“Put them on the Filter” Renal Replacement Therapy in ITU Susanne Young Aug 04

content Indications for RRT Dialysis vs Haemofiltration recap Variations in RRT What we need to know!

Indications for RRT Uraemia Acidosis Fluid overload Hyperkalaemia Pericarditis

DIALYSIS V FILTRATION Diffusion based solute removal Convection based water (& sol) rem Int. 4-6 hrs. Rapid rate sol/fl loss “go slow dialysis” continuous Usually av access. BP driven (7l/d) VV needs extra cor blood pump (16l/d) Dialysate flows countercurrent <5000 Da get dragged across

DIALYSIS Aggressive removal of small solutes: Ur, Crn, K, move down concn gradient Ca, HCO3 moves from dialysate to blood Fluid removal slower but reduction in solute concentration faster Replacement fluid not usually given More risk arterial embolisation

FILTRATION Removal of fluid Filtration itself removes small solutes in roughly the same concentrations as plasma Removes large solutes High flow rates would cause hypovolaemia So, admin of (solute poor) substitution fluid will reduce solute concentration by dilution.

Types of RRT SCUF- no replacement fluid, dehydrating CVVH- replacement solution CVVHD- replacement and dialysate soln. CVVHDF IAVHD

SCUF

CVVH

When are you checking the coag? HEPARIN lock the lines at insertion (5000iu/ml) or when not in use. ?Heparin bolus- yes unless contraindicated 50iu/kg Aim for APR 1.5x normal only. Start at 800-10000iu/hr (1000iu/ml ALWAYS) Check at 4hrs then daily

How much fluid do you want off FLUID REMOVAL in CVVH Patient Fluid removal rate: 10-1000ml/h, (higher in SCUF) around 100ml/h ballpark AS PER FLUID BALANCE Replacement fluid flow rate: 100-4500ml/h, (lower in HD mode) Blood flow 10-180ml/min (120 ususal) Check U&E at 4hrs

What bags do you want me to use Standard bag composition: Lactate free if Met Acidosis More K+ if hypokalaemic 2-4mmol/h. Now could you fill out the prescription?