Fluid management in children with gastroenteritis
Overview
Gastroenteritis is a common cause of dehydration in children. The primary goals in the emergency department are to assess dehydration and either restore intravascular volume rapidly (if shock) or rehydrate safely and correct electrolyte disturbance while avoiding iatrogenic harm.
Oral rehydration therapy (ORT) with low‑osmolarity oral rehydration solution (ORS) is first‑line for most children; intravenous (IV) fluids are reserved for shock, failed ORT, persistent vomiting, or specific situations such as marked hypernatraemia that require specialist input (NICE CG84; NG29).
Assessment - what to look for
- Identify shock: tachycardia, poor peripheral perfusion (prolonged capillary refill), cool extremities, weak pulses, altered conscious state, and hypotension (a late sign).
- Estimate dehydration severity: sunken eyes/fontanelle, dry mucous membranes, reduced skin turgor, oliguria/absent wet nappies, tachypnoea, and lethargy.
- Red flags requiring urgent escalation: inability to tolerate any oral fluids, persistent high fever, bilious or bloody vomiting/stools, signs of systemic infection/sepsis, marked lethargy, or deterioration despite ORT.
- Document weight where possible and record fluid input/output.
- If IV therapy is planned, obtain baseline labs: Na+, K+, urea, creatinine, and glucose.
Oral rehydration therapy (ORS)
Why ORS is first-line
- Low‑osmolarity ORS (≈240-250 mOsm/L) is effective at replacing isotonic diarrhoeal losses, reduces stool output and vomiting, and lowers the need for IV rehydration compared with older formulas.