Something important to keeping him alive might burst at any moment.

They burst through the door one at a time in quick succession.

Then she burst into laughter at the expression on her father's face.

My head felt as if it would burst at any moment.

This meant it was almost certain to burst at some point.

"How long should that be so we burst at the enemy's feet?"

His head felt as if it could burst at any moment.

"And you fear they might burst free at any moment?"

The excitement alone would burst his heart at this rate.

My heart is bursting and breaking at the same time.