There are various ways that an approval process can be set up in Flosum.
1) Create a field IsApproved on the Deployment object.
2) Create an approval process on the Deployment object
3) Update IsApproved= true in case of Approved.
4) Update IsApproved= false in case of Rejected.
5) In Deployment trigger, you can stop user if the IsApproved field does not equal to true on Deployment (or use a Validation Rule for the same).
For deploying the same patch to next org, we would need to reset the IsApproved field.