REACTIVE OR PROACTIVE: WHICH IS BEST IN RENAL REPLACEMENT THERAPY PHOSPHATE CONTROL? Joanna Campion-Smith Gurudutta Venkatesha Molly McLaughlin Meeta Mallik Patrick Davies On behalf of the Trent Renal Critical Care Network

Hypophosphataemia is common in critically ill patients Predisposed by: ◦ Malnutrition & inadequate body stores ◦ Sepsis ◦ Hyperventilation ◦ Glucose infusions Side effects include: ◦ Muscle weakness ◦ Myocardial dysfunction ◦ Encephalopathy

Background CRRT fluids: ◦ Bicarbonate-buffered solutions ◦ Containing:  Calcium  Magnesium  Sodium  Chloride  Lactate  Glucose  +/- Potassium But no phosphate

Maintenance of normophosphataemia A balancing act: Adequate phosphate removal Prevention of hypophosphataemia

Two possible solutions What happens in the UK? Straw poll of 9 UK PICUs: 7 bolus correct2 add to CRRT fluids Is one method better? Bolus phosphate correction Addition of phosphate to CRRT fluids

Phosphate stability in CRRT fluids Work by Wignell, McLaughlin & Davies from our unit (poster presentation at this meeting) Chemical stability of sodium glycerophosphate in CRRT fluids proven up to 48h Calcium and bicarbonate also stable

Aims Compare phosphate level stability in CRRT patients who had bolus correction vs continuous correction One previous paediatric study has suggested that continuous correction improves phosphate control (Santiago et al.)

Methods 2 PICUs ◦ Same CRRT machine & fluids ◦ Same CRRT protocols ◦ Different phosphate correction protocols

Methods Retrospective analysis of phosphate control of all patients who underwent CRRT during a 13 month period

Study population (n=21) Bolus group (n=10) Continuous correction group (n=11)

Demographics Age ◦ Mean: 3.4 years ◦ Range: 0 – 13.1 years Weight ◦ Mean: 14.8 kg ◦ Range: 2.8 – 48 kg CRRT duration ◦ Mean: 65.3 hours ◦ Range: 0.5 – 216 hours

Underlying diagnosis

Indications for CRRT

More hypophosphataemic episodes in the bolus group hourly blood tests 57 episodes of hypophosphataemia 1 episode per 22.5 hours in the bolus group 1 episode per 31.3 hours in the continuous correction group p = in bolus group (38 normal) 23 in continuous correction group (57 normal)

More bolus patients hypophosphataemic at 24 hours Bolus group Continuous correction group % patients hypophosphataemic at 24 hours

Depth of hypophosphataemia greater in bolus group 0.65 mmol/l Bolus group 0.65 mmol/l Bolus group 0.77 mmol/l Continuous correction group 0.77 mmol/l Continuous correction group p = 0.036

Phosphate level mean variance Bolus group Bolus group Continuous correction group Continuous correction group

Conclusions & Recommendations Continuous correction: ◦ Tighter phosphate control ◦ With fewer hypophosphataemic episodes No documented side effects in either group We recommend addition of phosphate to CRRT fluids

References Wignell A et al., Is the addition of Phosphate to Continuous Venous-Venous Haemofiltration fluids safe? (2011) Santiago MJ et al., Hypophosphataemia and phosphate supplementation during continuous renal replacement therapy in children. Kidney International (2009) 75,

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