I am just starting to pick up NODE-RED so bear with me. I do have a coding background so I may be over analysing this a little bit 
I am using the Home Assistant module to trigger off some flows. I know that I can trigger off an entity state changing. I would like to only trigger if a certain attribute changes.
For example, wanting to watch just the temperature on a thermostat. I don't care about anything else except if that temperature gets to a critical level I want to set off an alert. (think pipes freezing) So, the trigger state goes off anything in the entity changing.. what I really want is just if the temperature drops below 45F.
So setting up the trigger on the thermostat, do i then have to wire that into a switch that checks the temperature that then goes into my alert notification if the attribute is below 45? I think that would work but seems a little complicated and I am wondering if I am missing something on the state trigger setup where i can limit to just that attribute changing instead of evaluating the temperature every time something on the thermostat changes.
If it helps here is the object coming out of the thermostat state change trigger:
