Case in the Spotlight 15 - answers


The case: An older man with rheumatoid arthritis on presents with acute confusion.

He has not been seen for two days, a family member checked on him today after he did not answer the phone.
Past medical history. Rheumatoid arthritis. Hypertension. GORD.
Medications. Prednisolone 20mg daily. Methotrexate weekly. Pantoprazole 40mg nocte. Prazosin nocte.
Physical signs HR 120 RR 30 BP 110/70

Blood gas is performed on room air
Ph   7.16 mmHg
pCO2   28 mmHg
pO2   100 mmHg
BE   -8
HCO3   14
Lactate  1.2
Na   120
K   7.6
Cl   100
Glucose 4

Describe the acid base disturbance and put it into the clinical context – outline the key management priorities.

• The acid base disturbance is metabolic acidosis, essentially acidosis plus low HCO3
• ** The anion gap is 120+7 – (100+14) = 14 so not elevated
• You expect the CO2 to be 8 + (1.4 x 14) = 29  so appropriate respiratory compensation
• There is a low sodium and high potassium + low BP, so acute adrenal crisis due so sudden cessation of steroids should be considered

What is the likely diagnosis

Differential diagnoses for NAGMA
• Diuretics
• Diarrhoea
• Fistulas
• Renal Failure

Other management issues –

on floor for 2 days, check CK and temperature

Look for causes of this, eg sepsis and stroke, and for consequences of a fall, such as fractured ribs, hip, pelvis, don’t forget the cervical spine.