NPO status and fluid deficit

[militarymd]

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So a 70kg guy is NPO for 12 hours....what is his "deficit"?

 

[VentdependenT]

So a 70kg guy is NPO for 12 hours....what is his "deficit"?

4:2:1 rule assuming no fever, nausea & vomiting, bowel preps, etc...around 1300 ml.

 

[jetproppilot]

4:2:1 rule assuming no fever, nausea & vomiting, bowel preps, etc...around 1300 ml.

I dont know Venty, Military's got somethin up his sleeve asking (here in New Orleans its "axing" by the way...weird dialect here) a question like that...

 

[Arch Guillotti]

I go NPO before every day in the OR from about 9 pm till 11 am the next day.

 

[VentdependenT]

I dont know Venty, Military's got somethin up his sleeve asking (here in New Orleans its "axing" by the way...weird dialect here) a question like that...

Somebody has to walk into the claymore.

 

[camkiss]

So a 70kg guy is NPO for 12 hours....what is his "deficit"?

I estimate 12-16 oz., about the size of the cup of coffee I drink after being NPO after MN everyday.

Mike

 

[militarymd]

Not too many replies....I was just wondering how many folks go with the 4-2-1 rules and come up with approximately 1000 to 1300 ml of some sort of crystalloid.

Maintenance fluid is 1/2 NS, but when we give back deficit we give back LR or NS which has twice as much sodium content....why?

If your deficit is really 1000ml , then that means you lost 2 pounds in fluid during that time....I don't think we do.

I now treat a person like this as if their deficit is 200 ml of 1/3 to 1/4 normal saline....so essentially no deficit....anyone else does this?

 

[jwk]

Not too many replies....I was just wondering how many folks go with the 4-2-1 rules and come up with approximately 1000 to 1300 ml of some sort of crystalloid.

Maintenance fluid is 1/2 NS, but when we give back deficit we give back LR or NS which has twice as much sodium content....why?

If your deficit is really 1000ml , then that means you lost 2 pounds in fluid during that time....I don't think we do.

I now treat a person like this as if their deficit is 200 ml of 1/3 to 1/4 normal saline....so essentially no deficit....anyone else does this?

4-2-1 is an OK guideline, and besides that, it's fun to make students and residents work through all the calculations. 😉 And in practice, it's actually worked pretty well for me over the years in longer cases.

In shorter cases (knee scopes, D&C's, etc.) I dump in the first liter as fast as it will go, hopefully getting it in before they head for PACU. I think a lot of the early post-op nausea and vomiting is because patients are dry, and of course the first thing the PACU nurses want to do is sit them up and start the discharge process in the first five minutes. No studies or data, just a personal observation.

 

[militarymd]

....because patients are dry.....

define "dry"....kind of a layman's term that we all use freely....and yet I don't really know what it means.

 

[jwk]

define "dry"....kind of a layman's term that we all use freely....and yet I don't really know what it means.

Ah - "dry" is a highly technical term when used in an anesthesia context. 😉

IF (and I guess that's the point of this discussion) you are playing with the 4-2-1 guideline or other fluid replacement formula, the average patient will end up having a theoretical fluid deficit of a liter or so. Do they really? Hell, I don't know. But I feel better starting off with a liter fairly quickly (except for renal failure patients) and I really do think I get less PONV with those patients.

 

[militarymd]

...... fluid deficit of a liter or so.

Ahh yes....but a liter of what?

There is very good data to support volume overload to prevent PONV...so it isn't just your personal observation.

 

[jwk]

Ahh yes....but a liter of what?

Wait - it's a trick question - where's my student? 😕

We use LR for everything except hanging with PRBC's - don't know if it's institutional custom or what but that's all we ever give.

There is very good data to support volume overload to prevent PONV...so it isn't just your personal observation.

Wait - someone else published my observation? I'm shocked and disheartened - I could have retired. 😀

 

[VentdependenT]

Not too many replies....I was just wondering how many folks go with the 4-2-1 rules and come up with approximately 1000 to 1300 ml of some sort of crystalloid.

Maintenance fluid is 1/2 NS, but when we give back deficit we give back LR or NS which has twice as much sodium content....why?

If your deficit is really 1000ml , then that means you lost 2 pounds in fluid during that time....I don't think we do.

I now treat a person like this as if their deficit is 200 ml of 1/3 to 1/4 normal saline....so essentially no deficit....anyone else does this?

Whats wrong with LR in this situation? Its fairly physiologic and we are interstitially dry anyhoots. Most of us don't drink enough fluids in the first place so we are all essentially dry.

 

[jetproppilot]

Wait - it's a trick question - where's my student? 😕

We use LR for everything except hanging with PRBC's - don't know if it's institutional custom or what but that's all we ever give.

😀

We have both, but I use whatever one my hand comes upon. No preference one way or the other...have never seen any evidence to prove otherwise, unless you're giving many many liters, then I think theres some potential pH sequalae if you're using .9%NaCl instead of LR.

 

[militarymd]

Whats wrong with LR in this situation? Its fairly physiologic and we are interstitially dry anyhoots. Most of us don't drink enough fluids in the first place so we are all essentially dry.

LR and other isotonic crystalloids are "resuscitative" fluids....ie used for resuscitation....research done by a surgeon (scheier?? don't remember the spelling) ...that's were lr came from..

Maintenance fluids have much lower sodium content..usually 50 to 77 meq/liter of sodium....and we calculate deficits based on loss of maintenance fluids.

You don't drink salt water everyday.