A 50-year-old female is admitted to ICU following an elective anterior communicating artery aneurysm clipping procedure. The patient was extubated post-procedure. Her background medical conditions include hypertension, Type 2 diabetes mellitus (T2DM) and dyslipidaemia. Her medications include perindopril, metformin, pioglitazone, empagliflozin, and atorvastatin. The following arterial blood gas analysis was taken on day 2 post-operative.
Parameter | Patient Value | Adult Normal Range | ||||||||||
FiO2 | 0.21 | |||||||||||
pH | 6.81* | 7.35 – 7.45 | ||||||||||
pO2 | 138 mmHg (18.4 kPa) | |||||||||||
pCO2 | 11.0 mmHg (1.5 kPa)* | 35.0 – 45.0 (4.6 – 6.0) | ||||||||||
SpO2 | 98% | |||||||||||
Bicarbonate | 2.0 mmol/L* | 22.0 – 26.0 | ||||||||||
Base Excess | -31.3 mmol/L* | -2.0 – +2.0 | ||||||||||
Lactate | 3.2 mmol/L* | 0.5 – 1.6 | ||||||||||
Sodium | 142 mmol/L | 135 – 145 | ||||||||||
Potassium | 4.3 mmol/L | 3.5 – 5.0 | ||||||||||
Chloride | 116 mmol/L* | 95 – 105 | ||||||||||
Glucose | 10.5 mmol/L* | 3.5 – 6.0 | ||||||||||
Osmolal gap | 8 | < 10 |
a) List the abnormalities on the blood gas analysis. (20% marks)
b) Explain the most likely diagnosis and outline how you would investigate this further.
(20% marks)
Not available.
Empagliflozin? They are basically throwing this at you.
No, wait, wait. Let us dissect these results systematically.
So, this high anion gap metabolic acidosis in a euglycaemic diabetic. What could this possibly be?
Euglycaemic ketoacidosis comes to mind. It is the natural conclusion in this situation, where the stem clearly gives a history of an SGLT2 inhibitor. It is possible that the college would have wanted more detail, as they asked to "explain" rather than "list" or "give" the most likely diagnosis. In that case, one could go into the mechanism, where:
Or at least that's the shortest version of a mechanism described by Bui & Nawathe (2018). Now, to "outline how you would investigate this further". The diagnosis of EDKA rests on the finding of a high anion gap acidosis with raised ketones, where the BSL is below 200 mg/dL, which is 11.1 mmol/L in local terms (Barski et al, 2019). So... a blood ketone level is "how you would investigate this further". However, the college have attributed 20% of the marks to this question, which suggests they might have expected something more than just a one-liner. If one felt compelled to write more, one could hold forth as follows:
Kalra, Sanjay, and Yashdeep Gupta. "The insulin: glucagon ratio and the choice of glucose-lowering drugs." Diabetes Therapy 7.1 (2016): 1-9.
Wahid, Maryam, Abdul Khaliq Naveed, and Imad Hussain. "Insulin and glucagon ratio in the patho-physiology of diabetic ketoacidosis and hyperosmolar hyperglycemic non-ketotic diabetes." Journal of the College of Physicians and Surgeons--pakistan: JCPSP 16.1 (2006): 11-14.
Bui, Patrick, and Amar C. Nawathe. "Euglycemic Diabetic Ketoacidosis: Challenge is in the Diagnosis." Proceedings of UCLA Healthcare 22 (2018).
Barski, Leonid, et al. "Euglycemic diabetic ketoacidosis." European journal of internal medicine 63 (2019): 9-14.