
Hartmann's
Plasmalyte

Question 24

What are crystalloids?

Answer 24

Water with electrolytes

Question 25

What are types of isotonic IV solutions?

Answer 25

0.9% NaCl
Glucose 4% in 0.18% NaCl
Hartmann’s
Plasmalyte

Question 26

What is Hartmann’s solution?

Answer 26

Similar in composition to normal plasma except that it does not contain Mg+2

Question 27

What is Hartmann’s used for?

Answer 27

Losses from burns and lower GI tract
Peri-op fluid
Mild metabolic acidosis (lactate converted to bicarb)

Question 28

What are the contraindications for Hartmann’s?

Answer 28

Alkalosis

Liver impairment

Question 29

What are types of hypotonic solutions?

Answer 29

0.45% NaCl

5% dextrose in water (once dextrose is metabolised and only free water remains)

Question 30

What are types of hypertonic solutions?

Answer 30

Dextrose 5% in 0.9% NaCl
Dextrose 10% in water
Mannitol 10% and 20% in water
3% NaCl

Question 31

What are the types of protein colloid solutions?

Answer 31

Albumin

Gelatin solutions

Question 32

What are the types of non-protein colloid (starch) solutions?

Answer 32

Dextran

polygeline

Question 33

Why are colloid solutions used?

Answer 33

Expand plasma volume to a greater extent than crystalliods

Question 34

What are the issues with using colloid solutions?

Answer 34

Expensive
Coagulopathywith some of the starches
Anaphylaxis
HES –increased risk of death

Question 35

What are the different types of blood products?

Answer 35

Whole blood
Packed cells
Platelets
Fresh frozen plasma

Question 36

What are the phases of fluid resuscitation?

Answer 36

Salvage
Optimisation
Stabilisation
De-escalation

Question 37

What is the salvage phase of resuscitation?

Answer 37

Symptomatic hypovolaemia
Most resuscitation fluid administered in this stage
Crystalloid
Blood
Permissive hypotension

Question 38

What is the optimisation phase of resuscitation?

Answer 38

Smaller volumes of resuscitation fluid

Accumulation of fluid in the interstitial space