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Infusion calculations in premature infants

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Dear colleagues!

Please share your experience regarding 2 issues about infusion in preterm infants. Unfortunately there are no solid guidelines but questions of fluid supplementation and parenteral nutrition are obviously important for premature patients.  

       There are considerable differences in proposed volumes of fluid requirement per day in literature. For example, Avery’s Diseases of the Newborn (10th edition from 2018, freshest one) provides following numbers:


From the other hand, European Consensus Guidelines on the Management of Respiratory Distress Syndrome – 2016 Update states that “Typically fluids are initiated at about 70–80 ml/kg/ day and adjustments individualized according to fluid balance, weight change and serum electrolyte levels”.

From the third point of view, National Guidelines for Parenteral Nutrition of Neonates in Russian Federation has following recommendation for daily fluid requirements:

Bodyweight, grams

Daily Fluid Requirements (mL/kg/day)


0-24 hours

24-48 hours

48-72 hours

>72 hours


























Which numbers are closest to yours?

2.       2. Second question. Clinical case J

 Premature infant with sepsis on Dopamine with edema because of boluses and severe condition. Now there is a beginning of the 3rd day of life. When calculating infusion for him what bodyweight we consider:

1. actual one (plus 15% of birthweight)

2. minus 3-4,5% from birthweight (ideally we need at least 1,5% of weight loss per day)

3. birthweight

4. something else?

Thanks a lot!



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For maintainace fluid in FT we start on 60 ml/kg/d and according to weight measures, s. Na , UOP... We calculate the coming days. In PT babies we start on 80 ml /kg/d, in ELBW we calculate on 90 and we measure wt, UOP, s. Na every 12hrs in acute stage till stabilized(if s. Na is high, wt loss... we increase IVF)
In FT we calculate fluid on BW till first 7 days, in PT till 10 days.

Sent from my MHA-L29 using Tapatalk

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For infants with sepsis/ septic shock due to their third spacing secondary to capillary leaks plus they require multiple fluids blouses/ colloids etc, we use weight prior to sepsis call it as dry weight till he or she is back to dry weight. If the kid is still puffy for few wks or month, we take 25th percentile for that age and calculate all fluids based on it. 

I hope it helps


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This is an interesting dialogue. I just had a long disuccussion about fluid management from the delivery room with our neonatal response team nurses. They see quite a bit of variability from our physicians. When we talk about fluids on the first day, we are usually thinking of so much more than just the dextrose/ nutrition containing fluids. We have to consider the "to keep open" fluids running in additional lumens of our UVC and UAC lines. Premature babies are often on antibiotics the first 2 days. Some get saline boluses or blood products. It is very easy to give 20-40mL/kg/d of fluid above the baseline nutrition containing fluid before you even realize it. 

The 2014 cochrane review of fluid restriction in preterm infants (https://www.cochranelibrary.com/cdsr/doi/10.1002/14651858.CD000503.pub3/full) includes only 5 trials done in 1980-2000. The fluid restricted arm in the individual studies ranged from 50mL/kg/d to 120mL/kg/d. "Fluid restriction" had more PDAs close and less NEC. The incidence of BPD, IVH, and death were in the right direction (favoring fluid restriction) but not significant.

Trying to tie all these factors together and deliver an adequate GIR, I start with D10 fluid at 65mL/kg/d. I presume that flushes and medications will add an additional volume that will quickly put my total fluids in the range of 80 - 110 mL/kg/d, which I think is acceptable on the first day. If I have a low glucose, I first increase GIR by going up on the D10 to 80mL/kg/d, but thereafter I try to concentrate the dextrose containing fluids to deliver more GIR over increaseing the rate of administration. In subsequent days I use weight and sodium values to guide increasing total fluid targets. For almost all circumstances i use birthweight for calculations and continue to use it until the baby is back above birthweight. If the baby has edema and is above birthweight in the first week I stick with birthweight until the edema is resolved.

I'm interested in others initial fluid strategies when leaving the delivery room. Where do you start - 60, 80, or more? Do you use D10 or D5 or something else? Thanks in advance for the replies.

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Nathan, many thanks for your suggestions. It is really true that additional fluids for catheters and drugs (incl. Dopamine and vasopressors) have considerable contribution to the daily volume. Interestingly we also do not have consensus even in our NICU about daily fluid requirements. Frankly speaking we are not very restrictive -- we start from 80-90 ml for premature infants with D10, quite liberal in boluses and excessively sticking to the numbers of median arterial pressure on monitor (we love to see MAP 30 mmHg at least and do not like less even if there are no acidosis and other signs of hypoperfusion). We have plenty of BPD and quite many PDA. Sticking to the birthweight until edema is resolved -- it is very good idea.

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I agree with Nathan about it being very easy to forget about the 'other' sources of fluid the baby is getting and that these are more significant the smaller the baby gets.  One thing I will take exception to is TKO fluids for the second lumen of UVC.  I would argue that if you care about volume of infusions in a specific baby, you should be writing your orders such that you don't need a TKO in the second lumen (either by running needed things in each lumen or by using a splitter to run one back through both lumens).  Furthermore, if your baby is small enough/sick enough you need to be counting the UAC fluid into your total.

When we write for fluids out of the DR, our practice is to specify the total fluid goal inclusive of all infusions.  If the baby is small enough or edematous enough, we will also ask the pharmacy to maximally concentrate all medications and give us their best estimate of all drug volumes and flushes etc.

