The relevant section of the Opening Statement seems to be this (see pages 19 and 20 of the Opening Statement):
24 I propose to call medical evidence to deal with the
25 state of Dr Kelly's physical health and to explain why
1 he had electrocardiogram electrode pads on his chest
2 when his body was discovered.
The answer to that question is very obvious. The paramedics attached them to David Kelly's chest.
The following is a rough description of how I interpet what the paramedics did to establish death by ECG analysis. It's based on past personal experience as an ambulanceman, and as a doctor in a Casualty department and Coronary Care Unit.
Why did the paramedics, apparently, use both paddles and electrodes.
As I understand what they did, they weren't able to get a good enough electrical contact using paddles to be sure if asystole was present or not.
Asystole is when there is essentially no electrical activity in the heart (at least as detected externally).
If the contact at the skin is poor or there is movement of the paddles, then you would expect artefact, meaning seeming electrical activity of the heart which actually arises, at least in part, from movement of the paddles where they contact the skin of the chest.
Another possible source of artefact is contact between the paddles and David Kelly's clothing.
To get a better contact self-adhesive electrodes can be attached. The contact would tend to improve, there would less (or no) artefact from movement against the skin or clothes and it would be much easier to be confident that asystole was established.
That's a quick and simple description. If there's detail I've missed please feel free to comment or ask about it.
I don't see any obvious cause for suspicion about this, but I'm willing to listen to any discrepancies that others may perceive.