14th August 2024

A 62-year-old female is admitted with confusion and lethargy. She has a known past medical history of hypertension

A 62-year-old female is admitted with confusion and lethargy. She has a known past medical history of hypertension and type 2 diabetes but is poorly concordant with medication. She is usually independent at baseline.

You are asked to review her on account of her becoming progressively more drowsy.

Observations are taken at the time of your review: heart rate 109 bpm, blood pressure 174/97 mmHg, respiratory rate 22/minute, SpO2 97% on air, temperature 37.1℃. On examination, she is listless and incoherent. GCS is E4V3M5. The heart sounds are difficult to appreciate, and there are bibasal crackles. The abdomen is non tender. There is mild pedal oedema. You are not able to elicit any gross neurological deficit.

A venous blood gas is returned:

Which single additional investigation result explains this patient’s alteration in mental status?

Select the SINGLE most appropriate option from the list below. Select ONE option only.