The challenge then, becomes picking a number to target.  The second table you posted best approximates our local practice, with the understanding that we're including almost everything, not just nutritional fluids in this volume.  For the sickest/smallest we're then following urine output and serum sodiums as a guide to whether or not we're over- or under-shooting on total volume.

As regards BP targeting, we are VERY permissive of low MAPs if there is no evidence of impaired end organ perfusion, especially in the first 6-12 hours or even 24 hours.  Over the period of 24-72 hours we start to care more about MAP > 30mmHg even in the absence of evidence of organ dysfunction.


Finally, as regards your hypothetical patient, I would pick some dry weight, probably birthweight unless born edematous.

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Thanks @Andrej Vitushka for posting about this every-day NICU question!

In Stockholm, I think we are mostly following the table 30.1 from Avery (in the first post), i.e. a rather high fluid intake in the smallest infants, typically ~100/110 ml/kg/d in the most immature infants and going down to 60 in term infants.

@Nathan Sundgren - with regard to what to give: we tend to start with parenteral nutrition right away, in infants that we judge will not take much enterally: in practise all infants <1500g.

As already pointed out - it is always a question about fluids from medications, boluses, low-flow infusions keeping catheters open etc. The principle is easy :) (count everything that is not fluid therapy due to hypovolemia) but in practise there is variation.

My experience from infants above the extremely preterm range (i.e. ≥28 weeks) is that it is hard to know what is the right thing. Even with slightly different fluid regimes, they mostly seem to do good in terms of water balance.

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17 hours ago, Andrej Vitushka said:

Bimalc, thank you for your suggestions! Regarding dry/birthweight. Until what day will you use it in VLBW infants? 10th? 14th?  

in VLBW who is not edematous we use BW until 14d or until regain of BW, which ever is first.  In the case of an edematous baby, our local practice is not uniform and I think you really need to tailor that to the clinical course (continued edema, or had some diuresis and now is gaining weight again but this time it is 'good weight'  and not 'water weight', etc.)

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  • 1 year later...

Hi. What do you think about this case?:

RNPT 26 sem. 650 g.  Ex SDR with a good evolution.

In her 8 day of live 640 gr, diuresis 2.5 cc/kg/h.  The Day before she recived 170 ml /kg/d  (enteral 40 ml/kg/d y Parenteral 130 ml/kg/d)

Electrolytes: normal. CPAPn con PEEP 5 / FiO2 30%. 

Bad tolerance, with reduccion in entereal feedings, to trofic enteral (20 ml/kg/d) with donor milk.  Rx with  distension of intestinal track, and edema of wall. 

Some milk with bili (rest) . Sospected NEC I de Bell.

We dicussed about iv liquid: I agree with 170 ml/kg/d ef parenteral nutricion.  What do you think?

Thank you.



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If you're going to run that much fluid at this age you will need to keep an eye on Na and volume status.  As the skin keratinizes, lung disease evolves, renal concentrating ability fluctuates and you're possibly trying to coax a PDA to close you may need to be quite nimble in your goals for the day.  In my experience, I am good about proactively considering fluids as we come out of the DR, but could perhaps be better with the 1-2 week olds who still need IV fluids/nutrition.

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We use a calculation of Total Fluid per day (on day zero) based on birthweight. 

<750 gram = 120 mL/kg/day

750 - 1000 grams = 100 mL/kg/day

1000 - 2000 grams = 80 mL/kg/day

>2000 grams = 60 mL/kg/day

For us, total fluids DOES NOT include medications, flushes and boluses/transfusions, rather we have guidelines in place to minimize extra fluid in medications and flushes, and we are very judicious with respect to boluses/transfusions. We increase total fluid by 20 mL/kg/day, assuming no edema. Whenever possible, we convert IV medications to po to avoid excess flushes (and also decrease risk of CLABSI). For example, we convert caffeine to po once the baby reaches 60 mL/kg/day of enteral feeds. 

Our Total Fluid goal on preterm babies is 160 mL/kg/day. On term babies it is 150 mL/kg/day. 

We consider insensible losses to be 60 mL/kg/day for patients with oliguric renal disease. 

Rarely do we exceed 160 mL/kg/day of total fluid on any baby unless there are weight gain issues, with fortified feeds, in the absence of respiratory/cardiac compromise. 

As I have gained experience, I rarely follow daily electrolytes, unless there is evidence of excessive weight loss, weight gain, poor urine output, or IV fluids lacking electrolytes. Essentially, I consider the kidneys to be smarter than me. Too often I see Neos getting daily electrolytes; on Monday they increase the Na, Tuesday they decrease the Na, increase the K, fudge the Ca, Wednesday they increase the Na, decrease the K, fudge the Ca, etc, etc, etc. At the end of the week, the baby has had 10% of their blood volume removed because of "tinkeritis". Labs beget labs, then they beget blood transfusions. 

We consider birthweight the calculable weight until the baby exceeds the birthweight, without signs of edema. 

Fluid restriction has no evidence to promote the closure of a PDA, and as long as total fluid is < 180 mL/kg/day, I have found no evidence that excess fluid volumes increase the length of time to close the PDA and affect respiratory status. In my readings/experience, PDA closure is more about minimizing inflammation, rather than fluid balance. 

We are strong advocates of enteral feeds and human-milk products vs. bovine-milk products. 


All the best!

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