​So, back to last week’s ABG conundrum.
 
We were deliberately light with the information we gave you.
 
If you’re serious about sitting the fellowship, you need to be able to work through an ABG.
 
Calculating through this one you should have confirmed an isolated raised anion gap metabolic acidosis with appropriate respiratory compensation.
 
That’s great, as far as it goes…..(We’re not going to get into the CAT MUDPILES debate here – Luke has made his thoughts on this perfectly clear in his ABG book…..)
 
Even remembering there’s only 4 causes of a RAGMA, the numbers still aren’t very helpful in terms of giving a diagnosis. So, what other information can we glean?
 
Fortunately this is an exam, not the real world.
 
Let’s go to the information most people overlook – the questions. We asked:
 
1.What are the possible diagnoses?
2.Are there any further bloods you need to check?
3.Are there any other bedside tests you’d run?
4.Is there a rare antidote you might have to give this patient?
 
In particular, if the answers to any of questions 2,3 and 4 were ‘no’, then what were we asking them for??


The only possible conclusions are:
 
1.There are specific further tests we should run both on bloods and the bedside.
2.There is an unusual antidote to be given.
 
Then step back to the stem, and find the word ‘epileptic’. There’s no reason to put it in, unless it’s a pointer to the answer.
 
So, to revise for this week, you need to find:
-An anti-epileptic medication
-That causes a RAGMA without renal failure or ketosis.
-Whose pathophysiology can be measured with further blood tests.
-That requires an unusual antidote.
 
Good luck. If you know the answer feel free to take a punt on our facebook page.

This is the first of 3 weeks of posts. We’d love readers to play along and post up some answer suggestions on our facebook page (https://www.facebook.com/fellowshipexam).
 
A patient presents semiconscious after an unknown overdose. His medical history indicates a history of epilepsy, but there is no medical record of his medications listed. Initial bloods in resus are taken:
 
Venous gas:
pH                               7.12
pCO2                          26        mmHg
HCO3-                        12        mmol/L
Na+                             140      mmol/L
Cl-                                104      mmol/L
 
Creatinine                  60        umol/L
Urea                            4          mmol/L
 
BSL                              5.5       mmol/L
Ketones                      Not detected.
 
Lactate                       10        mmol/L
​
We’ve thrown this out in this week’s 5 point fellowship Friday to emphasise a couple of really important points about understanding the exam.
 
Work through the ABG and calculate the acid base disturbances.
 
Then ask yourself:
 
1.What are the possible diagnoses?
2.Are there any further bloods you need to check?
3.Are there any other bedside tests you’d run?
4.Is there a rare antidote you might have to give this patient?
 
*Every piece of information you have been given is fair game for your analysis.*
 
Share your  thoughts on our facebook page at https://www.facebook.com/fellowshipexam.
If you want to read an ABG/VBG in 5 steps go to the RESUS Page