FW: {Pediatric Doctors} Few formulas which might help doctors working in NICU

 

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.

1)Potdar's Neonatal formula to decrease the dextrosity of solution

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.

2)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 if clinically feasible.

3)Making IVF mix with D10% and D 50% (or any two solutions of different dextrosity)
In many neonatal nursery IVF mix is made by adding sterile water and D 50%. Which is more costlier. We can make IVF mix by D10 and D50%.

Formula--

General formula for any two solutions with different dextrosity=

Total volume required= TV

ml of solution containing higher dextrosity(HD%)= X ml

ml of solution containing lower dextrosity(LD%)= TV- X ml

Desired dextrosity= DD

X ml = TV(DD-LD)/(HD-LD) ml of HD in TV

ml of LD in TV = TV- X ml

exp-

Total volume required is 100 ml

Desired dextrosity is 16% and we have D10 and D50%

HD=50%
LD= 10%

ml of D 50 (X ml) = 100(DD-10)/(50-10)

ml of D 50% ( X ml) =100(16-10)/40 ml

= 600/40 ml
= 15 ml

ml of D10%= 100-15=85 ml
 

 

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