Intravenous Electrolyte Correction

Introduction

apart from acid-base balance, electrolyte levels immediately after birth reflect maternal electrolyte status and are therefore only useful as a baseline. The exception might be a mother who has been water overloaded during labour with the result of both her and the fetus becoming hyponatraemic. In some cases the infant may be symptomatic (seizures) and require treatment
an unexpectedly abnormal result in a well, asymptomatic infant is most likely to be due to sampling or laboratory error. In this situation, it always advisable to repeat the test before embarking upon a potentially risky correction
as with all interventions, it is wise to consider the risks vs benefits of correcting any electrolyte disturbance
refer to the section on normal laboratory values for definitions
these recommendations are a guide only

1.5 mL x wt(kg) of 10% calcium gluconate in maintenance intravenous fluid over 4 hours
1 mL of 10% calcium gluconate contains 0.2 mmol calcium
only indicated if the baby is symptomatic
- hypotension requiring inotropic support
- persistent pulmonary hypertension of the newborn (PPHN)
- unexplained jitteriness
- seizures
side effects include
- reduced IV half life
- risk of IV burn

0.18 x deficit (from lower limit of normal for age) mL x wt(kg) of 20% sodium chloride over 6 hours (12 hours if <120 mmol/L as rapid or over correction can cause neurological complications)
1 mL of 20% sodium chloride contains 3.42 mmol sodium
consider cause of hyponatraemia
- urinary losses - check urinary sodium
- GIT losses
- inadequate intake of sodium
- excessive intake of water
- SIADH (rare in very premature infants)

1.2 mls x wt(kg) of 15% potassium chloride over 6 hours
do not exceed 0.4 mmol/kg/hr
1 ml of 15% potassium chloride contains 2 mmol potassium
consider cause of hypokalaemia
- resolving/recent metabolic acidosis
- diuretics, particularly frusemide
N.B. true hypokalaemia may be missed if haemolysis occurs during sampling. Capillary specimens are usually haemolysed to a greater or lesser degree.

0.2 mls x wt(kg) 50% MgSO4, diluted to 20% IV slowly (may be arrhythmogenic). IMI administration, although painful, is an alternative if there is no intravenous cannula in situ
do not exceed 0.75 mls/minute
1 ml of 50% magnesium sulphate contains 2 mmol magnesium
consider with
- recalcitrant hypocalcaemia
- PPHN
- seizures
may cause hypotension if given too quickly

0.25 x base deficit x wt(kg) of 8.4% NaHCO₃, diluted 1:1 with H₂O, given slowly over 30 - 60 minutes
1 ml 8.4% NaHCO₃ contains 1 mmol bicarbonate
do not dilute with 10% dextrose as
- increases osmolality and risk of IVH
- unnecessary
- disturbs glucose homeostasis
consider if B.E. < -8.0, although pointless if pCO₂ not controlled
consider and treat underlying cause
- hypoxia
- hypotension
- poor perfusion
- patent ductus arteriosus
- sepsis
if chronic acidosis, consider renal tubular cause and check urine pH at time of acidosis (if acidotic, should be <=5)