Intro to IV fluids?

Started by wAyRadikull
Get help with your application

Use all the free resources available to you from SDN: articles, guides, expert advising, forums discussions, and school research.

Browse articles Compare schools My application plan Read Interview Feedback
Practice for interviews Ask an Advisor
wAyRadikull

wAyRadikull

Full Member
10+ Year Member
5+ Year Member
15+ Year Member
I just started my surgery rotation a few weeks ago and was wondering if any one had any source (pref. online) where I could find the basics on some of the IV fluids we use in the ICU and on the wards.

I looked up ccmtutorials.com and google'd a bit but couldn't find a worthwhile document that answered my questions. I was flipping through Secrets Anesthesia and it had a great section on IV fluids and what type to use and when (D5 vs LR vs NS etc), but I'm trying not to drop 40 bucks on a book right now (read: can't, haha). So if any one can help me out, I'd greatly appreciate it.

Thanks in advance.
 
wAyRadikull said:
I just started my surgery rotation a few weeks ago and was wondering if any one had any source (pref. online) where I could find the basics on some of the IV fluids we use in the ICU and on the wards.

I looked up ccmtutorials.com and google'd a bit but couldn't find a worthwhile document that answered my questions. I was flipping through Secrets Anesthesia and it had a great section on IV fluids and what type to use and when (D5 vs LR vs NS etc), but I'm trying not to drop 40 bucks on a book right now (read: can't, haha). So if any one can help me out, I'd greatly appreciate it.

Thanks in advance.
Click to expand...

There doesn't appear to be some sort of super science to IV fluids for adults on Sx. The Peds guys have this down to a science. Probably the most important thing to remember for Sx is that they think NS=poison. They resuscitate with LR and blood (they especially like to use this when people are bleeding) - dump it in until the bleeding stops and/or blood pressure reaches acceptable MAPs. When patients are not bleeding and NPO for surgery D5 1/2NS + K20Meq, even though it doesn't really matter that the calories form the sugar and the K in the bag basically equal to not giving anything, that is what they do. Run these fluids at 100 or 125 cc per hour because that is what everyone does and you should be fine for a Sx rotation. The end. Don't buy a book.
 
jdh71 said:
There doesn't appear to be some sort of super science to IV fluids for adults on Sx. The Peds guys have this down to a science. Probably the most important thing to remember for Sx is that they think NS=poison. They resuscitate with LR and blood (they especially like to use this when people are bleeding) - dump it in until the bleeding stops and/or blood pressure reaches acceptable MAPs. When patients are not bleeding and NPO for surgery D5 1/2NS + K20Meq, even though it doesn't really matter that the calories form the sugar and the K in the bag basically equal to not giving anything, that is what they do. Run these fluids at 100 or 125 cc per hour because that is what everyone does and you should be fine for a Sx rotation. The end. Don't buy a book.
Click to expand...

This is the truth.
 
Thanks for the quick breakdown, helped clarify a few things.I talked to an anesthesiologist and a pulm/cc doc and they said the exact same thing haha
 
There is a long winded explanation that involves osmolarity and electroneutrality of different fluids that is not important for reasons why you choose a fluid. I will leave it out. This is still long winded but gives far more insight than you'd get from a chapter on fluid. I would not share this information with your surgery team; surgeons dont know why they give LR, they just do.

Essentially,

Lactated Ringers is used by surgeons. It is isotonic as is Normal Saline, but it has the interesting property of not causing an acidosis. Inherently, you understand that if you get a contraction alkalosis you should therefore be able to induce an expansion acidosis. Lactated Ringers is unfortunately named because the lactate has actually nothing to do with its use. You can dump 20L of LR into a person during resusciation in surgery and not change their pH status. The draw back to LR is that is contains a ton of Potassium. This is not a big deal in someone who has a good heart and clean kidneys (i.e. the "medically cleared surgical candidate"), but can be devestating in a renal patient. Surgeons use LR because they can give large amounts without altering the pH of the patient, while medicine doctors stay away from LR because of the Potassium.

Normal Saline is used by medicine doctors. This is because medicine rarely, if ever, will give more than 10 Liters of fluid in a day. At small volumes of NS, there is no pH alteration. But, if you give fluid like you need to in surgery, you will produce an acidosis. Medicine keeps to small fluid volumes and is in fear of the potassium of LR. This is especially true in the renal, heart, and liver patients (i.e. every hospitalized medicine patient). medicine doctors use NS because the volume is low so no acidosis will develop and they fear potassium. Surgeons stay away from NS because large volumes produce acidosis.

D5W is a hypotonic fluid. Its usually a bad idea. It would take 10L to get the nutrional value of a can of coke. 10L of hypotonic solution will dilute their blood, cause a nasty (and rapid) hyponatremia, and give them a seizure. Basically, never use D5W unless in special situations such as DKA.

Rather than confuse people and make them decide, its simple to say "Surgeons LR, Medicine NS...always"

Bottom Line:
(1) LR used by surgeons. Large volumes do not cause acidosis, potassium load is usually able to be handled by most surgical candidates (if they were medically sick, they wouldnt operate).

(2) NS used by medicine. Large volumes would cause acidosis, but medicine does not give large volumes. There is no potassium in NS to worry about.

(3) D5W is a foolish fluid to use. It is hypotonic, has a nutritional content of 0, so use it only in special cases like DKA where the goal is to drive down the serum osmolarity.
 
OveractiveBrain said:
The draw back to LR is that is contains a ton of Potassium. This is not a big deal in someone who has a good heart and clean kidneys (i.e. the "medically cleared surgical candidate"), but can be devestating in a renal patient.
Click to expand...

In my opinion, this is a myth. The amount of K in LR (just 4 mEq/L) is dwarfed by the huge intracellular stores that can be shifted out by an acidosis (such as that induced by large volumes of NS). An RCT of end-stage renal patients undergoing renal transplantation found that hyperkalemia was an issue in a significant number of patients receiving NS, but none who received large amounts of LR.

http://www.anesthesia-analgesia.org/content/100/5/1518.abstract

I admit that trying to convince a medicine attending of this would be a futile battle. At small volumes it doesn't matter anyway.
 
Last edited:
well to the above D5W is moreused for free water deficit causing hypernatremia than it is for DKA. For DKA you just pour in the saline, and then you shift to balance it with D5NS or D10NS rather than D5W when the sugars hit 300 or so (with K supplementing)
 
Also, show me one single bit of data that supports that a chloremic acidosis from NS is detrimental to any of our common patient measurements of what's important, ie. LOS, morbidity, mortality . . .

Every time they randomize NS to LR there's no difference, though last time I looked really closely was beginning of 2009. Anything changed?
 
jdh71 said:
Also, show me one single bit of data that supports that a chloremic acidosis from NS is detrimental to any of our common patient measurements of what's important, ie. LOS, morbidity, mortality . . .

Every time they randomize NS to LR there's no difference, though last time I looked really closely was beginning of 2009. Anything changed?
Click to expand...

Nope, it's still pretty much equal, just use whichever fluid you and your culture of practice prefer.
 
Caveat: If a patient is already profoundly acidotic, like a CO2 <10, and they need fluid support I do use LR.

The thing I really like best about NS is that I find it very predictable. It does what I want it to without any surprises.
 
You must log in or register to reply here.