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Welcome Applicants!. January 28, 2011. Hypernatremia. Deficit of water in relation to total body sodium Serum Sodium: >145 Severe: >160. Hypernatremic Dehydration. Causes Pure Water Loss Diabetes insipidus Hypotonic fluid loss Vomiting or diarrhea Hypertonic sodium gain
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Welcome Applicants! January 28, 2011
Hypernatremia Deficit of water in relation to total body sodium Serum Sodium: >145 Severe: >160
Hypernatremic Dehydration • Causes • Pure Water Loss • Diabetes insipidus • Hypotonic fluid loss • Vomiting or diarrhea • Hypertonic sodium gain • Improperly prepared infant formula
Presentation Decreased tone Poor feeding High-pitched cry Insomnia Lethargy
Serious Matter • Severe hypovolemic, hypernatremic dehydration • Brain shrinkage • Tearing of blood vessels • Hemorrhage • Rapid correction • Cerebral edema/herniation
Treatment • Emergency Phase • Restoration of vascular volume • 20mL/kg isotonic fluids • Rehydration Phase • Free water deficit • Maintenance fluids • On going losses
Emergency Phase How do we safely stabilize the patient?
The Dilemma:Severehypernatremia… • If patient’s Na >175 • 0.9% Normal Saline (154mEq/L) is relatively hypotonic • Beware rapid infusion of fluids with 15mEq/L lower than serum • May need to add 3% NS (513mEq/L)
Rehydration Phase: How do we replace the free water?
Rehydration Phase:How quickly to correct? • Maximum rate • 0.6mEq/L/hour • 15mEq/L/day
Calculate Free Water Deficit • Assume 70% of infant’s body wt is water • (50% in adults) • 0.7 X wt (1-- serum Na/desired Na) • Choose “desired Na” as 15mEq less than serum • Yields amount of free water to be administered over next 24hrs
The BIG Question • How much free water are we infusing with any given concentration of IVF? • It depends two factors: • Sodium concentration of IVF • The patient’s sodium level!!!!
Free Water Content of IVF • % Free Water = 1 – (IV fluid Na/serum Na) • Patient with serum Na 154 • If give NS: giving 0% free water • Patient with serum Na 195 • If give NS: giving 21% free water
Bottom Line • Emergency Phase may be most dangerous • If serum Na > 175: NS is too hypotonic • Rehydration Phase • Calculate free water to be replaced over 24hrs • Max 15mEq/L change • FREE WATER + MAINTENANCE + ONGOING LOSSES • Yields total fluids for next 24hrs • Administer in form of D5 ½ NS • Follow lytes closely!!!!!
Classic Presentation • 1 to 3 weeks old • Firstborn • Poor feeding • Weight loss • Extremely hypernatremic • Mean 180mEq/L • Remember P.E. findings with Hypernatremic dehydration
Physiology • Human milk under normal circumstances • At delivery: Na 65 mEq/L • On day 3: Na 20 mEq/L • On day 14: Na 7 mEq/L