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Nutrition Support Blog: Clinical Observations, Hypernatremia: Which is Best--Enteral or IV Hydration Correction?*

Posted by SF8N at Aug 10, 2014 08:45 PM |
August 10, 2014
Nutrition Support Blog:  Clinical Observations, Hypernatremia: Which is Best--Enteral or IV Hydration Correction?*

by Carol Rees Parrish, MS, RD

The best route for correction of hypernatremia?  Well, it depends.  As a GI nutritionist, I think the GI tract is brilliant in its ability to convert food and fluid into “us.”  However, I also accept that there is a time and place for all hydration routes.

Case 1: A 54 year old male was admitted with possible sepsis & mental status changes presumed to be due to hepatic encephalopathy; he was intubated to protect his airway. His past medical history was significant for ETOH-induced cirrhosis and hepatic encephalopathy.  An OGT was placed for feeding and consistent lactulose delivery.  Enteral feedings began, and given  patient’s mental status was slow to clear, 500mg IV thiamine TID was added as a safeguard against Wernicke’s.  His stool output rose from 1000mL day 1, to 1500mL day 2 then over 2 liters day three.  Clostridium difficile was checked as a precaution (negative).  His serum sodium rose to 152 by day 3.  Primary team started water flushes of 300mL every 4 hours to correct his water deficit, and lactulose dose was decreased.  Unfortunately, the patient vomited.  IV fluid replacement was initiated.

Practical “Water Replacement”

The GI tract normally does a great job of nutrient and fluid utilization, however, in the setting of critical illness or serious GI compromise, we may need to tread more softly and take a step back and think about what we are asking of our patients.  Although water given via the enteral vs. the intravenous route is equally as effective, there are considerations in those sickest of our patients.  IV correction allows for a reliable, continuous delivery of hydration at a rate deemed appropriate for the individual patient.  Enteral delivery requires that the water actually be given, and then it must be absorbed.  Unfortunately, no one has devised a way to give water that stays in the vascular space indefinitely – water by either route can eventually contribute to ascites or pulmonary edema in the certain clinical circumstances.

Issues Affecting the Reliability of Enteral Water Delivery:

·  What if the patient has excess losses, how much can one reasonably give? 

·   If the patient is on enteral feedings, are they at goal and tolerating the feedings?  If not, to put more volume into the gut to treat a potentially serious medical problem is risky and decreases your chances of the patient getting fed a reasonable amount of nutrition.  If the patient vomits, aspiration can be added to their list of co-morbid conditions.

·   Futhermore, there are many reasons why enteral is not consistently reliable: feedings and pumps are put on hold, stopped for procedures, the OR, other road trips, emesis, lost enteral access, PT, etc.

·    In summary, consider the following:

   --Is the patient at enteral feeding goal without signs of enteral intolerance?

   --Any GI issues at play?

   --When was the last stool?

   --Does the patient have excessive exogenous losses  (stool/ostomy, gastric, drains, fistulas), and hence will require a significant (and perhaps unreasonable) amount of water to correct?

   --Remember: when large and frequent water flushes are ordered (such as 300mL every 4 hours), each time the flush is scheduled to go in, the enteral feedings are stopped (or automatically shut off if a dual pump) while the water is infused--the larger the flush, the more time it takes to run in.  If the patient has frequent and large flushes, this can translate into considerable lost feeding time and the patient’s nutritional status is compromised.

   --If a dual enteral pump (feeding + water) is used and the patient is on a nocturnal, or other cycled delivery mode (< 24 hours), when the cycle ends and the pump is turned off, water flushes cannot be infused.

Consider the following (assuming all of the above have been attended to that is):

1)   For serum Na < 150, it is reasonable to try more enteral water up to 1 liter in divided doses of maybe 250mL every 6 hours, or 165mL every 4 hours.

2)For serum Na > 150, IV hydration should be used to carefully and in a controlled and reliable fashion with D5 or 1/4 normal saline as appropriate for the individual patient.

While we are all about “if the gut works...” once your hydration efforts begin interfering with basic nutrition goals or risking emesis, it may be time to use some IV hydration, at least initially.

*Adapted from: Parrish CR, Rosner, MH.  Clinical Observations: Correcting Hypernatremia: Enteral or Intravenous Hydration?  Practical Gastroenterology 2014;XXXVIII:In press.

Further Reading

1)   Lindner G, Funk GC.  Hypernatremia in critically ill patients.  J Crit Care. 2013;28(2):216.e11-20.

2)   Overgaard-Steensen C, Ring T.  Clinical review: Practical approach to hyponatraemia and hypernatraemia in critically ill patients.  Crit Care. 2013;17(1):206. [Epub ahead of print].

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