Isotonic fluids – are they better than hypotonic fluids for children? Journal Club Thursday 16 th April 2015 Charlotte Elder
Jan 19, 2016
Isotonic fluids – are they better than
hypotonic fluids for children?
Journal Club
Thursday 16th April 2015
Charlotte Elder
The maintenance need for water in parenteral fluid therapy
Holliday and SegarPediatrics 1957
0.9%
0.45%0.18%
HypernatraemiaHyperchloraemic acidosisFluid overload
HyponatraemiaDehydration
The Clinical Question
Population In children requiring intravenous fluid
Intervention Isotonic fluid (Na140)
Comparison Hypotonic fluid (Na77)
Outcome Reduce hyponatraemia
Design Randomised, double-bind, placebo controlled trial
50% - 150% maintenance
Recruited from ED and pre-ops
Na >150 mmol/LNa <130 mmol/L
IVI < 6 hours
LOT OF exclusions – basically any condidtion in which “standard fluid” may not be given DI, neuro surg, meningitis,
• 1:1 NA140:Na77
• Stratified by baseline Na
• >135, 135-145, >145
• All HCP
• Fluid bags A-H
• Identical looking
Normal saline: 154 mEq/L sodium and 154 mEq/L chloride.
Methods• Serum Na within 4 hours
• Post-op – serum Na end of procedure
• Rate determined by clinicians
• Study fluid for 72 hrs or <50% maintenance
• Study fluid stopped if:
– Na <130
– Na >150
– With Δ baseline 3+ mmol/L
– Clincian decided not in pt’s best interest
– Intention to treat data
Methods• Serum electrolytes
– 6, 24, 48, 72
– Na, K, Cl, HCO3, U, Cr, Gl
• Blood gas analyser OR Vitros lab assay
• Urine electrolytes at ~24 hours
• Clinical team monitored fluid status:
– Standardised hydration assessment – if indicated and when fluid
stopped
• SAEs recorded e.g. ITU admissions
Outcome measures• Primary
– Occurrance of hyponatraemia within 72 hours
• Na <135 mmol/L with ≥3 mmol/L
• Secondary
– Severe hyponatraemia <130 mmol/L
– Hypernatraemia >145 mmolL
– Severe hypernatraemia >150 mmolL
– Hyperchloraemia >110 mmol/L
– Hypermagnesaemia >1.2 mmol/L
– Hypercarbia >30 mmol/L
– Mean serum Na and wt at 6, 24, 48, 72 hours
– Others: fits, CO, coma, recannulation, hydration changes
Stats• Sample size: 320 per arm
– Reduction of hyponatraemia from 10% Na77 to 4% Na140
– Power: 80%
• Intention to treat analysis
• OR – measure of association between an exposure and an outcome– Odds of hyponatraemia occurring with Na77
– >1 is association
• Sensitivity and subgroup analyses– Age, total fluid, ITU/surgery, contaminated samples,
Study flow chart
http://www.casp-uk.net/
Hyponatraemia 4% vs 11%
Significant difference
0.16-0.61
p=0.001
Limitations
• Blood gas vs lab assay
• Not a trial of 0.9% fluid
• Not powered for symptomatic hyponatraemia
• Multiple exclusions
Summary and Conclusion
Very well designed study
CLINICAL BOTTOM LINE
– Don’t use IV fluids unless clinically indicated
– Watch for signs of hypoNa EARLY - within first 6 hrs
– Consider use of isotonic fluids as routine?