While I am on a roll…
Fluid restriction as a means of treating babies with BPD makes no sense.
It is also unsupported by any literature.
I think this practice may have arisen because diuretics are given to infants with BPD (don’t get me started on that one) which may lead to modest improvements in pulmonary function. However, here again I think there is a confusion between the effects of changing sodium balance, and the effects of how much free water we give to babies. Diuretics decrease total body water by causing a natriuresis, the sodium depletion leads to reduced body water. Now it isn’t entirely clear that all the pulmonary function changes are because the babies are drier, therefore have less lung water; it may be direct effects of furosemide in particular on ion pumps in the lung (even inhaled furosemide has some effect, without causing a diuresis: Reference at the end).
I reiterate, any reasonable decrease in fluid intake will not affect total body water, and there is no reason to believe that it will affect pulmonary function. If you give 60 mL/kg of fluid less a day, then urine will be more concentrated, increasing risks of nephrocalcinosis, and nutrition is likely to be affected, compounding the growth failure common in BPD.
I have only ever found one relevant trial: Fewtrell MS, Adams C, Wilson DC, Cairns P, Mcclure G, Lucas A: Randomized trial of high nutrient density formula versus standard formula in chronic lung disease. Acta Paediatrica 1997, 86(6):577-582. http://onlinelibrary.wiley.com/doi/10.1111/j.1651-2227.1997.tb08937.x/abstract.
VLBW babies with BPD (O2 at 28 days) were randomized to either high density formula at 140 ml/kg/d or a low density formula at 180 ml/kg/d. the nutrition of the two groups was close to identical, the high-density formula group just had less free water intake. Although the low density group did not quite reach the desired volume, there were substantial differences in the volumes of liquid actually received. However, there were no detectable differences in respiratory outcomes (or indeed in growth).
Babies with BPD are often referred to as being ‘fluid sensitive’ I don’t actually know what that means!
Fluid restriction of babies with BPD may be thought to be a benign intervention, but I often see babies whose nutrition also gets restricted at the same time, nutrition they desperately need to repair their lungs.
Just like for the PDA, restricting sodium (but not free water) in the first few days of life decreases the development of BPD, but restricting free water administration when the condition has occurred has no demonstrated benefit, and no demonstrable effects at all except on urine output.
There is no evidence to support the common practice of fluid restricting babies with BPD, it should not be done.
Prabhu V, Keszler M, Dhaniereddy R: Pulmonary function changes after nebulised and intravenous fresemide in ventilated premature infants. Arch Dis Child 1997, 77:F32-F35. http://fn.bmj.com/content/77/1/F32.long