Neonatal fluid, electrolyte and nutritional management — case

Case summary

A 1000-gram male infant is born at 28 weeks' gestation to a 29-year-old primigravida after preterm labour. He is admitted to the neonatal unit and started on parenteral nutrition from birth. On day 2 of life he is on 80 mL/kg/day of parenteral fluid. His weight is now 6% below birthweight, his urine output is 3 mL/kg/h, and a routine electrolyte panel shows a potassium of 7.0 mmol/L with peaked T waves on the cardiac monitor. Sodium is 138 mmol/L, creatinine 96 µmol/L, and glucose 5.2 mmol/L on a glucose infusion rate of 6 mg/kg/min. He has not yet started enteral feeds. [4] [2]

Candidate tasks

1. Take a focused history and review the chart; formulate a one-line problem representation. [2]
2. Outline your immediate and stepwise management of the fluid, electrolyte and nutrition prescription. [4] [3]
3. Counsel the parents about the nutrition plan for the coming weeks and the long-term growth outlook. [1]

Focused history and chart review

• Perinatal: gestation 28 weeks, birthweight 1000 grams (appropriate for gestation), preterm labour, antenatal steroids given, day 2 of life. [2]
• Current prescription: 80 mL/kg/day parenteral fluid with parenteral amino acids 2 g/kg/day, lipid 1 g/kg/day, glucose infusion rate 6 mg/kg/min; no enteral feeds yet. [3]
• Monitoring: weight 6% below birthweight (within expected 5-15% diuresis), urine output 3 mL/kg/h (adequate), sodium 138 mmol/L (normal), creatinine 96 µmol/L (expected neonatal), glucose 5.2 mmol/L (normoglycaemic). [2]
• The acute issue: potassium 7.0 mmol/L with peaked T waves — non-oliguric hyperkalaemia of prematurity requiring immediate action. [4]

One-line summary: "A 1000-gram, 28-week infant on day 2, following the expected physiological diuresis on an appropriate fluid and early parenteral nutrition regimen, now with ECG-changed non-oliguric hyperkalaemia of prematurity requiring membrane stabilisation." [4]

Immediate and stepwise management

• Stabilise the hyperkalaemia: institute cardiac monitoring and an ECG; give calcium gluconate 0.5 mL/kg of 10% slowly with ECG monitoring to stabilise the myocardium; shift potassium into cells with insulin-dextrose or a beta-agonist; remove potassium with furosemide (given good urine output) or a potassium-binding resin; review the potassium content of the parenteral fluid and recheck the level. [4]
• Continue the fluid prescription as planned: the 6% weight loss is the expected physiological diuresis — do not add fluid. Advance by about 20 mL/kg/day toward 130-150 mL/kg/day, titrated to weight, intake/output and sodium. Withhold sodium until diuresis is established (day 2-3), then add 2-3 mmol/kg/day. [2]
• Advance the nutrition: continue parenteral amino acids (advance toward 3.5-4 g/kg/day) and lipid (advance toward 3-3.5 g/kg/day) to meet the energy target of 110-135 kcal/kg/day and prevent catabolism; maintain the glucose infusion rate at 4-6, advancing as tolerated toward 10-12 mg/kg/min. [3]
• Start enteral feeding: begin minimal enteral feeds of expressed breast milk (10-20 mL/kg/day) to prime the gut, advance cautiously at 20-30 mL/kg/day, and fortify the milk for the preterm as feeds build, weaning parenteral nutrition as the gut takes over. [1]
• Monitor the daily bundle: review weight, intake/output, electrolytes, glucose and the feeding plan together every round; track growth on the Fenton chart with a target of 10-15 g/kg/day and head growth following. [3]

Counselling the parents

• Explain that their baby was born very early and is being given fluids, minerals and nutrition through a vein because the gut is not yet ready to take enough milk to grow — and that the team has started amino acids from the first day because the premature brain is growing fast and needs building blocks now. [3]
• Address the day's event honestly: a routine blood test showed a high potassium that can affect the baby's heartbeat, which the team treated immediately with medicines that protect the heart and bring the level down; it is a common and usually temporary problem of babies born this early, and the team is watching it closely. [4]
• Set expectations for the weeks ahead: the plan is to gradually start and increase milk feeds (breast milk first, with added nutrients for premature babies) while reducing the intravenous nutrition, watching the weight and head growth to make sure the baby is growing well — a process that typically takes weeks, not days. [1]
• Be honest about the longer view: very premature babies are at risk of growth and developmental challenges, which is exactly why the team is so careful about nutrition and growth from the start; close follow-up after discharge will track progress. Invite questions, check understanding, and offer written information and a clear contact. [1]