Potdar's Neonatal formulas to change dextrosity without discarding TPN or IVF mix

[manojpotdar]

Dear Colleagues,

Its a common problem in NICU that due to hypoglycemia or hyperglycemia, we have to either discard the TPN or change the IVF mix. Its a huge loss to the hospitals. I made few formulas to change the
dextrosity which I want to share with all of you. Send me mail so that I can send directly to you.
manoj_potdar@yahoo.co.in

[rehman_naveed]

You can share here , we will love to see it and practice it. whats wrong here on this forum?

[manojpotdar]

Potdar’s Neonatal formula to increase the dextrosity


Present volume -- PV ml
Present dextrosity – PD%
Desired dextrosity – DD %
ml of 50% dextrose required— Y ml


Formula :-
(PV x PD) +(Y x 50) = (PV+Y) x DD

Y= PV(DD-PD)/50-DD ml of 50% dextrose required

Exp—
Weight of neonate-- 1 kg
Total fluid required @ 100 ml/kg/day—100 ml (PV)
Present dextrosity --- 18%
Desired dextrosity—20%
Ml of 50 % dextrose required—

= (100 x 18)+ 50 Y = (100+Y) x 20
= 1800 + 50 Y = 2000 + 20 Y
= 50Y- 20Y = 2000-1800
= 30 Y = 200
Y = 200/30
Y=6.7 ml of 50 % dextrose.

OR
Y = PV(DD-PD)/50-DD
Y = 100(20-18)/50-20
Y = 200/30
=6.7 ml of 50 % dextrose

This small amount of dextrose may dilute the electrolytes. For this, either you can add electrolyte in same proportion or may increase the fluid rate to give this extra amount in set time.

[manojpotdar]

Potdar’s Neonatal formula to decrease the dextrosity


Present volume-- PV ml
Present dextrosity – PD%
Desired dextrosity – DD%
ml of sterile water required— Y ml


Formula :-
(PV x PD) +(Y x 0) = (PV+Y) x DD

Y=PV(DD-PD)/DD ml of sterile water needed

Exp—
Weight of infant 1 kg
Total fluid required @100 ml/kg/day = 100(PV)
Present Volume—100 ml
Present dextrosity --- 20
Desired dextrosity—18
Ml of sterile water required—

= (100 x 20) + 0 = (100+Y) x 18
= 2000 = 1800 + 20 Y
= 20Y = 2000-1800
= 20 Y = 200
Y = 200/20
Y=10 ml of sterile water

OR

Y= PV(DD-PD)/DD

Y= 200/20

= 10 ml of water

This small amount of water may dilute the electrolytes. For this, either you can add electrolyte in same proportion or may increase the fluid rate to give this extra amount in set time if clinically feasible.

[rehman_naveed]

Thanks for sharing the formula but my question is How to decide that such baby require 20% Dextrose instead of 18% dextose, ( it can be any percentage). But for example if baby of 1kg is requiring 18% dextose @ fluid intake of 100ml/kg/day, it means you are giving too much sugar to this baby(12.3mg/kg/min). If such a scenario either some thing wrong with the baby (Hyperinsulinsim or other causes requiring high sugar). Premature ,low birth weight babies must be given at least 4-6mg/kg per min dextrose before starting insulin for any hyperglycemia.

[manojpotdar]

That was an example only.

[manojpotdar]

Dear Dr Naveed,

I made the equation more simple than before.

[jshenoy]

thanks potdar for the formula. but in one of your threads you have given the same formula,
X ml = TV(DD-LD)/(HD-LD) ml of HD in TV. accordingly in the current formula
Y= PV(DD-PD)/50-DD ml of 50% dextrose required it should be 50- PD & not 50-DD.(it makes only a small difference 6.25 ml instead of 6.7ml )

dr.j.shenoy
mangalore
india

[manojpotdar]

Dear Dr Shenoy,

These two formulas are for two different situations. I will reply you soon.

Potdar

[manojpotdar]

Dear Dr Shenoy

The first formula X ml = TV(DD-LD)/(HD-LD) ml of HD in TV is to get desired concentration (any) of dextrose solution by using solutions of two different dextrosity .

The second formula Y= PV(DD-PD)/50-DD ml of 50% dextrose required, is to increase the dextrosity of existing solution. like if you add 6.25 ml of D50 to 100 ml of of D18 % than dextrosity will increase to 19.88% while if you add 6.7 ml than dextrosity will increase to 20.00 %. Yes , it is a small difference but formulas are to give you exact desired dextrosity .