REACTIVE OR PROACTIVE: REACTIVE OR PROACTIVE: WHICH IS BEST IN RENAL WHICH IS BEST IN RENAL REPLACEMENT THERAPY REPLACEMENT THERAPY PHOSPHATE CONTROL?PHOSPHATE CONTROL?

Joanna Campion-SmithGurudutta VenkateshaMolly McLaughlinMeeta MallikPatrick Davies

On behalf of the Trent Renal Critical Care Network

Hypophosphataemia is Hypophosphataemia is common in critically ill common in critically ill patientspatientsPredisposed by:

◦Malnutrition & inadequate body stores

◦Sepsis◦Hyperventilation◦Glucose infusions

Side effects include:◦Muscle weakness◦Myocardial dysfunction◦Encephalopathy

BackgroundBackgroundCRRT fluids:

◦Bicarbonate-buffered solutions◦Containing:

Calcium Magnesium Sodium Chloride Lactate Glucose +/- Potassium

But no phosphate

Maintenance of Maintenance of normophosphataemianormophosphataemia

A balancing act:

Adequate phosphate removal

Prevention of hypophosphataemia

Two possible solutionsTwo possible solutions

What happens in the UK?

Straw poll of 9 UK PICUs:

7 bolus correct 2 add to CRRT fluids

Is one method better?

Phosphate stability in CRRT Phosphate stability in CRRT fluidsfluids

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

AimsAimsCompare 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.)

MethodsMethods

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

MethodsMethods

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

Study populationStudy population

DemographicsDemographicsAge

◦ 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 diagnosisUnderlying diagnosis

Indications for CRRTIndications for CRRT

More hypophosphataemic More hypophosphataemic episodes in the bolus groupepisodes in the bolus group

147 12 hourly blood

tests

57 episodes ofhypophosphata

emia

1 episode per 22.5 hours in the

bolus group

1 episode per 31.3 hours in the

continuous correction

groupp =

0.0019

29 in bolus group

(38 normal)

23 in continuous correction group

(57 normal)

More bolus patients More bolus patients hypophosphataemic at 24 hourshypophosphataemic at 24 hours

Bolus group

Continuous correction group

% patients hypophosphataemic at 24 hours

Depth of Depth of hypophosphataemia greater hypophosphataemia greater in bolus groupin bolus group

Phosphate level mean Phosphate level mean variancevariance

Conclusions & Conclusions & RecommendationsRecommendationsContinuous correction:

◦Tighter phosphate control◦With fewer hypophosphataemic

episodes

No documented side effects in either group

We recommend addition of phosphate to CRRT fluids

ReferencesReferencesWignell 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, 312-316

QUESTIONSQUESTIONS