Spread is the process of taking a successful implementation process from a pilot unit or pilot population and replicating that change or package of changes in other parts of the organization or other organizations. 
During implementation, teams learn valuable lessons necessary for successful spread, including key infrastructure issues, optimal sequencing of tasks, and working with people to help them adopt and adapt a change.
Spread efforts will benefit from the use of the PDSA cycle. Units adopting the change need to plan how best to adapt the change to their unit and to determine if the change resulted in the predicted improvement.
Example
If all 30 nurses on a pilot unit successfully implement a new medication reconciliation and order form, then spread would be replicating this change in all nursing units in the organization and assisting the units in adopting or adapting the change.