Percussion is used only after 48 hours when the secretions are very tenacious. So it is not used in the first 48 hours. Vibrations and shakings both can be used right after the cardiac surgery CABG along with other procedures like manual hyperinflation and modified postural drainage positionings (lying, half lying, alternate side lying) assisting in removal of secretions and suction manuever. These procedures are used in ICU during the IPPV while patient is on ventilator. When the ventilator is detached and patient is spontaneously breathing, the breathing exercises like ACBT, coughing and huffing and positioning in aiding the drainage and removal of secretions are useful.

References:

Cash's Texbook of Chest, heart and vascular disorders for Physiotherapist, 4th edition By Patricia A.Downie

Physiotherapy for respiratory and cardiac problems by Barbara A.Weber & Jenifer A.Pryor

Tidy's Physiotherapy, 12th edition by Ann Thomson, Alison Skinner & Joan Piercy