The impact of different infusates on the serum sodium in a patient with hyponatremia can be calculated based on clinical and chemical measurements.
change in serum sodium in mmol/L following infusion of 1 liter of IV fluid =
= (((infusate sodium concentration in mmol/L) + (infusate potassium concentration in mmol/L)) - (patient's serum sodium concentration in mmol/L)) / ((total body water in liters) + 1)
Estimated Total Body Water in Liters
0.6 * (body weight in kg)
0.5 * (body weight in kg)
0.45 * (body weight in kg)
• Need to clarify if ideal body weight or actual body weight should be used.
Sodium in mmol/L
0.2% sodium chloride in 5% dextrose in water
0.45% sodium chloride in water
0.9% sodium chloride in water
3% sodium chloride in water
5% sodium chloride in water
volume of IV fluid to infuse in mL =
= (target change in serum sodium to achieve in mmol/L) / (change in serum sodium in mmol/L per liter infusate) * 1000
rate to infuse IV fluid in mL/h =
= (volume to infuse in mL) / (time frame in hours)
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Purpose: To estimate the impact of a fluid replacement infusion on the serum sodium.
Specialty: Endocrinology, Clinical Laboratory, Emergency Medicine, Critical Care
Objective: laboratory tests