At level 50 you can have +200 hits from items. You can extend this by a further +200 via hit cap increase, making for a potential total of +400 hits. However, getting that +400 without sacrificing other stats is probably another matter. But worth doing if you can because the bigger your hit point pool the more chance a healer can save you once they've spotted you taking hits. As I'm sure you know, half the problem playing a healer is the moment you see someones health bar drop suddenly their death is probably already sealed. So you either need a sixth sense or hope that your group mates have a big enough health pool they can take a few hits in the time it takes you to respond.