ICM - Colloids Flashcards
Define colloid
A fluid Containing large molculesThat exert an oncotic pressureOn the capillary membraneMolecules effectively suspneded in a crystalloid
Classift colloids
Natural —> Blood, HASSynthetic -> Gelatins, starches
Describe gelatins and adv/disad
Modified bovine collagensAd - long shelf lifeDisadv - ANAPHYLAXIS Rapid excretion means actually effect lost after 1.5 hours
Describe starches, their adv/disadv
Corn/potato starch suspensionsVariety of molecular weightsAdv - much longer half life than gelativeDisad - High MW solutions > 450kDa —> impair vWF and Factor 8 —> coagulopathy Renal failure High mortality in critically ill
Desribe albumin
GlobularSingle polypeptideMW - 69 kDaNegatively charged - repelled by glycocalyxTherefore extends intravascular half life to 5-10
Describe HAS
Solution containing protein from plasma, serum and placentasIsotonic 4.5%Hypertonic 20%From pooled donations (thousands) —> risk of CJD
Where and how is albumin produced
0.2g/kg/dayInfluenced by neuro-endocrines and plasma oncotic pressuresMade in liver, released quickly without storageRange 35-50g/LSuppressed in critical illness (negative acute phase protein)
Functions of albumin
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
When do we use HAS
Fluid resus - weak recommendation in surviving sepsus once crystalloids givenProphylaxis and treatment of HRSParacentesis in cirrhosisPlasmaphoresis
Evidence on albumin
ALBIOS - no survival advantage in sepsis —> but quicker resolution of norad and better haemodynamicsSAFE - 4% versus saline for fluid resus —> equivalent mortality non significant trend for saline in trauma Sub group - BAD IN TBI
Disadvantages to HAS
DO NOT USE IN TBIExpensive to make and buyMay worsen things when there is endothelial dysfunctionCJD - pooledEvidence for benefit is poor
Evidence for starches
Many studies were withdrawn due to scientific misconductVISEP - starches increase AKI (used very high HES doses)6S - 28 day mort - no diff to Ringers, 90 day HES badChest - no differen tin mort, but greater renal risk/RRT
