Diabetic Ketoacidosis Initial Management
A 12 year old boy with type 1 diabetes stopped his insulin during 2 days of vomiting and polyuria. He is drowsy with deep sighing respirations, heart rate 134 beats/min, blood pressure 92/56 mm Hg and capillary refill 4 seconds. Capillary glucose is 29 mmol/L, venous pH 7.09, bicarbonate 7 mmol/L, potassium 4.1 mmol/L and urine ketones 4+. Which of the following is the most appropriate initial step in management?
- A.Intravenous sodium bicarbonate 1 mmol/kg over 1 hour
- B.Intravenous regular insulin infusion at 0.1 units/kg per hour
- C.Intravenous potassium chloride 40 mmol/L in maintenance fluid
- D.Intravenous 0.9% sodium chloride 10 mL/kg over 1 hourCorrect
Explanation
After airway, breathing and circulation are secured, the first therapeutic priority in paediatric diabetic ketoacidosis is intravenous fluid, not insulin. This child has tachycardia, hypotension, delayed capillary refill and dry mucous membranes, so he needs volume expansion with isotonic saline at roughly 10 mL/kg over the first hour to restore intravascular volume and renal perfusion. Rehydration alone lowers glucose substantially by improving glomerular filtration and diluting the extracellular space, and it protects against the circulatory collapse that ketoacidosis and osmotic diuresis produce. Insulin is started about 1 hour later as a continuous infusion of 0.1 units/kg per hour, deliberately delayed because giving insulin before volume repletion shifts water and potassium intracellularly, drops osmolality abruptly and is associated with cerebral oedema. Potassium is added to the fluid, usually 40 mmol/L, once the child is passing urine and serum potassium is not high, because total body potassium is always depleted even when the measured level looks normal, as it does here at 4.1 mmol/L. Bicarbonate is not given routinely; it worsens paradoxical central nervous system acidosis, aggravates hypokalaemia and is reserved for life threatening acidosis with haemodynamic compromise. The estimated fluid deficit should be replaced evenly over 48 hours, and once glucose falls to about 14 mmol/L the fluid is changed to dextrose 5% in half normal saline so the insulin infusion can continue to clear ketones. Insulin should not be stopped for hypoglycaemia; the dextrose concentration is increased instead.
Why each option
- A.
- Bicarbonate worsens central nervous system acidosis and hypokalaemia and is reserved for extreme, haemodynamically compromising acidosis.
- B.
- Insulin is essential but is started about 1 hour after fluids; giving it first accelerates osmolar shifts and increases the risk of cerebral oedema.
- C.
- Potassium is added to the maintenance infusion once urine output is confirmed, not as the very first intervention.
- D.
- Correct. Isotonic fluid resuscitation precedes insulin in paediatric diabetic ketoacidosis and restores perfusion while lowering glucose on its own.
Reference: ISPAD Clinical Practice Consensus Guidelines 2022, Diabetic Ketoacidosis and Hyperglycaemic Hyperosmolar State
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