i have seen adenocine given many times in SVT but never AF. if i patient is clinically unstable like your patient was they should of immediately went for more aggressive treatment RE cardio coversion you have to obviously way up other numerous factors like length of time patient in AF, new presentation etc.i wouldnt have give the adenosine for a drug that causes that amount of distress to a patient and wouldnt warrent its use un-nessacarily. however being a member ACLS team makes me clinicaly experienced to make those kinds of clinical decision in that kind of situation.
the problem possibly was the medical officer was unsure of the rythm as mentioned before it is hard to distinguish between and svt and a very rapid af. and in situations where the medical officer is unsure they go ahead an advise adenosine so they can slow down the rate long enough to confirm it. what they dont realise is if the actually take a deep breath and run a rythm strip they would be able to clarify the rythm without adenosine.
for a very rapid af if the patient was haemodynamically stable would be treated with a beat blockade or amiodarone infusion
if the patient has had a new presentation of AF and they are unsure for how long they have had it it is emensely dangerous to try and convert back to NSR therefore they must opt for rate control with say digoxin and either after and echo has confirmed no clotting in the chambers of the heart or at least six weeks post rate control can they warfrinise or DC convert. the risk of stroke if far far too high otherwise!!!
hope this helped
p.s i agree with dinith88.