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For discussion with final year medical students (March to July 2015)

1. Looking at this ABG report: pH 7.26; PaO2 94mm Hg; PaCO2 28mm Hg; Serum HCO3 16mmol/L,
a. A student said that it shows respiratory acidosis. Why is that wrong? b. Some students said that it shows metabolic acidosis with respiratory compensation while a few others said that it shows metabolic acidosis with respiratory alkalosis. Who is correct?

2. When asked for the treatment of hyperkalemia, a student answered "Insulin" and another student answered "Insulin and Glucose". Who is in error?

3. A patient has acute renal failure with oliguria. A student wanted to give her normal saline to promote diuresis. What is the error here?

4. Why is prescribing ACE inhibitors or ARB for patients with end stage renal failure and hyperkalemia a bad idea?

5. A patient with rheumatic heart disease and atrial fibrillation is on warfarin. He presents with mild bleeding from gums and nose. There is also hematuria. His INR is very high.
a. A student wanted the warfarin to be stopped and low molecular weight heparin to be given instead. Is that right? b A student wanted to evaluate this patient for bladder cancer and urinary infection in view of the hematuria. Is this appropriate?
c. A student wanted to give an intramuscular injection of Vitamin K for this patient. Is there a problem here?

6. A 12 year old girl is on Inj. Mixtard insulin 10 units in the morning before breakfast and 16 units in the night before dinner. Her fasting plasma glucose is 6.8mmol/L but her glycosylated hemoglobin is always above 8 percent. What will you do to achieve target HbA1c values?

7. A 28 year old man presented with a short history of left sided chest pain that is increased on inspiration and relieved by leaning forward. Auscultation revealed a friction rub audible during both inspiration and expiration over the left sternal edge. His ECG showed ST elevation in most of the chest leads. A small pericardial effusion was detected on echocardiogram. His serum Troponin I was elevated. What is your diagnosis that explains all the clinical information given here?

8. While discussing precipitating causes of heart failure, arrhythmia was mentioned as one of those things that can precipitate heart failure. When asked to name some specific kinds of arrhythmia that can precipitate heart failure, a student mentioned atrial fibrillation and ventricular fibrillation. What is odd about this answer?

9. A patient with sick sinus syndrome presented with syncope. Explain the link between syncope and sick sinus syndrome.

10. A patient has end stage renal failure and she presented with shortness of breath. On examination, crepitations were detected in the lungs. The diagnosis by a student was: Fluid overload secondary to end stage renal failure. How should the diagnosis be written?

Dr Vela Menon, MD
Clinical Associate Professor of Medicine
International Medical University, Malaysia

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