OSCE — emergency management of diabetic ketoacidosis

An 8-minute OSCE station assessing the candidate's structured assessment, confirmation of DKA, and protocolised management — fluids, fixed-rate insulin, potassium replacement (with the defer-insulin rule), precipitant hunt, monitoring and resolution criteria. Marks for the deferral rule and the two iatrogenic killers.

Brief (to candidate)

A 24-year-old woman with type 1 diabetes presents with 2 days of vomiting, abdominal pain and deep rapid breathing after missing her insulin. She is drowsy, dehydrated, respiratory rate 28, heart rate 118, blood pressure 102/64. Capillary glucose 29 mmol/L, venous pH 7.14, bicarbonate 8 mmol/L, beta-hydroxybutyrate 6.1 mmol/L, potassium 3.2 mmol/L, sodium 131 mmol/L. You have 8 minutes to confirm the diagnosis and outline the immediate and stepwise management. ^[2]

Candidate instructions

Confirm the diagnosis and grade severity using the biochemical triad. ^[2]
Outline the immediate resuscitation and the protocolised management with drug, dose, route and rationale.
State the potassium management rule and what specifically you do here (K 3.2 mmol/L).
Give the monitoring frequency and resolution criteria, including conversion to subcutaneous insulin.
State your disposition and the two life-threatening complications to prevent.

Examiner checklist (mark each domain / 10)

Domain	Key actions expected
Diagnosis & severity	Confirms DKA triad (glucose over 11, ketones over 3, pH under 7.30/bicarbonate under 15); grades severe (pH 7.14, bicarbonate 8); identifies insulin omission as precipitant^[1]
Resuscitation	ABCDE; IV access; 0.9% NaCl 1 L over 1 h then over 2 h etc.; oxygen only if hypoxic^[2]
Insulin	Fixed-rate soluble insulin 0.1 units/kg/h, no loading bolus; add 10% glucose at 125 mL/h when glucose under 14 mmol/L^[2]
Potassium (key safety)	K 3.2 is under 3.5 — DEFER insulin, replace potassium first (JBDS: senior review + additional potassium below 3.5; ADA/EASD 2024: replace at 10 mmol/h and delay insulin until over 3.5); add 40 mmol/L once insulin runs^[2]
Precipitant hunt	Cultures, ECG/troponin, amylase/lipase, chest X-ray; treats the cause
Monitoring	Glucose hourly; ketones, potassium, venous pH/bicarbonate 2-hourly; strict fluid balance; cardiac monitoring
Resolution & conversion	Ketones under 0.6 AND pH over 7.3 (no bicarbonate marker); subcutaneous insulin at a meal, stop infusion 30–60 min later^[2]
Complications & disposition	Names hypokalaemia and cerebral oedema as the killers; HDU/ICU for severe DKA

Model key actions

Confirm DKA, grade severe, identify insulin omission as the precipitant.^[1]
Fluids first (0.9% NaCl); defer insulin and give potassium because K is under 3.5 mmol/L; start fixed-rate insulin 0.1 units/kg/h once potassium is safe.^[1]^[2]
Add 10% glucose when glucose under 14 mmol/L; monitor glucose hourly, ketones/potassium/pH 2-hourly.
Resolution: ketones under 0.6 AND pH over 7.3 (do not use bicarbonate as the marker); overlap subcutaneous insulin for 30–60 min before stopping the infusion.^[2]
Prevent hypokalaemia and cerebral oedema; admit to HDU/ICU; educate and arrange a sick-day rule to prevent recurrence.

Common errors

Starting insulin before correcting potassium — with K 3.2 (under 3.5) this is dangerous; defer insulin, give potassium first. ^[2]
Treating glucose rather than ketones — stopping insulin once the sugar normalises leaves ongoing ketosis.
Using an old sliding scale instead of the fixed-rate infusion.
Not seeking the precipitant; missing infection, infarction or pancreatitis.
Stopping the infusion without overlapping subcutaneous insulin — rebound ketosis.

