A 60-year-old male with alcoholic cirrhosis and atrial fibrillation on regular flucloxacillin and paracetamol is admitted to your ICU post-variceal banding. His coagulation screen is displayed below:
Parameter |
Patient Value |
Adult Normal Range |
Prothrombin time (PT) |
28.0 sec* |
12.0 – 16.5 |
International normalised ratio (INR) |
2.4* |
0.9 – 1.3 |
Activated partial thromboplastin time (APTT) |
21.0 sec |
27.0 – 38.5 |
Fibrinogen |
2.1 g/L |
2.0 – 4.0 |
D-Dimer |
0.5 mg/L |
< 0.5 |
The arterial blood gas and biochemistry results from the same patient are given below:
Parameter |
Patient Value |
Adult Normal Range |
FiO2 |
0.21 |
|
pH |
7.23* |
7.35 – 7.45 |
pO2 |
90 mmHg (12 kPa) |
|
pCO2 |
22.0 mmHg (2.93 kPa)* |
35.0 – 45.0 (4.60 – 6.00) |
SpO2 |
92% |
|
Bicarbonate |
9.0 mmol/L* |
22.0 – 26.0 |
Base Excess |
-16.7 mmol/L* |
-2.0 to +2.0 |
Lactate |
1.3 mmol/L |
0.5 – 1.6 |
Parameter |
Patient Value |
Adult Normal Range |
Sodium |
135 mmol/L |
135 – 145 |
Potassium |
4.0 mmol/L |
3.5 – 5.0 |
Chloride |
100 mmol/L |
95 – 105 |
Bicarbonate |
9.0 mmol/L* |
22.0 – 26.0 |
Glucose |
6.0 mmol/L |
3.5 – 6.0 |
Urea |
7.0 mmol/L |
3.0 – 8.0 |
Creatinine |
120 μmol/L* |
45 – 90 |
Examiners Comments:
When asked for a specific number of responses (e.g. 'three causes of') please supply this number of responses. Extra responses will not gain extra marks. If there are more causes, then list the most likely. Many candidates did not appear to pay attention to the mark allocation and gave insufficient detail in sections of the question worth the most marks.
1) An isolated normal PT in a middle-aged alcoholic with known AF? What could it be??
2) A systematic approach to this gas:
Thus, this is a well-compensated severe metabolic acidosis with a high anion gap. And it's not due to lactate or uraemia. To apply a well-worn mnemonic, the differentials are
The investigations, therefore, are:
EMMETT, MICHAEL, and ROBERT G. NARINS. "Clinical use of the anion gap."Medicine 56.1 (1977): 38-54.
Salem, Mahmoud M., and Salim K. Mujais. "Gaps in the anion gap." Archives of internal medicine 152.8 (1992): 1625-1629.
Kraut, Jeffrey A., and Nicolaos E. Madias. "Serum anion gap: its uses and limitations in clini