1. Emergency neonatal resuscitation.
   1-2mmol/kg by slow IV push.
2. Metabolic acidosis
   1. Documented metabolic acidosis during prolonged resuscitation after establishment of effective ventilation. Administer half calculated dose then assess need for remainder. Administered by slow IV infusion over 30 minutes.
   2. Bicarbonate deficit caused by renal or gastrointestinal losses. Slow correction orally.

   Sodium bicarbonate dose (ml) = base deficit x 0.6 x weight (kg).

3. Persistent pulmonary hypertension of the newborn.
   0.25-0.50 mmol/kg/hour. Continuous IV infusion.
   Doses needs to be individualised and titrated according to response and to adverse effects (e.g. hypernatraemia)

Contraindications and Precautions

1. Respiratory or metabolic alkalosis.
2. Not recommended for hypercapnia or hypernatraemic states.
3. Caution in infants with renal impairment.
4. Caution in preterm infants. Rapid infusion of hypertonic NaHCO₃ has been incriminated in the pathogenesis of intraventricular haemorrhage in preterm infants.

Clinical Pharmacology

Sodium bicarbonate is the alkali most frequently employed for correction of metabolic acidosis. The drug is well absorbed from the gastrointestinal tract. Between 20-50% of an orally administered dose can be recovered in the form of expired carbon dioxide. The apparent bicarbonate space has been estimated to be 74% of body weight (range of 37-134%). Thus calculations of bicarbonate dosage are based on an apparent volume of distribution of 0.3 to 0.6 L/kg. Bicarbonate is rapidly metabolised to carbonic acid which rapidly dissociates into water and carbon dioxide. The carbon dioxide is excreted via the lungs.

Possible Adverse Effects

1. Venous irritation, soft tissue injury at the site of IV injection.
2. Increased vascular volume, serum osmolarity, serum sodium.
3. Hypercapnia and respiratory acidosis.
4. Hypocalcaemia.
5. Abdominal cramping, nausea, vomiting.
6. Oedema, congestive heart failure.
7. Hyperirritability, tetany.
8. Intraventricular haemorrhage.

Special Considerations

1. The osmolarity of molar sodium bicarbonate (8.4%) is approximately 1800 mOsm/kg H20.
2. The adverse effects of sodium bicarbonate are largely associated with the use of inappropriately excessive doses, infusion rate or concentrations of sodium bicarbonate. Some of these side effects, such as intracranial haemorrhage, may not be specific for sodium bicarbonate.
3. The recommended rate of infusion is no more rapid than 1 ml of bicarbonate IV per minute.
4. Paradoxical acidosis (intracellular, CSF) may occur. Carbon dioxide diffuses more readily across cell membranes than bicarbonate, thereby decreasing intracellular/CSF pH.