Cite this article as:
Marc Anders. Haemofiltration and dialysis, Don't Forget the Bubbles, 2013. Available at: https://doi.org/10.31440/DFTB.3735
Indications:
Correction of water overload
To remove larger quantities of water from the body than the kidney is able to achieve in order to enable the administration of therapeutic fluids such as parenteral nutrition
To remove excess electrolytes
Correction of disorders of acid/base homeostasis, including inborn errors of metabolism, particularly metabolic acidosis
Liver failure (but it does not substitute liver function!)
Removal of urea and other waste products of metabolism in cases of renal failure or hypercatabolic state
Removal of ingested poisons, drugs or toxins in sepsis
Most common used: continuous veno-venous haemofiltration (CVVH or CVVHF) or continuos veno-venous haemodiafiltration (CVVHDF).
In CVVHF the filtrate depends on blood flow rate (aim for 3-5 ml/kg/min), the transmembrane pressure – TMP (change in oncotic pressure along the filter), prefilter dilution (decreases urea-/creatinine clearance) and the sieving coefficient (ratio between filtrate concentration and plasma concentration for a given molecule, e.g. urea=1, albumin=0).
The filtrate is replaced by a glucose/electrolyte solution (replacement fluid). In CVVHDF the clearance of small and middle sized molecules is enhanced by counter-current dialysate flow (diffusion).
Anticoagulation:
UFH/anticoagulation, aim ACT 160-180 secs
UFH/protamine: 1 mg protamine post-filter for every 100 U Heparin administered pre-filter
Citrate anticoagulation: 1ml citrate per 30 ml blood flow, aiming for pre-filter Ca++<0.4 mmol/l and replace post-filter with Ca++>1.2 mmol/l (Mg++, citrate accumulation → acidosis)
Electrolytes (glucose, Na+, K+, Cl–, HCO3–, Ca++) every 4 hrs, hourly for 1st 4 hours if they were abnormal
Magnesium and phosphate twice daily
Fluid balance per hour = IV fluids in per hour + enteral feeds per hour – urine – insensible losses – drain losses – patient Fluid removed per hour
Mode
Clinical Use
QDF (Diffusion)
UFR (Convection)
QRF
Total Clearance
SCUF
Water removal
Nil
=Filtrate flow
Nil
UFR
CVVH
Clearance depends on TMP, QBF, Sieving
Nil
=Filtrate flow
= QRF
UFR
CVVHD
Clearance depends on QBF, QDF
QDF
=QDF + UFR (small)
Nil
QD + UFR (small)
CVVHDF
Improved clearance of small and middle size
QDF
=QDF + UFR
= QRF
QDF + UFR
References:
[1] Pediatr Nephrol 2012 Feb28: Sutherland et al: Continuous renal replacement therapy
[2] Curr Opin Pediatr 2011 Apr;23(2)181-5: Goldstein: Continuos renal replacement therapy: mechanism of clearance, fluid removal, indications and outcome
[3] Crit Care 2011 Jan 24;15(1)202: Oudemans-van-Straaten et al: Clinical review: anitocagulation for continuous renal replacement therapy – heparin or citrate?
All Marc’s PICU cardiology FOAM can be found on PICU Doctor and can be downloaded as a handy app for free on iPhone or Android. A list of contributors can be seen here.
If you enjoyed this post, why not check out our online courses at DFTB Digital
Haemofiltration and dialysis
Tags: dineal, haemofiltration
Marc Anders. Haemofiltration and dialysis, Don't Forget the Bubbles, 2013. Available at:
https://doi.org/10.31440/DFTB.3735
Indications:
Most common used: continuous veno-venous haemofiltration (CVVH or CVVHF) or continuos veno-venous haemodiafiltration (CVVHDF).
In CVVHF the filtrate depends on blood flow rate (aim for 3-5 ml/kg/min), the transmembrane pressure – TMP (change in oncotic pressure along the filter), prefilter dilution (decreases urea-/creatinine clearance) and the sieving coefficient (ratio between filtrate concentration and plasma concentration for a given molecule, e.g. urea=1, albumin=0).
The filtrate is replaced by a glucose/electrolyte solution (replacement fluid). In CVVHDF the clearance of small and middle sized molecules is enhanced by counter-current dialysate flow (diffusion).
Anticoagulation:
Replacement fluid:
Catheter/blood Flow/filter:
Always aim blood flow/filtrate flow ratio > 5:1
recommended
Blood Flow
Patient monitoring:
References:
[1] Pediatr Nephrol 2012 Feb28: Sutherland et al: Continuous renal replacement therapy [2] Curr Opin Pediatr 2011 Apr;23(2)181-5: Goldstein: Continuos renal replacement therapy: mechanism of clearance, fluid removal, indications and outcome [3] Crit Care 2011 Jan 24;15(1)202: Oudemans-van-Straaten et al: Clinical review: anitocagulation for continuous renal replacement therapy – heparin or citrate?All Marc’s PICU cardiology FOAM can be found on PICU Doctor and can be downloaded as a handy app for free on iPhone or Android. A list of contributors can be seen here.
About Marc Anders
View all posts by Marc Anders | Website