I remember when I first had to deal with the Kayran. It was the most intense fight I ever had in the Witcher Series.
Staying to the sides is the easiest way I found. Left two first, then move over to the right and get it over with in seconds by using the Kayran Trap. Quen was my friend during that bout and I avoided the breath of detest whenever possible.
When the Kayran goes aggro, I found that running towards the ledge where you entered was the most effective avoidance method.
The second time I tried (Difficulty:Hard), I did it in one go. Made my day.
That awkward moment when you realise after 10+ attempts that only the Mutated (Red glowing) tentacles can be trapped by Yrden..