SAQ 445 – Metabolic – hypoxaemia, high anion gap acidosis and hyperkalaemia

A 20-year-old woman with diabetes presents with fever, acute respiratory distress and chest pain. After 20 minutes of oxygen therapy her arterial blood gas and serum biochemistry are shown below.

Test	Result	Reference range
FiO2	100%
pH	7.20	7.36-7.44
pCO2	28 mmHg	35-45
pO2	150 mmHg	85-110
HCO3	15 mmol/L	21-28
Sodium	140 mmol/L	135-145
Potassium	6.0 mmol/L	3.2-4.3
Chloride	95 mmol/L	99-109

Using the alveolar gas equation, calculate the alveolar pO2. Show your working.

(Marked out of 5.0)

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Using your answer above, calculate the alveolar-arterial oxygen gradient.

(Marked out of 2.0)

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List two (2) possible causes of this oxygenation abnormality and justify each.

(Marked out of 2.0)
</p> <table class="saq-prop-table"> <thead> <tr> <th>Cause</th> <th>Justification</th> </tr> </thead> <tbody> <tr> <td>1.</td> <td></td> </tr> <tr> <td>2.</td> <td></td> </tr> </tbody> </table> <p>

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Calculate the anion gap from the results.

(Marked out of 2.0)

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List two (2) likely causes of the raised anion gap in this patient.

(Marked out of 2.0)

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Predict the serum potassium if her pH were corrected to 7.40, assuming no other factor changes it.

(Marked out of 3.0)

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Total Score: 0 / 16

Percentage: 0%