Higher Parenteral Electrolyte Intakes in Preterm Infants During First Week of Life: Effects on Electrolyte Imbalances. A Publication Summary

Objectives

Electrolyte imbalances are common during the first postnatal days in very low birth weight (VLBW, <1,500 g) infants. To ensure a rapid anabolic state, parenteral nutrition (PN) is recommended from the day of birth.

Current European guidance recommends relatively high total energy and protein intakes, which have been associated with improved postnatal growth. In addition, sodium and potassium intakes from PN are recommended to be minimized during the first 3 postnatal days. However, higher amino acid intakes may increase the risk of hypophosphatemia and hypokalemia. This is recognized as a significant problem in VLBW infants receiving recommended levels of parenteral amino acids without adequate provision of electrolytes. Nonetheless, the optimal concentrations of electrolytes for use in PN solutions is currently unknown. There was consequently a need to understand the effects of higher levels of electrolytes in VLBW infants, to prevent the development of hypophosphatemia and hypokalemia.

Methods

A single-center, retrospective, observational, cohort study was conducted in 134 VLBW infants born in Sweden between 1 February 2010, and 30 September 2013. These patients were admitted to the neonatal intensive care unit at Umeå University Hospital within 24 hours after birth and treated there for at least 7 days.

They received either an original PN regimen (consisting of a pharmacy-prepared all-in-one bag combined with a glucose bag containing individually added electrolytes) or a concentrated PN regimen (consisting of a commercially available bag containing glucose, amino acids, and electrolytes with a routine addition of trace elements and the possibility to add further electrolytes combined with lipids). Enteral nutrition was also started as soon as possible after birth for all patients and increased according to clinical decision.

Results

Higher electrolyte intakes did not cause increased electrolyte imbalances

During the first postnatal week, electrolyte intakes were significantly higher in infants who received concentrated PN compared with infants who received original PN. However, the study showed that the higher electrolyte intakes did not cause increased electrolyte imbalances during the first postnatal week in VLBW infants.

Infants receiving concentrated PN had a lower incidence of hypokalemia and severe hypophosphatemia

Infants who received concentrated PN had a lower incidence of hypokalemia (<3.5 mmol/L; 30 vs 76%, p<0.001) and severe hypophosphatemia (<1.0 mmol/L; 2.2 vs 17%, p=0.02) than those who received the original regimen. Consequently, providing at least 1 mmol potassium/kg/d during the first 3 postnatal days might be necessary to prevent early hypokalemia.

Incidence of hypernatremia was similar in both groups

The incidence of early hypernatremia was similar in infants who received concentrated PN compared with those infants who received the original regimen (>145 mmol/L; 35 vs 30%, p=0.7). Therefore, although the concentrated PN group received more than twice the quantity of sodium (2.04 vs 0.75 mmol/kg/day), the incidence of early hypernatremia was not affected.

Reduced surgical outcomes in infants receiving concentrated PN

Infants in the concentrated PN group received pharmacological and surgical treatment for patent ductus arteriosus less often than those in the original PN group (28 vs 49%, p=0.02).

Conclusions

• A concentrated PN regimen with relatively high intakes of sodium (2 mmol/kg/d) during the first 3 days of life was well tolerated in VLBW infants and does not cause hypernatremia, suggesting that there might not be a need of a special low-sodium PN solution during the first postnatal days.
• An advantage of a higher sodium tolerance is that it allows a higher phosphorus intake from sodium glycerophosphate.
• A higher parenteral potassium intake was associated with lower risk of hypokalemia, suggesting that the minimum recommended potassium intake during the first 3 postnatal days should be increased from 0 to 1 mmol/kg/d in VLBW infants.
• The increased supply of electrolytes by the concentrated PN regimen, including additional phosphorus supplements, provided the necessary amounts to compensate for the higher protein intake while the original PN regimen provided insufficient amounts of potassium and phosphorus in relation to protein intake.

Disclaimer

This summary is a derivative work from the open access paper “Higher Parenteral Electrolyte Intakes in Preterm Infants During First Week of Life: Effects on Electrolyte Imbalances” by C. Späth, RD, PhD, E. S. Sjöström, RD, PhD, and M.Domellöf, MD, PhD which can be found at: Journal of Pediatric Gastroenterology and Nutrition, September 2022 - Volume 75 - Issue 3. Baxter assumes no responsibility and does not extend any representation and warranty (expressed or implied) as to accuracy or completeness of the contents of this summary or original articles summarized herein. The original article was selected for reasons of relevance, but Baxter does not make any representation that selected publications are representative. Baxter does not represent or warrant:
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Conflict of interest statement: C.S. and M.D. have received lecture honoraria from Baxter. The remaining author reports no conflicts of interest.

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