DKA and HHS — Viva

Long Case Viva Defence

Candidate's opening statement (model answer)

"This is a 19-year-old man with type 1 diabetes who presents with two days of vomiting, abdominal pain and drowsiness, having stopped his insulin. He is drowsy with deep, rapid breathing, tachycardic and hypotensive. His glucose is 31 mmol/L, venous pH 6.98, bicarbonate 6 mmol/L, beta-hydroxybutyrate 7.8 mmol/L and potassium 5.8 mmol/L, and his chest X-ray shows left lower lobe consolidation. My problems are severe DKA, a pneumonia as a likely precipitant, and recurrent insulin omission."

Examiner probing questions and model answers

Q1: "Grade the severity."

"His beta-hydroxybutyrate above 6.0 mmol/L, pH below 7.0 and bicarbonate below 10 mmol/L fall in the consensus severe band, for which it suggests the intensive care unit. Not all variables need to be fulfilled to define severity, and the admission site remains a clinical decision." ^[1]

Q2: "Fluids and insulin, please."

"Isotonic saline or a balanced crystalloid at 500 to 1,000 mL/h for the first 2 to 4 hours, then fluid guided by haemodynamics, fluid balance and sodium. A fixed-rate intravenous insulin infusion at 0.1 units/kg/h as soon as possible. When glucose falls below 13.9 mmol/L, I add 5 to 10 percent dextrose, reduce the infusion to 0.05 units/kg/h and continue until the ketoacidosis resolves." ^[1]

Q3: "His potassium is 5.8 mmol/L. Is it safe to give insulin?" ^[1]

"Yes. The consensus delays insulin only when potassium is below 3.5 mmol/L. Despite a total-body potassium depletion of 3 to 6 mmol/kg, most patients with DKA present with normal or high serum potassium, because metabolic acidosis and insulin deficiency move potassium from the intracellular to the extracellular compartment. I start replacement once it falls below 5.0 mmol/L, aiming for 4 to 5 mmol/L, and recheck 2 hours after starting insulin, then every 4 hours." ^[1]

Q4: "His pH is 6.98. Bicarbonate?"

"Routine bicarbonate is not recommended, but the consensus says it should be considered when pH is below 7.0, as 100 mmol in 400 mL of sterile water every 2 hours until pH is above 7.0. Reported harms include hypokalaemia, reduced tissue oxygen uptake, cerebral oedema and paradoxical central nervous system acidosis." ^[1]

Q5: "He is young. What about cerebral oedema?"

"Kitabchi notes that cerebral oedema occurs in about 0.3 to 1.0 percent of DKA episodes in children and is extremely rare in adults, with a mortality of 20 to 40 percent. In children, Glaser associated it with low arterial carbon dioxide, high serum urea nitrogen and bicarbonate treatment." ^{[3] [5]}

Q6: "When is the DKA over?"

"When ketones are below 0.6 mmol/L and venous pH is 7.3 or more, or bicarbonate 18 mmol/L or more. I would not use the anion gap or urine ketones. I overlap subcutaneous and intravenous insulin by 1 to 2 hours." ^[1]

Q7: "How do you stop him coming back?"

"In patients with recurrent DKA, up to 75 percent of admissions have been attributed to insufficient use of insulin therapy, such as missed insulin doses, so education on insulin administration and sick day advice must be reinforced. Close follow-up within 2 to 4 weeks after discharge may reduce recurrent DKA, and mental health conditions such as eating disorders and depression are independent risk factors for DKA." ^[1]