Topic 2 - Fluid Therapy And Transfusion Medicine

Question 1

What is the equation for Calculated Osmolalilty?

Answer 1

= 2 (Na+) + BUN mmol/L + Glucose mmol/L

Question 2

What is the difference between effective and ineffective osmoles?

Answer 2

Effective osmoles cannot cross cell membranes and are excluded from intracellular fluid (e.g. sodium). Ineffective osmoles can cross cell membrane and are unable to contribute to the osmotic pressure gradient (e.g. urea and glucose when insulin is present).

Question 3

What is the 60-40-20 rule?

Answer 3

60% BW is water, 40% BW is intracellular fluid, 20% extracellular fluid (broken down into interstitial and plasma)

Question 4

Traditional Starling’s Forces equation

Answer 4

J(v) = K (fc) [P capillary - P interstitium] - omega (pi capillary - pi interstitium)
The difference between the hydrostatic pressure in the capillary and the interstitial space less the difference between the oncotic pressure in the capillary and the interstitial space.

Question 5

What is the glycocalyx?

Answer 5

It is a gel matrix layer, made of glycoproteins and proteoglycans that covers the endothelium of all blood vessels. This layer varies with different organs.

Question 6

What are the functions of the endothelial glycocalyx?

Answer 6

1. Modulates inflammation, anti-inflammatory
2. Modulates haemostasis, anti-coagulant
3. Modulates shear stress
4. Modulates transcapillary fluid flux (modified Starling’s equation)

Question 7

Common causes of destruction of the glycocalyx

Answer 7

1. Hypervolaemia
2. Rapid administration of crystalloids
3. Hyperglycaemia
4. Surgery/trauma
5. Ischaemic or reperfusion
6. Cytokines (sepsis)

Question 8

What are the six perfusion parameters?

Answer 8

1. Pale mucous membranes
2. Prolonged CRT
3. Tachycardia
4. Low amplitude femoral pulses
5. Cool extremities
6. Obtundation

Question 9

What is the signs of interstitial fluid volume dehydration?

Answer 9

1. Decreased skin turgor, elasticity
2. Dry/tacky mucous membranes
3. Decreased tear film

Question 10

What is the delivery of oxygen equation?

Answer 10

DO2 = CO x CaO2 [(1.36xHCT x SaO2) + PaO2 x 0.003]

Question 11

How do mitochondria make energy? Equation

Answer 11

O2 + Glu -> CO2 + 36 ATP

Question 12

How much isotonic crystalloids is left in intravascular space after 30min?

Answer 12

1/4 amount

Question 13

What are the hormones that regulate Na balance?

Answer 13

Angiotensin II, aldosterone, catecholamines, atrial natriuretic peptide

Question 14

What are the hormones that regular water balance?

Answer 14

Vasopressin (ADH), atrial natriuretic peptide (ANP)

Question 15

Draw and describe the renin angiotensin aldosterone system

Answer 15

Draw as required

Question 16

What is the main hormone that regulates water balance?

Answer 16

Vasopressin (ADH) - produced in the hypothalamus, released into circulation at the level of posterior pituitary gland

Question 17

What is ADH stimulated by?

Answer 17

Hyper osmolarity, sensed by hypothalamus, hypovolaemia, hypotension, SNS, Angiotensin II

Question 18

What is the most common cause of hyponatraemia?

Answer 18

Loss of intravascular volume, compensatory mechanism to try and a result of ADH release. Note: cortisol inhibits ADH. Therefore Addison’s patients are hyponatraemic

Question 19

What is central pontine myelinosis? Related to hypo or hypernatraemia?

Answer 19

Commonly caused by hyponatraemia corrected too quickly — when the myelin sheath pulls away from the nerve. Signs start to appear in 2-3 days.

Question 20

How quickly should chronic hyponatraemia be corrected? ( mEq/L/hr)

Answer 20

0.5mEq/L/hr