Baited breath
waiting with baited breath?
bated breath. bated, shortened from abated, temporarily halted. Hold your breath while you wait to see the outcome.
Breath: If someone has bated breath they are holding their breath with suspense or fear. This use of bated is about the only example left in the English language; abate is much more common. Both words come from the Old French "abatre", to "beat down" or "fell".