Red Book - Colloids

Question 1

Define colloid

Answer 1

A fluid

Containing large molcules

That exert an oncotic pressure

On the capillary membrane

Molecules effectively suspneded in a crystalloid

Question 2

Classift colloids

Answer 2

Natural —> Blood, HAS

Synthetic -> Gelatins, starches

Question 3

Describe gelatins and adv/disad

Answer 3

Modified bovine collagens

Ad - long shelf life

Disadv - ANAPHYLAXIS
Rapid excretion means actually effect lost after 1.5 hours

Question 4

Describe starches, their adv/disadv

Answer 4

Corn/potato starch suspensions

Variety of molecular weights

Adv - much longer half life than gelative

Disad - High MW solutions > 450kDa —> impair vWF and Factor 8 —> coagulopathy

	Renal failure
	High mortality in critically ill

Question 5

Desribe albumin

Answer 5

Globular

Single polypeptide

MW - 69 kDa

Negatively charged - repelled by glycocalyx

Therefore extends intravascular half life to 5-10

Question 6

Describe HAS

Answer 6

Solution containing protein from plasma, serum and placentas

Isotonic 4.5%

Hypertonic 20%

From pooled donations (thousands) —> risk of CJD

Question 7

Where and how is albumin produced

Answer 7

0.2g/kg/day

Influenced by neuro-endocrines and plasma oncotic pressures

Made in liver, released quickly without storage

Range 35-50g/L

Suppressed in critical illness (negative acute phase protein)

Question 8

Functions of albumin

Answer 8

Acid-base balance (buffer)

Maintain oncotic pressure (80% of the colloid oncotic pressure(

Transport molecule:
	Ca, Na, K
	Hormones, T4, steroids
	Bile salts
	Acidic drugs, warfarin, NSAIDs

Question 9

When do we use HAS

Answer 9

Fluid resus - weak recommendation in surviving sepsus once crystalloids given

Prophylaxis and treatment of HRS

Paracentesis in cirrhosis

Plasmaphoresis

Question 10

Evidence on albumin

Answer 10

ALBIOS - no survival advantage in sepsis —> but quicker resolution of norad and better haemodynamics

SAFE - 4% versus saline for fluid resus —> equivalent mortality
non significant trend for saline in trauma
Sub group - BAD IN TBI

Question 11

Disadvantages to HAS

Answer 11

DO NOT USE IN TBI

Expensive to make and buy

May worsen things when there is endothelial dysfunction

CJD - pooled

Evidence for benefit is poor

Question 12

Evidence for starches

Answer 12

Many studies were withdrawn due to scientific misconduct

VISEP - starches increase AKI (used very high HES doses)

6S - 28 day mort - no diff to Ringers, 90 day HES bad

Chest - no differen tin mort, but greater renal risk/RRT