ADROGUE MADIAS FORMULA
FREE WATER

programmed by Stephen Z Fadem

CAUTION!! AVOID OVER CORRECTION

1. Change in Serum Na = (infusate Na - serum Na)/(tbw+1)
2. Change in serum Na = (((Infusate Na + infusate K) - (serum Na) ))/(tbw+1)
Water Deficit (liters) = TBW X ((serum Na/Reference Na)-1)
NOTE: Use of this formula stipulates the physician is highly familiar with the medical literature with respect to the management of hyponatremia. Patients with severe acute symptomatic hyponatremia must be managed in the intensive care unit. Electrolytes need to be checked frequently, and fluids adjusted as needed. Do not exceed guidelines for correction. The patient may require DDAVP to avoid overshooting. Intake and output need to be watched closely. The urine output may increase dramatically during correction, leading to over correction Over correction may result in osmotic demyelination, and although this may not be initially apparent, can be a very serious complication. Consult a nephrologist early. Nephrologists must monitor electrolytes and fluid output very closely.

POST OP: Avoid hypotonic fluids after surgery. Whenever using intravenous solutions post operatively, check serum electrolytes at least daily.

Formulas may overcorrect the serum sodium so one must use clinical judgment and monitor the serum sodium, intake and output very closely during the critical period.
TARGET SODIUM CHANGE mmol/L
NUMBER OF HOURS hours
TARGET RATE PER HOUR
INFUSATE SODIUM
INFUSATE POTASSIUM mmol/L
OBSERVED SODIUM mmol/L
PERCENT WATER PATIENT'S WEIGHT kg
TOTAL BODY WATER (TBW) ??? kg
SODIUM CHANGE ??? mmol/L
VOLUME TO INFUSE ??? ml
INFUSION RATE ??? ml/hour
REFERENCE SODIUM FOR CALCULATING FREE WATER DEFICITmmol/L
FREE WATER DEFICIT ??? liters
REFERENCES:

© 2008-24, Stephen Z. Fadem, M.D., FASN. All rights reserved. No part of this application may be duplicated without written permission from the author.

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The licensee or user understand and agree that the technology and content of this application are provided for educational purposes only. All calculations must be checked for accuracy and confirmed before use, clinical or otherwise. All medical decisions must be based upon the clinical judgment of a licensed physician. Licensee or user assumes the duty to have any and all laboratory values or calculations verified by a licensed physician. Neither licensor nor its associated authors or other entities warrant the accuracy of any information provided by or resulting from the technology or the content for clinical management, and licensee or user agree that no such persons or entities shall be liable for any adverse consequences resulting from the use of any of the same.

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TOUCHCALC