January 28, 2011

 Deficit of water in relation to total body sodium  Serum Sodium: >145  Severe: >160

 Causes Pure Water Loss  Diabetes insipidus Hypotonic fluid loss  Vomiting or diarrhea Hypertonic sodium gain  Improperly prepared infant formula

 Decreased tone  Poor feeding  High-pitched cry  Insomnia  Lethargy

 Severe hypovolemic, hypernatremic dehydration Brain shrinkage Tearing of blood vessels Hemorrhage  Rapid correction Cerebral edema/herniation

 Emergency Phase Restoration of vascular volume 20mL/kg isotonic fluids  Rehydration Phase Free water deficit Maintenance fluids On going losses

How do we safely stabilize the patient?

 If patient’s Na > % 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)

How do we replace the free water?

 Maximum rate 0.6mEq/L/hour 15mEq/L/day

 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

 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 = 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

 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!!!!!

 1 to 3 weeks old  Firstborn  Poor feeding  Weight loss  Extremely hypernatremic Mean 180mEq/L  Remember P.E. findings with Hypernatremic dehydration

 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