what are ventilator bundles?

It is a "bundle" of four actions done to a merciful on a ventilator to prevent problems, especially pneumonia.
From Florida Baycare
The "ventilator bundle" includes four components: elevation of the head of the bed to between 30 and 45 degree, daily "sedation vacation" and day after day assessment of readiness to extubate, peptic ulser disease (PUD) prophylaxis, and adjectives vein thrombosis (DVT) prophylaxis (unless contraindicated). ..