PEDIATRICS Vol. 114 No. 5 November 2004, pp. 1368 (doi:10.1542/peds.2004-1350)
Hospital-Acquired Hyponatremia Is Associated With Excessive Administration of Intravenous Maintenance Fluid
Mark Hatherill, FCPaedZainab Waggie, FCPaed
Shamiel Salie, FCPaed
Andrew Argent, FCPaed
Paediatric Intensive Care Unit
Red Cross Children's Hospital and University of Cape Town
Cape Town 7700, South Africa
To the Editor.
Hoorn et al report an observational study of hospital-acquired hyponatremia.1 A larger volume of electrolyte-free water was administered to these children, compared with a control group who did not develop hyponatremia. The authors conclude that the most important causative factor was the administration of hypotonic maintenance fluid. In an accompanying commentary, Moritz and Ayus recommend that clinicians should abandon hypotonic solutions in favor of isotonic maintenance fluid.2
Because both hyponatremic and normonatremic children received the same hypotonic (0.3% saline) maintenance solution, we question the validity of these conclusions.1,2 Comprehensive data for urine volume and electrolyte content are not given, and therefore we are unable to judge whether hyponatremia resulted from a net sodium deficit. Additionally, because insensible water loss varies greatly with age (70 mL/kg per day in preterm infants compared with 7 mL/kg per day in adults), activity, and body temperature, we are not in a position to calculate the net gain or loss of electrolyte-free water with any certainty.3,4
However, the authors clearly demonstrate that hyponatremic children received more than twice the amount of fluid (98 vs 47 mL/hour, respectively), resulting in a positive fluid balance twice that of normonatremic controls (4 vs 2 mL/kg per hour, respectively).1 The traditional maintenance recommendation for this group of patients (mean weight: 25 kg) would be 67 mL/hour (64 mL/kg per day).5 We agree with the authors that even traditional maintenance-fluid recommendations have been overestimated and may be 40% to 50% greater than actual water needs in children at risk of excess antidiuretic hormone production.1,5,6 Therefore, it is notable that 73% of hyponatremic children received even more fluid than the traditional recommendation, compared with 23% of normonatremic controls.1,5
The inescapable conclusion is that acute hyponatremia in these children was associated with an excess of water rather than a deficit of sodium.1 It follows that hyponatremia should be prevented by reducing the volume of maintenance fluid rather than by increasing the sodium content.6 This hypothesis is supported by experimental and clinical data, in that the secondary natriuresis caused by antidiuretic hormone may be prevented by fluid restriction, whereas administration of isotonic saline does not prevent hyponatremia in the absence of appropriate fluid restriction.7,8 Note that maintenance fluid, required to replace ongoing sensible and insensible fluid loss, should not be confused with isotonic resuscitation or replacement fluid, required for correction of preexisting fluid deficit.9
We suggest that the most important factor contributing to hyponatremia in these patients was not the sodium content of the intravenous maintenance fluid but rather the administration of excessive amounts of that fluid.1 Additionally, we believe that undue emphasis has been placed on the tonicity of maintenance solutions.2,6 Unless isotonic maintenance fluid is shown to be effective in preventing hospital-acquired hyponatremia, calls for a change in practice are premature.1,2,8 It is imperative that solid evidence be collected to guide the revision of traditional maintenance-fluid guidelines.6 Until such time, administration of excessive intravenous maintenance fluid is likely to result in more cases of hospital-acquired hyponatremia and avoidable morbidity and mortality.1,2
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[Abstract/Free Full Text] - Moritz ML, Ayus JC. Hospital-acquired hyponatremia: why are there still deaths [commentary]?
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[Abstract/Free Full Text] - Powell KR, Sugarman LI, Eskanazi AE, et al. Normalization of plasma arginine vasopressin concentrations when children with meningitis are given maintenance plus replacement fluid therapy. J Pediatr. 1990;117 :515 –522[CrossRef][Web of Science][Medline]
PEDIATRICS (ISSN 1098-4275). ©2004 by the American Academy of Pediatrics
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Pediatrics 2004 114: 1368-1369.[Extract] [Full Text]
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