Residency · Residency · Pediatrics
Diabetic Ketoacidosis in Pediatric Emergency Medicine
Introduction
Diabetic ketoacidosis (DKA) is the most common endocrine emergency in children and remains the leading cause of morbidity and mortality in children with type 1 diabetes mellitus (T1DM). DKA occurs at diagnosis of new-onset T1DM in 15-70% of cases (varying by region and age) and recurrently in known diabetics due to insulin omission, illness, or pump failure. The hallmark of DKA is the triad of hyperglycemia, ketosis, and metabolic acidosis. Management requires careful fluid and insulin administration, with cerebral edema being the most feared complication unique to the pediatric population.
Pathophysiology
Insulin deficiency (absolute in new-onset T1DM, relative in stress or illness) combines with excess counter-regulatory hormones (glucagon, cortisol, catecholamines, growth hormone) to drive the metabolic derangements. Unrestrained hepatic gluconeogenesis and glycogenolysis produce hyperglycemia, which causes osmotic diuresis leading to profound dehydration and electrolyte losses (sodium, potassium, phosphate, magnesium). Lipolysis releases free fatty acids that undergo hepatic beta-oxidation to produce ketone bodies (beta-hydroxybutyrate, acetoacetate, acetone). Ketone accumulation causes a high anion gap metabolic acidosis. Severe acidosis impairs cardiac contractility, causes peripheral vasodilation, and contributes to altered consciousness.
Diagnostic Criteria
Biochemical Criteria (ISPAD 2022)
Diagnosis requires blood glucose greater than 200 mg/dL (or known diabetes), venous pH less than 7.3 or serum bicarbonate less than 18 mmol/L, and ketonemia (blood beta-hydroxybutyrate 3 mmol/L or greater) or significant ketonuria.
Severity Classification
| Severity | pH | Bicarbonate (mmol/L) | Estimated Dehydration |
|---|---|---|---|
| Mild | 7.2-7.3 | 10-18 | ~5% |
| Moderate | 7.1-7.2 | 5-10 | ~7% |
| Severe | <7.1 | <5 | ~10% |
Mild DKA is defined by a pH of 7.2-7.3 and bicarbonate of 10-18 mmol/L. Moderate DKA has a pH of 7.1-7.2 and bicarbonate of 5-10 mmol/L. Severe DKA presents with pH less than 7.1 and bicarbonate less than 5 mmol/L.
Important Lab Considerations
Serum sodium is often "pseudohyponatremic" due to hyperglycemia, and the corrected sodium should be calculated as measured Na plus 1.6 multiplied by [(glucose minus 100) divided by 100]. A falling corrected sodium during treatment suggests excessive free water administration and increased risk of cerebral edema. Serum potassium may be initially normal or elevated despite total body depletion due to acidosis-driven transcellular shift and will fall with insulin and correction of acidosis. The anion gap is elevated (typically greater than 16), calculated as Na minus (Cl plus HCO3), and should normalize with treatment. Venous pH is adequate and correlates with arterial pH within 0.03.
<image>Pathophysiology flowchart of diabetic ketoacidosis showing the cascade from insulin deficiency through counter-regulatory hormone excess, leading to three parallel pathways: hyperglycemia and osmotic diuresis causing dehydration, lipolysis and ketogenesis causing metabolic acidosis, and electrolyte derangements, all converging on the clinical presentation of DKA</image>
Management
Initial Stabilization (First 1-2 Hours)
The ABCs are assessed first, including airway, breathing, circulation, and GCS documentation. Two peripheral IVs are placed with comprehensive labs drawn (glucose, electrolytes, BUN, creatinine, blood gas, beta-hydroxybutyrate, CBC, urinalysis, HbA1c). Blood cultures and chest radiograph are obtained if infection is suspected as a precipitant. A recent well weight should be used rather than the current dehydrated weight. The initial fluid bolus of 10 mL/kg 0.9% normal saline is given over 30-60 minutes for hemodynamic stabilization, repeated only if needed for persistent poor perfusion, while avoiding excessive boluses beyond 20 mL/kg unless shock is present. NPO status is maintained until clinical improvement and there is no concern for cerebral edema.
Fluid Management
Dehydration is estimated at approximately 5% for mild DKA, 7% for moderate, and 10% for severe. The deficit is replaced evenly over 24-48 hours rather than front-loaded. Maintenance plus deficit fluids minus boluses already given determine the rate. Either 0.9% NS or 0.45% NS with appropriate potassium supplementation is used. When blood glucose falls to 250-300 mg/dL, dextrose (D5 or D10) is added to IV fluids to prevent hypoglycemia while continuing insulin to clear ketosis. Total fluid administration should not exceed 1.5-2 times maintenance rate, and oral fluids should not be started until substantial clinical improvement.
