The new text about Critical Condition states that only effects that revive someone from crit or suspend the death count can be used on them.
1) Can effects that increase the critical death count, such as preserve life, be used on someone in critical condition?
2) Encase with Ice says that it suspends someone's death count. Can that be used on someone in critical condition?
A character in the Critical State may not be targeted by effects other than ones that would bring them out of the Critical condition (by healing or killing them), or otherwise suspend the character's time in this state. Any existing active effects on the character are removed when the character enters the Critical condition.
Preserve life would not work - you need it on you before you enter the Critical State. Encase with Ice would, because it specifically states it suspends the death count.