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ARTICLE: Michael L. Moritz and Juan Carlos Ayus Prevention of Hospital-Acquired Hyponatremia: A Case for Using Isotonic Saline Pediatrics 2003; 111: 227-230 [Abstract] [Full text] [PDF]

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Water balance: is more always better?

Khalid Aziz   (1 February 2003)

Rewriting Maintenance Fluids

Narinder S. Bhatia Bhatia   (27 February 2003)

Re: Water balance: is more always better?

Michael L Moritz, J. Carlos Ayus   (28 April 2003)

Re: Rewriting Maintenance Fluids

Michael L Moritz, J. Carlos Ayus   (28 April 2003)

Water balance: is more always better? 1 February 2003
Khalid Aziz, Neonatologist Memorial University of Newfoundland Send letter to journal: Re: Water balance: is more always better? kaziz{at}mun.ca Khalid Aziz	I thank Moritz and Ayus for pointing out the importance of attending to sodium balance in sick children, particularly in clinical states where antidiuretic hormone (ADH) secretion may be innappropriately elevated. They were, however, less emphatic about the risks associated with water and sodium overload. In preterm newborns, excess water and sodium intake may have serious adverse effects on outcome(1)(2). These children seem to fair better with less sodium and water in the first few days of life, rather than more. Can this evidence be extrapolated to the older child? An alternative approach to excess ADH production would be to restrict water intake to 50 to 70% (approximately 800 to 1100 ml/m2/day) of maintenance until the period of stress is over. Maintenance fluids would contain daily requirements of nutrients and minerals. Necessary volume expansion, rehydration, and replacement of surgical losses would be with isotonic solutions (or those that replace the loss/deficit) - no restrictions would apply to these. This method would avoid hyponatremia and hypernatremia, while maintaining sodium and water balance. Given the experience in newborns, it would seem prudent to aim for balance, particularly in younger children. Ideally, we should avoid excess (maintenance) water and sodium intake in sick children of all ages until clinical trials demonstrate that more is actually better. Khalid Aziz, Associate Professor of Pediatrics, Memorial University of Newfoundland, St. John's NL, Canada (1) Bell EF, Acarregui MJ. Restricted versus liberal water intake for preventing morbidity and mortality in preterm infants. The Cochrane Database of Systematic Reviews, Issue 1. Substantively amended: 27 April 2001 (2) Costarino AT Jr, Gruskay JA, Corcoran L, Polin RA, Baumgart S. Sodium restriction versus daily maintenance replacement in very low birth weight premature neonates: a randomized, blind therapeutic trial. J Pediatr. 1992 Jan; 120(1): 99-106
Rewriting Maintenance Fluids 27 February 2003
Narinder S. Bhatia Bhatia, Assistant Professor in Pediatrics Texas Tech University Health Sciences Center, Dept. of Pediatrics, Lubbock, TX 79430 Send letter to journal: Re: Rewriting Maintenance Fluids narinder.bhatia2{at}ttuhsc.edu Narinder S. Bhatia Bhatia	Moritz and Ayos’ wakeup call regarding the risk of iatrogenic hyponatremia in pediatric patients receiving hypotonic maintenance fluids is indeed a great service to children. Their review merits serious notice by those involved not only in the care of sick children but also those undertaking to write guidelines for fluid management for use by pediatric and other residents in training. In this context it would be timely also to highlight the danger faced by hospitalized children from liberal overuse of potassium chloride in “routine” maintenance fluids. Vast majority of sick children are not potassium depleted and are unlikely to develop hypokalemia in the absence of conditions such as prolonged diahrrea with or without vomiting, diuretic therapy, continuous beta-agonist nebulizations and diabetic ketoacidosis etc. Indeed many pediatric patients are at risk of dangerous hyperkalemia from diminished urine output, acidosis of varying etiology or tissue breakdown such as in trauma, sepsis and hemolysis of intrinsic or transfused red cells. Potassium chloride is lethal in overdose and prescribing and dispensing errors while preparing infusions are not rare. On the other hand low potassium levels are well tolerated in children over at least a short period of time in the absence of digoxin therapy or recent cardiac surgery. While it may not be unreasonable to add potassium chloride in maintenance fluids for patients with say ongoing gastrointestinal or urinary losses etc., the “one size fit all” approach to adding potassium chloride to maintenance fluid is fraught with danger, and should be abandoned in favour of more individualized prescribing practice based on the patient’s diagnosis, concurrent drug therapy and actual potassium level. References: Low systemic blood flow and hyperkalemia in preterm infants. Kluckow M - J Pediatr - 01-Aug-2001; 139(2): 227-32 Hyperkalemic cardiac arrest during anesthesia in infants and children with occult myopathies. Larach MG - Clin Pediatr (Phila) - 01-Jan-1997; 36(1): 9-16 Sudden unexpected death in hospitalized children. Buchino JJ - J Pediatr - 01-Apr-2002; 140(4): 461-5
Re: Water balance: is more always better? 28 April 2003
Michael L Moritz, Physician Children's Hospital of Pittsburgh, J. Carlos Ayus Send letter to journal: Re: Re: Water balance: is more always better? moriml{at}chp.edu Michael L Moritz, et al.	We agree with Dr. Aziz that isotonic saline may not be appropriate in the newborn; therefore we state in our manuscript that “The maintenance fluid requirements of the term and preterm neonate may differ from the older child as a result of unique physiological issues, and our recommendations do not extend to this group of patients.” We agree with Dr. Aziz that fluid restriction is both appropriate and advisable in patients known to have SIADH, though it would not be advisable to prophylactically fluid restrict all patients at risk for SIADH. Many patients at risk for developing SIADH; such as those with CNS infections or pulmonary disease, may present with subclinical volume depletion. Fluid restricting these patients would perpetuate a state of volume depletion. Isotonic saline administration serves only as a prophylactic measure in preventing hyponatremia. In confirmed SIADH fluid restriction in addition to isotonic saline will be required.
Re: Rewriting Maintenance Fluids 28 April 2003
Michael L Moritz, Pediatric Nephrologist Children's Hospital of Pittsburgh, J. Carlos Ayus Send letter to journal: Re: Re: Rewriting Maintenance Fluids moriml{at}chp.edu Michael L Moritz, et al.	Dr. Bhatia raises an important point by highlighting the dangers of routinely adding potassium chloride to parenteral fluids. We agree with Dr. Bhatia that amount of potassium added to parenteral fluids should be on an individualized basis. The original recommendations of adding potassium to parenteral fluids stemmed from Darrow’s work in the 1940’s in children with diarrheal dehydration.1,2 Since then the addition of potassium to parenteral fluids has taken on a life of its own and has become a routine. This can be particularly dangerous in patients with renal disease or on medications that can cause hyperkalemia such as cyclosporine or prograf. The addition of potassium to parenteral fluids is probably unnecessary for most patients who are receiving parenteral fluids for only a few days. The standard practice of adding 20 mEq of potassium per liter of fluid is much higher than the 4 mEq per liter in Ringers Lactate. The amount of potassium added to parenteral fluids should be based on the urinary and extrarenal potassium losses and on the serum potassium level. The administration of intravenous fluids should be viewed as an invasive procedure that can have serious complications. 1. Darrow DC. The retention of electrolyte during recovery from severe dehydration due to diarrhea. J Pediatr 1946;28:515 2. Govan CD, Darrow DC. The use of potassium chloride in the treatment of dehydration of diarrhea in infants. J Pediatr 1946;28:541-9.