Insulin Therapy
Continuous IV insulin infusion at 0.05-0.1 units/kg/hour is initiated without an initial bolus, as bolus insulin increases cerebral edema risk. The goal is to reduce blood glucose by 50-75 mg/dL per hour. If glucose drops too rapidly, the dextrose concentration in IV fluids should be increased rather than decreasing the insulin rate, as insulin is needed to clear ketones. The infusion continues until resolution of DKA (pH greater than 7.3, bicarbonate greater than 18, anion gap closed, beta-hydroxybutyrate less than 1 mmol/L). Transition to subcutaneous insulin requires overlap: the subcutaneous dose is given 15-30 minutes before stopping the infusion for rapid-acting insulin, or 1-2 hours before for intermediate or long-acting insulin.
Potassium Replacement
Potassium is not given in the initial bolus. If initial K+ is less than 3.5 mEq/L, aggressive replacement is needed before insulin initiation (40 mEq/L in fluids). If K+ is 3.5-5.5 mEq/L, 20-40 mEq/L potassium is added to IV fluids (using KCl and KPhos in equal proportions). If K+ is greater than 5.5 mEq/L, potassium is deferred but monitored closely, as it will drop with insulin therapy. Continuous cardiac monitoring is maintained for all patients receiving potassium replacement.
Bicarbonate
Routine bicarbonate administration is not recommended, as it is associated with paradoxical CNS acidosis and increased risk of cerebral edema. It should be considered only for life-threatening hyperkalemia or pH less than 6.9 with hemodynamic compromise.
<image>Two-panel clinical monitoring diagram for pediatric DKA management: Panel A shows a sample DKA flow sheet with hourly documentation of vital signs, neurologic checks, glucose, electrolytes, fluid input/output, and insulin rate; Panel B illustrates the fluid and insulin adjustment algorithm with decision points based on glucose levels and acid-base status</image>
Cerebral Edema
Epidemiology and Risk Factors
Cerebral edema occurs in 0.5-1% of pediatric DKA episodes with a mortality rate of 21-24%. It is the leading cause of DKA-related mortality in children and typically occurs 4-12 hours after initiation of treatment, though it can present earlier or later. Risk factors include younger age (under 5 years), new-onset diabetes, severe acidosis (low pH, low pCO2), high BUN at presentation, failure of corrected sodium to rise with treatment, excessive fluid administration in the first 4 hours, bicarbonate administration, and insulin boluses.
Clinical Recognition
Signs include altered mental status, headache, and recurrent vomiting after initial improvement. Cushing triad (hypertension, bradycardia, irregular respirations) represents a late finding. Pupillary changes, posturing, and seizures may occur. Bedside neurologic assessments (GCS) should be performed every 1-2 hours during DKA treatment.
Management of Cerebral Edema
Immediate actions include reducing the IV fluid rate and elevating the head of bed to 30 degrees. Hypertonic saline (3% NaCl) at 2.5-5 mL/kg over 10-15 minutes is the first-line osmotic agent. Mannitol at 0.5-1 g/kg over 15-20 minutes is an alternative if hypertonic saline is not available. The airway should be secured if GCS is 8 or less, with hyperventilation avoided (targeting normal pCO2). Emergent neuroimaging (CT head) is obtained once stabilized, and the patient is transferred to the ICU with neurosurgical consultation.
Prevention and Anticipatory Guidance
Education for known diabetics includes sick-day management rules, never omitting long-acting insulin, checking ketones when glucose exceeds 300 mg/dL, and contacting the endocrinology team early. Insulin pump users should check the pump site, tubing, and battery, and switch to injections if DKA develops. Community awareness campaigns for early signs of T1DM (polyuria, polydipsia, weight loss) can reduce DKA at diagnosis.
Clinical Pearls
DKA is defined by the triad of hyperglycemia (greater than 200 mg/dL), ketonemia, and metabolic acidosis (pH less than 7.3 or bicarbonate less than 18). Cerebral edema is the most feared complication, and excessive fluid boluses, insulin boluses, and bicarbonate administration should be avoided. Corrected sodium should be monitored closely, as it should rise with treatment; failure to rise indicates excess free water and increased cerebral edema risk. Dextrose is added to IV fluids when glucose drops below 250-300 mg/dL, while insulin is continued to clear ketosis. Potassium will fall rapidly with insulin and acidosis correction, so replacement needs should be anticipated. Transition to subcutaneous insulin occurs only after biochemical resolution of DKA with overlap of infusion and injection.
References
- Wolfsdorf JI, Glaser N, Agus M, et al. ISPAD Clinical Practice Consensus Guidelines 2022: Diabetic ketoacidosis and hyperglycemic hyperosmolar state. Pediatric Diabetes. 2022;23(7):835-856.
- Glaser N, Barnett P, McCaslin I, et al. Risk factors for cerebral edema in children with diabetic ketoacidosis. New England Journal of Medicine. 2001;344(4):264-269.
- Kuppermann N, Ghetti S, Schunk JE, et al. Clinical trial of fluid infusion rates for pediatric diabetic ketoacidosis (PECARN FLUID Study). New England Journal of Medicine. 2018;378(24):2275-2287.
- American Diabetes Association. Standards of Medical Care in Diabetes — 2023. Diabetes Care. 2023;46(Suppl 1):S1-S291.
