Renal Replacement Therapy Prescription

OVERVIEW

Aims of Treatment

  • fluid management
  • acidosis correction
  • hyperkalaemia correction
  • uraemia
  • toxin removal

RRT Prescription is altered depending on:

  • aims of treatment
  • patient factors
  • resources available

PRESCRIPTION ELEMENTS

Mode

  • CVVH
  • CVVHD
  • CVVHDF

Blood flow rate (QB)

  • e.g. 150mL/min
  • 50-200mL/min is range for CVVHDF

Dialysate flow rate (QD)

  • e.g. 16mL/kg/min (1000mL/hr)
  • cannot be more than 1/3 of blood flow rate

Ultrafiltrate/replacement rate + composition (QF)

  • often altered to target fluid removal target (see below)
  • Filtration fraction is usually 20-25% at most
  • K+ supplementation if needed (do not put more than 20 mmol/5L bag i.e. 4 mmol/L)
  • most bags now HCO3 based (lactate-free)

Fluid removal

  • mL/hr
  • can usually tolerate up to 300-400 mL/h
  • based on overall fluid status
  • fluid removal

Dilution Technique and ratio

  • pre-filter
  • post-filter
  • often 1:1 ratio (standard was 70:30 at one place I worked)

Dose = effluent rate = (dialysate + ultrafiltrate) (QE)

  • mininum 20-25 mL/kg/h
  • aproximates urea Kt/V = 1 for intermittent haemodialysis
  • no evidence of mortality benefit with up to 40 mL/kg/h (but increases rate of solute clearance and fluid removal)

Anticoagulation Strategy

  • none
  • heparin
  • LMWH
  • regional heparinsation (protamine post filter)
  • regional citrate
  • prostacycline
  • heparinoids (danaparoid)
  • serine protease inhibitors
  • direct thrombin inhibitors (bivalirudin, hirudin)
  • fondaparinux
  • NSAIDS
  • anti-platelet agents
  • warfarin

What do if filters fails

  • re-start
  • give patient break

EXAMPLE

80 kg male with AKI

  • CVVHDF
  • QB = 150 mL/min
  • QD = 1,000 mL/h
  • QF = 1,000 mL/h
  • QE = 2,400 mL/h (=30 mL/kg/h)
  • anticoagulation = 200 mL/h heparin
  • net fluid removal = 200 mL/h

CCC 700 6

Critical Care

Compendium

Chris is an Intensivist and ECMO specialist at the Alfred ICU in Melbourne. He is also the Innovation Lead for the Australian Centre for Health Innovation at Alfred Health and Clinical Adjunct Associate Professor at Monash University. He is a co-founder of the Australia and New Zealand Clinician Educator Network (ANZCEN) and is the Lead for the ANZCEN Clinician Educator Incubator programme. He is on the Board of Directors for the Intensive Care Foundation and is a First Part Examiner for the College of Intensive Care Medicine. He is an internationally recognised Clinician Educator with a passion for helping clinicians learn and for improving the clinical performance of individuals and collectives.

After finishing his medical degree at the University of Auckland, he continued post-graduate training in New Zealand as well as Australia’s Northern Territory, Perth and Melbourne. He has completed fellowship training in both intensive care medicine and emergency medicine, as well as post-graduate training in biochemistry, clinical toxicology, clinical epidemiology, and health professional education.

He is actively involved in in using translational simulation to improve patient care and the design of processes and systems at Alfred Health. He coordinates the Alfred ICU’s education and simulation programmes and runs the unit’s education website, INTENSIVE.  He created the ‘Critically Ill Airway’ course and teaches on numerous courses around the world. He is one of the founders of the FOAM movement (Free Open-Access Medical education) and is co-creator of litfl.com, the RAGE podcast, the Resuscitology course, and the SMACC conference.

His one great achievement is being the father of two amazing children.

On Twitter, he is @precordialthump.

| INTENSIVE | RAGE | Resuscitology | SMACC

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