Overview
Definition:
Diabetes pump failure in pediatrics refers to the malfunction or interruption of an insulin pump's delivery of insulin, leading to inadequate basal and/or bolus insulin coverage
This can rapidly result in hyperglycemia and, if unaddressed, diabetic ketoacidosis (DKA).
Epidemiology:
While specific incidence data for pediatric pump failure is scarce, insulin pump use is increasing in pediatric populations
Factors contributing to failure include mechanical issues, infusion set problems, user errors, and pump reservoir depletion
Children are particularly vulnerable due to their smaller body mass and potentially less robust physiological reserves.
Clinical Significance:
Prompt recognition and management of pump failure are critical in pediatric diabetes care
Failure to provide adequate insulin can quickly lead to severe metabolic disturbances like DKA, requiring immediate hospitalization and intensive management, impacting long-term health outcomes and increasing the burden on healthcare systems
Understanding back-up plans is essential for resident preparedness.
Clinical Presentation
Symptoms:
Sudden onset of hyperglycemia symptoms: increased thirst (polydipsia)
Increased urination (polyuria)
Fatigue and lethargy
Blurred vision
Nausea and vomiting
Abdominal pain
Fruity breath odor
Confusion or altered mental status (in severe DKA).
Signs:
Elevated blood glucose readings (often >250 mg/dL, but can vary)
Ketones detected in urine or blood
Tachypnea (Kussmaul respirations)
Dehydration signs: dry mucous membranes, decreased skin turgor, sunken eyes
Hypotension and tachycardia (in advanced DKA).
Diagnostic Criteria:
Diagnosis of DKA, the most common consequence of pump failure, typically involves: Blood glucose > 250 mg/dL
Arterial pH < 7.3 or venous pH < 7.2
Serum bicarbonate < 18 mEq/L
Moderate or large ketones in urine or serum
Presence of an anion gap acidosis.
Diagnostic Approach
History Taking:
When pump failure is suspected, the immediate history should focus on the timeline of symptoms, recent insulin doses (basal and bolus), any alerts or errors from the pump, recent food intake, exercise, and illness
Ask about recent infusion set changes and any challenges experienced.
Physical Examination:
A thorough physical examination is paramount
Assess vital signs (heart rate, blood pressure, respiratory rate, temperature)
Evaluate hydration status (mucous membranes, skin turgor, capillary refill)
Check for abdominal tenderness
Assess neurological status (alertness, orientation).
Investigations:
Immediate investigations include: Blood glucose monitoring (fingerstick and/or venous/arterial)
Urine or serum ketone levels (using dipsticks or quantitative assays)
Electrolytes (sodium, potassium, chloride, bicarbonate)
Blood gas analysis (venous or arterial) for pH and anion gap
Complete blood count (CBC) to assess for infection
Blood urea nitrogen (BUN) and creatinine for renal function
Serum osmolality calculation.
Differential Diagnosis:
While DKA is the primary concern, other causes of hyperglycemia should be considered if symptoms are milder or atypical, such as stress hyperglycemia due to infection or illness, or rebound hyperglycemia after a missed insulin dose
However, pump failure specifically necessitates immediate insulin replacement and DKA management.
Management
Initial Management:
Discontinue the malfunctioning pump immediately
Initiate back-up basal insulin (long-acting analog like glargine or detemir, or NPH)
Administer correction boluses of rapid-acting insulin (e.g., lispro, aspart) based on current blood glucose levels and insulin sensitivity factor
If DKA is present, follow DKA management protocols: fluid resuscitation, IV insulin infusion, and electrolyte correction, particularly potassium.
Back Up Basal Plan:
The back-up basal plan involves administering a long-acting basal insulin analog (e.g., insulin glargine U100 or U300, insulin detemir) via subcutaneous injection
The dose should approximate the pump's usual basal rate, adjusted for illness, activity, and previous glucose trends
Typically, 40-50% of the total daily insulin dose (TDD) is a starting point, to be divided into one or two injections depending on the analog used.
Back Up Bolus Plan:
The back-up bolus plan requires manual administration of rapid-acting insulin via subcutaneous injection for meals and correction doses
Patients and caregivers must accurately calculate carb intake and use the appropriate insulin-to-carbohydrate ratio (ICR) and correction factor (CF)
Frequent blood glucose monitoring is essential to adjust bolus doses and prevent hypoglycemia or hyperglycemia.
Supportive Care:
Close monitoring of blood glucose, ketones, and electrolytes is crucial
Hydration should be maintained, with oral fluids if tolerated or IV fluids if in DKA
Monitor for signs of complications like cerebral edema, hypokalemia, or infection
Educate parents and the child about recognizing pump failure and implementing back-up plans.
Complications
Early Complications:
Diabetic Ketoacidosis (DKA) is the most significant early complication
Cerebral edema can occur during DKA treatment, especially with rapid correction of hyperglycemia and osmolality
Hypoglycemia can occur if bolus insulin doses are not carefully calculated or if carbohydrate intake is insufficient.
Late Complications:
Prolonged or recurrent episodes of pump failure and DKA can contribute to chronic microvascular and macrovascular complications over time
Psychological distress and burnout related to the intensive management required can also be considered a late complication.
Prevention Strategies:
Regular pump maintenance and troubleshooting training for patients and caregivers are key
Establishing clear protocols for when to switch to back-up plans
Maintaining adequate insulin and supplies
Educating on recognizing pump alerts and early signs of malfunction
Ensuring reliable glucose monitoring methods (CGM or frequent fingersticks).
Prognosis
Factors Affecting Prognosis:
The prognosis is generally good with prompt recognition and appropriate management
Factors influencing outcome include the severity of DKA at presentation, the speed of treatment initiation, the presence of co-morbidities, and the quality of ongoing diabetes self-management education.
Outcomes:
With effective back-up plans and timely intervention, most children can avoid severe complications and return to pump therapy once the issue is resolved
Long-term outcomes depend on consistent adherence to diabetes management strategies and prevention of recurrent DKA.
Follow Up:
Close follow-up with the pediatric endocrinology team is essential after an episode of pump failure and/or DKA
This includes reviewing the pump malfunction, reinforcing back-up strategies, assessing adherence, and addressing any psychosocial impact
Regular diabetes care appointments should continue as usual.
Key Points
Exam Focus:
Remember the definition and immediate management of DKA
Differentiate between back-up basal and bolus insulin administration
Understand the principles of fluid and electrolyte management in DKA
Know the common causes of pump failure in children.
Clinical Pearls:
Always have a written back-up plan readily accessible
Ensure parents/patients know how to administer long-acting and rapid-acting insulins via injection
Carry spare supplies including vials of insulin and syringes/pens
Frequent glucose and ketone monitoring is non-negotiable during pump failure.
Common Mistakes:
Delaying recognition of pump failure and DKA
Underestimating the insulin needs during illness or severe hyperglycemia
Incorrect calculation of insulin doses for injections
Inadequate fluid resuscitation or potassium replacement in DKA
Forgetting to restart basal insulin after correcting hyperglycemia.