How bolus infusions of NaCl may affect low sodium levels...?

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    So, the other day in clinical I had an elderly patient who had low sodium levels and low blood pressure. They gave the pt two bolus infusions of NaCl to help get his/her bp back up, and afterward my instructor asked me a few questions about the effects of giving boluses of NS NaCl to someone who already has low sodium levels. The instructor said that giving those boluses would dilute the sodium levels in the pt even further, causing his/her [Na+] ratios to drop. For some reason, I'm having a really hard time believing that. My reasoning:

    1) NS NaCl concentrations are based on regular sodium levels. So, if you have a pt who has lower-than-normal sodium in his/her system, then the NS solutions are hypertonic to the pt's Na+ solutes, and that should cause there to be an increase in [Na+] ratio levels, right?

    2) Also, even if the pt's Na+ levels were average, shouldn't the 0.9% NaCl solution not dilute the sodium in the pt's system?

    I'm just having issues with this because to me it does not logically follow. What do you all say? Am I mistaken or is my instructor?
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  4. 1
    I am assuming these are IV infusions?

    Add intravascular sodium = water flowing from interstitial space into the plasma.

    This = great blood interstitial volume = more urination if the kidneys are functioning, which is going to have them peeing more and thus dropping their serum Sodium further.....
    wooh likes this.
  5. 0
    Even if everything is isotonic and osmosis is not a factor, just the virtue of the added fluid volume will equal more excretion which will equal sodium leaving the body.....
  6. 2
    I probably said that all wrong. here is a link to a much more astute expanation LOL...

    http://www.globalrph.com/hyponatremia.htm
    Esme12 and leslie :-D like this.
  7. 2
    To raise levels the pt should be on 2% or3% (central line only) hypertonic saline.
    MomRN0913 and xtxrn like this.
  8. 1
    Quote from nrsang97
    To raise levels the pt should be on 2% or3% (central line only) hypertonic saline.
    For severe hyponatremia yes?

    otherwise fluid restriction if medically possible? for mild to moderate?
    xtxrn likes this.
  9. 4
    So, the other day in clinical I had an elderly patient who had low sodium levels and low blood pressure. They gave the pt two bolus infusions of NaCl to help get his/her bp back up, and afterward my instructor asked me a few questions about the effects of giving boluses of NS NaCl to someone who already has low sodium levels. The instructor said that giving those boluses would dilute the sodium levels in the pt even further, causing his/her [Na+] ratios to drop. For some reason, I'm having a really hard time believing that. My reasoning:

    1) NS NaCl concentrations are based on regular sodium levels. So, if you have a pt who has lower-than-normal sodium in his/her system, then the NS solutions are hypertonic to the pt's Na+ solutes, and that should cause there to be an increase in [Na+] ratio levels, right?

    2) Also, even if the pt's Na+ levels were average, shouldn't the 0.9% NaCl solution not dilute the sodium in the pt's system?

    I'm just having issues with this because to me it does not logically follow. What do you all say? Am I mistaken or is my instructor?
    It isn't as easy as hyponatremia = treatment X.

    It depends on the patient's intravascular volume and underlying cause of the hyponatremia.

    If the patient had acute hypovolemic hyponatremia (you mentioned a low BP, which I assume is not a baseline BP), then isotonic saline infusion would be appropriate to treat both issues.
    netglow, xtxrn, fiveofpeep, and 1 other like this.
  10. 3
    As others have said, it depends on the underlying issue.

    In my line of work, hyponatremia is usually related to an underlying endocrine disorder (SIADH or Cerebral Salt Wasting). In SIADH, you would never bolus to raise serum sodium as the inappropriate levels of circulating ADH would cause the kidneys to retain the fluid thereby possibly dropping the sodium level even more. In Cerebral Salt Wasting, I have given NS boluses to raise serum sodium with good results (123-129-131) throughout the course of the night. In this case, you would use standing NaCl supps to maintain normal sodium levels. In the case of SIADH, you would use fluid restriction.
  11. 0
    Quote from mindlor
    Even if everything is isotonic and osmosis is not a factor, just the virtue of the added fluid volume will equal more excretion which will equal sodium leaving the body.....
    Now, wait a second. An increase in fluid volume doesn't automatically equate to an increased output of Na+. There can be fluid excretion that doesn't necessitate the movement of Na+ particles out of the body via voiding (aldosterone, no?) At least I think that can be the case...

    @Dudette very interesting. so, given that it was acute hypervolemic hyponatremia (which is what it was) you're agreeing with what i was saying then? NS shouldn't dilute the na+ levels even more?

    Also, if this'll help to guide anyone's answer, the pt had a GFR calculation that was only in the low 50s.
  12. 1
    Great thread!

    Not to derail the thread, but here's a link to CPM and "Locked in Syndrome." It results most commonly from raising NA+ too rapidly in patients with chronic hyponatremia.

    Locked in Syndrome will leave you with your cognition intact, but completely paralyzed except for the ability to blink your eyes, and may be permanent. Frightening.

    http://en.wikipedia.org/wiki/Central...e_myelinolysis
    fiveofpeep likes this.


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