Clinical scenario: DKA | Bradycardia | Hypertension | Management
A previously healthy 9-year-old boy is brought to the emergency department with a 3-day history of polyuria, polydipsia, weight loss, and increasing lethargy. On examination, he is dehydrated, tachycardic, and has deep, rapid respirations. He is diagnosed with severe diabetic ketoacidosis.
Initial investigations:
- Blood glucose: 34 mmol/L (612 mg/dL)
- Venous pH: 6.91
- Serum bicarbonate: 4 mmol/L
- Serum sodium: 130 mmol/L
- Serum potassium: 5.5 mmol/L
He receives fluid resuscitation according to protocol and is started on an intravenous insulin infusion. Six hours later, the nursing staff report that he has become increasingly irritable and difficult to arouse. He complains of a severe headache and vomits twice. His vital signs now show:
- Heart rate: 68 beats/min (previously 126 beats/min)
- Blood pressure: 130/84 mmHg (previously 96/58 mmHg)
His pupils are equal and reactive, and there are no focal neurological deficits.
What is the most appropriate next step in management?
A. Administer intravenous sodium bicarbonate to correct severe acidosis
B. Administer intravenous mannitol (or hypertonic saline) immediately
C. Increase the insulin infusion to accelerate correction of ketoacidosis
D. Obtain an urgent CT scan of the brain before initiating treatment
E. Perform lumbar puncture to exclude meningitis
Correct answer & Explanation
Correct Answer: B. Administer intravenous mannitol (or hypertonic saline) immediately
Explanation: Cerebral edema
This child has developed cerebral edema, the most serious complication of pediatric DKA and the leading cause of DKA-related mortality.
The diagnosis is clinical. Warning signs include:
- Altered mental status
- Severe headache
- Recurrent vomiting
- Bradycardia with hypertension (features of raised intracranial pressure)
- Progressive decline in consciousness
Treatment should not be delayed for neuroimaging. Immediate administration of mannitol (0.5–1 g/kg IV over 10–15 minutes) or 3% hypertonic saline (2.5–5 mL/kg IV) is recommended while reducing ongoing fluid administration to maintenance and arranging intensive care support.
Why the other options are incorrect
A. Sodium bicarbonate
- Not indicated. Routine bicarbonate therapy does not improve outcomes and may increase the risk of cerebral edema.
B. Mannitol or hypertonic saline
- Correct. Immediate osmotherapy is the standard of care for suspected cerebral edema.
C. Increase insulin infusion
- Higher insulin doses do not improve recovery and may worsen osmotic shifts.
D. CT scan before treatment
- Incorrect. Imaging may initially be normal and should never delay treatment.
E. Lumbar puncture
- Contraindicated in suspected raised intracranial pressure because of the risk of brain herniation.
High-Yield Pearl
In a child with DKA, any deterioration in neurological status should be assumed to represent cerebral edema until proven otherwise, and treatment must begin immediately without waiting for imaging.
