Pharmacology - IV fluid therapy

Question 1

what percent of the body is TBW

Answer 1

60%, 40% ICF and 20% ECF (made of interstitial fluid and plasma)

Question 2

equation for osmotic pressure…

Answer 2

n x c(c/m)RT

Question 3

what is osmolality?

Answer 3

The measure of solute concentration per unit MASS of solvent. Number of osmoles of solute/kg. 1 osmole contains 6.02 x 1023 particles, Body fluids measured in millimolar concentrations (mosm/kg)

Question 4

what is osmolarity?

Answer 4

The measure of solute concentration per unit VOLUME of solvent. Number of osmoles of solute/litre. Estimated osmolarity of body fluids can be calculated, 2([na+] + [k+]) + urea + glucose

Question 5

what is normal plasma osmolarity?

Answer 5

298mosm/L

Question 6

what is the daily maintainance requirement for iv fluids, in terms of fluid and electrolytes?

Answer 6

water = 30ml/kg, Na = 1 mmol/kg, K = 1 mmol/kg, Glucose = 50-100 g

Question 7

what is Tonicity?

Answer 7

The measure of the osmotic pressure gradient between two solutions. Tonicity = effective osmolality, Only particles restricted to one of the compartments will determine water distribution, Particles which move freely will not influence water distribution ECF>Na, ICF>K and macromolecules.

Question 8

if a soultion is hypertonic…

Answer 8

cells will dehydrate

Question 9

if a solution is hypotonic…

Answer 9

cells will swell

Question 10

what are Crystalloids?

Answer 10

aqueous solutions of mineral salts or other water-soluble molecules, cheap, non-allergenic, ECF expansion, (oedema, inceased vascular pressure), high Na load - may cuase hypernatraemia, useful in acute dehydration, resus.

Question 11

what are Colloids?

Answer 11

contain larger insoluble molecules, such as gelatin; blood itself is acolloid, Anaphylaxis, Coagulopathy, Renal failure, rheology

Question 12

give egs of Crystalloids

Answer 12

dextrose, saline, hartmanns solution, plasmalyte

Question 13

give egs of Colloids

Answer 13

gelatins, starches, albumin, blood products.

Question 14

what is dextrose?

Answer 14

Simple sugar. Total Body Water, Moves through all compartments, Not useful for Blood volume expansion, Zero sodium load, isotonic. For Chronic Dehydration and
Hypernatraemia

Question 15

what does saline contain?

Answer 15

Nacl 0.9% give at 100ml/hour, Contains - Sodium 154 mmol/l – 10% higher than ECF, Choride 154 mmol/l – 50% higher than ECF

Question 16

how much fluid (Slaine) is given for maintainance

Answer 16

30ml/kg/24hrs (20-25ml in frail & elderly), Never give over 100ml/hr due to risk of hyponatraemia

Question 17

how much and what is given for replacement?

Answer 17

PlasmaLyte 148

Question 18

questions to ask when giving fluid replacement…

Answer 18

pt volume status? Need for iv fluids? How much? What type?

Question 19

what happens if the pt is HYPOvolaemic?

Answer 19

Feels nauseous, thirsty, Flat veins, Cool peripheries, No sweat, Low or postural BP and high HR, Concentrate oliguria, Responds to SLR = give fluids

Question 20

what happens if the pt is HYPERvolaemic?

Answer 20

Feels breathless, not thirsty, Veins distended, Warm and oedematous extremities, Sweaty, High BP and High HR, Dilute urine (could be oliguric or polyuric) = give diuretics

Question 21

what helps workout how much fluid is needed due to water defecit?

Answer 21

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

Question 22

what are insensible losses?

Answer 22

sweat, ventilation, open wounds, burns, bleeding. Normal daily loss = 400-800mls in adults.

Question 23

what are the 5 R’s?

Answer 23

resus, routine maintainance, replacement, redistribution, Reassessment.

Question 24

CASE 1

Answer 24

30 year old female, 49kg, Elective hysterectomy (low blood loss), Plasmalyte intraoperatively, Post op fluids: 0.18% saline/4% dextrose @ 62.5ml/hr, Speeded-up because of nausea (5L given over 16 hours [312.5ml/hr], Tailor iv fluid to compartment requiring filling, Excess hypotonic fluid in a patient secreting adh
Assume sodium of 138 at end of operation, 5l dextrose/saline (4l 5% dextrose + 1l 0.9% saline), Tbw = 55% of 49kg = 27l; ecf (before fluid) 9L, Saline distributes only in ecf. Water will fill all compartments, Ecf following fluid = 9l + 1l (saline) + 1.3 = 11.3l, Na content before fluid = 9 x 138mmol/l = 1242mmol/l, Na content after fluid = (9l X 138) + (154 in 1l 0.9% saline) = 1396mol/l, [na] after fluid = 1392/11.3 = 123mmol/l