Thursday, August 2, 2012

Topic Discussion: Rule of 6s

Hyponatremia- Rule of 6 correction.
The Stern Approach

Correction and then over correction is the concern especially in two populations.
Low Solute intake individuals and Alcoholics.

They are the highest risk for CPM following rapid correction.

The cause of hyponatremia and its reversibility must also be considered when deciding a course of action. In hypovolemia-induced hyponatremia, vasopressin levels decline and sodium levels rise as volume status is restored to normal.
The Stern approach from Rochester has come up with a protocol that is worth noting year after year regarding giving hypertonic saline with ddavp. The reason why trouble arises in the treatment with just 3% in the above population is due to emerging quick water diuresis that sometimes gets not well accounted.
Ddavp administered q6-8 hours has been shown by this same Rochester group to be effective and more practical than hypotonic fluids in preventing overcorrection of hyponatremia. They administer desmopressin immediately without waiting for the onset of water diuresis, and concurrently administer 3% saline solution. Based on their data, this prevents significant rises in Na rapidly and provides the “brakes” with the “acceleration”. The formula of the 6s is recommended. Correction with 6mEq in 6 hours on the first day if symptoms are severe with neurological symptoms. 

Sterns approached was studied in a retrospective manner in a CJASN study found free online.  In another article, this approach is discussed using an alcoholic case in AJKD. Concerns using ddavp is that perhaps there is no control  over the effect once you give it. At least with D5W or hypotonic solutions, one can control the rate. Perhaps, more data will be coming out on this approach as years progress. 

In summary, correction of hyponatremia by 4-6 mEq/l within 6 h, with bolus infusions of 3% saline if necessary, is sufficient to manage the most severe manifestations of hyponatremia. Planning therapy to achieve a 6 mEq/l daily increase in the serum sodium concentration can avoid iatrogenic brain damage by staying well clear of correction rates that are harmful. Administration of desmopressin to halt a water diuresis can help prevent overcorrection; if overcorrection occurs, therapeutic relowering of the serum sodium concentration is supported by data in experimental animals and was found to be safe in a small observational clinical trial. 

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