If you are looking to retrieve a list of dispatches for multiple "down" impacting dispatch types at once via API, instead of running each individually, you may consider the following steps in this example below:
Make a call to api/1.0/dispatchtypes with "impact=0", then save all the "code" fields in a comma-separated list. Like this: Code Red,Changeover,Cleaning
Then make a call to api/1.0/dispatches with "dispatchtypecode__in=(Code Red,Changeover,Cleaning)"
It's not in the official documentation, but it is the most efficient way to get dispatches of a specific impact in as few calls as possible.