Renal rescue therapy

• Dopamine infusion
• Theophylline
• Frusemide
• GTN infusion (NOS) vasodilatory properties

• N-acetyl cysteine: 200mg/kg/4hours + 100mg/kg/20 hours

Indications for dialysis/filtration

1. Fluid overload
2. Uraemia >30mmol/l
   
3. Hyperkalaemia
4. Acidosis: pH < 7.2
5. Creatinine clearance < 10ml/min
6. Encepalopathy

Renal replacement therapies

1. Haemodialysis
   • Blood interfaces dialysis solution across selectively permeable membrane
   • Permits passage of molecules < 5kDa down diffusion gradient
   • Can be intermittent or continous
   • Vascular access > extracorporeal circuit (air trap + heparin pump) > dialysis machine driven by roller pump

     

2. Haemofiltration
   • Continous convection of molecules across membrane
   • Fluid removed is replaced with buffered physiological solution
   • Effective at removing volume but not as effective as dialysis in clearing smaller molecules

     Continous arteriovenous haemofiltration: CAVHF (flow driven by AV pressure difference
     Continous Venovenous haemofiltration: CVVHF (flow relies on roller pumps)

3. Combination
4. Peritoneal dialysis
   • Slow form of continous dialysis
   • Dialysate introduced into peritoneum via Tenckhoff catheter
   • Relies on peritoneum and capillary network to act as selectively permeable membrane
   • Solute flows down diffusion gradient, fluid flows by osmosis
   • Fluid then drained off after several hours

     Complications - gram+ infection

Complications

1. Dysequilibrium syndrome
   • Sudden changes in serum osmolarity - leading to cerebral oedema
2. Hypotension
   • Sudden reduction in intravascular volume
3. Immune reactions
   • Extracorporeal circuit causes systemic complement cascade activation
4. Hypoxia
   • Immune response leading to neutrophil aggregation in lungs
5. Line sepsis
6. Air embolism / haemorrhage