Severe dehydration and electrolyte disturbance — Rapid

Synopsis

Assess dehydration and shock without relying on one sign, choose oral, nasogastric or intravenous rehydration in the correct order, prescribe resuscitation, deficit, maintenance and ongoing losses separately, and correct dangerous sodium, potassium and glucose abnormalities at a safe rate.

Assess recent weight change, intake, urine, stool and vomit losses, thirst, behaviour, tears, mucosa, eyes, skin, pulses, refill, blood pressure and breathing.
Use a pattern and trajectory rather than assigning an exact dehydration percentage from one examination sign.
First-line rehydration for clinical dehydration without shock is low-osmolarity oral rehydration solution, 50 mL/kg over 4 hours plus maintenance and ongoing losses.
Give ORS frequently in small amounts and use a nasogastric tube when the child cannot drink enough or persistently vomits but does not need immediate IV resuscitation.
Use IV fluid when shock is present, the child deteriorates despite ORS or oral and nasogastric treatment cannot be delivered successfully.
For shock give 10 mL/kg glucose-free isotonic crystalloid rapidly, reassess and repeat once when still shocked while considering another cause and PICU advice.
Separate resuscitation, routine maintenance, existing deficit and ongoing loss in the prescription; calculate each from current weight and review all fluid sources.
First-line blood tests for severe disease or IV therapy are sodium, potassium, chloride, bicarbonate, urea, creatinine and glucose, with gas and cause-directed tests.
Hypernatraemic dehydration requires expert advice, isotonic fluid initially and slow deficit replacement, generally over 48 hours, with sodium falling no faster than 0.5 mmol/L/hour or 12 mmol/L/day.
Acute symptomatic hyponatraemia is treated with 2.7% sodium chloride 2 mL/kg, maximum 100 mL, over 10–15 minutes and repeated by symptoms and sodium under immediate expert supervision.
Do not add potassium until the serum result and renal function or urine output support safe replacement.
Renal, cardiac and hepatic impairment, oedema, DKA and severe malnutrition need condition-specific modification rather than standard rehydration volumes.

Key red flags

Reduced consciousness, weak central pulses, hypotension, bradycardia or anuria indicates severe hypovolaemia and decompensated shock.

A doughy skin feel, jitteriness, hyperreflexia, high-pitched cry or unexpectedly preserved skin turgor can accompany hypernatraemic dehydration.

Headache, vomiting, confusion, lethargy, seizure, coma or apnoea with acute hyponatraemia suggests cerebral oedema requiring hypertonic saline, not fluid restriction alone.

ECG change, weakness, arrhythmia or potassium above the severe emergency threshold requires immediate monitored treatment.

Fever, non-blanching rash, severe abdominal pain, bilious vomiting, blood in stool or peritonism points beyond uncomplicated gastroenteritis.

Faltering growth, repeated dehydration, polyuria, polydipsia, abnormal urine concentration or recurrent electrolyte disturbance suggests renal, endocrine, metabolic or safeguarding causes.

Cardiac disease, renal impairment, liver failure, oedema and severe malnutrition alter fluid distribution and require specialist prescriptions rather than standard deficit formulae.

Investigation priorities

First-line bedside glucoseFirst stepFirst line

Detect hypoglycaemia or hyperglycaemic illness immediately in altered or significantly dehydrated children.

First-line sodium, potassium, chloride, bicarbonate, urea and creatinineFirst line

Guide fluid composition and rate and identify renal and electrolyte risk when IV therapy or severe illness is present.

Management branches

Enteral rehydrationORS before IV

Clinical dehydration is present without shock or another IV indication.

Give low-osmolarity ORS 50 mL/kg over four hours plus maintenance.
Offer frequent small volumes and continue breastfeeding.
Use a nasogastric route if drinking is inadequate or vomiting persists.
Reassess clinical response, urine and ongoing losses throughout.

Key medicines

Low-osmolarity oral rehydration solutionFor clinical dehydration from gastroenteritis without an IV indication, give 50 mL/kg orally or by nasogastric tube over 4 hours in frequent small amounts, in addition to maintenance and replacement of ongoing losses.Use a correctly constituted licensed ORS rather than juice, fizzy drink or home-mixed salt solution. Escalate for shock, deterioration or persistent failure; modify the plan in renal, cardiac, hepatic or metabolic disease.

Sodium chloride 2.7%For acute symptomatic hyponatraemia, give 2 mL/kg IV, maximum 100 mL, over 10–15 minutes; repeat the same bolus once if symptoms persist and consider a third only after checking sodium with immediate specialist guidance.Use a controlled hospital protocol with secure IV access, independent concentration and dose check, continuous clinical monitoring and at least hourly sodium initially. Do not use fluid restriction alone for encephalopathy or exceed the subsequent safe correction rate.

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