Our ABG Toxicology conundrum

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