Question 5.2

A 67-year-old patient is admitted with an altered mental state. There is a history of type 2 diabetes on oral agents

Parameter

Patient Value

Adult Normal Range

pH

7.42

7.35 – 7.45

pO2

60 mmHg (7.9 kPa)

pCO2

37 mmHg (4.9 kPa)

35 – 45 (4.7 – 6.0)

Standard bicarbonate

24 mmol/L

22 – 29

Base excess

0 mmol/L

-3 to +3

Blood haemoglobin

178 g/L*

115 – 155

Haematocrit

0.54*

0.35 – 0.46

Sodium

136 mmol/L

135 – 145

Potassium

3.7 mmol/L

3.5 – 5.2

Ionised Calcium

1.06 mmol/L*

1.15 – 1.30

Chloride

95 mmol/L

95 – 110

Glucose

47 mmol/L*

4.0 – 8.0

Lactate

5.9 mmol/L*

0.5 – 1.3

Urea

22 mmol/L*

3.0 – 8.0

Creatinine

209 µmol/L*

45 – 90

a) List the important biochemical abnormalities, showing your calculations where appropriate. (10% marks)

b) List the diagnosis most consistent with these abnormalities. (5% marks)

c) List three complications of this condition. (15% marks)

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College answer

Not available.

Discussion

a)

The biochemical abnormalities, important and unimportant, are:

  • Hypoxia (assuming this is a gas on 21% FiO2)
  • Either polycythaemia or - more likely, looking at the rest of the results - haemoconcentration (a raised haemoglobin, a haematocrit of 0.54)
  • Mild hypokalemia
  • Hyperglycaemia: BSl 47 mmol/L
  • Hypernatremia: the sodium, corrected by a conventional formula, is 148 mmol/L, which is probably what they meant when they said "showing your calculations".  

Sodium (corrected) = Sodium (measured) + glucose / 4 

= 136 + (47/4)

= 136+ 11.75

= 148, or so

  • Lactate is elevated, contributing to the impression that the patient is dehydrated
  • The creatinine and urea are raised, in a ration which also supports water loss

b)

This is HHS, an obvious spot diagnosis which was rewarded with the absolute minimum of marks.

c)

To pick three complications would be hard, as this condition has a million possible complications:

  • HHS-specific physiological abnormalities
    • Hypotension and shock
    • Metabolic acidosis
    • Coma
  • Complications arising from the HHS disease state:
    • Cardiac arrest
    • Cardiovascular collapse
    • Myocardial infarction
    • Pulmonary oedema
    • Stroke
    • Cerebral oedema and brain injury
    • Venous thrombosis (DVT, PE)
    • Aspiration
    • Osmotic demyelination (Hegazi et al, 2013)
  • Complications of therapy for HHS:
    • Dysnatraemia
    • Hyperchloremia from saline administration.
    • Phosphate depletion
    • Hypokalemia
    • Hypoglycaemia
    • Cerebral oedema

References

Hyperglycemic Comas by P. VERNON VAN HEERDEN from Vincent, Jean-Louis, et al. Textbook of Critical Care: Expert Consult Premium. Elsevier Health Sciences, 2011.

Rosenbloom, Arlan L. "Intracerebral crises during treatment of diabetic ketoacidosis." Diabetes care 13.1 (1990): 22-33.

Hegazi, Mohamed Osama, and Anant Mashankar. "Central pontine myelinolysis in the hyperosmolar hyperglycaemic state." Medical Principles and Practice 22.1 (2013): 96-99.

Kitabchi, Abbas E., et al. "Hyperglycemic crises in adult patients with diabetes." Diabetes care 32.7 (2009): 1335-1343.