Fluid Balance

[Captain Planet]

---

Members do not see this ad.

Hey Guys,
Sorry to be the med student posting on your forum. but i figured you guys were probably the best ones to answer this.
just wondering if there's anyone who can give me a clinical overview of fluid selection? All the stuff I can find is very theoretical. I really just want to know what to hang when i'm actually having to take care of someone.
Things like best selection for increasing BP, how to avoid hypernatremia/hypokalemia in people that are nil orally. All that kind of stuff.
If that's too much to go through is there a good book/website to look at?
Thanks guys

 

[sluggo]

Very general question , so GENERALLY:

Use .9 NS to resuscitate/give volume unless the patient is extremely acidotic, then you can use water with 3 amps of sodium bicarb.
If the patient is hypernatremic, and you just want to give maintenance fluids to correct, use .45 NS or D5 water to give back nutrition (calculate a sodium deficit and use targeted replacement).
If you want to give a little nutrition, add a little dextrose until starting tube feeds.
Replace lytes as needed.
Did you have something specific in mind?

 

[J-Rad]

http://www.amazon.com/Acid-Base-Fluids-Electrolytes-Ridiculously-MedMaster/dp/0940780313

 

[Stitch]

http://www.amazon.com/Acid-Base-Fluids-Electrolytes-Ridiculously-MedMaster/dp/0940780313

Fantastic book and immensely useful!

 

[jdh71]

Hey Guys,
Sorry to be the med student posting on your forum. but i figured you guys were probably the best ones to answer this.
just wondering if there's anyone who can give me a clinical overview of fluid selection? All the stuff I can find is very theoretical. I really just want to know what to hang when i'm actually having to take care of someone.
Things like best selection for increasing BP, how to avoid hypernatremia/hypokalemia in people that are nil orally. All that kind of stuff.
If that's too much to go through is there a good book/website to look at?
Thanks guys

I think most people get too abstract about all of this.

Use NS for basically everything, especially resuscitation - ie. raising blood pressure (I guess if you are a surgeon and think NS is poison, then you may use LR for resuscitation - and I do use LR if patients have a low CO2 on the BMP). Dump it in, and don't be a ***** if you've got a crashing patient. - 20ml/Kg is a good goal to bolus and run it wide open.

Everything else . . . meh . . .

Maintain with D5 1/2NS with K

You can use bicarb if very acidotic and it is 3 AMPs in D5W, but interestingly enough according to Stewart's strong ion, physical chemistry derivation, it's not the bicarb that actually correct the pH, but the sodium. Neat huh?

Check your lytes, mg, and phos regularly and replace. If not orally then by IV.

Most people are ******* with the K. Most people need ~100-120mEq (assuming ideal body weight - use your brain if you're got an 80lb woman) a day to maintain their stores if they are not eating, so give a patient with low K at least 120mEq + the correction needed (10mEq = 0.1 increase on the BMP). Run it in at 40mEq over 4 hours and repeat as many times as necessary to get the amount of K you want in. If you have been giving a patient an extra 40 mEq of K per day and don't know why they're not bumping up, now you know. If patients are eating, replace as needed. A common order I write for this is: KCl 120mEq IV, given as 40mEq over 4 hours x 3 doses.

Mg is in intracellular ion, so if it's low in the periphery is LOW everywhere. Write for it like this: Magnesium Sulfate 2grams IV Q8* for 3 days . . . don't forget to spell out "magnesium sulfate", it's one of those "no-nos" for abreviating in the hospital

Phos is important for breathing and especially for getting ventilated patients off of the vent (if you forget why this is, please revisit your cellular and molecular biology). Phos is given as KPhos in mmols, which are close enough to mEq that I treat them essentially the same . . . KPhos 18mmol IV x once, give over six hours. Remember to factor the K into your lytes for the day, you may convert it, but 18mmol of K is going to move your K on the BMP ~0.2+ . . . basically if your K is 4.8 or lower, you're fine to replace the phos as written above

EDIT: Also a little bit of D5 in the bag is not very many calories. Patient will NEED nutrition within about 24-48 hours, if they are truly NPO, will need TPN and a line, but if their gut works, enteric feeding the best way to go

EDIT #2: Calcium. I always calculate the correction for the albumin and if they are low and not a rhabdo patient, I throw a couple of amps at them. I'm sure someone has a more scientific way of going about this, and I'd love to hear it if they do.

Remember, generally, if the gut works there is really not many reasons NOT to replace much of this stuff that way.

 

[MTGas2B]

I think most people get too abstract about all of this.

Use NS for basically everything, especially resuscitation - ie. raising blood pressure (I guess if you are a surgeon and think NS is poison, then you may use LR for resuscitation - and I do use LR if patients have a low CO2 on the BMP). Dump it in, and don't be a ***** if you've got a crashing patient. - 20ml/Kg is a good goal to bolus and run it wide open.

Everything else . . . meh . . .

Maintain with D5 1/2NS with K

You can use bicarb if very acidotic and it is 3 AMPs in D5W, but interestingly enough according to Stewart's strong ion, physical chemistry derivation, it's not the bicarb that actually correct the pH, but the sodium. Neat huh?

Check your lytes, mg, and phos regularly and replace. If not orally then by IV.

