How to access serviceRequests variable in action chain?

Summary:

How to access serviceRequests variable which is present in edit page which holds all service request related data in action chain.

Content (please ensure you mask any confidential information):

We have one standard object type variable serviceRequests on edit page which holds the data related to service request. I want to use that variable in one of my action chain.

I tried accessing that variable with service request field like below but it is showing error in action chain and due to that error my action chain is breaking.

$base.page.variables.serviceRequests.ProblemDescription

$page.variables.serviceRequests.ProblemDescription

If anyone aware of this then please share the approach with me.