20.1 A 50-year-old male with a history of chronic pancreatitis presents with several days of nausea and vomiting. His biochemistry profile is below. Interpret the abnormalities in the above results and give likely underlying causes. (30% marks):
20.2 A 28-year-old previously fit male presents with a two-day history of fever, headache and a widespread rash. Results of investigations are below:
Blood cultures show Gram-negative cocci.
- a) List the abnormalities shown by the ABG. (10% marks)
- b) Give the most likely diagnosis. (5% marks)
- c) What complication of this condition may have occurred? (5% marks)
20.3 The following arterial blood gas result was obtained from a 65-year-old lady with exacerbation of chronic obstructive pulmonary disease (COPD), day 7 in ICU following intubation and ventilation for respiratory failure.
- a) Interpret the arterial blood gas. (10% marks)
- b) Give four possible reasons for the acid-base disturbance seen. (10% marks)
20.4 The following biochemical profile is from a 65-year-old male who has been admitted to your Intensive Care Unit with a diagnosis of pancreatitis of unknown aetiology. What blood test would you now order? Give your reasoning. (30% marks)
Answer and interpretation
- Severe metabolic alkalosis (raised SID)
- Respiratory compensation (incomplete)
- High anion gap (approx. 31) metabolic acidosis
- Profound hypochloraemia
- Gastric losses and fluid depletion causing chloride loss and metabolic alkalosis
- Metabolic acidosis secondary to renal failure (acute? Acute on chronic?) +/- sepsis from pancreatitis and/or gastro-enteritis
- CO2 retention as compensation for severe metabolic alkalosis
a) List the abnormalities shown by the ABG. (10% marks)
- Severe lactic acidosis with inadequate respiratory compensation and acute renal impairment and hypoglycaemia.
b) Give the most likely diagnosis. (5% marks)
- Meningococcal septicaemia
c) What complication of this condition may have occurred? (5% marks)
- Waterhouse-Friderichsen syndrome.
Multi-organ failure with liver and renal dysfunction is a reasonable answer and was given some credit.
a) Interpret the arterial blood gas. (10% marks)
- Metabolic alkalosis
- Raised A-a gradient
b) Give four possible reasons for the acid-base disturbance seen. (10% marks)
- NG losses
- Post hypercapnia
- Lipid profile.
- The patient has low serum sodium but a normal measured osmolarity and hence has pseudohyponatraemia
- His glucose and protein levels are not elevated. He therefore is likely to have hypertriglyceridemia, which may be the underlying cause of his pancreatitis.
- Pass rate: 71%
- Highest mark: 8.9
Additional Examiners’ Comments:
- 20.4 was the least well answered section with many candidates failing to recognise pseudohyponatraemia.