A child with diabetic ketoacidosis and a headache
A 9-year-old girl (weight 30 kg) with newly diagnosed type 1 diabetes is admitted to a district hospital with vomiting and drowsiness. Glucose 32 mmol/L, pH 7.09, bicarbonate 8 mmol/L, ketones 5.8 mmol/L, sodium 131 mmol/L, urea 11 mmol/L. She has received 10 mL/kg of 0.9% saline and an insulin infusion is running at 0.05 units/kg/hour. Four hours later she complains of a severe frontal headache and vomits again. Observations: heart rate 62/min (was 118), blood pressure 128/84 mmHg (was 96/60), GCS 13, pupils equal and reactive, capillary glucose 14 mmol/L. The paediatric retrieval team is 3 hours away by road.
1. What is the most likely diagnosis and what is the immediate management priority?
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This is cerebral oedema complicating diabetic ketoacidosis until proven otherwise. The red flags are the timing (typically 4 to 12 hours into treatment), the new severe headache with vomiting, and the triad of bradycardia, hypertension, and a falling conscious level - a Cushing-type response indicating raised intracranial pressure. She is also in the highest-risk demographic: a child, newly diagnosed, with a low initial bicarbonate and a high urea, which are recognised risk factors.
The immediate priority is treating raised intracranial pressure before transferring her anywhere. Do not wait for imaging and do not transfer before the first measures are underway; the road journey is 3 hours and she may deteriorate en route.
Immediate steps:
- Sit her up to 30 degrees, ensure the airway is protected and oxygenation adequate, and avoid hypoxia and hypercapnia.
- Give hypertonic saline (3%) 3 to 5 mL/kg over 10 to 15 minutes, or mannitol 0.5 to 1 g/kg if hypertonic saline is unavailable. Repeat if there is no response.
- Reduce the fluid rate to maintenance or below and stop any bolus.
- Continue the insulin infusion but do not chase the glucose aggressively; avoid a rapid fall in osmolality.
- Call for senior paediatric and anaesthetic help, and arrange urgent CT only once she is stabilised.
- Escalate the retrieval team and consider air transfer if available.
2. The retrieval team asks you to describe the fluid and insulin plan you would run for the next 24 hours, and what you would change given her sodium of 131 mmol/L.
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The principles are slow, controlled correction of osmolality with avoidance of rapid shifts.
Fluid. Use an isotonic fluid - 0.9% saline with added potassium, or a balanced solution if available - at a rate calculated to replace the deficit over 48 hours plus maintenance. For a 30 kg child, maintenance is roughly 60 to 70 mL/hour by the Holliday-Segar calculation, and the deficit (assume 5 to 10%) should be spread over 48 hours rather than 24. In practice this means a rate of the order of 60 to 90 mL/hour, adjusted to haemodynamics. Avoid hypotonic fluids entirely: they worsen hyponatraemia and cerebral oedema.
Sodium. Her measured sodium of 131 mmol/L is low, but the corrected sodium (adding 2.4 mmol/L for every 5.5 mmol/L of glucose above 5.5) is much higher. Recalculate it explicitly - at a glucose of 32 mmol/L the correction is about 11.6 mmol/L, giving a corrected sodium near 143 mmol/L. That means she is not truly sodium-depleted, and the falling measured sodium during treatment is a warning sign of free water excess and rising cerebral oedema risk. Do not give hypotonic fluid to "treat" the number.
Insulin. Continue at 0.05 to 0.1 units/kg/hour. Do not stop it when glucose falls; instead add dextrose-containing fluid (for example 0.9% saline with 5% glucose) when glucose reaches about 14 to 17 mmol/L, and titrate to keep glucose in that range while ketones clear. The endpoint of therapy is ketone clearance and resolution of acidosis, not a normal glucose.
Monitoring. Hourly neurological observations, hourly glucose, two-hourly electrolytes and blood gases, strict fluid balance, and a low threshold to repeat hypertonic saline if headache or conscious level worsens.