I've noticed, running 4e, that PC hit point totals don't really matter. On a round by round basis, yeah -- if they're bloodied, or if they're low enough that a monster can take them down in one hit, that matters. But just paying attention to their hit point totals doesn't let me know how they're doing, what the pace of the fight is, or how close they are to defeat.
Because hit point levels go up and down a lot. Even at 1st level, they have a lot of healing. Whether they've used their second wind matters, how many players have used theirs matters, how much major healing the cleric has left matters. I'm used to keeping rough track of hit point totals, and the enemy hit point totals, to tell where the battle is headed, but running KotS I've had to adjust that strategy.
What I should do is make up a little battle tracker, where I can mark how many healing surges everyone has used throughout the day, who's used their healing surges, and what healing the cleric and the paladin (or the warlord, if they team had one) have used. Probably track dailies, too, because they're as important as surges in determining when the PCs should rest, and at least at this level they're a measure of the PCs abilities to get themselves out of trouble if things really go south.