Automatic defibrillators can be used in a seating position, BUT the use of them is generally supplemented by CPR. which cannot be given in this position. Automatic defibs are simple to use, the instructions are verbal when the lid is opened, and the voice is very clear and easy for anyone to follow. It is not good enough on it's own, however, and if it gives instruction,after auto assessment, 'shock not advised, continue with CPR', then there is a problem if the victim is still in the seat. Clever piece of kit tho'.