Careful management of fluid and electrolyte balance is important in the treatment of meningitis. Over or under hydration are associated with adverse outcomes. Many children have increased antidiuretic hormone secretion, and some will have dehydration due to vomiting, poor fluid intake or septic shock. Hyponatramia occurs in about one third of children with meningitis, and may be due to increased ADH secretion, increased urine sodium losses, and excessive electrolyte-free water intake or administration. Children with meningitis require careful and regular monitoring of: clinical signs of hydration state, including signs of over hydration, serum sodium and laboratory markers of hypovolaemia.

Under most circumstances any intravenous fluids given to a child with meningitis should be isonatraemic eg Plasma-Lyte 148 or 0.9% sodium chloride (normal saline) with additional glucose. Hyponatramic solutions (eg 4% dextrose and one-fifth normal saline), which deliver excess free-water, may worsen hyponatraemia and increase the risk of cerebral oedema, and have no place in the management of meningitis.

Immediate resuscitation if required

Clinical signs of shock or hypovolaemia are hypotension, poor peripheral perfusion, cool pale extremities, tachycardia with low volume pulses, high blood lactate or large base deficit. Children with more than one of these signs should be given 10-20 mL per kg of normal saline as a bolus. If signs of hypovolaemia persist the child should be referred to the ICU. A child with meningitis and shock requires careful balancing of fluid volume, electrolytes and cardiovascular status and should be managed in the ICU.

Fluid management for the severely ill child who is not feeding during first 24-48 hours of treatment

Refer to the table for initial fluid volume recommendations (mL per hour)

Decide if the child has:

Normal serum [Na+] and no signs of hypovolaemia, dehydration or raised intracranial pressure

• Fluid guideline based on giving 3 mL/kg/hour up to a weight of 10 kg (about 70% of 'maintenance fluid requirements') as Plasma-Lyte 148 and 5% Glucose OR 0.9% sodium chloride (normal saline) and 5% glucose.

Hyponatraemia ([Na+]<135) but no signs of hypovolaemia, dehydration or raised intracranial pressure

• Fluid guideline based on giving 2 mL/kg/hour up to a weight of 10 kg (about 50% of 'maintenance fluid requirements') as Plasma-Lyte 148 and 5% Glucose OR 0.9% sodium chloride (normal saline) and 5% glucose. If the serum [Na+] is very low (<130mmol/L) refer to the ICU.

Signs of dehydration or hypovolaemia at presentation

• Give repeated boluses of 10 mL/kg of normal saline until hypovolaemia is corrected. Refer to ICU if signs of hypovolaemia persist. Ongoing fluid guideline based on giving 3 mL/kg/hour up to a weight of 10 kg as Plasma-Lyte 148 and 5% Glucose OR 0.9% sodium chloride (normal saline) and 5% glucose.

Signs of raised intracranial pressure or generalised oedema

• Fluid guideline based on giving 1-2 mL/kg/hour up to 10 kg (about 25-50% of 'maintenance fluid requirements') as Plasma-Lyte 148 and 5% Glucose OR 0.9% sodium chloride (normal saline) and 5% glucose. A child with any clinical signs of raised intracranial pressure (eg very bulging fontanelle, unresponsiveness to painful stimuli or papilloedema) or of over hydration (eg facial or generalized oedema) should have fluids restricted and referred to the ICU. Development of generalised oedema is a major risk factor for serious adverse outcomes in meningitis, and is at least in part due to excessive fluid administration.

In all children with meningitis, regardless of the presence of intracranial hypertension it is essential to ensure normal blood pressure and adequate circulating volume.

Table. Total fluids intake (mL per hour): if using intravenous fluids use normal saline plus 5% dextrose.

• * Give rapid boluses of 10 mL per kg normal saline to correct hypovolaemia.
• # The child must be referred to the ICU

Monitoring

The rates suggested in the table are starting rates only and subsequent frequent evaluation is necessary.

Assessment of the clinical signs of hydration, including weight, measurement of the serum sodium and acid-base status, and clinical assessment of the neurological state should be repeated every 6-12 hours for the first 48 hours, and the total fluid intake adjusted accordingly.

Enteral feeds

Enteral feeds should be started when the child is stable. Enteral feeding should be withheld in children who are poorly conscious, vomiting or having frequent convulsions. Children who drinking well should have intravenous fluids run very slowly (just to keep the cannula patent).

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