References2Show

[1]Kitabchi AE, et al. Hyperglycemic crises in adult patients with diabetes: ADA consensus statement. Diabetes Care, 2006.PMID 17130218
[2]Dhatariya KK, et al. The management of diabetic ketoacidosis in adults: An updated guideline from the Joint British Diabetes Society for Inpatient Care Diabetic Medicine, 2022.PMID 35224769

OSCE — emergency management of diabetic ketoacidosis

Brief (to candidate)

Candidate instructions

Confirm the diagnosis and grade severity using the biochemical triad. ^[2]

Outline the immediate resuscitation and the protocolised management with drug, dose, route and rationale.

State the potassium management rule and what specifically you do here (K 3.2 mmol/L).

Give the monitoring frequency and resolution criteria, including conversion to subcutaneous insulin.

State your disposition and the two life-threatening complications to prevent.

Examiner checklist (mark each domain / 10)

Domain	Key actions expected
Diagnosis & severity	Confirms DKA triad (glucose over 11, ketones over 3, pH under 7.30/bicarbonate under 15); grades severe (pH 7.14, bicarbonate 8); identifies insulin omission as precipitant^[1]
Resuscitation	ABCDE; IV access; 0.9% NaCl 1 L over 1 h then over 2 h etc.; oxygen only if hypoxic^[2]
Insulin	Fixed-rate soluble insulin 0.1 units/kg/h, no loading bolus; add 10% glucose at 125 mL/h when glucose under 14 mmol/L^[2]
Potassium (key safety)	K 3.2 is under 3.5 — DEFER insulin, replace potassium first (JBDS: senior review + additional potassium below 3.5; ADA/EASD 2024: replace at 10 mmol/h and delay insulin until over 3.5); add 40 mmol/L once insulin runs^[2]
Precipitant hunt	Cultures, ECG/troponin, amylase/lipase, chest X-ray; treats the cause
Monitoring	Glucose hourly; ketones, potassium, venous pH/bicarbonate 2-hourly; strict fluid balance; cardiac monitoring
Resolution & conversion	Ketones under 0.6 AND pH over 7.3 (no bicarbonate marker); subcutaneous insulin at a meal, stop infusion 30–60 min later^[2]
Complications & disposition	Names hypokalaemia and cerebral oedema as the killers; HDU/ICU for severe DKA

Model key actions

Confirm DKA, grade severe, identify insulin omission as the precipitant.^[1]

Fluids first (0.9% NaCl); defer insulin and give potassium because K is under 3.5 mmol/L; start fixed-rate insulin 0.1 units/kg/h once potassium is safe.^[1]^[2]

Add 10% glucose when glucose under 14 mmol/L; monitor glucose hourly, ketones/potassium/pH 2-hourly.

Resolution: ketones under 0.6 AND pH over 7.3 (do not use bicarbonate as the marker); overlap subcutaneous insulin for 30–60 min before stopping the infusion.^[2]

Prevent hypokalaemia and cerebral oedema; admit to HDU/ICU; educate and arrange a sick-day rule to prevent recurrence.

Common errors

Starting insulin before correcting potassium — with K 3.2 (under 3.5) this is dangerous; defer insulin, give potassium first. ^[2]

Treating glucose rather than ketones — stopping insulin once the sugar normalises leaves ongoing ketosis.

Using an old sliding scale instead of the fixed-rate infusion.

Not seeking the precipitant; missing infection, infarction or pancreatitis.

Stopping the infusion without overlapping subcutaneous insulin — rebound ketosis.

References2Show

[1]Kitabchi AE, et al. Hyperglycemic crises in adult patients with diabetes: ADA consensus statement. Diabetes Care, 2006.PMID 17130218
[2]Dhatariya KK, et al. The management of diabetic ketoacidosis in adults: An updated guideline from the Joint British Diabetes Society for Inpatient Care Diabetic Medicine, 2022.PMID 35224769