What is the 421 rule for IV fluids?

[joe6102]

My resident told me to look this up tonight, but I can't find anything about. Has anyone heard of this?

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[smq123]

My resident told me to look this up tonight, but I can't find anything about. Has anyone heard of this?

I think it's the rule that says:
In one hour -

• 4 cc/kg for the first 10 kgs of a patient's weight
• 2 cc/kg for the next 10 kgs of a patient's weight
• 1 cc/kg for the rest of the patient's weight

So for a 60 kg patient, he should get 100 cc/hr.

I think this is right, but I'd appreciate anyone correcting me.

 

[GregsAnatomy]

The 421 rule is used to calcuate the hourly infusion rate for maintenance fluids (generally just for pediatrics).

4 cc/hr for kg 1-10
2 cc/hr for kg 11-30
1 cc/hr for each additional kg

So for a 70-kg male, the infusion rate would be 40 + 40 + 40 = 120 cc/hr.

This is similar to the daily requirement method:

100 cc/day for kg 1-10
50 cc/day for kg 11-30
25 cc/day for each additional kg

So again for a 70-kg male, 1000 + 1000 + 1000 = 3000 cc/day / 24 hrs = 125 cc/hr.

 

[joe6102]

The 421 rule is used to calcuate the hourly infusion rate for maintenance fluids (generally just for pediatrics).

4 cc/hr for kg 1-10
2 cc/hr for kg 11-30
1 cc/hr for each additional kg

So for a 70-kg male, the infusion rate would be 40 + 40 + 40 = 120 cc/hr.

This is similar to the daily requirement method:

100 cc/day for kg 1-10
50 cc/day for kg 11-30
25 cc/day for each additional kg

So again for a 70-kg male, 1000 + 1000 + 1000 = 3000 cc/day / 24 hrs = 125 cc/hr.

Thanks, that's exactly what I was looking for.

 

[m1dawg]

that will come in handy during situations like the one you encountered.

 

[QuinnB]

The 421 rule is used to calcuate the hourly infusion rate for maintenance fluids (generally just for pediatrics).

4 cc/hr for kg 1-10
2 cc/hr for kg 11-30
1 cc/hr for each additional kg

So for a 70-kg male, the infusion rate would be 40 + 40 + 40 = 120 cc/hr.

This is similar to the daily requirement method:

100 cc/day for kg 1-10
50 cc/day for kg 11-30
25 cc/day for each additional kg

So again for a 70-kg male, 1000 + 1000 + 1000 = 3000 cc/day / 24 hrs = 125 cc/hr.

This part is incorrect (maybe some people learn it differently, I don't know) - it is 2 cc/hr for kg 11-20, NOT 11-30. I use the following shortcut (not so useful on peds where a lot of patients are less than 20 kg):

Add the number of kg above 20 kg to 60 for the maintenance per hour (basically just reduced the math a little):

120 kg male (I'm from the midwest, this is the smallest they come) would therefore have 60+100 (from 120-20) = 160 cc/hr

 

[Fin-Nor]

This part is incorrect (maybe some people learn it differently, I don't know) - it is 2 cc/hr for kg 11-20, NOT 11-30. I use the following shortcut (not so useful on peds where a lot of patients are less than 20 kg):

Add the number of kg above 20 kg to 60 for the maintenance per hour (basically just reduced the math a little):

120 kg male (I'm from the midwest, this is the smallest they come) would therefore have 60+100 (from 120-20) = 160 cc/hr

yeah, it should have been 110 for maintenance on previous dude's calcuations. i think

 

[GregsAnatomy]

This part is incorrect (maybe some people learn it differently, I don't know) - it is 2 cc/hr for kg 11-20, NOT 11-30.

I actually thought it was 11-20 as well, but I checked my Maxwell's and it says 11-30. I'm not sure who to believe any more!! Oh well...your 120-kg Midwesterner could probably use the extra fluids anyway

 

[Tired]

The difference between 11-20 and 11-30 is pretty small (20cc/hr = an extra can of Coke every 18hrs) in adults. I wouldn't sweat it in adults, and in fact I don't even calculate maintenance fluids in adults unless I'm particularly worried about their fluid status (ie - cardiac or renal failure).

This rule is mainly for kids. Screw Maxwells, someone go look it up in Harriet Lane please. I personally used 11-20, and am betting good money that 11-30 is a typo.

 

[QuinnB]

The difference between 11-20 and 11-30 is pretty small (20cc/hr = an extra can of Coke every 18hrs) in adults. I wouldn't sweat it in adults, and in fact I don't even calculate maintenance fluids in adults unless I'm particularly worried about their fluid status (ie - cardiac or renal failure).

This rule is mainly for kids. Screw Maxwells, someone go look it up in Harriet Lane please. I personally used 11-20, and am betting good money that 11-30 is a typo.

You're totally right about the adult. Although, given that in a 2 month old, an extra 10 cc/hr could make a huge difference I guess someone should know for sure - I've never heard of the 11-30 stuff.

 

[domer621]

The peds director went over this with us yesterday.

4 cc/hr for kg 1-10
2 cc/hr for kg 11-20
1 cc/hr for each additional kg over 20

 

[DrStevo]

you can also just add 40 to their weight in kilograms and almost always works out unless they weight 10kg or less. Hope that helps. Also to convert from lbs to kg. Here an easy calculation. divide the weight in lbs in half then take 10% from that and subtract it, and it should give a pretty good estimate of their weight in kg.

eg. 200lb

200/2 = 100
10% of 100 is 10
100-10= 90 kg

hope that helps to somebody