Most people are ******* with the K. Most people need ~100-120mEq (assuming ideal body weight - use your brain if you're got an 80lb woman) a day to maintain their stores if they are not eating, so give a patient with low K at least 120mEq + the correction needed (10mEq = 0.1 increase on the BMP). Run it in at 40mEq over 4 hours and repeat as many times as necessary to get the amount of K you want in. If you have been giving a patient an extra 40 mEq of K per day and don't know why they're not bumping up, now you know. If patients are eating, replace as needed. A common order I write for this is: KCl 120mEq IV, given as 40mEq over 4 hours x 3 doses.

Mg is in intracellular ion, so if it's low in the periphery is LOW everywhere. Write for it like this: Magnesium Sulfate 2grams IV Q8* for 3 days . . . don't forget to spell out "magnesium sulfate", it's one of those "no-nos" for abreviating in the hospital

Phos is important for breathing and especially for getting ventilated patients off of the vent (if you forget why this is, please revisit your cellular and molecular biology). Phos is given as KPhos in mmols, which are close enough to mEq that I treat them essentially the same . . . KPhos 18mmol IV x once, give over six hours. Remember to factor the K into your lytes for the day, you may convert it, but 18mmol of K is going to move your K on the BMP ~0.2+ . . . basically if your K is 4.8 or lower, you're fine to replace the phos as written above

EDIT: Also a little bit of D5 in the bag is not very many calories. Patient will NEED nutrition within about 24-48 hours, if they are truly NPO, will need TPN and a line, but if their gut works, enteric feeding the best way to go

EDIT #2: Calcium. I always calculate the correction for the albumin and if they are low and not a rhabdo patient, I throw a couple of amps at them. I'm sure someone has a more scientific way of going about this, and I'd love to hear it if they do.

Remember, generally, if the gut works there is really not many reasons NOT to replace much of this stuff that way.

I'll add my two cents to the above. As far as resuscitation (not maintenance), there's a reason the surgeons like LR (and I like plasma-lyte). I've been on rounds in the morning on more than one occasion where a fresh trauma patient came in over night, acidosis, hypotensive, etc. Got fluid, urine output picked up, normotensive, but it took 10 liters, or so. Despite all that they have still have a base defecit of 12 and a pH of 7.25 from a metabolic acidosis. A quick look at the chem panel and their chloride is now 112. Hyperchloremic acidosis can be problem with large volume NS resuscitations.

 

[jdh71]

I'll add my two cents to the above. As far as resuscitation (not maintenance), there's a reason the surgeons like LR (and I like plasma-lyte). I've been on rounds in the morning on more than one occasion where a fresh trauma patient came in over night, acidosis, hypotensive, etc. Got fluid, urine output picked up, normotensive, but it took 10 liters, or so. Despite all that they have still have a base defecit of 12 and a pH of 7.25 from a metabolic acidosis. A quick look at the chem panel and their chloride is now 112. Hyperchloremic acidosis can be problem with large volume NS resuscitations.

I promise I am aware of this phenomenon. What I've always wondered is does it really matter? There hasn't been single trial that I'm aware of that demonstrated any improvement in final outcomes with NS vs LR, other than a better buffed BMP in the AM. Pigs, apparently, require less LR than NS with hemorrhage 😀 . . . I understand the intuitive connections; however, the question is: do the end points that really matter improve with LR vs NS, such as death, length of stay, icu admission, etc.

I suppose it'd be tough to do that study in a trauma cohort

 

[SLUser11]

I promise I am aware of this phenomenon. What I've always wondered is does it really matter? There hasn't been single trial that I'm aware of that demonstrated any improvement in final outcomes with NS vs LR, other than a better buffed BMP in the AM. Pigs, apparently, require less LR than NS with hemorrhage 😀 . . . I understand the intuitive connections; however, the question is: do the end points that really matter improve with LR vs NS, such as death, length of stay, icu admission, etc.

I suppose it'd be tough to do that study in a trauma cohort

Agreed that it might not matter much. There have been a couple studies in the critical care literature that showed that patients with hyperchloremic acidosis did just as well as patients with normal pHs.....as opposed to other causes of acidosis that had worse outcomes.

I guess the only reason to avoid massive NS resuscitation is if it is clouding the clinical picture, and people start treating the pH or base deficit that's really caused by chloride, etc.

 

[Hernandez]

base deficit

Do people actually still use the BD? Lawrence Martin's ABG/acid basse book puts up a pretty good argument on why not to bother with it so I never bothered to learn it, do you find it useful clinically?

 

[jdh71]

Do people actually still use the BD? Lawrence Martin's ABG/acid basse book puts up a pretty good argument on why not to bother with it so I never bothered to learn it, do you find it useful clinically?

Had one of the 4th year medical students rotating through with us two months ago in the unit - gunner, wants to do surgery and had just spent the last two months with surgery. He's presenting a patient and at one point during the presentation says the base deficit, and the conversation to follow goes like this . . .

Dr. M. "Whoa, wait a minute, what did you say?"

M4 " The base deficit is X"

Dr. M. "Only douchebags and surgeons care about base deficits, which are you?"

M4 "Well, I want to do surgery, I'm applying this year . . . *some stammering soon cut off*"

Dr. M. "Well, that makes sense then, what do you want do about it?"

M4 "Uhhhh, well, uhhh . . . I don't know"

Dr. M. "Exactly - neither do I. Continue your presentation"

 

[Hernandez]

Dr. M. "Only douchebags and surgeons care about base deficits, which are you?"

I could see that being said by a Dr M in your general vicinity.